Add LayerCommand.blockingRegion

This hint tells the HWC that it may use a blocking feature to skip a
portion of the layer's buffer.

Bug: 212736475
Test: TODO (b/213361853)
Change-Id: Ib0fa41e56196feeff201637d5599830d2565da2b

graphics/composer/aidl/aidl_api/android.hardware.graphics.composer3/current/android/hardware/graphics/composer3/LayerCommand.aidl

@@ -54,4 +54,5 @@ parcelable LayerCommand {
   @nullable android.hardware.graphics.composer3.WhitePointNits whitePointNits;
   @nullable android.hardware.graphics.composer3.PerFrameMetadata[] perFrameMetadata;
   @nullable android.hardware.graphics.composer3.PerFrameMetadataBlob[] perFrameMetadataBlob;
+  @nullable android.hardware.graphics.common.Rect[] blockingRegion;
 }

graphics/composer/aidl/android/hardware/graphics/composer3/LayerCommand.aidl

@@ -264,4 +264,15 @@ parcelable LayerCommand {
      * This command may be called every frame.
      */
     @nullable PerFrameMetadataBlob[] perFrameMetadataBlob;
+
+    /**
+     * Specifies a region of the layer that is transparent and may be skipped
+     * by the DPU, e.g. using a blocking region, in order to save power. This
+     * is only a hint, so the composition of the layer must look the same
+     * whether or not this region is skipped.
+     *
+     * The region is in screen space and must not exceed the dimensions of
+     * the screen.
+     */
+    @nullable Rect[] blockingRegion;
 }

graphics/composer/aidl/include/android/hardware/graphics/composer3/ComposerClientWriter.h

@@ -213,6 +213,10 @@ class ComposerClientWriter {
                 .whitePointNits.emplace(WhitePointNits{.nits = whitePointNits});
     }
 
+    void setLayerBlockingRegion(int64_t display, int64_t layer, const std::vector<Rect>& blocking) {
+        getLayerCommand(display, layer).blockingRegion.emplace(blocking.begin(), blocking.end());
+    }
+
     const std::vector<DisplayCommand>& getPendingCommands() {
         flushLayerCommand();
         flushDisplayCommand();