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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "ui/gfx/blit.h"
- #include <stddef.h>
- #include "base/check.h"
- #include "build/build_config.h"
- #include "skia/ext/platform_canvas.h"
- #include "third_party/skia/include/core/SkPixmap.h"
- #include "ui/gfx/geometry/point.h"
- #include "ui/gfx/geometry/rect.h"
- #include "ui/gfx/geometry/vector2d.h"
- namespace gfx {
- namespace {
- // Returns true if the given canvas has any part of itself clipped out or
- // any non-identity tranform.
- bool HasClipOrTransform(SkCanvas& canvas) {
- if (!canvas.getTotalMatrix().isIdentity())
- return true;
- if (!canvas.isClipRect())
- return true;
- // Now we know the clip is a regular rectangle, make sure it covers the
- // entire canvas.
- SkIRect clip_bounds = canvas.getDeviceClipBounds();
- SkImageInfo info;
- size_t row_bytes;
- void* pixels = canvas.accessTopLayerPixels(&info, &row_bytes);
- DCHECK(pixels);
- if (!pixels)
- return true;
- if (clip_bounds.fLeft != 0 || clip_bounds.fTop != 0 ||
- clip_bounds.fRight != info.width() ||
- clip_bounds.fBottom != info.height())
- return true;
- return false;
- }
- } // namespace
- void ScrollCanvas(SkCanvas* canvas,
- const gfx::Rect& in_clip,
- const gfx::Vector2d& offset) {
- DCHECK(!HasClipOrTransform(*canvas)); // Don't support special stuff.
- SkPixmap pixmap;
- bool success = skia::GetWritablePixels(canvas, &pixmap);
- DCHECK(success);
- // We expect all coords to be inside the canvas, so clip here.
- gfx::Rect clip = gfx::IntersectRects(
- in_clip, gfx::Rect(0, 0, pixmap.width(), pixmap.height()));
- // Compute the set of pixels we'll actually end up painting.
- gfx::Rect dest_rect = gfx::IntersectRects(clip + offset, clip);
- if (dest_rect.size().IsEmpty())
- return; // Nothing to do.
- // Compute the source pixels that will map to the dest_rect
- gfx::Rect src_rect = dest_rect - offset;
- size_t row_bytes = dest_rect.width() * 4;
- if (offset.y() > 0) {
- // Data is moving down, copy from the bottom up.
- for (int y = dest_rect.height() - 1; y >= 0; y--) {
- memcpy(pixmap.writable_addr32(dest_rect.x(), dest_rect.y() + y),
- pixmap.addr32(src_rect.x(), src_rect.y() + y),
- row_bytes);
- }
- } else if (offset.y() < 0) {
- // Data is moving up, copy from the top down.
- for (int y = 0; y < dest_rect.height(); y++) {
- memcpy(pixmap.writable_addr32(dest_rect.x(), dest_rect.y() + y),
- pixmap.addr32(src_rect.x(), src_rect.y() + y),
- row_bytes);
- }
- } else if (offset.x() != 0) {
- // Horizontal-only scroll. We can do it in either top-to-bottom or bottom-
- // to-top, but have to be careful about the order for copying each row.
- // Fortunately, memmove already handles this for us.
- for (int y = 0; y < dest_rect.height(); y++) {
- memmove(pixmap.writable_addr32(dest_rect.x(), dest_rect.y() + y),
- pixmap.addr32(src_rect.x(), src_rect.y() + y),
- row_bytes);
- }
- }
- }
- } // namespace gfx
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