Add PlatformPictureSkia and RecordingPlatformDeviceSkia.

skia/ext/recording_platform_device_skia.cc

+// 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 "skia/ext/recording_platform_device_skia.h"
+
+#include "skia/ext/platform_canvas.h"
+#include "third_party/skia/include/core/SkClipStack.h"
+#include "third_party/skia/include/core/SkDraw.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkRegion.h"
+#include "third_party/skia/include/core/SkScalar.h"
+
+namespace skia {
+
+SkDevice* CreateRecordingPlatformDeviceSkia(
+    SkPicture* picture, int width, int height) {
+  SkBitmap bm;
+  bm.setConfig(SkBitmap::kNo_Config, width, height);
+  return new RecordingPlatformDeviceSkia(bm, picture);
+}
+
+RecordingPlatformDeviceSkia::RecordingPlatformDeviceSkia(
+    const SkBitmap& bitmap, SkPicture* picture)
+    : SkDevice(bitmap),
+      picture_(picture) {
+  SetPlatformDevice(this, this);
+}
+
+RecordingPlatformDeviceSkia::~RecordingPlatformDeviceSkia() {
+}
+
+bool RecordingPlatformDeviceSkia::IsNativeFontRenderingAllowed() {
+  return false;
+}
+
+bool RecordingPlatformDeviceSkia::IsNativeRenderingAllowed() {
+  return true;
+}
+
+PlatformSurface RecordingPlatformDeviceSkia::BeginPlatformPaint() {
+  // Even when recording drawing commands of the page, we have to
+  // provide a raster surface for plugins to render into. Therefore we
+  // create a BitmapPlatformDevice here and return the context from it,
+  // then layer on the raster data as an image in EndPlatformPaint.
+  SkASSERT(raster_canvas_ == NULL);
+  raster_canvas_ = CreateBitmapCanvas(width(), height(), false);
+  raster_canvas_->unref();  // SkRefPtr and create both took a reference.
+
+  // Copy picture and playback to raster surface.

[reed1, 2012/09/17 16:51:24]

Why do you need to make a copy of the picture?

[reveman, 2012/09/17 21:22:16]

Is there another way to playback a SkPicture without stopping the current
recording?

+  SkPicture raster_picture(*picture_);
+  raster_canvas_->drawPicture(raster_picture);
+  // Save the effect of all currently recorded matrix operations.
+  raster_matrix_ = raster_canvas_->getTotalMatrix();
+
+  return skia::BeginPlatformPaint(raster_canvas_.get());
+}
+
+void RecordingPlatformDeviceSkia::EndPlatformPaint() {
+  SkASSERT(raster_canvas_ != NULL);
+  SkMatrix inverse;
+  // To add a drawing command that will render the raster surface at the
+  // correct origin we need to revert the effect of all currently
+  // recorded matrix operations.

[reed1, 2012/09/17 16:51:24]

If you're done with the raster after this call, it will be more efficient to
mark that bitmap has being "immutable" before it is recorded, otherwise the
picture-recording code will make a deep-copy of it.

[reveman, 2012/09/17 21:22:16]

Ah, thanks for pointing this out! It would be nice to avoid a deep-copy here.

Looks like I'll have to add some PlatformDevice API to support this though. I'd
like this initial patch to not grow too large. Would it be OK that I add a TODO
here and follow up with this improvement in a separate patch?

+  if (raster_matrix_.invert(&inverse)) {
+    SkCanvas* canvas = picture_->getRecordingCanvas();

[reed1, 2012/09/17 16:51:24]

Shouldn't we "reset" the recording at this point, since the bitmap, by
definition, contains all of the necessary data for the drawing up to this point?

[reveman, 2012/09/17 21:22:16]

We need to maintain all the state that's been set by previous commands. Also any
kind of absolute matrix modification here would break the typical per-tile
painting usage pattern of SkPicture where we playback with a different initial
X/Y translation.

+    SkASSERT(canvas != NULL);
+    canvas->save();
+    canvas->concat(inverse);
+    SkPaint paint;
+    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
+    canvas->drawBitmap(
+        raster_canvas_->getDevice()->accessBitmap(false), 0, 0, &paint);
+    canvas->restore();
+  }
+  // PlatformCanvas matches begin and end calls.

[reed1, 2012/09/17 16:51:24]

1. not sure what that comment means.
2. who deletes the canvas that raster_canvas_ points to?

[reveman, 2012/09/17 21:22:16]

hm, I copied that from vector_platform_device_skia. I don't think the comment is
needed. I assumed it was supposed to mean that this is the PlatformCanvas call
that matches our previous BeginPlatformPaint call.
It's a SkRefPtr so my assumption was that this is done automatically when all
references are dropped.

+  skia::EndPlatformPaint(raster_canvas_.get());
+  raster_canvas_ = NULL;

[reed1, 2012/09/17 16:51:24]

At this point, perhaps we should just covert over to a raster from now own. Why
have a raster + more picture opts, when we could just become a raster?

[reveman, 2012/09/17 21:22:16]

The current patch is creating temporary bitmaps the size of the device but
that's just a detail of the current implementation that I intend to improve soon
after this lands as that's not really an option when recording full pages.

My current plan is to limit the size of the temporary bitmap to the current
clip. Seems like that would work well as we already propagate the clip to
platform device. 

+}
+
+#if defined(OS_WIN)
+void RecordingPlatformDeviceSkia::DrawToNativeContext(
+    HDC dc, int x, int y, const RECT* src_rect) {
+  SkASSERT(false);
+}
+#elif defined(OS_MACOSX)
+void RecordingPlatformDeviceSkia::DrawToNativeContext(
+    CGContext* context, int x, int y, const CGRect* src_rect) {
+  SkASSERT(false);
+}
+
+CGContextRef RecordingPlatformDeviceSkia::GetBitmapContext() {
+  SkASSERT(false);
+  return NULL;
+}
+#elif defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_OPENBSD)
+void RecordingPlatformDeviceSkia::DrawToNativeContext(
+    PlatformSurface surface, int x, int y, const PlatformRect* src_rect) {
+  // Should never be called on Linux.
+  SkASSERT(false);
+}
+#endif
+
+}  // namespace skia