drm_hwcomposer: have DrmDisplayCompositor do its own OpenGL composition

To accomplish this a few things changed:
- DrmComposition::GetRemainingLayers always returns the number of planes needed
- DrmComposition::AddLayer succeeds even if no DrmPlane was found for it
- DrmDisplayComposition::AddLayer has overload that imports the given buffer
- GLWorkerCompositor has a function to finish its composite before returning

Put together this change makes DrmComposition always accepts all layers given to
it even if it means some of those layers are assigned a NULL DrmPlane. The
DrmDisplayCompositor will scan its given layers for any that are missing planes.
In such a case, a DrmPlane is stolen from the last layer to receive a plane.
Then all layers in the DrmDisplayComposition that have no planes (including the
one stolen from) are composited synchronously using a GLWorkerCompositor and a
new layer is generated from the results. That layer is added to the
DrmDisplayComposition using the new import AddLayer function and the stolen
DrmPlane. DrmDisplayCompostior then continues as usual.

Change-Id: Ia6477c210c8f1307a4e537bec46889110d79ca18

1 files changed, 10 insertions, 0 deletions

diff --git a/drmdisplaycompositor.h b/drmdisplaycompositor.h
index 9f50664..46d71ae 100644
--- a/drmdisplaycompositor.h
+++ b/drmdisplaycompositor.h
@@ -20,6 +20,7 @@
 #include "drm_hwcomposer.h"
 #include "drmcomposition.h"
 #include "drmcompositorworker.h"
+#include "drmframebuffer.h"
 
 #include <pthread.h>
 #include <queue>
@@ -28,8 +29,12 @@
 #include <hardware/hardware.h>
 #include <hardware/hwcomposer.h>
 
+#define DRM_DISPLAY_BUFFERS 2
+
 namespace android {
 
+class GLWorkerCompositor;
+
 class DrmDisplayCompositor {
  public:
   DrmDisplayCompositor();
@@ -46,6 +51,7 @@ class DrmDisplayCompositor {
  private:
   DrmDisplayCompositor(const DrmDisplayCompositor &) = delete;
 
+  int ApplyPreComposite(DrmDisplayComposition *display_comp);
   int ApplyFrame(DrmDisplayComposition *display_comp);
   int ApplyDpms(DrmDisplayComposition *display_comp);
 
@@ -62,6 +68,10 @@ class DrmDisplayCompositor {
   bool initialized_;
   bool active_;
 
+  int framebuffer_index_;
+  DrmFramebuffer framebuffers_[DRM_DISPLAY_BUFFERS];
+  std::unique_ptr<GLWorkerCompositor> pre_compositor_;
+
   // mutable since we need to acquire in HaveQueuedComposites
   mutable pthread_mutex_t lock_;