Fix cursor missing in tabCapture on OSX Sierra

content/browser/media/capture/cursor_renderer.cc

Index: content/browser/media/capture/cursor_renderer.cc
diff --git a/content/browser/media/capture/cursor_renderer.cc b/content/browser/media/capture/cursor_renderer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..33223a706aa8b7d3f2b357577d35b74227c7a013
--- /dev/null
+++ b/content/browser/media/capture/cursor_renderer.cc
@@ -0,0 +1,212 @@
+// Copyright (c) 2016 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 "content/browser/media/capture/cursor_renderer.h"
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "skia/ext/image_operations.h"
+
+#if defined(USE_AURA)

[miu, 2016/12/27 23:21:03]

It seems these platform-specific includes should be removed.

[braveyao, 2017/01/04 01:57:48]

Done.

+#include "content/browser/media/capture/cursor_renderer_aura.h"
+#elif defined(OS_MACOSX)
+#include "content/browser/media/capture/cursor_renderer_mac.h"
+#endif
+
+namespace content {
+
+namespace {
+
+inline int clip_byte(int x) {
+  return std::max(0, std::min(x, 255));
+}
+
+inline int alpha_blend(int alpha, int src, int dst) {
+  return (src * alpha + dst * (255 - alpha)) / 255;
+}
+
+}  // namespace
+
+CursorRenderer::CursorRenderer(gfx::NativeView view,
+                               CursorDisplaySetting cursor_display_setting)
+    : captured_view_(view),
+      cursor_display_setting_(cursor_display_setting),
+      tick_clock_(&default_tick_clock_),
+      weak_factory_(this) {
+  Clear();
+}
+
+CursorRenderer::~CursorRenderer() {}
+
+base::WeakPtr<CursorRenderer> CursorRenderer::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
+}
+
+void CursorRenderer::Clear() {
+  last_cursor_ = gfx::NativeCursor();
+  last_cursor_hot_point_ = gfx::Point();
+  window_size_when_cursor_last_updated_ = gfx::Size();
+  scaled_cursor_bitmap_.reset();
+  last_mouse_position_x_ = 0;
+  last_mouse_position_y_ = 0;
+  last_mouse_movement_timestamp_ = base::TimeTicks::Now();
+  if (cursor_display_setting_ == kCursorEnabledOnMouseMovement) {
+    cursor_displayed_ = false;
+  } else {
+    cursor_displayed_ = true;
+  }
+}
+
+bool CursorRenderer::SnapshotCursorState(const gfx::Rect& region_in_frame) {
+  if (!captured_view_) {
+    DVLOG(2) << "Skipping update with no window being tracked";

[miu, 2016/12/27 23:21:02]

nit: For consistency, let's call it a "view" instead of a "window" here and
everywhere else. The "window" terminology referred to an Aura Window (which
corresponds to a view). I know, confusing. ;-)

[braveyao, 2017/01/04 01:57:48]

Done.

+    return false;
+  }
+
+  // If we are sharing the root window, or namely the whole screen, we will
+  // render the mouse cursor. For ordinary window, we only render the mouse
+  // cursor when the window is active.
+  if (!IsCapturedViewActive()) {
+    // Return early if the target window is not active.
+    DVLOG(2) << "Skipping update on an inactive window";
+    Clear();
+    return false;
+  }
+
+  gfx::NativeCursor cursor = GetLastKnownCursor();

[miu, 2016/12/27 23:21:03]

Please move this down to just before it will first be used. (Since we will only
use this once we know the cursor should be displayed.)

[braveyao, 2017/01/04 01:57:49]

Done.

+  gfx::Point cursor_position = GetCursorPositionInView();

[miu, 2016/12/27 23:21:03]

Please move this down to just before it will first be used. (Since there is no
reason to invoke the method if |view_size| is empty.)

[braveyao, 2017/01/04 01:57:48]

Done.

+  gfx::Size view_size = GetCapturedViewSize();
+
+  if (view_size.IsEmpty()) {
+    DVLOG(2) << "Skipping update on an empty view";
+    Clear();
+    return false;
+  }
+
+  if (cursor_position.x() < 0 || cursor_position.y() < 0 ||

[miu, 2016/12/27 23:21:02]

nit: A trick to make this simpler:

  if (!gfx::Rect(view_size).Contains(cursor_position)) {
    ...
    return false;
  }

[braveyao, 2017/01/04 01:57:49]

Done.

+      cursor_position.x() > view_size.width() ||
+      cursor_position.y() > view_size.height()) {
+    DVLOG(2) << "Skipping update with cursor outside the window";
+    Clear();
+    return false;
+  }
+
+  if (cursor_display_setting_ == kCursorEnabledOnMouseMovement) {
+    if (cursor_displayed_) {
+      // Stop displaying cursor if there has been no mouse movement
+      base::TimeTicks now = tick_clock_->NowTicks();
+      if ((now - last_mouse_movement_timestamp_) >
+          base::TimeDelta::FromSeconds(MAX_IDLE_TIME_SECONDS)) {
+        cursor_displayed_ = false;
+        DVLOG(2) << "Turning off cursor display after idle time";
+      }
+    }
+    if (!cursor_displayed_)
+      return false;
+  }
+
+  const float x_scale =
+      static_cast<float>(region_in_frame.width()) / view_size.width();
+  const float y_scale =
+      static_cast<float>(region_in_frame.height()) / view_size.height();
+
+  if (last_cursor_ != cursor ||
+      window_size_when_cursor_last_updated_ != view_size) {

[miu, 2016/12/27 23:21:03]

The scaled size also depends on |region_in_frame.size()|, so it seems this
should be:

  if (last_cursor_ != cursor ||
      window_size_when_cursor_last_updated_ != view_size ||
      last_region_in_frame_size_ != region_in_frame.size()) {
    ...
  }

However, from the code within the then-block, only |x_scale| and |y_scale|
affect the result, so this would be simpler:

  if (last_cursor_ != cursor || last_x_scale_ != x_scale ||
      last_y_scale_ != y_scale) {
    ...
  }

[braveyao, 2017/01/04 01:57:48]

Done.

+    SkBitmap cursor_bitmap = GetLastKnownCursorImage();
+    const int scaled_width = cursor_bitmap.width() * x_scale;
+    const int scaled_height = cursor_bitmap.height() * y_scale;
+    if (scaled_width <= 0 || scaled_height <= 0) {
+      DVLOG(2) << "scaled_width <= 0";
+      Clear();
+      return false;
+    }
+    scaled_cursor_bitmap_ = skia::ImageOperations::Resize(
+        cursor_bitmap, skia::ImageOperations::RESIZE_BEST, scaled_width,
+        scaled_height);
+
+    last_cursor_hot_point_ = GetLastKnownCursorHotPoint();
+    last_cursor_ = cursor;
+    window_size_when_cursor_last_updated_ = view_size;
+  }
+
+  cursor_position.Offset(-last_cursor_hot_point_.x(),
+                         -last_cursor_hot_point_.y());
+  cursor_position_in_frame_ =
+      gfx::Point(region_in_frame.x() + cursor_position.x() * x_scale,
+                 region_in_frame.y() + cursor_position.y() * y_scale);
+  return true;
+}
+
+// Helper function to composite a cursor bitmap on a YUV420 video frame.
+void CursorRenderer::RenderOnVideoFrame(
+    const scoped_refptr<media::VideoFrame>& target) const {
+  if (scaled_cursor_bitmap_.isNull())
+    return;
+
+  DCHECK(target);
+
+  gfx::Rect rect = gfx::IntersectRects(
+      gfx::Rect(scaled_cursor_bitmap_.width(), scaled_cursor_bitmap_.height()) +
+          gfx::Vector2d(cursor_position_in_frame_.x(),
+                        cursor_position_in_frame_.y()),
+      target->visible_rect());
+
+  scaled_cursor_bitmap_.lockPixels();
+  for (int y = rect.y(); y < rect.bottom(); ++y) {
+    int cursor_y = y - cursor_position_in_frame_.y();
+    uint8_t* yplane = target->data(media::VideoFrame::kYPlane) +
+                      y * target->row_bytes(media::VideoFrame::kYPlane);
+    uint8_t* uplane = target->data(media::VideoFrame::kUPlane) +
+                      (y / 2) * target->row_bytes(media::VideoFrame::kUPlane);
+    uint8_t* vplane = target->data(media::VideoFrame::kVPlane) +
+                      (y / 2) * target->row_bytes(media::VideoFrame::kVPlane);
+    for (int x = rect.x(); x < rect.right(); ++x) {
+      int cursor_x = x - cursor_position_in_frame_.x();
+      SkColor color = scaled_cursor_bitmap_.getColor(cursor_x, cursor_y);
+      int alpha = SkColorGetA(color);
+      int color_r = SkColorGetR(color);
+      int color_g = SkColorGetG(color);
+      int color_b = SkColorGetB(color);
+      int color_y = clip_byte(
+          ((color_r * 66 + color_g * 129 + color_b * 25 + 128) >> 8) + 16);
+      yplane[x] = alpha_blend(alpha, color_y, yplane[x]);
+
+      // Only sample U and V at even coordinates.
+      if ((x % 2 == 0) && (y % 2 == 0)) {
+        int color_u = clip_byte(
+            ((color_r * -38 + color_g * -74 + color_b * 112 + 128) >> 8) + 128);
+        int color_v = clip_byte(
+            ((color_r * 112 + color_g * -94 + color_b * -18 + 128) >> 8) + 128);
+        uplane[x / 2] = alpha_blend(alpha, color_u, uplane[x / 2]);
+        vplane[x / 2] = alpha_blend(alpha, color_v, vplane[x / 2]);
+      }
+    }
+  }
+  scaled_cursor_bitmap_.unlockPixels();
+}
+
+void CursorRenderer::OnMouseMoved(const gfx::Point& location,
+                                  base::TimeTicks timestamp) {
+  if (!cursor_displayed_) {
+    if (std::abs(location.x() - last_mouse_position_x_) > MIN_MOVEMENT_PIXELS ||
+        std::abs(location.y() - last_mouse_position_y_) > MIN_MOVEMENT_PIXELS)
+      cursor_displayed_ = true;
+  }
+
+  if (cursor_displayed_) {
+    last_mouse_movement_timestamp_ = timestamp;
+    last_mouse_position_x_ = location.x();
+    last_mouse_position_y_ = location.y();
+  }
+}
+
+void CursorRenderer::OnMouseClicked(const gfx::Point& location,
+                                    base::TimeTicks timestamp) {
+  cursor_displayed_ = true;
+  last_mouse_movement_timestamp_ = timestamp;
+  last_mouse_position_x_ = location.x();
+  last_mouse_position_y_ = location.y();
+}
+
+}  // namespace content