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Pre-multiply images for MouseCursorShape.

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BUG=chromium:267270
R=sergeyu@chromium.org

Review URL: https://webrtc-codereview.appspot.com/2173004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4685 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
alexeypa@chromium.org 2013-09-05 19:32:46 +00:00
parent 31b4a5ac82
commit bebf3995ce
1 changed files with 17 additions and 11 deletions
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28
webrtc/modules/desktop_capture/win/cursor.cc
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@ -74,19 +74,21 @@ void AddCursorOutline(int width, int height, uint32_t* data) {
}
}
// Premultiplies RGB components of a pixel by its alpha component.
uint32_t AlphaMul(uint32_t pixel) {
// Premultiplies RGB components of the pixel data in the given image by
// the corresponding alpha components.
void AlphaMul(uint32_t* data, int width, int height) {
COMPILE_ASSERT(sizeof(uint32_t) == kBytesPerPixel);
RGBQUAD from = *reinterpret_cast<RGBQUAD*>(&pixel);
RGBQUAD to = {
(static_cast<uint16_t>(from.rgbBlue) * from.rgbReserved) / 0xff,
(static_cast<uint16_t>(from.rgbGreen) * from.rgbReserved) / 0xff,
(static_cast<uint16_t>(from.rgbRed) * from.rgbReserved) / 0xff,
from.rgbReserved
};
return *reinterpret_cast<uint32_t*>(&to);
for (uint32_t* data_end = data + width * height; data != data_end; ++data) {
RGBQUAD* from = reinterpret_cast<RGBQUAD*>(data);
RGBQUAD* to = reinterpret_cast<RGBQUAD*>(data);
to->rgbBlue =
(static_cast<uint16_t>(from->rgbBlue) * from->rgbReserved) / 0xff;
to->rgbGreen =
(static_cast<uint16_t>(from->rgbGreen) * from->rgbReserved) / 0xff;
to->rgbRed =
(static_cast<uint16_t>(from->rgbRed) * from->rgbReserved) / 0xff;
}
}
// Scans a 32bpp bitmap looking for any pixels with non-zero alpha component.
@ -244,6 +246,10 @@ MouseCursorShape* CreateMouseCursorShapeFromCursor(HDC dc, HCURSOR cursor) {
}
}
// Pre-multiply the resulting pixels since MouseCursorShape uses premultiplied
// images.
AlphaMul(color_plane, width, height);
scoped_ptr<MouseCursorShape> result(new MouseCursorShape());
result->data.assign(reinterpret_cast<char*>(color_plane),
height * width * kBytesPerPixel);