gecko-dev/gfx/2d/BufferEdgePad.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include "BufferEdgePad.h"

#include "2D.h"     // for DrawTarget
#include "Point.h"  // for IntSize
#include "Types.h"  // for SurfaceFormat

#include "nsRegion.h"

namespace mozilla {
namespace gfx {

void PadDrawTargetOutFromRegion(DrawTarget* aDrawTarget,
                                const nsIntRegion& aRegion) {
  struct LockedBits {
    uint8_t* data;
    IntSize size;
    int32_t stride;
    SurfaceFormat format;
    static int clamp(int x, int min, int max) {
      if (x < min) x = min;
      if (x > max) x = max;
      return x;
    }

    static void ensure_memcpy(uint8_t* dst, uint8_t* src, size_t n,
                              uint8_t* bitmap, int stride, int height) {
      if (src + n > bitmap + stride * height) {
        MOZ_CRASH("GFX: long src memcpy");
      }
      if (src < bitmap) {
        MOZ_CRASH("GFX: short src memcpy");
      }
      if (dst + n > bitmap + stride * height) {
        MOZ_CRASH("GFX: long dst mempcy");
      }
      if (dst < bitmap) {
        MOZ_CRASH("GFX: short dst mempcy");
      }
    }

    static void visitor(void* closure, VisitSide side, int x1, int y1, int x2,
                        int y2) {
      LockedBits* lb = static_cast<LockedBits*>(closure);
      uint8_t* bitmap = lb->data;
      const int bpp = gfx::BytesPerPixel(lb->format);
      const int stride = lb->stride;
      const int width = lb->size.width;
      const int height = lb->size.height;

      if (side == VisitSide::TOP) {
        if (y1 > 0) {
          x1 = clamp(x1, 0, width - 1);
          x2 = clamp(x2, 0, width - 1);
          ensure_memcpy(&bitmap[x1 * bpp + (y1 - 1) * stride],
                        &bitmap[x1 * bpp + y1 * stride], (x2 - x1) * bpp,
                        bitmap, stride, height);
          memcpy(&bitmap[x1 * bpp + (y1 - 1) * stride],
                 &bitmap[x1 * bpp + y1 * stride], (x2 - x1) * bpp);
        }
      } else if (side == VisitSide::BOTTOM) {
        if (y1 < height) {
          x1 = clamp(x1, 0, width - 1);
          x2 = clamp(x2, 0, width - 1);
          ensure_memcpy(&bitmap[x1 * bpp + y1 * stride],
                        &bitmap[x1 * bpp + (y1 - 1) * stride], (x2 - x1) * bpp,
                        bitmap, stride, height);
          memcpy(&bitmap[x1 * bpp + y1 * stride],
                 &bitmap[x1 * bpp + (y1 - 1) * stride], (x2 - x1) * bpp);
        }
      } else if (side == VisitSide::LEFT) {
        if (x1 > 0) {
          while (y1 != y2) {
            memcpy(&bitmap[(x1 - 1) * bpp + y1 * stride],
                   &bitmap[x1 * bpp + y1 * stride], bpp);
            y1++;
          }
        }
      } else if (side == VisitSide::RIGHT) {
        if (x1 < width) {
          while (y1 != y2) {
            memcpy(&bitmap[x1 * bpp + y1 * stride],
                   &bitmap[(x1 - 1) * bpp + y1 * stride], bpp);
            y1++;
          }
        }
      }
    }
  } lb;

  if (aDrawTarget->LockBits(&lb.data, &lb.size, &lb.stride, &lb.format)) {
    // we can only pad software targets so if we can't lock the bits don't pad
    aRegion.VisitEdges(lb.visitor, &lb);
    aDrawTarget->ReleaseBits(lb.data);
  }
}

}  // namespace gfx
}  // namespace mozilla