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GLConsumer: Fix crop math

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When we have excess pixels that need to be removed from (for example)
the left and right sides, we currently do something like:

  left += excess / 2;
  right -= excess / 2;

If excess is odd, however, this removes 1 too few pixels since the odd
pixel gets rounded down twice. This changes the math to effectively:

  left += excess / 2;
  right -= (excess - excess / 2);

Which removes the correct total number of pixels.

Bug: 19611086
Change-Id: I8d1ad9fe7ba67c149794c148663d12acbccccef0
This commit is contained in:
Dan Stoza 2015-06-09 15:05:23 -07:00
parent 47a7dc81d0
commit ec4cb38750
1 changed files with 10 additions and 6 deletions
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16
libs/gui/GLConsumer.cpp
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@ -901,14 +901,18 @@ Rect GLConsumer::getCurrentCrop() const {
// The crop is too wide
if (newWidth < currentWidth) {
uint32_t dw = (currentWidth - newWidth) / 2;
outCrop.left += dw;
outCrop.right -= dw;
uint32_t dw = currentWidth - newWidth;
auto halfdw = dw / 2;
outCrop.left += halfdw;
// Not halfdw because it would subtract 1 too few when dw is odd
outCrop.right -= (dw - halfdw);
// The crop is too tall
} else if (newHeight < currentHeight) {
uint32_t dh = (currentHeight - newHeight) / 2;
outCrop.top += dh;
outCrop.bottom -= dh;
uint32_t dh = currentHeight - newHeight;
auto halfdh = dh / 2;
outCrop.top += halfdh;
// Not halfdh because it would subtract 1 too few when dh is odd
outCrop.bottom -= (dh - halfdh);
}
GLC_LOGV("getCurrentCrop final crop [%d,%d,%d,%d]",