libgui: Allow an IGBProducer to disable allocation

Adds a new method IGBP::allowAllocation, which controls whether
dequeueBuffer is permitted to allocate a new buffer. If allocation is
disallowed, dequeueBuffer will block or return an error as it
normally would (as controlled by *ControlledByApp).

If there are free buffers, but they are not of the correct dimensions,
format, or usage, they may be freed if a more suitable buffer is not
found first.

Bug: 19801715
Change-Id: I0d604958b78b2fd775c2547690301423f9a52165

2 files changed, 5 insertions, 0 deletions

diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index 0e94f0d..11cbdc6 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -526,6 +526,10 @@ void VirtualDisplaySurface::allocateBuffers(bool /* async */,
     // TODO: Should we actually allocate buffers for a virtual display?
 }
 
+status_t VirtualDisplaySurface::allowAllocation(bool /* allow */) {
+    return INVALID_OPERATION;
+}
+
 void VirtualDisplaySurface::updateQueueBufferOutput(
         const QueueBufferOutput& qbo) {
     uint32_t w, h, transformHint, numPendingBuffers;
diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
index 0a3f4a1..97af980 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
@@ -115,6 +115,7 @@ private:
     virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
     virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
             PixelFormat format, uint32_t usage);
+    virtual status_t allowAllocation(bool allow);
 
     //
     // Utility methods