gecko-dev/gfx/layers/TiledLayerBuffer.h

511 lines
20 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_TILEDLAYERBUFFER_H
#define GFX_TILEDLAYERBUFFER_H
// Debug defines
//#define GFX_TILEDLAYER_DEBUG_OVERLAY
//#define GFX_TILEDLAYER_PREF_WARNINGS
#include <stdint.h> // for uint16_t, uint32_t
#include <sys/types.h> // for int32_t
#include "gfxPrefs.h" // for gfxPrefs::LayersTileWidth/Height
#include "nsDebug.h" // for NS_ABORT_IF_FALSE
#include "nsPoint.h" // for nsIntPoint
#include "nsRect.h" // for nsIntRect
#include "nsRegion.h" // for nsIntRegion
#include "nsTArray.h" // for nsTArray
#if defined(MOZ_WIDGET_GONK) && ANDROID_VERSION >= 17
#include <ui/Fence.h>
#endif
namespace mozilla {
namespace layers {
// An abstract implementation of a tile buffer. This code covers the logic of
// moving and reusing tiles and leaves the validation up to the implementor. To
// avoid the overhead of virtual dispatch, we employ the curiously recurring
// template pattern.
//
// Tiles are aligned to a grid with one of the grid points at (0,0) and other
// grid points spaced evenly in the x- and y-directions by GetTileSize()
// multiplied by mResolution. GetScaledTileSize() provides convenience for
// accessing these values.
//
// This tile buffer stores a valid region, which defines the areas that have
// up-to-date content. The contents of tiles within this region will be reused
// from paint to paint. It also stores the region that was modified in the last
// paint operation; this is useful when one tiled layer buffer shadows another
// (as in an off-main-thread-compositing scenario), so that the shadow tiled
// layer buffer can correctly reflect the updates of the master layer buffer.
//
// The associated Tile may be of any type as long as the derived class can
// validate and return tiles of that type. Tiles will be frequently copied, so
// the tile type should be a reference or some other type with an efficient
// copy constructor.
//
// It is required that the derived class specify the base class as a friend. It
// must also implement the following public method:
//
// Tile GetPlaceholderTile() const;
//
// Returns a temporary placeholder tile used as a marker. This placeholder tile
// must never be returned by validateTile and must be == to every instance
// of a placeholder tile.
//
// Additionally, it must implement the following protected methods:
//
// Tile ValidateTile(Tile aTile, const nsIntPoint& aTileOrigin,
// const nsIntRegion& aDirtyRect);
//
// Validates the dirtyRect. The returned Tile will replace the tile.
//
// void ReleaseTile(Tile aTile);
//
// Destroys the given tile.
//
// void SwapTiles(Tile& aTileA, Tile& aTileB);
//
// Swaps two tiles.
//
// The contents of the tile buffer will be rendered at the resolution specified
// in mResolution, which can be altered with SetResolution. The resolution
// should always be a factor of the tile length, to avoid tiles covering
// non-integer amounts of pixels.
template<typename Derived, typename Tile>
class TiledLayerBuffer
{
public:
TiledLayerBuffer()
: mRetainedWidth(0)
, mRetainedHeight(0)
, mResolution(1)
, mTileSize(gfxPrefs::LayersTileWidth(), gfxPrefs::LayersTileHeight())
{}
~TiledLayerBuffer() {}
// Given a tile origin aligned to a multiple of GetScaledTileSize,
// return the tile that describes that region.
// NOTE: To get the valid area of that tile you must intersect
// (aTileOrigin.x, aTileOrigin.y,
// GetScaledTileSize().width, GetScaledTileSize().height)
// and GetValidRegion() to get the area of the tile that is valid.
Tile GetTile(const nsIntPoint& aTileOrigin) const;
// Given a tile x, y relative to the top left of the layer, this function
// will return the tile for
// (x*GetScaledTileSize().width, y*GetScaledTileSize().height,
// GetScaledTileSize().width, GetScaledTileSize().height)
Tile GetTile(int x, int y) const;
// This operates the same as GetTile(aTileOrigin), but will also replace the
// specified tile with the placeholder tile. This does not call ReleaseTile
// on the removed tile.
bool RemoveTile(const nsIntPoint& aTileOrigin, Tile& aRemovedTile);
// This operates the same as GetTile(x, y), but will also replace the
// specified tile with the placeholder tile. This does not call ReleaseTile
// on the removed tile.
bool RemoveTile(int x, int y, Tile& aRemovedTile);
const gfx::IntSize& GetTileSize() const { return mTileSize; }
gfx::IntSize GetScaledTileSize() const { return RoundedToInt(gfx::Size(mTileSize) / mResolution); }
unsigned int GetTileCount() const { return mRetainedTiles.Length(); }
const nsIntRegion& GetValidRegion() const { return mValidRegion; }
const nsIntRegion& GetPaintedRegion() const { return mPaintedRegion; }
void ClearPaintedRegion() { mPaintedRegion.SetEmpty(); }
void ResetPaintedAndValidState() {
mPaintedRegion.SetEmpty();
mValidRegion.SetEmpty();
mRetainedWidth = 0;
mRetainedHeight = 0;
for (size_t i = 0; i < mRetainedTiles.Length(); i++) {
if (!IsPlaceholder(mRetainedTiles[i])) {
AsDerived().ReleaseTile(mRetainedTiles[i]);
}
}
mRetainedTiles.Clear();
}
// Given a position i, this function returns the position inside the current tile.
int GetTileStart(int i, int aTileLength) const {
return (i >= 0) ? (i % aTileLength)
: ((aTileLength - (-i % aTileLength)) %
aTileLength);
}
// Rounds the given coordinate down to the nearest tile boundary.
int RoundDownToTileEdge(int aX, int aTileLength) const { return aX - GetTileStart(aX, aTileLength); }
// Get and set draw scaling. mResolution affects the resolution at which the
// contents of the buffer are drawn. mResolution has no effect on the
// coordinate space of the valid region, but does affect the size of an
// individual tile's rect in relation to the valid region.
// Setting the resolution will invalidate the buffer.
float GetResolution() const { return mResolution; }
void SetResolution(float aResolution) {
if (mResolution == aResolution) {
return;
}
Update(nsIntRegion(), nsIntRegion());
mResolution = aResolution;
}
bool IsLowPrecision() const { return mResolution < 1; }
typedef Tile* Iterator;
Iterator TilesBegin() { return mRetainedTiles.Elements(); }
Iterator TilesEnd() { return mRetainedTiles.Elements() + mRetainedTiles.Length(); }
protected:
// The implementor should call Update() to change
// the new valid region. This implementation will call
// validateTile on each tile that is dirty, which is left
// to the implementor.
void Update(const nsIntRegion& aNewValidRegion, const nsIntRegion& aPaintRegion);
nsIntRegion mValidRegion;
nsIntRegion mPaintedRegion;
/**
* mRetainedTiles is a rectangular buffer of mRetainedWidth x mRetainedHeight
* stored as column major with the same origin as mValidRegion.GetBounds().
* Any tile that does not intersect mValidRegion is a PlaceholderTile.
* Only the region intersecting with mValidRegion should be read from a tile,
* another other region is assumed to be uninitialized. The contents of the
* tiles is scaled by mResolution.
*/
nsTArray<Tile> mRetainedTiles;
int mRetainedWidth; // in tiles
int mRetainedHeight; // in tiles
float mResolution;
gfx::IntSize mTileSize;
private:
const Derived& AsDerived() const { return *static_cast<const Derived*>(this); }
Derived& AsDerived() { return *static_cast<Derived*>(this); }
bool IsPlaceholder(Tile aTile) const { return aTile == AsDerived().GetPlaceholderTile(); }
};
class ClientTiledLayerBuffer;
class SurfaceDescriptorTiles;
class ISurfaceAllocator;
// Shadow layers may implement this interface in order to be notified when a
// tiled layer buffer is updated.
class TiledLayerComposer
{
public:
/**
* Update the current retained layer with the updated layer data.
* It is expected that the tiles described by aTiledDescriptor are all in the
* ReadLock state, so that the locks can be adopted when recreating a
* ClientTiledLayerBuffer locally. This lock will be retained until the buffer
* has completed uploading.
*/
virtual void UseTiledLayerBuffer(ISurfaceAllocator* aAllocator,
const SurfaceDescriptorTiles& aTiledDescriptor) = 0;
/**
* If some part of the buffer is being rendered at a lower precision, this
* returns that region. If it is not, an empty region will be returned.
*/
virtual const nsIntRegion& GetValidLowPrecisionRegion() const = 0;
#if defined(MOZ_WIDGET_GONK) && ANDROID_VERSION >= 17
/**
* Store a fence that will signal when the current buffer is no longer being read.
* Similar to android's GLConsumer::setReleaseFence()
*/
virtual void SetReleaseFence(const android::sp<android::Fence>& aReleaseFence) = 0;
#endif
};
// Normal integer division truncates towards zero,
// we instead want to floor to hangle negative numbers.
static inline int floor_div(int a, int b)
{
int rem = a % b;
int div = a/b;
if (rem == 0) {
return div;
} else {
// If the signs are different substract 1.
int sub;
sub = a ^ b;
// The results of this shift is either 0 or -1.
sub >>= 8*sizeof(int)-1;
return div+sub;
}
}
template<typename Derived, typename Tile> Tile
TiledLayerBuffer<Derived, Tile>::GetTile(const nsIntPoint& aTileOrigin) const
{
// TODO Cache firstTileOriginX/firstTileOriginY
// Find the tile x/y of the first tile and the target tile relative to the (0, 0)
// origin, the difference is the tile x/y relative to the start of the tile buffer.
gfx::IntSize scaledTileSize = GetScaledTileSize();
int firstTileX = floor_div(mValidRegion.GetBounds().x, scaledTileSize.width);
int firstTileY = floor_div(mValidRegion.GetBounds().y, scaledTileSize.height);
return GetTile(floor_div(aTileOrigin.x, scaledTileSize.width) - firstTileX,
floor_div(aTileOrigin.y, scaledTileSize.height) - firstTileY);
}
template<typename Derived, typename Tile> Tile
TiledLayerBuffer<Derived, Tile>::GetTile(int x, int y) const
{
int index = x * mRetainedHeight + y;
return mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
}
template<typename Derived, typename Tile> bool
TiledLayerBuffer<Derived, Tile>::RemoveTile(const nsIntPoint& aTileOrigin,
Tile& aRemovedTile)
{
gfx::IntSize scaledTileSize = GetScaledTileSize();
int firstTileX = floor_div(mValidRegion.GetBounds().x, scaledTileSize.width);
int firstTileY = floor_div(mValidRegion.GetBounds().y, scaledTileSize.height);
return RemoveTile(floor_div(aTileOrigin.x, scaledTileSize.width) - firstTileX,
floor_div(aTileOrigin.y, scaledTileSize.height) - firstTileY,
aRemovedTile);
}
template<typename Derived, typename Tile> bool
TiledLayerBuffer<Derived, Tile>::RemoveTile(int x, int y, Tile& aRemovedTile)
{
int index = x * mRetainedHeight + y;
const Tile& tileToRemove = mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
if (!IsPlaceholder(tileToRemove)) {
aRemovedTile = tileToRemove;
mRetainedTiles[index] = AsDerived().GetPlaceholderTile();
return true;
}
return false;
}
template<typename Derived, typename Tile> void
TiledLayerBuffer<Derived, Tile>::Update(const nsIntRegion& aNewValidRegion,
const nsIntRegion& aPaintRegion)
{
gfx::IntSize scaledTileSize = GetScaledTileSize();
nsTArray<Tile> newRetainedTiles;
nsTArray<Tile>& oldRetainedTiles = mRetainedTiles;
const nsIntRect oldBound = mValidRegion.GetBounds();
const nsIntRect newBound = aNewValidRegion.GetBounds();
const nsIntPoint oldBufferOrigin(RoundDownToTileEdge(oldBound.x, scaledTileSize.width),
RoundDownToTileEdge(oldBound.y, scaledTileSize.height));
const nsIntPoint newBufferOrigin(RoundDownToTileEdge(newBound.x, scaledTileSize.width),
RoundDownToTileEdge(newBound.y, scaledTileSize.height));
const nsIntRegion& oldValidRegion = mValidRegion;
const nsIntRegion& newValidRegion = aNewValidRegion;
const int oldRetainedHeight = mRetainedHeight;
// Pass 1: Recycle valid content from the old buffer
// Recycle tiles from the old buffer that contain valid regions.
// Insert placeholders tiles if we have no valid area for that tile
// which we will allocate in pass 2.
// TODO: Add a tile pool to reduce new allocation
int tileX = 0;
int tileY = 0;
int tilesMissing = 0;
// Iterate over the new drawing bounds in steps of tiles.
for (int32_t x = newBound.x; x < newBound.XMost(); tileX++) {
// Compute tileRect(x,y,width,height) in layer space coordinate
// giving us the rect of the tile that hits the newBounds.
int width = scaledTileSize.width - GetTileStart(x, scaledTileSize.width);
if (x + width > newBound.XMost()) {
width = newBound.x + newBound.width - x;
}
tileY = 0;
for (int32_t y = newBound.y; y < newBound.YMost(); tileY++) {
int height = scaledTileSize.height - GetTileStart(y, scaledTileSize.height);
if (y + height > newBound.y + newBound.height) {
height = newBound.y + newBound.height - y;
}
const nsIntRect tileRect(x,y,width,height);
if (oldValidRegion.Intersects(tileRect) && newValidRegion.Intersects(tileRect)) {
// This old tiles contains some valid area so move it to the new tile
// buffer. Replace the tile in the old buffer with a placeholder
// to leave the old buffer index unaffected.
int tileX = floor_div(x - oldBufferOrigin.x, scaledTileSize.width);
int tileY = floor_div(y - oldBufferOrigin.y, scaledTileSize.height);
int index = tileX * oldRetainedHeight + tileY;
// The tile may have been removed, skip over it in this case.
if (IsPlaceholder(oldRetainedTiles.
SafeElementAt(index, AsDerived().GetPlaceholderTile()))) {
newRetainedTiles.AppendElement(AsDerived().GetPlaceholderTile());
} else {
Tile tileWithPartialValidContent = oldRetainedTiles[index];
newRetainedTiles.AppendElement(tileWithPartialValidContent);
oldRetainedTiles[index] = AsDerived().GetPlaceholderTile();
}
} else {
// This tile is either:
// 1) Outside the new valid region and will simply be an empty
// placeholder forever.
// 2) The old buffer didn't have any data for this tile. We postpone
// the allocation of this tile after we've reused any tile with
// valid content because then we know we can safely recycle
// with taking from a tile that has recyclable content.
newRetainedTiles.AppendElement(AsDerived().GetPlaceholderTile());
if (aPaintRegion.Intersects(tileRect)) {
tilesMissing++;
}
}
y += height;
}
x += width;
}
// Keep track of the number of horizontal/vertical tiles
// in the buffer so that we can easily look up a tile.
mRetainedWidth = tileX;
mRetainedHeight = tileY;
// Pass 1.5: Release excess tiles in oldRetainedTiles
// Tiles in oldRetainedTiles that aren't in newRetainedTiles will be recycled
// before creating new ones, but there could still be excess unnecessary
// tiles. As tiles may not have a fixed memory cost (for example, due to
// double-buffering), we should release these excess tiles first.
int oldTileCount = 0;
for (size_t i = 0; i < oldRetainedTiles.Length(); i++) {
Tile oldTile = oldRetainedTiles[i];
if (IsPlaceholder(oldTile)) {
continue;
}
if (oldTileCount >= tilesMissing) {
oldRetainedTiles[i] = AsDerived().GetPlaceholderTile();
AsDerived().ReleaseTile(oldTile);
} else {
oldTileCount ++;
}
}
NS_ABORT_IF_FALSE(aNewValidRegion.Contains(aPaintRegion), "Painting a region outside the visible region");
#ifdef DEBUG
nsIntRegion oldAndPainted(oldValidRegion);
oldAndPainted.Or(oldAndPainted, aPaintRegion);
#endif
NS_ABORT_IF_FALSE(oldAndPainted.Contains(newValidRegion), "newValidRegion has not been fully painted");
nsIntRegion regionToPaint(aPaintRegion);
// Pass 2: Validate
// We know at this point that any tile in the new buffer that had valid content
// from the previous buffer is placed correctly in the new buffer.
// We know that any tile in the old buffer that isn't a place holder is
// of no use and can be recycled.
// We also know that any place holder tile in the new buffer must be
// allocated.
tileX = 0;
#ifdef GFX_TILEDLAYER_PREF_WARNINGS
printf_stderr("Update %i, %i, %i, %i\n", newBound.x, newBound.y, newBound.width, newBound.height);
#endif
for (int x = newBound.x; x < newBound.x + newBound.width; tileX++) {
// Compute tileRect(x,y,width,height) in layer space coordinate
// giving us the rect of the tile that hits the newBounds.
int tileStartX = RoundDownToTileEdge(x, scaledTileSize.width);
int width = scaledTileSize.width - GetTileStart(x, scaledTileSize.width);
if (x + width > newBound.XMost())
width = newBound.XMost() - x;
tileY = 0;
for (int y = newBound.y; y < newBound.y + newBound.height; tileY++) {
int tileStartY = RoundDownToTileEdge(y, scaledTileSize.height);
int height = scaledTileSize.height - GetTileStart(y, scaledTileSize.height);
if (y + height > newBound.YMost()) {
height = newBound.YMost() - y;
}
const nsIntRect tileRect(x, y, width, height);
nsIntRegion tileDrawRegion;
tileDrawRegion.And(tileRect, regionToPaint);
if (tileDrawRegion.IsEmpty()) {
// We have a tile but it doesn't hit the draw region
// because we can reuse all of the content from the
// previous buffer.
#ifdef DEBUG
int currTileX = floor_div(x - newBufferOrigin.x, scaledTileSize.width);
int currTileY = floor_div(y - newBufferOrigin.y, scaledTileSize.height);
int index = currTileX * mRetainedHeight + currTileY;
NS_ABORT_IF_FALSE(!newValidRegion.Intersects(tileRect) ||
!IsPlaceholder(newRetainedTiles.
SafeElementAt(index, AsDerived().GetPlaceholderTile())),
"If we don't draw a tile we shouldn't have a placeholder there.");
#endif
y += height;
continue;
}
int tileX = floor_div(x - newBufferOrigin.x, scaledTileSize.width);
int tileY = floor_div(y - newBufferOrigin.y, scaledTileSize.height);
int index = tileX * mRetainedHeight + tileY;
NS_ABORT_IF_FALSE(index >= 0 &&
static_cast<unsigned>(index) < newRetainedTiles.Length(),
"index out of range");
Tile newTile = newRetainedTiles[index];
// Try to reuse a tile from the old retained tiles that had no partially
// valid content.
while (IsPlaceholder(newTile) && oldRetainedTiles.Length() > 0) {
AsDerived().SwapTiles(newTile, oldRetainedTiles[oldRetainedTiles.Length()-1]);
oldRetainedTiles.RemoveElementAt(oldRetainedTiles.Length()-1);
if (!IsPlaceholder(newTile)) {
oldTileCount--;
}
}
// We've done our best effort to recycle a tile but it can be null
// in which case it's up to the derived class's ValidateTile()
// implementation to allocate a new tile before drawing
nsIntPoint tileOrigin(tileStartX, tileStartY);
newTile = AsDerived().ValidateTile(newTile, nsIntPoint(tileStartX, tileStartY),
tileDrawRegion);
NS_ABORT_IF_FALSE(!IsPlaceholder(newTile), "index out of range");
#ifdef GFX_TILEDLAYER_PREF_WARNINGS
printf_stderr("Store Validate tile %i, %i -> %i\n", tileStartX, tileStartY, index);
#endif
newRetainedTiles[index] = newTile;
y += height;
}
x += width;
}
// At this point, oldTileCount should be zero
NS_ABORT_IF_FALSE(oldTileCount == 0, "Failed to release old tiles");
mRetainedTiles = newRetainedTiles;
mValidRegion = aNewValidRegion;
mPaintedRegion.Or(mPaintedRegion, aPaintRegion);
}
} // layers
} // mozilla
#endif // GFX_TILEDLAYERBUFFER_H