Implements core logic for Pixel Canvas

ui/views/paint_info.cc

Index: ui/views/paint_info.cc
diff --git a/ui/views/paint_info.cc b/ui/views/paint_info.cc
new file mode 100644
index 0000000000000000000000000000000000000000..36accfb1a4d62b4dd3ef3f1685c6334de91482ec
--- /dev/null
+++ b/ui/views/paint_info.cc
@@ -0,0 +1,122 @@
+// Copyright 2017 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/views/paint_info.h"
+
+namespace views {
+
+// static
+PaintInfo PaintInfo::CreateRootPaintInfo(const ui::PaintContext& root_context,
+                                         const gfx::Size& size) {
+  return PaintInfo(root_context, size);
+}
+
+//  static
+PaintInfo PaintInfo::CreateChildPaintInfo(const PaintInfo& other,
+                                          const gfx::Rect& bounds,
+                                          const gfx::Size& parent_size,
+                                          ScaleType scale_type) {
+  return PaintInfo(other, bounds, parent_size, scale_type);
+}
+
+PaintInfo::PaintInfo(const ui::PaintContext& root_context,

[sky, 2017/07/28 16:02:11]

Style guide says order of declarations and definitions should match.

[malaykeshav, 2017/07/31 18:54:29]

The style guide mentions that classes should be defined before any other methods
but below the static methods. So I am not sure what the right order is in this
case.

[sky, 2017/08/01 15:10:24]

Here's the relevant item, "Function declaration order should match function
definition order." So, in the header you have CreateRootPaintInfo, which means
that should be the first function you have here.

[malaykeshav, 2017/08/01 19:31:01]

Done

+                     const gfx::Size& size)
+    : paint_recording_scale_x_(root_context.is_pixel_canvas()
+                                   ? root_context.device_scale_factor()
+                                   : 1.f),
+      paint_recording_scale_y_(paint_recording_scale_x_),
+      paint_recording_bounds_(
+          gfx::ScaleToRoundedRect(gfx::Rect(size), paint_recording_scale_x_)),
+      context_(root_context, gfx::Vector2d()),
+      root_context_(&root_context) {}
+
+PaintInfo::PaintInfo(const PaintInfo& other,
+                     const gfx::Rect& bounds,
+                     const gfx::Size& parent_size,
+                     ScaleType scale_type)
+    : paint_recording_scale_x_(1.f),
+      paint_recording_scale_y_(1.f),
+      paint_recording_bounds_(
+          other.GetSnappedRecordingBounds(parent_size, bounds)),
+      offset_from_parent_(paint_recording_bounds_.OffsetFromOrigin() -
+                          other.paint_recording_bounds_.OffsetFromOrigin()),
+      context_(other.context(), offset_from_parent_),
+      root_context_(nullptr) {
+  ComputePaintRecordingScales(bounds.size(), scale_type);
+}
+
+PaintInfo::PaintInfo(const PaintInfo& other)
+    : paint_recording_scale_x_(other.paint_recording_scale_x_),
+      paint_recording_scale_y_(other.paint_recording_scale_y_),
+      paint_recording_bounds_(other.paint_recording_bounds_),
+      offset_from_parent_(other.offset_from_parent_),
+      context_(other.context(), ui::PaintContext::CLONE_WITHOUT_INVALIDATION),
+      root_context_(nullptr) {}
+
+PaintInfo::~PaintInfo() {}
+
+bool PaintInfo::IsPixelCanvas() const {
+  return context().is_pixel_canvas();
+}
+
+void PaintInfo::ComputePaintRecordingScales(const gfx::Size& size,

[sky, 2017/07/28 16:02:11]

You only call this from one place, how about moving it to the place it's called?
I could see keeping it if the calling function was long, but it's not.

[malaykeshav, 2017/07/31 18:54:29]

Done

+                                            ScaleType scale_type) {
+  if (!IsPixelCanvas()) {
+    // If pixel canvas is disabled, all recordings are done in DIPs. These are
+    // later played back on to the raster canvas at |device_scale_factor_|.
+    paint_recording_scale_x_ = paint_recording_scale_y_ = 1.f;

[sky, 2017/07/28 16:02:11]

When you inline this function in the constructor that calls it you should be
able to remove this line, because the constructor already sets it.

[malaykeshav, 2017/07/31 18:54:29]

Ack

+    return;
+  }
+
+  paint_recording_scale_x_ = paint_recording_scale_y_ =
+      context().device_scale_factor();
+  if (scale_type == ScaleType::kScaleToScaleFactor)
+    return;
+
+  if (size.width() > 0) {
+    paint_recording_scale_x_ =
+        static_cast<float>(paint_recording_bounds_.width()) /
+        static_cast<float>(size.width());
+  }
+
+  if (size.height() > 0) {
+    paint_recording_scale_y_ =
+        static_cast<float>(paint_recording_bounds_.height()) /
+        static_cast<float>(size.height());
+  }
+}
+
+gfx::Rect PaintInfo::GetSnappedRecordingBounds(
+    const gfx::Size& parent_size,
+    const gfx::Rect& child_bounds) const {
+  if (!IsPixelCanvas())
+    return (child_bounds + paint_recording_bounds_.OffsetFromOrigin());
+
+  const gfx::Vector2d& child_origin = child_bounds.OffsetFromOrigin();
+
+  int right = child_origin.x() + child_bounds.width();
+  int bottom = child_origin.y() + child_bounds.height();
+
+  int new_x = std::round(child_origin.x() * context().device_scale_factor());
+  int new_y = std::round(child_origin.y() * context().device_scale_factor());
+
+  int new_right;
+  int new_bottom;
+
+  if (right == parent_size.width())
+    new_right = paint_recording_bounds_.width();
+  else
+    new_right = std::round(right * context().device_scale_factor());
+
+  if (bottom == parent_size.height())
+    new_bottom = paint_recording_bounds_.height();
+  else
+    new_bottom = std::round(bottom * context().device_scale_factor());
+
+  return gfx::Rect(new_x + paint_recording_bounds_.x(),
+                   new_y + paint_recording_bounds_.y(), new_right - new_x,
+                   new_bottom - new_y);
+}
+
+}  // namespace views