Reland "Update documentation for DISPLAY_DECORATION"
The first time this topic landed, it resulted in b/212402133. We avoid
running into this bug with Ib11d46439db57b90486bad07dd90f2cf0822182a.
Remove references to 8 bit alpha.
Original commit message:
After some discussion, we've decided to always set the ScreenDecorations
to DISPLAY_DECORATION. HWC can decide, based on the format, whether to
truly treat it as DISPLAY_DECORATION, or to change to DEVICE
composition.
Update the documentation to reflect this change.
See also I1da3199bacf5877e88876249c60c0a33fcd44c1e.
Bug: 193170859
Test: NA
Change-Id: Iaf5385c38f6827e07b91a9a0a8769fb7a125e847
diff --git a/graphics/composer/aidl/android/hardware/graphics/composer3/Composition.aidl b/graphics/composer/aidl/android/hardware/graphics/composer3/Composition.aidl
index 4947463..803de06 100644
--- a/graphics/composer/aidl/android/hardware/graphics/composer3/Composition.aidl
+++ b/graphics/composer/aidl/android/hardware/graphics/composer3/Composition.aidl
@@ -74,16 +74,17 @@
*/
SIDEBAND = 5,
/**
- * A display decoration layer contains a buffer which is an 8 bit
- * alpha mask. Pixels in the mask with an alpha of 0 (transparent) will
- * show the content underneath, and pixels with an alpha of 255 will be
- * be rendered in black. An alpha in between will show the content
- * blended with black. This is useful, for example, to provide
+ * A display decoration layer contains a buffer which is used to provide
* anti-aliasing on the cutout region/rounded corners on the top and
* bottom of a display.
*
+ * Pixels in the buffer with an alpha of 0 (transparent) will show the
+ * content underneath, and pixels with a max alpha value will be rendered in
+ * black. An alpha in between will show the underlying content blended with
+ * black.
+ *
* Upon validateDisplay, the device may request a change from this type
- * to CLIENT.
+ * to either DEVICE or CLIENT.
*/
DISPLAY_DECORATION = 6,
}