scummvm/scumm/gfx.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2001  Ludvig Strigeus
 * Copyright (C) 2001-2004 The ScummVM project
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header$
 *
 */

#include "stdafx.h"
#include "scumm/scumm.h"
#include "scumm/actor.h"
#include "scumm/charset.h"
#include "scumm/resource.h"
#include "scumm/usage_bits.h"

namespace Scumm {

struct StripTable {
	int offsets[160];
	int run[160];
	int color[160];
	int zoffsets[120];	// FIXME: Why only 120 here?
	int zrun[120];		// FIXME: Why only 120 here?
};

enum {
	kScrolltime = 500,  // ms scrolling is supposed to take
	kPictureDelay = 20
};

#define NUM_SHAKE_POSITIONS 8
static const int8 shake_positions[NUM_SHAKE_POSITIONS] = {
	0, 1 * 2, 2 * 2, 1 * 2, 0 * 2, 2 * 2, 3 * 2, 1 * 2
};

/**
 * The following structs define four basic fades/transitions used by 
 * transitionEffect(), each looking differently to the user.
 * Note that the stripTables contain strip numbers, and they assume
 * that the screen has 40 vertical strips (i.e. 320 pixel), and 25 horizontal
 * strips (i.e. 200 pixel). There is a hack in transitionEffect that
 * makes it work correctly in games which have a different screen height
 * (for example, 240 pixel), but nothing is done regarding the width, so this
 * code won't work correctly in COMI. Also, the number of iteration depends
 * on min(vertStrips, horizStrips}. So the 13 is derived from 25/2, rounded up.
 * And the 25 = min(25,40). Hence for Zak256 instead of 13 and 25, the values
 * 15 and 30 should be used, and for COMI probably 30 and 60. 
 */
struct TransitionEffect {
	byte numOfIterations;
	int8 deltaTable[16];	// four times l / t / r / b
	byte stripTable[16];	// ditto
};

#ifdef __PALM_OS__
static const TransitionEffect *transitionEffects;
#else
static const TransitionEffect transitionEffects[5] = {
	// Iris effect (looks like an opening/closing camera iris)
	{
		13,		// Number of iterations
		{
			1,  1, -1,  1,
		   -1,  1, -1, -1,
			1, -1, -1, -1,
			1,  1,  1, -1
		},
		{
			0,  0, 39,  0,
		   39,  0, 39, 24,
			0, 24, 39, 24,
			0,  0,  0, 24
		}
	},
	
	// Box wipe (a box expands from the upper-left corner to the lower-right corner)
	{
		25,		// Number of iterations
		{
			0,  1,  2,  1,
			2,  0,  2,  1,
			2,  0,  2,  1,
			0,  0,  0,  0
		},
		{
			0,  0,  0,  0,
			0,  0,  0,  0,
			1,  0,  1,  0,
		  255,  0,  0,  0
		}
	},
	
	// Box wipe (a box expands from the lower-right corner to the upper-left corner)
	{
		25,		// Number of iterations
		{
		   -2, -1,  0, -1,
		   -2, -1, -2,  0,
		   -2, -1, -2,  0,
			0,  0,  0,  0
		},
		{
		   39, 24, 39, 24,
		   39, 24, 39, 24,
		   38, 24, 38, 24,
		  255,  0,  0,  0
		}
	},
	
	// Inverse box wipe
	{
		25,		// Number of iterations
		{
			0, -1, -2, -1,
		   -2,  0, -2, -1,
		   -2,  0, -2, -1,
		    0,  0,  0,  0
		},
		{
			0, 24, 39, 24,
		   39,  0, 39, 24,
		   38,  0, 38, 24,
		  255,  0,  0,  0
		}
	},

	// Inverse iris effect, specially tailored for V1/V2 games
	{
		9,		// Number of iterations
		{
			-1, -1,  1, -1,
			-1,  1,  1,  1,
			-1, -1, -1,  1,
			 1, -1,  1,  1
		},
		{
			 7, 7, 32, 7,
			 7, 8, 32, 8,
			 7, 8,  7, 8,
			32, 7, 32, 8
		}
	}
};
#endif

static inline void copy8PixelsWithMasking(byte *dst, const byte *src, byte maskbits) {
	if (!(maskbits & 0x80))
		dst[0] = src[0];
	if (!(maskbits & 0x40))
		dst[1] = src[1];
	if (!(maskbits & 0x20))
		dst[2] = src[2];
	if (!(maskbits & 0x10))
		dst[3] = src[3];
	if (!(maskbits & 0x08))
		dst[4] = src[4];
	if (!(maskbits & 0x04))
		dst[5] = src[5];
	if (!(maskbits & 0x02))
		dst[6] = src[6];
	if (!(maskbits & 0x01))
		dst[7] = src[7];
}

static inline void clear8PixelsWithMasking(byte *dst, const byte color, byte maskbits) {
	if (!(maskbits & 0x80))
		dst[0] = color;
	if (!(maskbits & 0x40))
		dst[1] = color;
	if (!(maskbits & 0x20))
		dst[2] = color;
	if (!(maskbits & 0x10))
		dst[3] = color;
	if (!(maskbits & 0x08))
		dst[4] = color;
	if (!(maskbits & 0x04))
		dst[5] = color;
	if (!(maskbits & 0x02))
		dst[6] = color;
	if (!(maskbits & 0x01))
		dst[7] = color;
}

#pragma mark -
#pragma mark --- Virtual Screens ---
#pragma mark -



Gdi::Gdi(ScummEngine *vm) {
	memset(this, 0, sizeof(*this));
	_vm = vm;
	_roomPalette = vm->_roomPalette;
	if ((vm->_features & GF_AMIGA) && (vm->_version >= 4))
		_roomPalette += 16;
}

void ScummEngine::initScreens(int b, int h) {
	int i;

	for (i = 0; i < 3; i++) {
		nukeResource(rtBuffer, i + 1);
		nukeResource(rtBuffer, i + 5);
	}

	if (!getResourceAddress(rtBuffer, 4)) {
		// Since the size of screen 3 is fixed, there is no need to reallocate
		// it if its size changed.
		// Not sure what it is good for, though. I think it may have been used
		// in pre-V7 for the games messages (like 'Pause', Yes/No dialogs,
		// version display, etc.). I don't know about V7, maybe the same is the
		// case there. If so, we could probably just remove it completely.
		if (_version >= 7) {
			initVirtScreen(kUnkVirtScreen, 0, (_screenHeight / 2) - 10, _screenWidth, 13, false, false);
		} else {
			initVirtScreen(kUnkVirtScreen, 0, 80, _screenWidth, 13, false, false);
		}
	}
	initVirtScreen(kMainVirtScreen, 0, b, _screenWidth, h - b, true, true);
	initVirtScreen(kTextVirtScreen, 0, 0, _screenWidth, b, false, false);
	initVirtScreen(kVerbVirtScreen, 0, h, _screenWidth, _screenHeight - h, false, false);

	_screenB = b;
	_screenH = h;
}

void ScummEngine::initVirtScreen(VirtScreenNumber slot, int number, int top, int width, int height, bool twobufs,
													 bool scrollable) {
	VirtScreen *vs = &virtscr[slot];
	int size;

	assert(height >= 0);
	assert(slot >= 0 && slot < 4);

	if (_version >= 7) {
		if (slot == 0 && (_roomHeight != 0))
			height = _roomHeight;
	}

	vs->number = slot;
	vs->width = width;
	vs->topline = top;
	vs->height = height;
	vs->hasTwoBuffers = twobufs;
	vs->xstart = 0;
	vs->backBuf = NULL;

	size = vs->width * vs->height;
	if (scrollable) {
		// Allow enough spaces so that rooms can be up to 4 resp. 8 screens
		// wide. To achieve (horizontal!) scrolling, we use a neat trick:
		// only the offset into the screen buffer (xstart) is changed. That way
		// very little of the screen has to be redrawn, and we have a very low
		// memory overhead (namely for every pixel we want to scroll, we need
		// one additional byte in the buffer).
		if (_version >= 7) {
			size += width * 8;
		} else {
			size += width * 4;
		}
	}

	createResource(rtBuffer, slot + 1, size);
	vs->screenPtr = getResourceAddress(rtBuffer, slot + 1);
	memset(vs->screenPtr, 0, size);			// reset background

	if (twobufs) {
		vs->backBuf = createResource(rtBuffer, slot + 5, size);
	}

	if (slot != 3) {
		vs->setDirtyRange(0, height);
	}
}

VirtScreen *ScummEngine::findVirtScreen(int y) {
	VirtScreen *vs = virtscr;
	int i;

	for (i = 0; i < 3; i++, vs++) {
		if (y >= vs->topline && y < vs->topline + vs->height) {
			return vs;
		}
	}
	return NULL;
}

void ScummEngine::markRectAsDirty(VirtScreenNumber virt, int left, int right, int top, int bottom, int dirtybit) {
	VirtScreen *vs = &virtscr[virt];
	int lp, rp;

	if (left > right || top > bottom)
		return;
	if (top > vs->height || bottom < 0)
		return;

	if (top < 0)
		top = 0;
	if (bottom > vs->height)
		bottom = vs->height;

	if (virt == kMainVirtScreen && dirtybit) {
		lp = left / 8 + _screenStartStrip;
		if (lp < 0)
			lp = 0;
		if (_version >= 7) {
#ifdef V7_SMOOTH_SCROLLING_HACK
			rp = (right + vs->xstart) / 8;
#else
			rp = right / 8 + _screenStartStrip;
#endif
			if (rp > 409)
				rp = 409;
		} else {
			rp = right / 8 + _screenStartStrip;
			if (rp >= 200)
				rp = 200;
		}
		for (; lp <= rp; lp++)
			setGfxUsageBit(lp, dirtybit);
	}

	// The following code used to be in the separate method setVirtscreenDirty
	lp = left / 8;
	rp = right / 8;

	if ((lp >= gdi._numStrips) || (rp < 0))
		return;
	if (lp < 0)
		lp = 0;
	if (rp >= gdi._numStrips)
		rp = gdi._numStrips - 1;

	while (lp <= rp) {
		if (top < vs->tdirty[lp])
			vs->tdirty[lp] = top;
		if (bottom > vs->bdirty[lp])
			vs->bdirty[lp] = bottom;
		lp++;
	}
}

/**
 * Update all dirty screen areas. This method blits all of the internal engine
 * graphics to the actual display, as needed. In addition, the 'shaking'
 * code in the backend is controlled from here.
 */
void ScummEngine::drawDirtyScreenParts() {
	// Update verbs
	updateDirtyScreen(kVerbVirtScreen);
	
	// Update the conversation area (at the top of the screen)
	updateDirtyScreen(kTextVirtScreen);

	// Update game area ("stage")
	if (camera._last.x != camera._cur.x || (_features & GF_NEW_CAMERA && (camera._cur.y != camera._last.y))) {
		// Camera moved: redraw everything
		// Small side note: most of our GFX code relies on this identity:
		// gdi._numStrips * 8 == _screenWidth == vs->width
		VirtScreen *vs = &virtscr[kMainVirtScreen];
		gdi.drawStripToScreen(vs, 0, vs->width, 0, vs->height);
		vs->setDirtyRange(vs->height, 0);
	} else {
		updateDirtyScreen(kMainVirtScreen);
	}

	// Handle shaking
	if (_shakeEnabled) {
		_shakeFrame = (_shakeFrame + 1) % NUM_SHAKE_POSITIONS;
		_system->set_shake_pos(shake_positions[_shakeFrame]);
	} else if (!_shakeEnabled &&_shakeFrame != 0) {
		_shakeFrame = 0;
		_system->set_shake_pos(shake_positions[_shakeFrame]);
	}
}

void ScummEngine::updateDirtyScreen(VirtScreenNumber slot) {
	gdi.updateDirtyScreen(&virtscr[slot]);
}

/**
 * Blit the dirty data from the given VirtScreen to the display. If the camera moved,
 * a full blit is done, otherwise only the visible dirty areas are updated.
 */
void Gdi::updateDirtyScreen(VirtScreen *vs) {
	// Do nothing for unused virtual screens
	if (vs->height == 0)
		return;

	int i;
	int w = 8;
	int start = 0;

	for (i = 0; i < _numStrips; i++) {
		if (vs->bdirty[i]) {
			const int top = vs->tdirty[i];
			const int bottom = vs->bdirty[i];
			vs->tdirty[i] = vs->height;
			vs->bdirty[i] = 0;
			if (i != (_numStrips - 1) && vs->bdirty[i + 1] == bottom && vs->tdirty[i + 1] == top) {
				// Simple optimizations: if two or more neighbouring strips
				// form one bigger rectangle, coalesce them.
				w += 8;
				continue;
			}
			drawStripToScreen(vs, start * 8, w, top, bottom);
			w = 8;
		}
		start = i + 1;
	}
}

/**
 * Blit the specified rectangle from the given virtual screen to the display.
 * Note: t and b are in *virtual screen* coordinates, while x is relative to
 * the *real screen*. This is due to the way tdirty/vdirty work: they are
 * arrays which map 'strips' (sections of the real screen) to dirty areas as
 * specified by top/bottom coordinate in the virtual screen.
 */
void Gdi::drawStripToScreen(VirtScreen *vs, int x, int width, int top, int bottom) {
	byte *ptr;
	int height;

	if (bottom <= top)
		return;

	if (top >= vs->height)
		return;

	assert(top >= 0 && bottom <= vs->height);	// Paranoia checks

	height = bottom - top;
	// We don't clip height and width here, rather we rely on the backend to
	// perform any needed clipping.
	ptr = vs->screenPtr + (x + vs->xstart) + top * vs->width;
	_vm->_system->copyRectToScreen(ptr, vs->width, x, vs->topline + top - _vm->_screenTop, width, height);
}

#pragma mark -
#pragma mark --- Background buffers & charset mask ---
#pragma mark -


void ScummEngine::initBGBuffers(int height) {
	const byte *ptr;
	int size, itemsize, i;
	byte *room;

	if (_version >= 7) {
		// Resize main virtual screen in V7 games. This is necessary
		// because in V7, rooms may be higher than one screen, so we have
		// to accomodate for that.
		initVirtScreen(kMainVirtScreen, 0, virtscr[0].topline, _screenWidth, height, 1, 1);
	}

	if (_heversion >= 70)
		room = getResourceAddress(rtRoomStart, _roomResource);
	else
		room = getResourceAddress(rtRoom, _roomResource);

	if (_version <= 3) {
		gdi._numZBuffer = 2;
	} else if (_features & GF_SMALL_HEADER) {
		int off;
		ptr = findResourceData(MKID('SMAP'), room);
		gdi._numZBuffer = 0;

		if (_gameId == GID_MONKEY_EGA || _gameId == GID_PASS)
			off = READ_LE_UINT16(ptr);
		else
			off = READ_LE_UINT32(ptr);

		while (off && gdi._numZBuffer < 4) {
			gdi._numZBuffer++;
			ptr += off;
			off = READ_LE_UINT16(ptr);
		}
	} else if (_version == 8) {
		// in V8 there is no RMIH and num z buffers is in RMHD
		ptr = findResource(MKID('RMHD'), room);
		gdi._numZBuffer = READ_LE_UINT32(ptr + 24) + 1;
	} else if (_heversion >= 70) {
		ptr = findResource(MKID('RMIH'), room);
		gdi._numZBuffer = READ_LE_UINT16(ptr + 8) + 1;
	} else {
		ptr = findResource(MKID('RMIH'), findResource(MKID('RMIM'), room));
		gdi._numZBuffer = READ_LE_UINT16(ptr + 8) + 1;
	}
	assert(gdi._numZBuffer >= 1 && gdi._numZBuffer <= 8);

	if (_version >= 7)
		itemsize = (_roomHeight + 10) * gdi._numStrips;
	else
		itemsize = (_roomHeight + 4) * gdi._numStrips;


	size = itemsize * gdi._numZBuffer;
	memset(createResource(rtBuffer, 9, size), 0, size);

	for (i = 0; i < (int)ARRAYSIZE(gdi._imgBufOffs); i++) {
		if (i < gdi._numZBuffer)
			gdi._imgBufOffs[i] = i * itemsize;
		else
			gdi._imgBufOffs[i] = (gdi._numZBuffer - 1) * itemsize;
	}
}

/**
 * Redraw background as needed, i.e. the left/right sides if scrolling took place etc.
 * Note that this only updated the virtual screen, not the actual display.
 */
void ScummEngine::redrawBGAreas() {
	int i;
	int val;
	int diff;

	if (!(_features & GF_NEW_CAMERA))
		if (camera._cur.x != camera._last.x && _charset->_hasMask && (_version > 3 && _gameId != GID_PASS))
			stopTalk();

	val = 0;

	// Redraw parts of the background which are marked as dirty.
	if (!_fullRedraw && _BgNeedsRedraw) {
		for (i = 0; i != gdi._numStrips; i++) {
			if (testGfxUsageBit(_screenStartStrip + i, USAGE_BIT_DIRTY)) {
				redrawBGStrip(i, 1);
			}
		}
	}

	if (_features & GF_NEW_CAMERA) {
		diff = camera._cur.x / 8 - camera._last.x / 8;
		if (_fullRedraw == 0 && diff == 1) {
			val = 2;
			redrawBGStrip(gdi._numStrips - 1, 1);
		} else if (_fullRedraw == 0 && diff == -1) {
			val = 1;
			redrawBGStrip(0, 1);
		} else if (_fullRedraw != 0 || diff != 0) {
			_BgNeedsRedraw = false;
			redrawBGStrip(0, gdi._numStrips);
		}
	} else {
		if (_fullRedraw == 0 && camera._cur.x - camera._last.x == 8) {
			val = 2;
			redrawBGStrip(gdi._numStrips - 1, 1);
		} else if (_fullRedraw == 0 && camera._cur.x - camera._last.x == -8) {
			val = 1;
			redrawBGStrip(0, 1);
		} else if (_fullRedraw != 0 || camera._cur.x != camera._last.x) {
			_BgNeedsRedraw = false;
			_flashlight.isDrawn = false;
			redrawBGStrip(0, gdi._numStrips);
		}
	}

	drawRoomObjects(val);
	_BgNeedsRedraw = false;
}

void ScummEngine::redrawBGStrip(int start, int num) {
	byte *room;

	int s = _screenStartStrip + start;

	assert(s >= 0 && (size_t) s < sizeof(gfxUsageBits) / (3 * sizeof(gfxUsageBits[0])));

	for (int i = 0; i < num; i++)
		setGfxUsageBit(s + i, USAGE_BIT_DIRTY);

	if (_version == 1) {
		gdi._C64ObjectMode = false;
	}
	if (_heversion >= 70)
		room = getResourceAddress(rtRoomStart, _roomResource);
	else
		room = getResourceAddress(rtRoom, _roomResource);

	gdi.drawBitmap(room + _IM00_offs,
					&virtscr[0], s, 0, _roomWidth, virtscr[0].height, s, num, 0, _roomStrips);
}

void ScummEngine::restoreBG(Common::Rect rect, byte backColor) {
	VirtScreen *vs;
	byte *screenBuf;

	if (rect.top < 0)
		rect.top = 0;
	if (rect.left >= rect.right || rect.top >= rect.bottom)
		return;

	if ((vs = findVirtScreen(rect.top)) == NULL)
		return;

	if (rect.left > vs->width)
		return;

	// Convert 'rect' to local (virtual screen) coordinates
	rect.top -= vs->topline;
	rect.bottom -= vs->topline;

	rect.clip(vs->width, vs->height);

	markRectAsDirty(vs->number, rect, USAGE_BIT_RESTORED);

	const int offset = rect.top * vs->width + vs->xstart + rect.left;
	screenBuf = vs->screenPtr + offset;

	int height = rect.height();
	int width = rect.width();
	
	if (!height)
		return;

	if (vs->hasTwoBuffers && _currentRoom != 0 && isLightOn()) {
		blit(screenBuf, vs->backBuf + offset, width, height);
		if (vs->number == kMainVirtScreen && _charset->_hasMask) {
			// Note: At first sight it may look as if this could
			// be optimized to (rect.right - rect.left) / 8 and
			// thus to width / 8, but that's not the case since
			// we are dealing with integer math here.
			const int mask_width = ((rect.right + 7) / 8) - (rect.left / 8);

			byte *mask = getMaskBuffer(rect.left, rect.top, 0);

			do {
				memset(mask, 0, mask_width);
				mask += gdi._numStrips;
			} while (--height);
		}
	} else {
		while (height--) {
			memset(screenBuf, backColor, width);
			screenBuf += vs->width;
		}
	}
}

void CharsetRenderer::restoreCharsetBg() {
	_nextLeft = _vm->_string[0].xpos;
	_nextTop = _vm->_string[0].ypos;

	if (_hasMask) {
		_hasMask = false;
		_str.left = -1;
		_left = -1;

		// Restore background on the whole text area. This code is based on
		// restoreBG(), but was changed to only restore those parts which are
		// currently covered by the charset mask.

		// Loop over first three virtual screens
		VirtScreen *vs = &_vm->virtscr[_textScreenID];
		
		if (!vs->height)
			return;

		_vm->markRectAsDirty(vs->number, Common::Rect(vs->width, vs->height), USAGE_BIT_RESTORED);
	
		byte *screenBuf = vs->screenPtr + vs->xstart;

		if (vs->hasTwoBuffers && _vm->_currentRoom != 0 && _vm->isLightOn()) {
			const byte *backBuf = vs->backBuf + vs->xstart;

			if (vs->number == kMainVirtScreen) {
				// Restore from back buffer, but only those parts which are
				// currently covered by the charset mask. In addition, we
				// clean out the charset mask

				const int mask_width = _vm->gdi._numStrips;
				byte *mask = _vm->getMaskBuffer(0, 0, 0);
				assert(vs->width == 8 * _vm->gdi._numStrips);
				
				int height = vs->height;
				while (height--) {
					for (int w = 0; w < mask_width; ++w) {
						const byte maskbits = mask[w];
						if (maskbits) {
							copy8PixelsWithMasking(screenBuf + w*8, backBuf + w*8, ~maskbits);
							mask[w] = 0;
						}
					}
					screenBuf += vs->width;
					backBuf += vs->width;
					mask += _vm->gdi._numStrips;
				}
			} else {
				// Restore from back buffer
				_vm->blit(screenBuf, backBuf, vs->width, vs->height);
			}
		} else {
			// Clear area
			memset(screenBuf, 0, vs->height * vs->width);
		}
	}
}

void CharsetRenderer::clearCharsetMask() {
	memset(_vm->getResourceAddress(rtBuffer, 9), 0, _vm->gdi._imgBufOffs[1]);
}

bool CharsetRenderer::hasCharsetMask(int left, int top, int right, int bottom) {
	return _hasMask;
}

byte *ScummEngine::getMaskBuffer(int x, int y, int z) {
	return gdi.getMaskBuffer(x / 8, y, z) + _screenStartStrip;
}

byte *Gdi::getMaskBuffer(int x, int y, int z) {
	return _vm->getResourceAddress(rtBuffer, 9)
			+ x + y * _numStrips + _imgBufOffs[z];
}


#pragma mark -
#pragma mark --- Misc ---
#pragma mark -

void ScummEngine::blit(byte *dst, const byte *src, int w, int h) {
	assert(h > 0);
	assert(src != NULL);
	assert(dst != NULL);
	
	// TODO: This function currently always assumes that srcPitch == dstPitch
	// and furthermore that both equal _screenWidth.

	if (w==_screenWidth)
		memcpy (dst, src, w*h);
	else
	{
		do {
			memcpy(dst, src, w);
			dst += _screenWidth;
			src += _screenWidth;
		} while (--h);
	}
}

void ScummEngine::drawBox(int x, int y, int x2, int y2, int color) {
	int width, height;
	VirtScreen *vs;
	byte *backbuff, *bgbuff;

	if ((vs = findVirtScreen(y)) == NULL)
		return;

	if (x > x2)
		SWAP(x, x2);

	if (y > y2)
		SWAP(y, y2);

	x2++;
	y2++;

	// Adjust for the topline of the VirtScreen
	y -= vs->topline;
	y2 -= vs->topline;
	
	// Clip the coordinates
	if (x < 0)
		x = 0;
	else if (x >= vs->width)
		return;

	if (x2 < 0)
		return;
	else if (x2 > vs->width)
		x2 = vs->width;

	if (y < 0)
		y = 0;
	else if (y > vs->height)
		return;

	if (y2 < 0)
		return;
	else if (y2 > vs->height)
		y2 = vs->height;
	
	markRectAsDirty(vs->number, x, x2, y, y2);

	backbuff = vs->screenPtr + vs->xstart + y * vs->width + x;

	width = x2 - x;
	height = y2 - y;
	if (color == -1) {
		if (vs->number != kMainVirtScreen)
			error("can only copy bg to main window");
		bgbuff = vs->backBuf + vs->xstart + y * vs->width + x;
		blit(backbuff, bgbuff, width, height);
	} else {
		while (height--) {
			memset(backbuff, color, width);
			backbuff += vs->width;
		}
	}
}

void ScummEngine::drawFlashlight() {
	int i, j, offset, x, y;
	VirtScreen *vs = &virtscr[kMainVirtScreen];

	// Remove the flash light first if it was previously drawn
	if (_flashlight.isDrawn) {
		markRectAsDirty(kMainVirtScreen, _flashlight.x, _flashlight.x + _flashlight.w,
										_flashlight.y, _flashlight.y + _flashlight.h, USAGE_BIT_DIRTY);
		
		if (_flashlight.buffer) {
			i = _flashlight.h;
			do {
				memset(_flashlight.buffer, 0, _flashlight.w);
				_flashlight.buffer += vs->width;
			} while (--i);
		}
		_flashlight.isDrawn = false;
	}

	if (_flashlight.xStrips == 0 || _flashlight.yStrips == 0)
		return;

	// Calculate the area of the flashlight
	if (_gameId == GID_ZAK256 || _version <= 2) {
		x = _mouse.x + vs->xstart;
		y = _mouse.y - vs->topline;
	} else {
		Actor *a = derefActor(VAR(VAR_EGO), "drawFlashlight");
		x = a->_pos.x;
		y = a->_pos.y;
	}
	_flashlight.w = _flashlight.xStrips * 8;
	_flashlight.h = _flashlight.yStrips * 8;
	_flashlight.x = x - _flashlight.w / 2 - _screenStartStrip * 8;
	_flashlight.y = y - _flashlight.h / 2;

	if (_gameId == GID_LOOM || _gameId == GID_LOOM256)
		_flashlight.y -= 12;

	// Clip the flashlight at the borders
	if (_flashlight.x < 0)
		_flashlight.x = 0;
	else if (_flashlight.x + _flashlight.w > gdi._numStrips * 8)
		_flashlight.x = gdi._numStrips * 8 - _flashlight.w;
	if (_flashlight.y < 0)
		_flashlight.y = 0;
	else if (_flashlight.y + _flashlight.h> vs->height)
		_flashlight.y = vs->height - _flashlight.h;

	// Redraw any actors "under" the flashlight
	for (i = _flashlight.x / 8; i < (_flashlight.x + _flashlight.w) / 8; i++) {
		assert(0 <= i && i < gdi._numStrips);
		setGfxUsageBit(_screenStartStrip + i, USAGE_BIT_DIRTY);
		vs->tdirty[i] = 0;
		vs->bdirty[i] = vs->height;
	}

	byte *bgbak;
	offset = _flashlight.y * vs->width + vs->xstart + _flashlight.x;
	_flashlight.buffer = vs->screenPtr + offset;
	bgbak = vs->backBuf + offset;

	blit(_flashlight.buffer, bgbak, _flashlight.w, _flashlight.h);

	// Round the corners. To do so, we simply hard-code a set of nicely
	// rounded corners.
	static const int corner_data[] = { 8, 6, 4, 3, 2, 2, 1, 1 };
	int minrow = 0;
	int maxcol = _flashlight.w - 1;
	int maxrow = (_flashlight.h - 1) * vs->width;

	for (i = 0; i < 8; i++, minrow += vs->width, maxrow -= vs->width) {
		int d = corner_data[i];

		for (j = 0; j < d; j++) {
			_flashlight.buffer[minrow + j] = 0;
			_flashlight.buffer[minrow + maxcol - j] = 0;
			_flashlight.buffer[maxrow + j] = 0;
			_flashlight.buffer[maxrow + maxcol - j] = 0;
		}
	}
	
	_flashlight.isDrawn = true;
}

bool ScummEngine::isLightOn() const {
	return (VAR_CURRENT_LIGHTS == 0xFF) || (VAR(VAR_CURRENT_LIGHTS) & LIGHTMODE_screen);
}

#pragma mark -
#pragma mark --- Image drawing ---
#pragma mark -

/**
 * Draw a bitmap onto a virtual screen. This is main drawing method for room backgrounds
 * and objects, used throughout all SCUMM versions.
 */
void Gdi::drawBitmap(const byte *ptr, VirtScreen *vs, int x, int y, const int width, const int height,
					int stripnr, int numstrip, byte flag, StripTable *table) {
	assert(ptr);
	assert(height > 0);
	byte *backbuff_ptr, *bgbak_ptr;
	const byte *smap_ptr;
	const byte *z_plane_ptr;
	byte *mask_ptr;

	int i;
	const byte *zplane_list[9];

	int bottom;
	int numzbuf;
	int sx;
	bool lightsOn;
	bool useOrDecompress = false;

	// Check whether lights are turned on or not
	lightsOn = _vm->isLightOn();

	CHECK_HEAP;
	if (_vm->_features & GF_SMALL_HEADER)
		smap_ptr = ptr;
	else if (_vm->_version == 8)
		smap_ptr = ptr;
	else
		smap_ptr = _vm->findResource(MKID('SMAP'), ptr);

	// newer Humongous titles use this
	if (smap_ptr == NULL)
		smap_ptr = _vm->findResource(MKID('BMAP'), ptr);

	assert(smap_ptr);

	zplane_list[0] = smap_ptr;

	if (_zbufferDisabled)
		numzbuf = 0;
	else if (_numZBuffer <= 1 || (_vm->_version <= 2))
		numzbuf = _numZBuffer;
	else {
		numzbuf = _numZBuffer;
		assert(numzbuf <= ARRAYSIZE(zplane_list));
		
		if (_vm->_features & GF_SMALL_HEADER) {
			if (_vm->_features & GF_16COLOR)
				zplane_list[1] = smap_ptr + READ_LE_UINT16(smap_ptr);
			else
				zplane_list[1] = smap_ptr + READ_LE_UINT32(smap_ptr);
			if (_vm->_features & GF_OLD256) {
				if (0 == READ_LE_UINT32(zplane_list[1]))
					zplane_list[1] = 0;
			}
			for (i = 2; i < numzbuf; i++) {
				zplane_list[i] = zplane_list[i-1] + READ_LE_UINT16(zplane_list[i-1]);
			}
		} else if (_vm->_version == 8) {
			// Find the OFFS chunk of the ZPLN chunk
			const byte *zplnOffsChunkStart = smap_ptr + READ_BE_UINT32(smap_ptr + 12) + 24;
			
			// Each ZPLN contains a WRAP chunk, which has (as always) an OFFS subchunk pointing
			// at ZSTR chunks. These once more contain a WRAP chunk which contains nothing but
			// an OFFS chunk. The content of this OFFS chunk contains the offsets to the
			// Z-planes.
			// We do not directly make use of this, but rather hard code offsets (like we do
			// for all other Scumm-versions, too). Clearly this is a bit hackish, but works
			// well enough, and there is no reason to assume that there are any cases where it
			// might fail. Still, doing this properly would have the advantage of catching
			// invalid/damaged data files, and allow us to exit gracefully instead of segfaulting.
			for (i = 1; i < numzbuf; i++) {
				zplane_list[i] = zplnOffsChunkStart + READ_LE_UINT32(zplnOffsChunkStart + 4 + i*4) + 16;
			}
		} else {
			const uint32 zplane_tags[] = {
				MKID('ZP00'),
				MKID('ZP01'),
				MKID('ZP02'),
				MKID('ZP03'),
				MKID('ZP04')
			};
			
			for (i = 1; i < numzbuf; i++) {
				zplane_list[i] = _vm->findResource(zplane_tags[i], ptr);
			}
		}
	}
	
	if (_vm->_version == 8) {	
		// A small hack to skip to the BSTR->WRAP->OFFS chunk. Note: order matters, we do this
		// *after* the Z buffer code because that assumes' the orginal value of smap_ptr. 
		smap_ptr += 24;
	}

	bottom = y + height;
	if (bottom > vs->height) {
		warning("Gdi::drawBitmap, strip drawn to %d below window bottom %d", bottom, vs->height);
	}

	_vertStripNextInc = height * vs->width - 1;

	sx = x - vs->xstart / 8;

	//
	// Since V3, all graphics data was encoded in strips, which is very efficient
	// for redrawing only parts of the screen. However, V2 is different: here
	// the whole graphics are encoded as one big chunk. That makes it rather
	// dificult to draw only parts of a room/object. We handle the V2 graphics
	// differently from all other (newer) graphic formats for this reason.
	//
	if (_vm->_version == 2) {
		
		if (vs->hasTwoBuffers)
			bgbak_ptr = vs->backBuf + (y * _numStrips + x) * 8;
		else
			bgbak_ptr = vs->screenPtr + (y * _numStrips + x) * 8;

		mask_ptr = getMaskBuffer(x, y, 1);

		const int left = (stripnr * 8);
		const int right = left + (numstrip * 8);
		byte *dst = bgbak_ptr;
		const byte *src;
		byte color, data = 0;
		int run;
		bool dither = false;
		byte dither_table[128];
		byte *ptr_dither_table;
		memset(dither_table, 0, sizeof(dither_table));
		int theX, theY, maxX;
		
		if (table) {
			run = table->run[stripnr];
			color = table->color[stripnr];
			src = smap_ptr + table->offsets[stripnr];
			theX = left;
			maxX = right;
		} else {
			run = 1;
			color = 0;
			src = smap_ptr;
			theX = 0;
			maxX = width;
		}
		
		// Draw image data. To do this, we decode the full RLE graphics data,
		// but only draw those parts we actually want to display.
		assert(height <= 128);
		for (; theX < maxX; theX++) {
			ptr_dither_table = dither_table;
			for (theY = 0; theY < height; theY++) {
				if (--run == 0) {
					data = *src++;
					if (data & 0x80) {
						run = data & 0x7f;
						dither = true;
					} else {
						run = data >> 4;
						dither = false;
					}
					color = _roomPalette[data & 0x0f];
					if (run == 0) {
						run = *src++;
					}
				}
				if (!dither) {
					*ptr_dither_table = color;
				}
				if (left <= theX && theX < right) {
					*dst = *ptr_dither_table++;
					dst += vs->width;
				}
			}
			if (left <= theX && theX < right) {
				dst -= _vertStripNextInc;
			}
		}


		// Draw mask (zplane) data
		theY = 0;

		if (table) {
			src = smap_ptr + table->zoffsets[stripnr];
			run = table->zrun[stripnr];
			theX = left;
		} else {
			run = *src++;
			theX = 0;
		}
		while (theX < right) {
			const byte runFlag = run & 0x80;
			if (runFlag) {
				run &= 0x7f;
				data = *src++;
			}
			do {
				if (!runFlag)
					data = *src++;
				
				if (left <= theX) {
					*mask_ptr = data;
					mask_ptr += _numStrips;
				}
				theY++;
				if (theY >= height) {
					if (left <= theX) {
						mask_ptr -= _numStrips * height - 1;
					}
					theY = 0;
					theX += 8;
					if (theX >= right)
						break;
				}
			} while (--run);
			run = *src++;
		}
	}

	while (numstrip--) {
		CHECK_HEAP;

		if (sx < 0)
			goto next_iter;

		if (sx >= _numStrips)
			return;

		if (y < vs->tdirty[sx])
			vs->tdirty[sx] = y;

		if (bottom > vs->bdirty[sx])
			vs->bdirty[sx] = bottom;

		backbuff_ptr = vs->screenPtr + (y * _numStrips + x) * 8;
		if (vs->hasTwoBuffers)
			bgbak_ptr = vs->backBuf + (y * _numStrips + x) * 8;
		else
			bgbak_ptr = backbuff_ptr;

		if (_vm->_version == 1) {
			if (_C64ObjectMode)
				drawStripC64Object(bgbak_ptr, stripnr, width, height);
			else
				drawStripC64Background(bgbak_ptr, stripnr, height);
		} else if (_vm->_version > 2) {
			if (_vm->_features & GF_16COLOR) {
				decodeStripEGA(bgbak_ptr, smap_ptr + READ_LE_UINT16(smap_ptr + stripnr * 2 + 2), height);
			} else if (_vm->_features & GF_SMALL_HEADER) {
				useOrDecompress = decompressBitmap(bgbak_ptr, smap_ptr + READ_LE_UINT32(smap_ptr + stripnr * 4 + 4), height);
			} else {
				useOrDecompress = decompressBitmap(bgbak_ptr, smap_ptr + READ_LE_UINT32(smap_ptr + stripnr * 4 + 8), height);
			}
		}

		mask_ptr = getMaskBuffer(x, y);

		CHECK_HEAP;
		if (vs->hasTwoBuffers) {
			if (_vm->_charset->hasCharsetMask(sx * 8, y, (sx + 1) * 8, bottom)) {
				if (flag & dbClear || !lightsOn)
					clear8ColWithMasking(backbuff_ptr, height, mask_ptr);
				else
					draw8ColWithMasking(backbuff_ptr, bgbak_ptr, height, mask_ptr);
			} else {
				if (flag & dbClear || !lightsOn)
					clear8Col(backbuff_ptr, height);
				else
					draw8Col(backbuff_ptr, bgbak_ptr, height);
			}
		}
		CHECK_HEAP;

		if (_vm->_version == 1) {
			mask_ptr = getMaskBuffer(x, y, 1);
			drawStripC64Mask(mask_ptr, stripnr, width, height);
		} else if (_vm->_version == 2) {
			// Do nothing here for V2 games - zplane was handled already.
		} else if (flag & dbDrawMaskOnAll) {
			// Sam & Max uses dbDrawMaskOnAll for things like the inventory
			// box and the speech icons. While these objects only have one
			// mask, it should be applied to all the Z-planes in the room,
			// i.e. they should mask every actor.
			//
			// This flag used to be called dbDrawMaskOnBoth, and all it
			// would do was to mask Z-plane 0. (Z-plane 1 would also be
			// masked, because what is now the else-clause used to be run
			// always.) While this seems to be the only way there is to
			// mask Z-plane 0, this wasn't good enough since actors in
			// Z-planes >= 2 would not be masked.
			//
			// The flag is also used by The Dig and Full Throttle, but I
			// don't know what for. At the time of writing, these games
			// are still too unstable for me to investigate.

			if (_vm->_version == 8)
				z_plane_ptr = zplane_list[1] + READ_LE_UINT32(zplane_list[1] + stripnr * 4 + 8);
			else
				z_plane_ptr = zplane_list[1] + READ_LE_UINT16(zplane_list[1] + stripnr * 2 + 8);
			for (i = 0; i < numzbuf; i++) {
				mask_ptr = getMaskBuffer(x, y, i);
				if (useOrDecompress && (flag & dbAllowMaskOr))
					decompressMaskImgOr(mask_ptr, z_plane_ptr, height);
				else
					decompressMaskImg(mask_ptr, z_plane_ptr, height);
			}
		} else {
			for (i = 1; i < numzbuf; i++) {
				uint32 offs;

				if (!zplane_list[i])
					continue;

				if (_vm->_features & GF_OLD_BUNDLE)
					offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2);
				else if (_vm->_features & GF_OLD256)
					offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 4);
				else if (_vm->_features & GF_SMALL_HEADER)
					offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 2);
				else if (_vm->_version == 8)
					offs = READ_LE_UINT32(zplane_list[i] + stripnr * 4 + 8);
				else
					offs = READ_LE_UINT16(zplane_list[i] + stripnr * 2 + 8);

				mask_ptr = getMaskBuffer(x, y, i);

				if (offs) {
					z_plane_ptr = zplane_list[i] + offs;

					if (useOrDecompress && (flag & dbAllowMaskOr)) {
						decompressMaskImgOr(mask_ptr, z_plane_ptr, height);
					} else {
						decompressMaskImg(mask_ptr, z_plane_ptr, height);
					}

				} else {
					if (!(useOrDecompress && (flag & dbAllowMaskOr)))
						for (int h = 0; h < height; h++)
							mask_ptr[h * _numStrips] = 0;
					// FIXME: needs better abstraction
				}
			}
		}
		
#if 0
		// HACK: blit mask(s) onto normal screen. Useful to debug masking 
		for (i = 0; i < numzbuf; i++) {
			mask_ptr = getMaskBuffer(x, y, i);
			byte *dst = backbuff_ptr;
			byte *dst2 = bgbak_ptr;
			for (int h = 0; h < height; h++) {
				int maskbits = *mask_ptr;
				for (int j = 0; j < 8; j++) {
					if (maskbits & 0x80)
						dst[j] = dst2[j] = 12+i;
					maskbits <<= 1;
				}
				dst += vs->width;
				dst2 += vs->width;
				mask_ptr += _numStrips;
			}
		}
#endif

next_iter:
		CHECK_HEAP;
		x++;
		sx++;
		stripnr++;
	}
}

/**
 * Reset the background behind an actor or blast object.
 */
void Gdi::resetBackground(int top, int bottom, int strip) {
	VirtScreen *vs = &_vm->virtscr[0];
	byte *backbuff_ptr, *bgbak_ptr;
	int offs, numLinesToProcess;

	assert(0 <= strip && strip < _numStrips);

	if (top < vs->tdirty[strip])
		vs->tdirty[strip] = top;

	if (bottom > vs->bdirty[strip])
		vs->bdirty[strip] = bottom;

	offs = top * vs->width + vs->xstart + strip * 8;
	byte *mask_ptr = _vm->getMaskBuffer(strip * 8, top, 0);
	bgbak_ptr = vs->backBuf + offs;
	backbuff_ptr = vs->screenPtr + offs;

	numLinesToProcess = bottom - top;
	if (numLinesToProcess) {
		if (_vm->isLightOn()) {
			if (_vm->_charset->hasCharsetMask(strip * 8, top, (strip + 1) * 8, bottom))
				draw8ColWithMasking(backbuff_ptr, bgbak_ptr, numLinesToProcess, mask_ptr);
			else
				draw8Col(backbuff_ptr, bgbak_ptr, numLinesToProcess);
		} else {
			clear8Col(backbuff_ptr, numLinesToProcess);
		}
	}
}

/**
 * Create and fill a table with offsets to the graphic and mask strips in the
 * given V2 EGA bitmap.
 * @param src		the V2 EGA bitmap
 * @param width		the width of the bitmap
 * @param height	the height of the bitmap
 * @param table		the strip table to fill
 * @return filled strip table
 */
StripTable *Gdi::generateStripTable(const byte *src, int width, int height, StripTable *table) {

	// If no strip table was given to use, allocate a new one
	if (table == 0)
		table = (StripTable *)calloc(1, sizeof(StripTable));

	const byte *bitmapStart = src;
	byte color = 0, data = 0;
	int x, y, length = 0;
	byte run = 1;

	// Decode the graphics strips, and memorize the run/color values
	// as well as the byte offset.
	for (x = 0 ; x < width; x++) {

		if ((x % 8) == 0) {
			assert(x / 8 < 160);
			table->run[x / 8] = run;
			table->color[x / 8] = color;
			table->offsets[x / 8] = src - bitmapStart;
		}

		for (y = 0; y < height; y++) {
			if (--run == 0) {
				data = *src++;
				if (data & 0x80) {
					run = data & 0x7f;
				} else {
					run = data >> 4;
				}
				if (run == 0) {
					run = *src++;
				}
				color = data & 0x0f;
			}
		}
	}

	// The mask data follows immediately after the graphics.
	x = 0;
	y = height;
	width /= 8;
	
	for (;;) {
		length = *src++;
		const byte runFlag = length & 0x80;
		if (runFlag) {
			length &= 0x7f;
			data = *src++;
		}
		do {
			if (!runFlag)
				data = *src++;
			if (y == height) {
				assert(x < 120);
				table->zoffsets[x] = src - bitmapStart - 1;
				table->zrun[x] = length | runFlag;
			}
			if (--y == 0) {
				if (--width == 0)
					return table;
				x++;
				y = height;
			}
		} while (--length);
	}

	return table;
}

void Gdi::drawStripC64Background(byte *dst, int stripnr, int height) {
	int charIdx;
	height /= 8;
	for (int y = 0; y < height; y++) {
		_C64Colors[3] = (_C64ColorMap[y + stripnr * height] & 7);
		// Check for room color change in V1 zak
		if (_roomPalette[0] == 255) {
			_C64Colors[2] = _roomPalette[2];
			_C64Colors[1] = _roomPalette[1];
		}

		charIdx = _C64PicMap[y + stripnr * height] * 8;
		for (int i = 0; i < 8; i++) {
			byte c = _C64CharMap[charIdx + i];
			dst[0] = dst[1] = _C64Colors[(c >> 6) & 3];
			dst[2] = dst[3] = _C64Colors[(c >> 4) & 3];
			dst[4] = dst[5] = _C64Colors[(c >> 2) & 3];
			dst[6] = dst[7] = _C64Colors[(c >> 0) & 3];
			dst += _vm->_screenWidth;
		}
	}
}

void Gdi::drawStripC64Object(byte *dst, int stripnr, int width, int height) {
	int charIdx;
	height /= 8;
	width /= 8;
	for (int y = 0; y < height; y++) {
		_C64Colors[3] = (_C64ObjectMap[(y + height) * width + stripnr] & 7);
		charIdx = _C64ObjectMap[y * width + stripnr] * 8;
		for (int i = 0; i < 8; i++) {
			byte c = _C64CharMap[charIdx + i];
			dst[0] = dst[1] = _C64Colors[(c >> 6) & 3];
			dst[2] = dst[3] = _C64Colors[(c >> 4) & 3];
			dst[4] = dst[5] = _C64Colors[(c >> 2) & 3];
			dst[6] = dst[7] = _C64Colors[(c >> 0) & 3];
			dst += _vm->_screenWidth;
		}
	}
}

void Gdi::drawStripC64Mask(byte *dst, int stripnr, int width, int height) {
	int maskIdx;
	height /= 8;
	width /= 8;
	for (int y = 0; y < height; y++) {
		if (_C64ObjectMode)
			maskIdx = _C64ObjectMap[(y + 2 * height) * width + stripnr] * 8;
		else
			maskIdx = _C64MaskMap[y + stripnr * height] * 8;
		for (int i = 0; i < 8; i++) {
			byte c = _C64MaskChar[maskIdx + i];

			// V1/C64 masks are inverted compared to what ScummVM expects
			*dst = c ^ 0xFF;
			dst += _numStrips;
		}
	}
}

void Gdi::decodeC64Gfx(const byte *src, byte *dst, int size) {
	int x, z;
	byte color, run, common[4];

	for (z = 0; z < 4; z++) {
		common[z] = *src++;
	}

	x = 0;
	while (x < size) {
		run = *src++;
		if (run & 0x80) {
			color = common[(run >> 5) & 3];
			run &= 0x1F;
			for (z = 0; z <= run; z++) {
				dst[x++] = color;
			}
		} else if (run & 0x40) {
			run &= 0x3F;
			color = *src++;
			for (z = 0; z <= run; z++) {
				dst[x++] = color;
			}
		} else {
			for (z = 0; z <= run; z++) {
				dst[x++] = *src++;
			}
		}
	}
}

void Gdi::decodeStripEGA(byte *dst, const byte *src, int height) {
	byte color = 0;
	int run = 0, x = 0, y = 0, z;

	while (x < 8) {
		color = *src++;
		
		if (color & 0x80) {
			run = color & 0x3f;

			if (color & 0x40) {
				color = *src++;

				if (run == 0) {
					run = *src++;
				}
				for (z = 0; z < run; z++) {
					*(dst + y * _vm->_screenWidth + x) = (z & 1) ? _roomPalette[color & 0xf] : _roomPalette[color >> 4];

					y++;
					if (y >= height) {
						y = 0;
						x++;
					}
				}
			} else {
				if (run == 0) {
					run = *src++;
				}

				for (z = 0; z < run; z++) {
					*(dst + y * _vm->_screenWidth + x) = *(dst + y * _vm->_screenWidth + x - 1);

					y++;
					if (y >= height) {
						y = 0;
						x++;
					}
				}
			}
		} else {
			run = color >> 4;
			if (run == 0) {
				run = *src++;
			}
			
			for (z = 0; z < run; z++) {
				*(dst + y * _vm->_screenWidth + x) = _roomPalette[color & 0xf];

				y++;
				if (y >= height) {
					y = 0;
					x++;
				}
			}
		}
	}
}

bool Gdi::decompressBitmap(byte *bgbak_ptr, const byte *src, int numLinesToProcess) {
	assert(numLinesToProcess);

	byte code = *src++;
	bool useOrDecompress = false;
	
	if (code <= 10) {
		switch (code) {
		case 1:
			unkDecode7(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 2:
			unkDecode8(bgbak_ptr, src, numLinesToProcess);       /* Ender - Zak256/Indy256 */
			break;
	
		case 3:
			unkDecode9(bgbak_ptr, src, numLinesToProcess);       /* Ender - Zak256/Indy256 */
			break;
	
		case 4:
			unkDecode10(bgbak_ptr, src, numLinesToProcess);      /* Ender - Zak256/Indy256 */
			break;
	
		case 7:
			unkDecode11(bgbak_ptr, src, numLinesToProcess);      /* Ender - Zak256/Indy256 */
			break;
	
		// 8/9 used in 3do version of puttputt joins the parade maybe others
		case 8:
			useOrDecompress = true;
			decodeStrip3DO(bgbak_ptr, src, numLinesToProcess, true);
			break;
	
		case 9:
			decodeStrip3DO(bgbak_ptr, src, numLinesToProcess, false);
			break;
	
		// used in amiga version of Monkey Island
		case 10:
			decodeStripEGA(bgbak_ptr, src, numLinesToProcess);
			break;

		default:
			error("Gdi::decompressBitmap: default case %d", code);
		}
	} else {
		_decomp_shr = code % 10;
		_decomp_mask = 0xFF >> (8 - _decomp_shr);
		code /= 10;
		
		switch (code) {
		case 1:
			// FIXME: Ugly workaround for bug #901462
			if (_vm->_version == 8)
				useOrDecompress = true;
			unkDecodeC(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 2:
			unkDecodeB(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 3:
			useOrDecompress = true;
			unkDecodeC_trans(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 4:
			useOrDecompress = true;
			unkDecodeB_trans(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 6:
		case 10:
			// FIXME: Ugly workaround for bug #901462
			if (_vm->_version == 8 && code == 10)
				useOrDecompress = true;
			unkDecodeA(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 8:
		case 12:
			useOrDecompress = true;
			unkDecodeA_trans(bgbak_ptr, src, numLinesToProcess);
			break;
	
		case 13:
			decodeStripHE(bgbak_ptr, src, numLinesToProcess, false);
			break;
	
		case 14:
			useOrDecompress = true;
			decodeStripHE(bgbak_ptr, src, numLinesToProcess, true);
			break;
	
		default:
			error("Gdi::decompressBitmap: default case %d", code);
		}
	}
	
	return useOrDecompress;
}

void Gdi::draw8ColWithMasking(byte *dst, const byte *src, int height, byte *mask) {
	byte maskbits;

	do {
		maskbits = *mask;
		if (maskbits) {
			copy8PixelsWithMasking(dst, src, maskbits);
		} else {
#if defined(SCUMM_NEED_ALIGNMENT)
			memcpy(dst, src, 8);
#else
			((uint32 *)dst)[0] = ((const uint32 *)src)[0];
			((uint32 *)dst)[1] = ((const uint32 *)src)[1];
#endif
		}
		src += _vm->_screenWidth;
		dst += _vm->_screenWidth;
		mask += _numStrips;
	} while (--height);
}

void Gdi::clear8ColWithMasking(byte *dst, int height, byte *mask) {
	byte maskbits;

	do {
		maskbits = *mask;
		if (maskbits) {
			clear8PixelsWithMasking(dst, 0, maskbits);
		} else {
#if defined(SCUMM_NEED_ALIGNMENT)
			memset(dst, 0, 8);
#else
			((uint32 *)dst)[0] = 0;
			((uint32 *)dst)[1] = 0;
#endif
		}
		dst += _vm->_screenWidth;
		mask += _numStrips;
	} while (--height);
}

void Gdi::draw8Col(byte *dst, const byte *src, int height) {
	do {
#if defined(SCUMM_NEED_ALIGNMENT)
		memcpy(dst, src, 8);
#else
		((uint32 *)dst)[0] = ((const uint32 *)src)[0];
		((uint32 *)dst)[1] = ((const uint32 *)src)[1];
#endif
		dst += _vm->_screenWidth;
		src += _vm->_screenWidth;
	} while (--height);
}

void Gdi::clear8Col(byte *dst, int height)
{
	do {
#if defined(SCUMM_NEED_ALIGNMENT)
		memset(dst, 0, 8);
#else
		((uint32 *)dst)[0] = 0;
		((uint32 *)dst)[1] = 0;
#endif
		dst += _vm->_screenWidth;
	} while (--height);
}

void Gdi::decompressMaskImg(byte *dst, const byte *src, int height) {
	byte b, c;

	while (height) {
		b = *src++;

		if (b & 0x80) {
			b &= 0x7F;
			c = *src++;

			do {
				*dst = c;
				dst += _numStrips;
				--height;
			} while (--b && height);
		} else {
			do {
				*dst = *src++;
				dst += _numStrips;
				--height;
			} while (--b && height);
		}
	}
}

void Gdi::decompressMaskImgOr(byte *dst, const byte *src, int height) {
	byte b, c;

	while (height) {
		b = *src++;
		
		if (b & 0x80) {
			b &= 0x7F;
			c = *src++;

			do {
				*dst |= c;
				dst += _numStrips;
				--height;
			} while (--b && height);
		} else {
			do {
				*dst |= *src++;
				dst += _numStrips;
				--height;
			} while (--b && height);
		}
	}
}

#define READ_BIT (cl--, bit = bits & 1, bits >>= 1, bit)
#define FILL_BITS do {              \
		if (cl <= 8) {              \
			bits |= (*src++ << cl); \
			cl += 8;                \
		}                           \
	} while (0)

void Gdi::unkDecodeA(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	byte incm, reps;

	do {
		int x = 8;
		do {
			FILL_BITS;
			*dst++ = _roomPalette[color];

		againPos:
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
			} else {
				incm = (bits & 7) - 4;
				cl -= 3;
				bits >>= 3;
				if (incm) {
					color += incm;
				} else {
					FILL_BITS;
					reps = bits & 0xFF;
					do {
						if (!--x) {
							x = 8;
							dst += _vm->_screenWidth - 8;
							if (!--height)
								return;
						}
						*dst++ = _roomPalette[color];
					} while (--reps);
					bits >>= 8;
					bits |= (*src++) << (cl - 8);
					goto againPos;
				}
			}
		} while (--x);
		dst += _vm->_screenWidth - 8;
	} while (--height);
}

void Gdi::unkDecodeA_trans(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	byte incm, reps;

	do {
		int x = 8;
		do {
			FILL_BITS;
			if (color != _transparentColor)
				*dst = _roomPalette[color];
			dst++;

		againPos:
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
			} else {
				incm = (bits & 7) - 4;
				cl -= 3;
				bits >>= 3;
				if (incm) {
					color += incm;
				} else {
					FILL_BITS;
					reps = bits & 0xFF;
					do {
						if (!--x) {
							x = 8;
							dst += _vm->_screenWidth - 8;
							if (!--height)
								return;
						}
						if (color != _transparentColor)
							*dst = _roomPalette[color];
						dst++;
					} while (--reps);
					bits >>= 8;
					bits |= (*src++) << (cl - 8);
					goto againPos;
				}
			}
		} while (--x);
		dst += _vm->_screenWidth - 8;
	} while (--height);
}

void Gdi::unkDecodeB(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	int8 inc = -1;

	do {
		int x = 8;
		do {
			FILL_BITS;
			*dst++ = _roomPalette[color];
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
				inc = -1;
			} else if (!READ_BIT) {
				color += inc;
			} else {
				inc = -inc;
				color += inc;
			}
		} while (--x);
		dst += _vm->_screenWidth - 8;
	} while (--height);
}

void Gdi::unkDecodeB_trans(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	int8 inc = -1;

	do {
		int x = 8;
		do {
			FILL_BITS;
			if (color != _transparentColor)
				*dst = _roomPalette[color];
			dst++;
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
				inc = -1;
			} else if (!READ_BIT) {
				color += inc;
			} else {
				inc = -inc;
				color += inc;
			}
		} while (--x);
		dst += _vm->_screenWidth - 8;
	} while (--height);
}

void Gdi::unkDecodeC(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	int8 inc = -1;

	int x = 8;
	do {
		int h = height;
		do {
			FILL_BITS;
			*dst = _roomPalette[color];
			dst += _vm->_screenWidth;
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
				inc = -1;
			} else if (!READ_BIT) {
				color += inc;
			} else {
				inc = -inc;
				color += inc;
			}
		} while (--h);
		dst -= _vertStripNextInc;
	} while (--x);
}

void Gdi::unkDecodeC_trans(byte *dst, const byte *src, int height) {
	byte color = *src++;
	uint bits = *src++;
	byte cl = 8;
	byte bit;
	int8 inc = -1;

	int x = 8;
	do {
		int h = height;
		do {
			FILL_BITS;
			if (color != _transparentColor)
				*dst = _roomPalette[color];
			dst += _vm->_screenWidth;
			if (!READ_BIT) {
			} else if (!READ_BIT) {
				FILL_BITS;
				color = bits & _decomp_mask;
				bits >>= _decomp_shr;
				cl -= _decomp_shr;
				inc = -1;
			} else if (!READ_BIT) {
				color += inc;
			} else {
				inc = -inc;
				color += inc;
			}
		} while (--h);
		dst -= _vertStripNextInc;
	} while (--x);
}

#undef READ_BIT
#undef FILL_BITS

/* Ender - Zak256/Indy256 decoders */
#define READ_256BIT                        \
		do {                               \
			if ((mask <<= 1) == 256) {     \
				buffer = *src++;           \
				mask = 1;                  \
			}                              \
			bits = ((buffer & mask) != 0); \
		} while (0)

#define NEXT_ROW                           \
		do {                               \
			dst += _vm->_screenWidth;      \
			if (--h == 0) {                \
				if (!--x)                  \
					return;                \
				dst -= _vertStripNextInc;  \
				h = height;                \
			}                              \
		} while (0)

void Gdi::unkDecode7(byte *dst, const byte *src, int height) {
	uint h = height;

	if (_vm->_features & GF_OLD256) {
		int x = 8;
		for (;;) {
			*dst = *src++;
			NEXT_ROW;
		}
		return;
	}

	do {
#if defined(SCUMM_NEED_ALIGNMENT)
		memcpy(dst, src, 8);
#else
		((uint32 *)dst)[0] = ((const uint32 *)src)[0];
		((uint32 *)dst)[1] = ((const uint32 *)src)[1];
#endif
		dst += _vm->_screenWidth;
		src += 8;
	} while (--height);
}

void Gdi::unkDecode8(byte *dst, const byte *src, int height) {
	uint h = height;

	int x = 8;
	for (;;) {
		uint run = (*src++) + 1;
		byte color = *src++;

		do {
			*dst = _roomPalette[color];
			NEXT_ROW;
		} while (--run);
	}
}

void Gdi::unkDecode9(byte *dst, const byte *src, int height) {
	unsigned char c, bits, color, run;
	int i, j;
	uint buffer = 0, mask = 128;
	int h = height;
	i = j = run = 0;

	int x = 8;
	for (;;) {
		c = 0;
		for (i = 0; i < 4; i++) {
			READ_256BIT;
			c += (bits << i);
		}

		switch (c >> 2) {
		case 0:
			color = 0;
			for (i = 0; i < 4; i++) {
				READ_256BIT;
				color += bits << i;
			}
			for (i = 0; i < ((c & 3) + 2); i++) {
				*dst = _roomPalette[run * 16 + color];
				NEXT_ROW;
			}
			break;

		case 1:
			for (i = 0; i < ((c & 3) + 1); i++) {
				color = 0;
				for (j = 0; j < 4; j++) {
					READ_256BIT;
					color += bits << j;
				}
				*dst = _roomPalette[run * 16 + color];
				NEXT_ROW;
			}
			break;

		case 2:
			run = 0;
			for (i = 0; i < 4; i++) {
				READ_256BIT;
				run += bits << i;
			}
			break;
		}
	}
}

void Gdi::unkDecode10(byte *dst, const byte *src, int height) {
	int i;
	unsigned char local_palette[256], numcolors = *src++;
	uint h = height;

	for (i = 0; i < numcolors; i++)
		local_palette[i] = *src++;

	int x = 8;

	for (;;) {
		byte color = *src++;
		if (color < numcolors) {
			*dst = _roomPalette[local_palette[color]];
			NEXT_ROW;
		} else {
			uint run = color - numcolors + 1;
			color = *src++;
			do {
				*dst = _roomPalette[color];
				NEXT_ROW;
			} while (--run);
		}
	}
}


void Gdi::unkDecode11(byte *dst, const byte *src, int height) {
	int bits, i;
	uint buffer = 0, mask = 128;
	unsigned char inc = 1, color = *src++;

	int x = 8;
	do {
		int h = height;
		do {
			*dst = _roomPalette[color];
			dst += _vm->_screenWidth;
			for (i = 0; i < 3; i++) {
				READ_256BIT;
				if (!bits)
					break;
			}
			switch (i) {
			case 1:
				inc = -inc;
				color -= inc;
				break;

			case 2:
				color -= inc;
				break;

			case 3:
				color = 0;
				inc = 1;
				for (i = 0; i < 8; i++) {
					READ_256BIT;
					color += bits << i;
				}
				break;
			}
		} while (--h);
		dst -= _vertStripNextInc;
	} while (--x);
}


void Gdi::decodeStrip3DO(byte *dst, const byte *src, int height, byte transpCheck) {
	int destbytes, olddestbytes2, olddestbytes1;
	byte color;
	int data;

	olddestbytes1 = 0;

	destbytes = height << 3;

	if (!height)
		return;

	do {
		data = *src;
		src++;

		if (!(data & 1)) {
			data >>= 1;
			data++;
			destbytes -= data;
			if (destbytes < 0)
				data += destbytes;

			olddestbytes2 = destbytes;
			destbytes = olddestbytes1;

			for (; data > 0; data--, src++, dst++) {
				if (*src != _transparentColor || !transpCheck)
					*dst = _roomPalette[*src];
			
				destbytes++;
				if (!(destbytes & 7))
					dst += 312;
			}

			olddestbytes1 = destbytes;
			if (olddestbytes2 > 0) {
				destbytes = olddestbytes2;
			}
		} else {
			data >>= 1;
			color = *src;
			src++;

			data++;
			destbytes -= data;
			if (destbytes < 0)
				data += destbytes;

			olddestbytes2 = destbytes;
			destbytes = olddestbytes1;

			for (; data > 0; data--, dst++) {
				if (color != _transparentColor || !transpCheck)
					*dst = _roomPalette[color];
				destbytes++;
				if (!(destbytes & 7))
					dst += 312;
			}
			olddestbytes1 = destbytes;
			if (olddestbytes2 > 0) {
				destbytes = olddestbytes2;
			}
		}
	} while (olddestbytes2 > 0);
}


void Gdi::decodeStripHE(byte *dst, const byte *src, int height, byte transpCheck) {
	uint32 color, dataBit, data, shift, iteration;

     color = *src;
	 src++;
	 data = READ_LE_UINT24(src);
	 src += 3;
     shift = 24;

	 while (height) {
		 for (iteration = 0; iteration < 8; iteration++) {
			 if (color != _transparentColor || !transpCheck)
				 *dst = _roomPalette[color];
			 dst++;
			 if (shift <= 16) {
				 data |= *src << shift;
				 src++;
				 shift += 8;
				 data |= *src << shift;
				 src++;
				 shift += 8;
			 }
			 
			 dataBit = data & 1;
			 shift--;
			 data >>= 1;
			 if (dataBit) {
				 dataBit = data & 1;
				 shift--;
				 data >>= 1;
				 if (!dataBit) {
					 color = _decomp_mask & data;
					 shift -= _decomp_shr;
					 data >>= _decomp_shr;
				 } else {
					 dataBit = data & 7;
					 shift -= 3;
					 data >>= 3;
					 if (dataBit >= 4)
						 color += dataBit - 3;
					 else
						 color += dataBit - 4;
				 }
			 }
		 }
		 dst += 312;
		 height--;
	 }
}

#undef NEXT_ROW
#undef READ_256BIT

#pragma mark -
#pragma mark --- Transition effects ---
#pragma mark -

void ScummEngine::fadeIn(int effect) {
	updatePalette();

	switch (effect) {
	case 0:
		// seems to do nothing
		break;
	case 1:
	case 2:
	case 3:
	case 4:
	case 5:
		// Some of the transition effects won't work properly unless
		// the screen is marked as clean first. At first I thought I
		// could safely do this every time fadeIn() was called, but
		// that broke the FOA intro. Probably other things as well.
		//
		// Hopefully it's safe to do it at this point, at least.
		virtscr[0].setDirtyRange(0, 0);
 		transitionEffect(effect - 1);
		break;
	case 128:
		unkScreenEffect6();
		break;
	case 129:
		break;
	case 130:
	case 131:
	case 132:
	case 133:
		scrollEffect(133 - effect);
		break;
	case 134:
		dissolveEffect(1, 1);
		break;
	case 135:
		unkScreenEffect5(1);
		break;
	default:
		warning("Unknown screen effect, %d", effect);
	}
	_screenEffectFlag = true;
}

void ScummEngine::fadeOut(int effect) {
	VirtScreen *vs = &virtscr[0];

	vs->setDirtyRange(0, 0);
	if (!(_features & GF_NEW_CAMERA))
		camera._last.x = camera._cur.x;

	if (_screenEffectFlag && effect != 0) {
	
		// Fill screen 0 with black
		
		memset(vs->screenPtr + vs->xstart, 0, vs->width * vs->height);
	
		// Fade to black with the specified effect, if any.
		switch (effect) {
		case 1:
		case 2:
		case 3:
		case 4:
		case 5:
			transitionEffect(effect - 1);
			break;
		case 128:
			unkScreenEffect6();
			break;
		case 129:
			// Just blit screen 0 to the display (i.e. display will be black)
			vs->setDirtyRange(0, vs->height);
			updateDirtyScreen(kMainVirtScreen);
			break;
		case 134:
			dissolveEffect(1, 1);
			break;
		case 135:
			unkScreenEffect5(1);
			break;
		default:
			warning("fadeOut: default case %d", effect);
		}
	}

	// Update the palette at the end (once we faded to black) to avoid
	// some nasty effects when the palette is changed
	updatePalette();

	_screenEffectFlag = false;
}

/**
 * Perform a transition effect. There are four different effects possible:
 * 0: Iris effect
 * 1: Box wipe (a black box expands from the upper-left corner to the lower-right corner)
 * 2: Box wipe (a black box expands from the lower-right corner to the upper-left corner)
 * 3: Inverse box wipe
 * All effects operate on 8x8 blocks of the screen. These blocks are updated
 * in a certain order; the exact order determines how the effect appears to the user.
 * @param a		the transition effect to perform
 */
void ScummEngine::transitionEffect(int a) {
	int delta[16];								// Offset applied during each iteration
	int tab_2[16];
	int i, j;
	int bottom;
	int l, t, r, b;
	const int height = MIN((int)virtscr[0].height, _screenHeight);

	for (i = 0; i < 16; i++) {
		delta[i] = transitionEffects[a].deltaTable[i];
		j = transitionEffects[a].stripTable[i];
		if (j == 24)
			j = height / 8 - 1;
		tab_2[i] = j;
	}

	bottom = height / 8;
	for (j = 0; j < transitionEffects[a].numOfIterations; j++) {
		for (i = 0; i < 4; i++) {
			l = tab_2[i * 4];
			t = tab_2[i * 4 + 1];
			r = tab_2[i * 4 + 2];
			b = tab_2[i * 4 + 3];
			if (t == b) {
				while (l <= r) {
					if (l >= 0 && l < gdi._numStrips && t < bottom) {
						virtscr[0].tdirty[l] = t * 8;
						virtscr[0].bdirty[l] = (b + 1) * 8;
					}
					l++;
				}
			} else {
				if (l < 0 || l >= gdi._numStrips || b <= t)
					continue;
				if (b > bottom)
					b = bottom;
				if (t < 0)
					t = 0;
 				virtscr[0].tdirty[l] = t * 8;
				virtscr[0].bdirty[l] = (b + 1) * 8;
			}
			updateDirtyScreen(kMainVirtScreen);
		}

		for (i = 0; i < 16; i++)
			tab_2[i] += delta[i];

		// Draw the current state to the screen and wait half a sec so the user
		// can watch the effect taking place.
		_system->updateScreen();
		waitForTimer(30);
	}
}

/**
 * Update width*height areas of the screen, in random order, until the whole
 * screen has been updated. For instance:
 * 
 * dissolveEffect(1, 1) produces a pixel-by-pixel dissolve
 * dissolveEffect(8, 8) produces a square-by-square dissolve
 * dissolveEffect(virtsrc[0].width, 1) produces a line-by-line dissolve
 */
void ScummEngine::dissolveEffect(int width, int height) {
	VirtScreen *vs = &virtscr[0];
	int *offsets;
	int blits_before_refresh, blits;
	int x, y;
	int w, h;
	int i;

	// There's probably some less memory-hungry way of doing this. But
	// since we're only dealing with relatively small images, it shouldn't
	// be too bad.

	w = vs->width / width;
	h = vs->height / height;

	// When used correctly, vs->width % width and vs->height % height
	// should both be zero, but just to be safe...

	if (vs->width % width)
		w++;

	if (vs->height % height)
		h++;

	offsets = (int *) malloc(w * h * sizeof(int));
	if (offsets == NULL) {
		warning("dissolveEffect: out of memory");
		return;
	}

	// Create a permutation of offsets into the frame buffer

	if (width == 1 && height == 1) {
		// Optimized case for pixel-by-pixel dissolve

		for (i = 0; i < vs->width * vs->height; i++)
			offsets[i] = i;

		for (i = 1; i < w * h; i++) {
			int j;

			j = _rnd.getRandomNumber(i - 1);
			offsets[i] = offsets[j];
			offsets[j] = i;
		}
	} else {
		int *offsets2;

		for (i = 0, x = 0; x < vs->width; x += width)
			for (y = 0; y < vs->height; y += height)
				offsets[i++] = y * vs->width + x;

		offsets2 = (int *) malloc(w * h * sizeof(int));
		if (offsets2 == NULL) {
			warning("dissolveEffect: out of memory");
			free(offsets);
			return;
		}

		memcpy(offsets2, offsets, w * h * sizeof(int));

		for (i = 1; i < w * h; i++) {
			int j;

			j = _rnd.getRandomNumber(i - 1);
			offsets[i] = offsets[j];
			offsets[j] = offsets2[i];
		}

		free(offsets2);
	}

	// Blit the image piece by piece to the screen. The idea here is that
	// the whole update should take about a quarter of a second, assuming
	// most of the time is spent in waitForTimer(). It looks good to me,
	// but might still need some tuning.

	blits = 0;
	blits_before_refresh = (3 * w * h) / 25;
	
	// Speed up the effect for CD Loom since it uses it so often. I don't
	// think the original had any delay at all, so on modern hardware it
	// wasn't even noticeable.
	if (_gameId == GID_LOOM256)
		blits_before_refresh *= 2;

	for (i = 0; i < w * h; i++) {
		x = offsets[i] % vs->width;
		y = offsets[i] / vs->width;
		_system->copyRectToScreen(vs->screenPtr + vs->xstart + y * vs->width + x, vs->width, x, y + vs->topline, width, height);

		if (++blits >= blits_before_refresh) {
			blits = 0;
			_system->updateScreen();
			waitForTimer(30);
		}
	}

	free(offsets);

	if (blits != 0) {
		_system->updateScreen();
		waitForTimer(30);
	}
}

void ScummEngine::scrollEffect(int dir) {
	VirtScreen *vs = &virtscr[0];

	int x, y;
	int step;

	if ((dir == 0) || (dir == 1))
		step = vs->height;
	else
		step = vs->width;

	step = (step * kPictureDelay) / kScrolltime;

	switch (dir) {
	case 0:
		//up
		y = 1 + step;
		while (y < vs->height) {
			_system->move_screen(0, -step, vs->height);
			_system->copyRectToScreen(vs->screenPtr + vs->xstart + (y - step) * vs->width,
				vs->width,
				0, vs->height - step,
				vs->width, step);
			_system->updateScreen();
			waitForTimer(kPictureDelay);

			y += step;
		}
		break;
	case 1:
		// down
		y = 1 + step;
		while (y < vs->height) {
			_system->move_screen(0, step, vs->height);
			_system->copyRectToScreen(vs->screenPtr + vs->xstart + vs->width * (vs->height-y),
				vs->width,
				0, 0,
				vs->width, step);
			_system->updateScreen();
			waitForTimer(kPictureDelay);

			y += step;
		}
		break;
	case 2:
		// left
		x = 1 + step;
		while (x < vs->width) {
			_system->move_screen(-step, 0, vs->height);
			_system->copyRectToScreen(vs->screenPtr + vs->xstart + x - step,
				vs->width,
				vs->width - step, 0,
				step, vs->height);
			_system->updateScreen();
			waitForTimer(kPictureDelay);

			x += step;
		}
		break;
	case 3:
		// right
		x = 1 + step;
		while (x < vs->width) {
			_system->move_screen(step, 0, vs->height);
			_system->copyRectToScreen(vs->screenPtr + vs->xstart + vs->width - x,
				vs->width,
				0, 0,
				step, vs->height);
			_system->updateScreen();
			waitForTimer(kPictureDelay);

			x += step;
		}
		break;
	}
}

void ScummEngine::unkScreenEffect6() {
	// CD Loom (but not EGA Loom!) uses a more fine-grained dissolve
	if (_gameId == GID_LOOM256)
		dissolveEffect(1, 1);
	else
		dissolveEffect(8, 4);
}

void ScummEngine::unkScreenEffect5(int a) {
	// unkScreenEffect5(0), which is used by FOA during the opening
	// cutscene when Indy opens the small statue, has been replaced by
	// dissolveEffect(1, 1).
	//
	// I still don't know what unkScreenEffect5(1) is supposed to do.

	// FIXME: not implemented
	warning("stub unkScreenEffect(%d)", a);
}

void ScummEngine::setShake(int mode) {
	if (_shakeEnabled != (mode != 0))
		_fullRedraw = true;

	_shakeEnabled = mode != 0;
	_shakeFrame = 0;
	_system->set_shake_pos(0);
}

} // End of namespace Scumm

#ifdef __PALM_OS__
#include "scumm_globals.h"

_GINIT(Gfx)
_GSETPTR(Scumm::transitionEffects, GBVARS_TRANSITIONEFFECTS_INDEX, Scumm::TransitionEffect, GBVARS_SCUMM)
_GEND

_GRELEASE(Gfx)
_GRELEASEPTR(GBVARS_TRANSITIONEFFECTS_INDEX, GBVARS_SCUMM)
_GEND

#endif