Allow GPU composition to occur at a lower resolution

Add a vendor-specified system property to allow GPU fallback composition to occur at a lower resolution than the display mode resolution.

Bug: 144574809

Test: Tested with sysprop disabled, and tested backport in Android Q with sysprop enabled. Unable to test on Android R due to device issues.

Change-Id: I02948ce72f49d20416d0e4dd45a4cffe99e28820
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
index 36544b6..aeffb0e 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
@@ -57,9 +57,12 @@
  */
 
 FramebufferSurface::FramebufferSurface(HWComposer& hwc, DisplayId displayId,
-                                       const sp<IGraphicBufferConsumer>& consumer)
+                                       const sp<IGraphicBufferConsumer>& consumer,
+                                       uint32_t maxWidth, uint32_t maxHeight)
       : ConsumerBase(consumer),
         mDisplayId(displayId),
+        mMaxWidth(maxWidth),
+        mMaxHeight(maxHeight),
         mCurrentBufferSlot(-1),
         mCurrentBuffer(),
         mCurrentFence(Fence::NO_FENCE),
@@ -75,14 +78,16 @@
                                        GRALLOC_USAGE_HW_RENDER |
                                        GRALLOC_USAGE_HW_COMPOSER);
     const auto& activeConfig = mHwc.getActiveConfig(displayId);
-    mConsumer->setDefaultBufferSize(activeConfig->getWidth(),
-            activeConfig->getHeight());
+    ui::Size limitedSize =
+            limitFramebufferSize(activeConfig->getWidth(), activeConfig->getHeight());
+    mConsumer->setDefaultBufferSize(limitedSize.width, limitedSize.height);
     mConsumer->setMaxAcquiredBufferCount(
             SurfaceFlinger::maxFrameBufferAcquiredBuffers - 1);
 }
 
-void FramebufferSurface::resizeBuffers(const uint32_t width, const uint32_t height) {
-    mConsumer->setDefaultBufferSize(width, height);
+void FramebufferSurface::resizeBuffers(uint32_t width, uint32_t height) {
+    ui::Size limitedSize = limitFramebufferSize(width, height);
+    mConsumer->setDefaultBufferSize(limitedSize.width, limitedSize.height);
 }
 
 status_t FramebufferSurface::beginFrame(bool /*mustRecompose*/) {
@@ -177,6 +182,29 @@
     }
 }
 
+ui::Size FramebufferSurface::limitFramebufferSize(uint32_t width, uint32_t height) {
+    // TODO(b/149495759): Use the ui::Size constructor once it no longer is broken.
+    ui::Size framebufferSize;
+    framebufferSize.width = width;
+    framebufferSize.height = height;
+    bool wasLimited = true;
+    if (width > mMaxWidth && mMaxWidth != 0) {
+        float aspectRatio = float(width) / float(height);
+        framebufferSize.height = mMaxWidth / aspectRatio;
+        framebufferSize.width = mMaxWidth;
+        wasLimited = true;
+    }
+    if (height > mMaxHeight && mMaxHeight != 0) {
+        float aspectRatio = float(width) / float(height);
+        framebufferSize.height = mMaxHeight;
+        framebufferSize.width = mMaxHeight * aspectRatio;
+        wasLimited = true;
+    }
+    ALOGI_IF(wasLimited, "framebuffer size has been limited to [%dx%d] from [%dx%d]",
+             framebufferSize.width, framebufferSize.height, width, height);
+    return framebufferSize;
+}
+
 void FramebufferSurface::dumpAsString(String8& result) const {
     Mutex::Autolock lock(mMutex);
     result.appendFormat("  FramebufferSurface: dataspace: %s(%d)\n",
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
index 7f451a5..a1859f3 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
@@ -23,6 +23,7 @@
 #include <compositionengine/DisplaySurface.h>
 #include <compositionengine/impl/HwcBufferCache.h>
 #include <gui/ConsumerBase.h>
+#include <ui/Size.h>
 
 #include "DisplayIdentification.h"
 
@@ -39,7 +40,8 @@
 class FramebufferSurface : public ConsumerBase, public compositionengine::DisplaySurface {
 public:
     FramebufferSurface(HWComposer& hwc, DisplayId displayId,
-                       const sp<IGraphicBufferConsumer>& consumer);
+                       const sp<IGraphicBufferConsumer>& consumer, uint32_t maxWidth,
+                       uint32_t maxHeight);
 
     virtual status_t beginFrame(bool mustRecompose);
     virtual status_t prepareFrame(CompositionType compositionType);
@@ -47,7 +49,7 @@
     virtual void onFrameCommitted();
     virtual void dumpAsString(String8& result) const;
 
-    virtual void resizeBuffers(const uint32_t width, const uint32_t height);
+    virtual void resizeBuffers(uint32_t width, uint32_t height);
 
     virtual const sp<Fence>& getClientTargetAcquireFence() const override;
 
@@ -58,6 +60,9 @@
 
     virtual void dumpLocked(String8& result, const char* prefix) const;
 
+    // Limits the width and height by the maximum width specified in the constructor.
+    ui::Size limitFramebufferSize(uint32_t width, uint32_t height);
+
     // nextBuffer waits for and then latches the next buffer from the
     // BufferQueue and releases the previously latched buffer to the
     // BufferQueue.  The new buffer is returned in the 'buffer' argument.
@@ -66,6 +71,14 @@
 
     const DisplayId mDisplayId;
 
+    // Framebuffer size has a dimension limitation in pixels based on the graphics capabilities of
+    // the device.
+    const uint32_t mMaxWidth;
+
+    // Framebuffer size has a dimension limitation in pixels based on the graphics capabilities of
+    // the device.
+    const uint32_t mMaxHeight;
+
     // mCurrentBufferIndex is the slot index of the current buffer or
     // INVALID_BUFFER_SLOT to indicate that either there is no current buffer
     // or the buffer is not associated with a slot.