Move all the ImageWallpaper logic outside the main thread

In order to avoid any thread contention, all the ImageWallpaper logic should be moved out of the main thread. This CL moves the last things that were done on the main thread:
   - Call surface.lockCanvas and canvas.drawBitmap
   - Call reportEngineShown

Bug: 242969351
Test: atest ImageWallpaperTest
Test: treehugger
Change-Id: I2a4400c8eaf0d9b8a182e618655855188a15892b

packages/SystemUI/src/com/android/systemui/wallpapers/ImageWallpaper.java

@@ -45,7 +45,6 @@ import androidx.annotation.NonNull;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.systemui.dagger.qualifiers.Background;
-import com.android.systemui.dagger.qualifiers.Main;
 import com.android.systemui.flags.FeatureFlags;
 import com.android.systemui.util.concurrency.DelayableExecutor;
 import com.android.systemui.wallpapers.canvas.WallpaperLocalColorExtractor;
@@ -57,7 +56,6 @@ import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.Executor;
 
 import javax.inject.Inject;
 
@@ -88,17 +86,12 @@ public class ImageWallpaper extends WallpaperService {
     private final DelayableExecutor mBackgroundExecutor;
     private static final int DELAY_UNLOAD_BITMAP = 2000;
 
-    @Main
-    private final Executor mMainExecutor;
-
     @Inject
     public ImageWallpaper(FeatureFlags featureFlags,
-            @Background DelayableExecutor backgroundExecutor,
-            @Main Executor mainExecutor) {
+            @Background DelayableExecutor backgroundExecutor) {
         super();
         mFeatureFlags = featureFlags;
         mBackgroundExecutor = backgroundExecutor;
-        mMainExecutor = mainExecutor;
     }
 
     @Override
@@ -662,13 +655,9 @@ public class ImageWallpaper extends WallpaperService {
                 loadWallpaperAndDrawFrameInternal();
             } else {
                 mBitmapUsages++;
-
-                // drawing is done on the main thread
-                mMainExecutor.execute(() -> {
-                    drawFrameOnCanvas(mBitmap);
-                    reportEngineShown(false);
-                    unloadBitmapIfNotUsed();
-                });
+                drawFrameOnCanvas(mBitmap);
+                reportEngineShown(false);
+                unloadBitmapIfNotUsedInternal();
             }
         }
 
@@ -706,11 +695,15 @@ public class ImageWallpaper extends WallpaperService {
 
         private void unloadBitmapIfNotUsedSynchronized() {
             synchronized (mLock) {
-                mBitmapUsages -= 1;
-                if (mBitmapUsages <= 0) {
-                    mBitmapUsages = 0;
-                    unloadBitmapInternal();
-                }
+                unloadBitmapIfNotUsedInternal();
+            }
+        }
+
+        private void unloadBitmapIfNotUsedInternal() {
+            mBitmapUsages -= 1;
+            if (mBitmapUsages <= 0) {
+                mBitmapUsages = 0;
+                unloadBitmapInternal();
             }
         }
 

packages/SystemUI/tests/src/com/android/systemui/wallpapers/ImageWallpaperTest.java

@@ -108,7 +108,6 @@ public class ImageWallpaperTest extends SysuiTestCase {
     private FeatureFlags mFeatureFlags;
 
     FakeSystemClock mFakeSystemClock = new FakeSystemClock();
-    FakeExecutor mFakeMainExecutor = new FakeExecutor(mFakeSystemClock);
     FakeExecutor mFakeBackgroundExecutor = new FakeExecutor(mFakeSystemClock);
 
     private CountDownLatch mEventCountdown;
@@ -163,7 +162,7 @@ public class ImageWallpaperTest extends SysuiTestCase {
     }
 
     private ImageWallpaper createImageWallpaper() {
-        return new ImageWallpaper(mFeatureFlags, mFakeBackgroundExecutor, mFakeMainExecutor) {
+        return new ImageWallpaper(mFeatureFlags, mFakeBackgroundExecutor) {
             @Override
             public Engine onCreateEngine() {
                 return new GLEngine(mHandler) {
@@ -242,7 +241,7 @@ public class ImageWallpaperTest extends SysuiTestCase {
 
 
     private ImageWallpaper createImageWallpaperCanvas() {
-        return new ImageWallpaper(mFeatureFlags, mFakeBackgroundExecutor, mFakeMainExecutor) {
+        return new ImageWallpaper(mFeatureFlags, mFakeBackgroundExecutor) {
             @Override
             public Engine onCreateEngine() {
                 return new CanvasEngine() {
@@ -315,11 +314,10 @@ public class ImageWallpaperTest extends SysuiTestCase {
         assertThat(mFakeBackgroundExecutor.numPending()).isAtLeast(1);
 
         int n = 0;
-        while (mFakeBackgroundExecutor.numPending() + mFakeMainExecutor.numPending() >= 1) {
+        while (mFakeBackgroundExecutor.numPending() >= 1) {
             n++;
             assertThat(n).isAtMost(10);
             mFakeBackgroundExecutor.runNextReady();
-            mFakeMainExecutor.runNextReady();
             mFakeSystemClock.advanceTime(1000);
         }