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// Copyright (c) 2006-2008 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.
#import <Cocoa/Cocoa.h>
#include "chrome/browser/renderer_host/backing_store.h"
#include "chrome/browser/renderer_host/render_widget_host.h"
#include "chrome/browser/renderer_host/render_widget_host_view.h"
#include "base/logging.h"
#include "base/mac_util.h"
#include "chrome/common/transport_dib.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkCanvas.h"
// Mac Backing Stores:
//
// Since backing stores are only ever written to or drawn into windows, we keep
// our backing store in a CGLayer that can get cached in GPU memory. This
// allows acclerated drawing into the layer and lets scrolling and such happen
// all or mostly on the GPU, which is good for performance.
BackingStore::BackingStore(RenderWidgetHost* widget, const gfx::Size& size)
: render_widget_host_(widget),
size_(size),
cg_layer_(NULL) {
// We want our CGLayer to be optimized for drawing into our containing
// window, so extract a CGContext corresponding to that window that we can
// pass to CGLayerCreateWithContext.
NSWindow* containing_window = [widget->view()->GetNativeView() window];
if (!containing_window) {
// If we are not in a containing window yet, create a CGBitmapContext
// to use as a stand-in for the layer.
cg_bitmap_.reset(CGBitmapContextCreate(NULL, size.width(), size.height(),
8, size.width() * 8, mac_util::GetSystemColorSpace(),
kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
} else {
CGContextRef context = static_cast<CGContextRef>(
[[containing_window graphicsContext] graphicsPort]);
CGLayerRef layer = CGLayerCreateWithContext(context, size.ToCGSize(), NULL);
cg_layer_.reset(layer);
}
}
BackingStore::~BackingStore() {
}
size_t BackingStore::MemorySize() {
// Estimate memory usage as 4 bytes per pixel.
return size_.GetArea() * 4;
}
// Paint the contents of a TransportDIB into a rectangle of our CGLayer
void BackingStore::PaintRect(base::ProcessHandle process,
TransportDIB* bitmap,
const gfx::Rect& bitmap_rect) {
scoped_cftyperef<CGDataProviderRef> data_provider(
CGDataProviderCreateWithData(NULL, bitmap->memory(),
bitmap_rect.width() * bitmap_rect.height() * 4, NULL));
scoped_cftyperef<CGImageRef> image(
CGImageCreate(bitmap_rect.width(), bitmap_rect.height(), 8, 32,
4 * bitmap_rect.width(), mac_util::GetSystemColorSpace(),
kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host,
data_provider, NULL, false, kCGRenderingIntentDefault));
if (!cg_layer()) {
// we don't have a CGLayer yet, so see if we can create one.
NSWindow* containing_window =
[render_widget_host()->view()->GetNativeView() window];
if (containing_window) {
CGContextRef context = static_cast<CGContextRef>(
[[containing_window graphicsContext] graphicsPort]);
CGLayerRef layer =
CGLayerCreateWithContext(context, size().ToCGSize(), NULL);
cg_layer_.reset(layer);
// now that we have a layer, copy the cached image into it
scoped_cftyperef<CGImageRef> bitmap_image(
CGBitmapContextCreateImage(cg_bitmap_));
CGContextDrawImage(CGLayerGetContext(layer),
CGRectMake(0, 0, size().width(), size().height()),
bitmap_image);
// Discard the cache bitmap, since we no longer need it.
cg_bitmap_.reset(NULL);
}
}
if (cg_layer()) {
// The CGLayer's origin is in the lower left, but flipping the CTM would
// cause the image to get drawn upside down. So we move the rectangle
// to the right position before drawing the image.
CGContextRef layer = CGLayerGetContext(cg_layer());
gfx::Rect paint_rect = bitmap_rect;
paint_rect.set_y(size_.height() - bitmap_rect.bottom());
CGContextDrawImage(layer, paint_rect.ToCGRect(), image);
} else {
// The layer hasn't been created yet, so draw into the cache bitmap.
gfx::Rect paint_rect = bitmap_rect;
paint_rect.set_y(size_.height() - bitmap_rect.bottom());
CGContextDrawImage(cg_bitmap_, paint_rect.ToCGRect(), image);
}
}
// Scroll the contents of our CGLayer
void BackingStore::ScrollRect(base::ProcessHandle process,
TransportDIB* bitmap,
const gfx::Rect& bitmap_rect,
int dx, int dy,
const gfx::Rect& clip_rect,
const gfx::Size& view_size) {
// "Scroll" the contents of the layer by creating a new CGLayer,
// copying the contents of the old one into the new one offset by the scroll
// amount, swapping in the new CGLayer, and then painting in the new data.
//
// The Windows code always sets the whole backing store as the source of the
// scroll. Thus, we only have to worry about pixels which will end up inside
// the clipping rectangle. (Note that the clipping rectangle is not
// translated by the scroll.)
// We assume |clip_rect| is contained within the backing store.
CGSize layer_size = CGLayerGetSize(cg_layer());
DCHECK(clip_rect.bottom() <= layer_size.height);
DCHECK(clip_rect.right() <= layer_size.width);
if ((dx && abs(dx) < layer_size.width) ||
(dy && abs(dy) < layer_size.height)) {
if (cg_layer()) {
CGContextRef context = CGLayerGetContext(cg_layer());
scoped_cftyperef<CGLayerRef> new_layer(
CGLayerCreateWithContext(context, layer_size, NULL));
CGContextRef layer = CGLayerGetContext(new_layer);
CGContextDrawLayerAtPoint(layer, CGPointMake(0, 0), cg_layer());
CGContextSaveGState(layer);
CGContextClipToRect(layer, CGRectMake(clip_rect.x(),
size_.height() - clip_rect.bottom(),
clip_rect.width(),
clip_rect.height()));
CGContextDrawLayerAtPoint(layer, CGPointMake(dx, -dy), cg_layer());
CGContextRestoreGState(layer);
cg_layer_.swap(new_layer);
} else {
// We don't have a layer, so scroll the contents of the CGBitmapContext.
scoped_cftyperef<CGContextRef> new_bitmap(
CGBitmapContextCreate(NULL, size_.width(), size_.height(), 8,
size_.width() * 8, mac_util::GetSystemColorSpace(),
kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
scoped_cftyperef<CGImageRef> bitmap_image(
CGBitmapContextCreateImage(cg_bitmap_));
CGContextDrawImage(new_bitmap,
CGRectMake(0, 0, size_.width(), size_.height()),
bitmap_image);
CGContextSaveGState(new_bitmap);
CGContextClipToRect(new_bitmap,
CGRectMake(clip_rect.x(),
size_.height() - clip_rect.bottom(),
clip_rect.width(),
clip_rect.height()));
CGContextDrawImage(new_bitmap,
CGRectMake(dx, -dy, size_.width(), size_.height()),
bitmap_image);
CGContextRestoreGState(new_bitmap);
cg_bitmap_.swap(new_bitmap);
}
}
// Now paint the new bitmap data
PaintRect(process, bitmap, bitmap_rect);
return;
}
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