drm_hwcomposer: Use layer alpha to blend planes

Send the layer alpha to the drm plane's alpha property to
properly blend layers.

BUG=b/24821110
TEST=Tested on smaug with Downloads/About windows, blend properly

Change-Id: If96eb28d65d018863c39bc5a3554daef0264144b
Signed-off-by: Sean Paul <seanpaul@chromium.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drmplane.h b/drmplane.h
index 1969d52..ff3380f 100644
--- a/drmplane.h
+++ b/drmplane.h
@@ -52,6 +52,7 @@ class DrmPlane {
   const DrmProperty &src_w_property() const;
   const DrmProperty &src_h_property() const;
   const DrmProperty &rotation_property() const;
+  const DrmProperty &alpha_property() const;
 
  private:
   DrmPlane(const DrmPlane &);
@@ -74,6 +75,7 @@ class DrmPlane {
   DrmProperty src_w_property_;
   DrmProperty src_h_property_;
   DrmProperty rotation_property_;
+  DrmProperty alpha_property_;
 };
 }