4 files changed, 58 insertions, 5 deletions

diff --git a/libs/hwui/RenderNode.cpp b/libs/hwui/RenderNode.cpp
index b31c554c1914..5a3300ab8044 100644
--- a/libs/hwui/RenderNode.cpp
+++ b/libs/hwui/RenderNode.cpp
@@ -421,12 +421,14 @@ void RenderNode::prepareTreeImpl(TreeInfo& info, bool functorsNeedLayer) {
     prepareSubTree(info, childFunctorsNeedLayer, mDisplayList);
     pushLayerUpdate(info);
 
-    for (auto& vectorDrawable : mDisplayList->getVectorDrawables()) {
-        // If any vector drawable in the display list needs update, damage the node.
-        if (vectorDrawable->isDirty()) {
-            damageSelf(info);
+    if (mDisplayList) {
+        for (auto& vectorDrawable : mDisplayList->getVectorDrawables()) {
+            // If any vector drawable in the display list needs update, damage the node.
+            if (vectorDrawable->isDirty()) {
+                damageSelf(info);
+            }
+            vectorDrawable->setPropertyChangeWillBeConsumed(true);
         }
-        vectorDrawable->setPropertyChangeWillBeConsumed(true);
     }
 
     info.damageAccumulator->popTransform();
diff --git a/libs/hwui/renderthread/CanvasContext.cpp b/libs/hwui/renderthread/CanvasContext.cpp
index 597c5c56eec2..d4956bed25e8 100644
--- a/libs/hwui/renderthread/CanvasContext.cpp
+++ b/libs/hwui/renderthread/CanvasContext.cpp
@@ -149,6 +149,8 @@ void CanvasContext::setStopped(bool stopped) {
             if (mEglManager.isCurrent(mEglSurface)) {
                 mEglManager.makeCurrent(EGL_NO_SURFACE);
             }
+        } else if (mIsDirty && hasSurface()) {
+            mRenderThread.postFrameCallback(this);
         }
     }
 }
@@ -231,6 +233,8 @@ void CanvasContext::prepareTree(TreeInfo& info, int64_t* uiFrameInfo,
     freePrefetchedLayers(info.observer);
     GL_CHECKPOINT(MODERATE);
 
+    mIsDirty = true;
+
     if (CC_UNLIKELY(!mNativeSurface.get())) {
         mCurrentFrameInfo->addFlag(FrameInfoFlags::SkippedFrame);
         info.out.canDrawThisFrame = false;
@@ -504,6 +508,7 @@ void CanvasContext::draw() {
     // Even if we decided to cancel the frame, from the perspective of jank
     // metrics the frame was swapped at this point
     mCurrentFrameInfo->markSwapBuffers();
+    mIsDirty = false;
 
     if (drew || mEglManager.damageRequiresSwap()) {
         if (CC_UNLIKELY(!mEglManager.swapBuffers(frame, screenDirty))) {
diff --git a/libs/hwui/renderthread/CanvasContext.h b/libs/hwui/renderthread/CanvasContext.h
index e739b2949cf9..a6eb7adc3568 100644
--- a/libs/hwui/renderthread/CanvasContext.h
+++ b/libs/hwui/renderthread/CanvasContext.h
@@ -187,7 +187,12 @@ private:
     EglManager& mEglManager;
     sp<Surface> mNativeSurface;
     EGLSurface mEglSurface = EGL_NO_SURFACE;
+    // stopped indicates the CanvasContext will reject actual redraw operations,
+    // and defer repaint until it is un-stopped
     bool mStopped = false;
+    // CanvasContext is dirty if it has received an update that it has not
+    // painted onto its surface.
+    bool mIsDirty = false;
     bool mBufferPreserved = false;
     SwapBehavior mSwapBehavior = kSwap_default;
     struct SwapHistory {
diff --git a/libs/hwui/tests/unit/RenderNodeTests.cpp b/libs/hwui/tests/unit/RenderNodeTests.cpp
index b2997dfb357f..cf76a8691dcd 100644
--- a/libs/hwui/tests/unit/RenderNodeTests.cpp
+++ b/libs/hwui/tests/unit/RenderNodeTests.cpp
@@ -16,13 +16,26 @@
 
 #include <gtest/gtest.h>
 
+#include "AnimationContext.h"
+#include "DamageAccumulator.h"
+#include "IContextFactory.h"
 #include "RenderNode.h"
 #include "TreeInfo.h"
+#include "renderthread/CanvasContext.h"
 #include "tests/common/TestUtils.h"
 #include "utils/Color.h"
 
 using namespace android;
 using namespace android::uirenderer;
+using namespace android::uirenderer::renderthread;
+
+class ContextFactory : public android::uirenderer::IContextFactory {
+public:
+    android::uirenderer::AnimationContext* createAnimationContext
+        (android::uirenderer::renderthread::TimeLord& clock) override {
+        return new android::uirenderer::AnimationContext(clock);
+    }
+};
 
 TEST(RenderNode, hasParents) {
     auto child = TestUtils::createNode(0, 0, 200, 400,
@@ -89,3 +102,31 @@ TEST(RenderNode, releasedCallback) {
     TestUtils::syncHierarchyPropertiesAndDisplayList(node);
     EXPECT_EQ(0, refcnt);
 }
+
+RENDERTHREAD_TEST(RenderNode, prepareTree_nullableDisplayList) {
+    ContextFactory contextFactory;
+    CanvasContext canvasContext(renderThread, false, nullptr, &contextFactory);
+    TreeInfo info(TreeInfo::MODE_RT_ONLY, canvasContext);
+    DamageAccumulator damageAccumulator;
+    info.damageAccumulator = &damageAccumulator;
+    info.observer = nullptr;
+
+    {
+        auto nonNullDLNode = TestUtils::createNode(0, 0, 200, 400,
+                [](RenderProperties& props, TestCanvas& canvas) {
+            canvas.drawColor(Color::Red_500, SkXfermode::kSrcOver_Mode);
+        });
+        TestUtils::syncHierarchyPropertiesAndDisplayList(nonNullDLNode);
+        EXPECT_TRUE(nonNullDLNode->getDisplayList());
+        nonNullDLNode->prepareTree(info);
+    }
+
+    {
+        auto nullDLNode = TestUtils::createNode(0, 0, 200, 400, nullptr);
+        TestUtils::syncHierarchyPropertiesAndDisplayList(nullDLNode);
+        EXPECT_FALSE(nullDLNode->getDisplayList());
+        nullDLNode->prepareTree(info);
+    }
+
+    canvasContext.destroy(nullptr);
+}