[ANativeWindow] Add getLastQueuedBuffer api

Bug: 137012798
Bug: 148962594
Test: builds
Change-Id: I3dcf6741c8d5dc62b7ae13d5cf5dc56173f95660

3 files changed, 59 insertions, 0 deletions

diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index 23532e7e38..278cc593b7 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -1180,6 +1180,9 @@ int Surface::perform(int operation, va_list args)
         allocateBuffers();
         res = NO_ERROR;
         break;
+    case NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER:
+        res = dispatchGetLastQueuedBuffer(args);
+        break;
     default:
         res = NAME_NOT_FOUND;
         break;
@@ -1452,6 +1455,30 @@ int Surface::dispatchAddQueueInterceptor(va_list args) {
     return NO_ERROR;
 }
 
+int Surface::dispatchGetLastQueuedBuffer(va_list args) {
+    AHardwareBuffer** buffer = va_arg(args, AHardwareBuffer**);
+    int* fence = va_arg(args, int*);
+    float* matrix = va_arg(args, float*);
+    sp<GraphicBuffer> graphicBuffer;
+    sp<Fence> spFence;
+
+    int result = mGraphicBufferProducer->getLastQueuedBuffer(&graphicBuffer, &spFence, matrix);
+
+    if (graphicBuffer != nullptr) {
+        *buffer = reinterpret_cast<AHardwareBuffer*>(graphicBuffer.get());
+        AHardwareBuffer_acquire(*buffer);
+    } else {
+        *buffer = nullptr;
+    }
+
+    if (spFence != nullptr) {
+        *fence = spFence->dup();
+    } else {
+        *fence = -1;
+    }
+    return result;
+}
+
 bool Surface::transformToDisplayInverse() {
     return (mTransform & NATIVE_WINDOW_TRANSFORM_INVERSE_DISPLAY) ==
             NATIVE_WINDOW_TRANSFORM_INVERSE_DISPLAY;
diff --git a/libs/gui/include/gui/Surface.h b/libs/gui/include/gui/Surface.h
index 0139507101..4a353fc659 100644
--- a/libs/gui/include/gui/Surface.h
+++ b/libs/gui/include/gui/Surface.h
@@ -262,6 +262,7 @@ private:
     int dispatchAddDequeueInterceptor(va_list args);
     int dispatchAddPerformInterceptor(va_list args);
     int dispatchAddQueueInterceptor(va_list args);
+    int dispatchGetLastQueuedBuffer(va_list args);
     bool transformToDisplayInverse();
 
 protected:
diff --git a/libs/nativewindow/include/system/window.h b/libs/nativewindow/include/system/window.h
index 121374b1d5..f686147a5f 100644
--- a/libs/nativewindow/include/system/window.h
+++ b/libs/nativewindow/include/system/window.h
@@ -253,6 +253,7 @@ enum {
     NATIVE_WINDOW_SET_PERFORM_INTERCEPTOR         = 43,    /* private */
     NATIVE_WINDOW_SET_QUEUE_INTERCEPTOR           = 44,    /* private */
     NATIVE_WINDOW_ALLOCATE_BUFFERS                = 45,    /* private */
+    NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER          = 46,    /* private */
     // clang-format on
 };
 
@@ -1018,4 +1019,34 @@ static inline int native_window_set_frame_rate(struct ANativeWindow* window, flo
     return window->perform(window, NATIVE_WINDOW_SET_FRAME_RATE, (double)frameRate);
 }
 
+// ------------------------------------------------------------------------------------------------
+// Candidates for APEX visibility
+// These functions are planned to be made stable for APEX modules, but have not
+// yet been stabilized to a specific api version.
+// ------------------------------------------------------------------------------------------------
+
+/**
+ * Retrieves the last queued buffer for this window, along with the fence that
+ * fires when the buffer is ready to be read, and the 4x4 coordinate
+ * transform matrix that should be applied to the buffer's content. The
+ * transform matrix is represented in column-major order.
+ *
+ * If there was no buffer previously queued, then outBuffer will be NULL and
+ * the value of outFence will be -1.
+ *
+ * Note that if outBuffer is not NULL, then the caller will hold a reference
+ * onto the buffer. Accordingly, the caller must call AHardwareBuffer_release
+ * when the buffer is no longer needed so that the system may reclaim the
+ * buffer.
+ *
+ * \return NO_ERROR on success.
+ * \return NO_MEMORY if there was insufficient memory.
+ */
+static inline int ANativeWindow_getLastQueuedBuffer(ANativeWindow* window,
+                                                    AHardwareBuffer** outBuffer, int* outFence,
+                                                    float outTransformMatrix[16]) {
+    return window->perform(window, NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER, outBuffer, outFence,
+                           outTransformMatrix);
+}
+
 __END_DECLS