GLConsumer: Fix crop math
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
diff --git a/libs/gui/GLConsumer.cpp b/libs/gui/GLConsumer.cpp
index 9fcac2d..757e08a 100644
--- a/libs/gui/GLConsumer.cpp
+++ b/libs/gui/GLConsumer.cpp
@@ -901,14 +901,18 @@
// 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]",