commit e9953b1752a583058e639ef3de456988ab6ef7bf
author Robert Carr <racarr@google.com> Mon May 23 20:52:04 2016 -0700
committer Robert Carr <racarr@google.com> Mon May 23 20:57:11 2016 -0700
tree 55f6c2235feba13a4df849c9f83a4436c81a6cde
parent 2486cb2c8978003d2b5cfa7e8169019421582cb0

Force pending transactions to flush before screenshot.

Following 14e54ba747 (ag/1043009) we need to push an empty
synchronous transaction if we want to ensure all previous
transactions have occured before taking a screenshot. In
light of Bug 7552304 it seems wise to do this before screenshoting
applications.

Bug: 27098060
Bug: 7552304
Change-Id: I6d7dfbe634a288c55449d2f1d6fbbfc13bab08ad

core/java/android/view/SurfaceControl.java

diff --git a/core/java/android/view/SurfaceControl.java b/core/java/android/view/SurfaceControl.java
index 7b01267..b4131b4 100644
--- a/core/java/android/view/SurfaceControl.java
+++ b/core/java/android/view/SurfaceControl.java
@@ -46,7 +46,7 @@
             boolean allLayers, boolean useIdentityTransform);
 
     private static native void nativeOpenTransaction();
-    private static native void nativeCloseTransaction();
+    private static native void nativeCloseTransaction(boolean sync);
     private static native void nativeSetAnimationTransaction();
 
     private static native void nativeSetLayer(long nativeObject, int zorder);
@@ -372,7 +372,11 @@
 
     /** end a transaction */
     public static void closeTransaction() {
-        nativeCloseTransaction();
+        nativeCloseTransaction(false);
+    }
+
+    public static void closeTransactionSync() {
+        nativeCloseTransaction(true);
     }
 
     public void deferTransactionUntil(IBinder handle, long frame) {

core/jni/android_view_SurfaceControl.cpp

diff --git a/core/jni/android_view_SurfaceControl.cpp b/core/jni/android_view_SurfaceControl.cpp
index 864a0bf..a9ed9dc 100644
--- a/core/jni/android_view_SurfaceControl.cpp
+++ b/core/jni/android_view_SurfaceControl.cpp
@@ -223,8 +223,9 @@
     SurfaceComposerClient::openGlobalTransaction();
 }
 
-static void nativeCloseTransaction(JNIEnv* env, jclass clazz) {
-    SurfaceComposerClient::closeGlobalTransaction();
+
+static void nativeCloseTransaction(JNIEnv* env, jclass clazz, jboolean sync) {
+    SurfaceComposerClient::closeGlobalTransaction(sync);
 }
 
 static void nativeSetAnimationTransaction(JNIEnv* env, jclass clazz) {
@@ -649,7 +650,7 @@
             (void*)nativeScreenshot },
     {"nativeOpenTransaction", "()V",
             (void*)nativeOpenTransaction },
-    {"nativeCloseTransaction", "()V",
+    {"nativeCloseTransaction", "(Z)V",
             (void*)nativeCloseTransaction },
     {"nativeSetAnimationTransaction", "()V",
             (void*)nativeSetAnimationTransaction },

services/core/java/com/android/server/wm/WindowManagerService.java

diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 82cd0fa..d60e8d6 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -6381,6 +6381,11 @@
             if (DEBUG_SCREENSHOT && inRotation) Slog.v(TAG_WM,
                     "Taking screenshot while rotating");
 
+            // We force pending transactions to flush before taking
+            // the screenshot by pushing an empty synchronous transaction.
+            SurfaceControl.openTransaction();
+            SurfaceControl.closeTransactionSync();
+
             bm = SurfaceControl.screenshot(crop, width, height, minLayer, maxLayer,
                     inRotation, rot);
             if (bm == null) {