fixes buffer size and adds pixel size to paint event

atom/browser/api/atom_api_web_contents.cc

@@ -1345,11 +1345,19 @@ bool WebContents::IsOffScreen() const {
 
 void WebContents::OnPaint(const gfx::Rect& dirty_rect,
                           const gfx::Size& bitmap_size,
+                          const int pixel_size,
                           void* bitmap_pixels) {
   v8::MaybeLocal<v8::Object> buffer = node::Buffer::New(
-      isolate(), reinterpret_cast<char*>(bitmap_pixels), sizeof(bitmap_pixels));
+      isolate(), reinterpret_cast<char*>(bitmap_pixels),
+      pixel_size * dirty_rect.width() * dirty_rect.height());
+
+  mate::Dictionary dict = mate::Dictionary::CreateEmpty(isolate());
+  dict.Set("width", bitmap_size.width());
+  dict.Set("height", bitmap_size.height());
+  dict.Set("pixel", pixel_size);
+
   if (!buffer.IsEmpty())
-    Emit("paint", dirty_rect, buffer.ToLocalChecked(), bitmap_size);
+    Emit("paint", dirty_rect, buffer.ToLocalChecked(), dict);
 }
 
 void WebContents::StartPainting() {

atom/browser/api/atom_api_web_contents.h

@@ -160,6 +160,7 @@ class WebContents : public mate::TrackableObject<WebContents>,
   bool IsOffScreen() const;
   void OnPaint(const gfx::Rect& dirty_rect,
                const gfx::Size& bitmap_size,
+               const int pixel_size,
                void* bitmap_pixels);
   void StartPainting();
   void StopPainting();

atom/browser/osr/osr_output_device.cc

@@ -87,7 +87,7 @@ void OffScreenOutputDevice::OnPaint(const gfx::Rect& damage_rect) {
 
   SkAutoLockPixels bitmap_pixels_lock(*bitmap_);
   callback_.Run(rect, gfx::Size(bitmap_->width(), bitmap_->height()),
-                bitmap_->getPixels());
+                bitmap_->bytesPerPixel(), bitmap_->getPixels());
 }
 
 }  // namespace atom

atom/browser/osr/osr_output_device.h

@@ -12,8 +12,8 @@
 
 namespace atom {
 
-typedef base::Callback<void(const gfx::Rect&,
+typedef base::Callback<void(const gfx::Rect&, const gfx::Size&,
-                            const gfx::Size&, void*)> OnPaintCallback;
+                            const int, void*)> OnPaintCallback;
 
 class OffScreenOutputDevice : public cc::SoftwareOutputDevice {
  public:

atom/browser/osr/osr_render_widget_host_view.cc

@@ -262,7 +262,7 @@ class AtomCopyFrameGenerator {
       std::unique_ptr<SkAutoLockPixels> bitmap_pixels_lock) {
     view_->OnPaint(damage_rect,
                    gfx::Size(bitmap.width(), bitmap.height()),
-                   bitmap.getPixels());
+                   bitmap.bytesPerPixel(), bitmap.getPixels());
 
     if (frame_retry_count_ > 0)
       frame_retry_count_ = 0;
@@ -791,11 +791,12 @@ void OffScreenRenderWidgetHostView::SetPaintCallback(
 void OffScreenRenderWidgetHostView::OnPaint(
     const gfx::Rect& damage_rect,
     const gfx::Size& bitmap_size,
+    const int pixel_size,
     void* bitmap_pixels) {
   TRACE_EVENT0("electron", "OffScreenRenderWidgetHostView::OnPaint");
 
   if (!callback_.is_null())
-    callback_.Run(damage_rect, bitmap_size, bitmap_pixels);
+    callback_.Run(damage_rect, bitmap_size, pixel_size, bitmap_pixels);
 }
 
 void OffScreenRenderWidgetHostView::SetPainting(bool painting) {

atom/browser/osr/osr_render_widget_host_view.h

@@ -192,6 +192,7 @@ class OffScreenRenderWidgetHostView
   void SetPaintCallback(const OnPaintCallback& callback);
   void OnPaint(const gfx::Rect& damage_rect,
                const gfx::Size& bitmap_size,
+               const int pixel_size,
                void* bitmap_pixels);
 
   void SetPainting(bool painting);

docs/api/web-contents.md

@@ -352,7 +352,7 @@ Emitted when the cursor's type changes. The `type` parameter can be `default`,
 `not-allowed`, `zoom-in`, `zoom-out`, `grab`, `grabbing`, `custom`.
 
 If the `type` parameter is `custom`, the `image` parameter will hold the custom
-cursor image in a `NativeImage`, and `scale`, `size` and `hotspot` will hold 
+cursor image in a `NativeImage`, and `scale`, `size` and `hotspot` will hold
 additional information about the custom cursor.
 
 #### Event: 'context-menu'
@@ -471,6 +471,7 @@ Returns:
 * `bitmapSize` Object
   * `width` Number - the width of the whole bitmap
   * `height` Number - the height of the whole bitmap
+  * `pixel` Number - The number of bytes per pixel
 
 Emitted when a new frame is generated. Only the dirty area is passed in the
 buffer.