Implements core logic for Pixel Canvas

ui/compositor/paint_recorder.cc

Index: ui/compositor/paint_recorder.cc
diff --git a/ui/compositor/paint_recorder.cc b/ui/compositor/paint_recorder.cc
index 8a8c4c28caf55c97e0c6cc0c0bc55e86f98430cc..e3ac08d17b93f8dd6f9cc76c0053363eb23533c0 100644
--- a/ui/compositor/paint_recorder.cc
+++ b/ui/compositor/paint_recorder.cc
@@ -21,27 +21,41 @@ namespace ui {
 // to the |context|'s PaintOpBuffer.
 PaintRecorder::PaintRecorder(const PaintContext& context,
                              const gfx::Size& recording_size,
+                             const gfx::PointF recording_scale,
                              PaintCache* cache)
     : context_(context),
       record_canvas_(cache ? cache->ResetCache() : context_.list_->StartPaint(),
                      gfx::RectToSkRect(gfx::Rect(recording_size))),
-      canvas_(&record_canvas_, context.device_scale_factor_),
+      canvas_(&record_canvas_, context_.device_scale_factor_),

[danakj, 2017/07/25 17:58:56]

why these changes?

[malaykeshav, 2017/07/25 22:57:58]

Done

       cache_(cache),
       recording_size_(recording_size) {
 #if DCHECK_IS_ON()
-  DCHECK(!context.inside_paint_recorder_);
-  context.inside_paint_recorder_ = true;
+  DCHECK(!context_.inside_paint_recorder_);
+  context_.inside_paint_recorder_ = true;
 #endif
+  if (context_.is_pixel_canvas()) {
+    canvas()->Save();
+    canvas()->Scale(recording_scale.x(), recording_scale.y());
+  }
 }
 
 PaintRecorder::PaintRecorder(const PaintContext& context,
                              const gfx::Size& recording_size)
-    : PaintRecorder(context, recording_size, nullptr) {}
+    : PaintRecorder(
+          context,
+          gfx::ScaleToRoundedSize(

[danakj, 2017/07/25 17:58:56]

Why is this constructor changing the recording_size, but the other isn't? Should
the caller be deciding this?

[malaykeshav, 2017/07/25 22:57:58]

There are 32 occurrences to this and they need to be handled case by case. Some
of them need a simple scaling while others need to call
paint_info->paint_recording_size(). Since this is behind a flag, I am trying to
keep the core changes to a minimum. In the end, this will be moved out to the
caller.

[danakj, 2017/07/26 16:06:03]

Can you add a TODO that explains this and points to a bug for this cleanup?

+              recording_size,
+              context.is_pixel_canvas() ? context.device_scale_factor_ : 1.f),
+          gfx::PointF(context.device_scale_factor_,
+                      context.device_scale_factor_),
+          nullptr) {}
 
 PaintRecorder::~PaintRecorder() {
 #if DCHECK_IS_ON()
   context_.inside_paint_recorder_ = false;
 #endif
+  if (context_.is_pixel_canvas())
+    canvas()->Restore();
   // If using cache, append what we've saved there to the PaintContext.
   // Otherwise, the content is already stored in the PaintContext, and we can
   // just close it.