Backport 'Add ability to disable GL draws'.

This feature is intended for use in headless test environments,
where disabling drawing has minimal compatibility impact and can
save significant resource usage when running UI tests.

This feature is controlled via a new system property
'debug.hwui.drawing_enabled', and a HardwareRenderer API that can
override the property value on a per-process basis.

Bug: 201691826
Test: boot emulator
Merged-In: I93c21e680382e03342f235dbf58bd7a5c8a6f767
Change-Id: I391c841e3a0cdcfcc6c7910a316a4dd5e970547d

graphics/java/android/graphics/HardwareRenderer.java

@@ -22,6 +22,7 @@ import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.app.Activity;
 import android.app.ActivityManager;
+import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
 import android.content.pm.ActivityInfo;
 import android.content.res.Configuration;
@@ -1075,6 +1076,53 @@ public class HardwareRenderer {
         ProcessInitializer.sInstance.setContext(context);
     }
 
+    /**
+     * Returns true if HardwareRender will produce output.
+     *
+     * This value is global to the process and affects all uses of HardwareRenderer,
+     * including
+     * those created by the system such as those used by the View tree when using hardware
+     * accelerated rendering.
+     *
+     * Default is true in all production environments, but may be false in testing-focused
+     * emulators or if {@link #setDrawingEnabled(boolean)} is used.
+     *
+     * Backported from android T.
+     *
+     * @hide
+     */
+    @UnsupportedAppUsage
+    public static boolean isDrawingEnabled() {
+        return nIsDrawingEnabled();
+    }
+
+    /**
+     * Toggles whether or not HardwareRenderer will produce drawing output globally in the current
+     * process.
+     *
+     * This applies to all HardwareRenderer instances, including those created by the platform such
+     * as those used by the system for hardware accelerated View rendering.
+     *
+     * The capability to disable drawing output is intended for test environments, primarily
+     * headless ones. By setting this to false, tests that launch activities or interact with Views
+     * can be quicker with less RAM usage by skipping the final step of View drawing. All View
+     * lifecycle events will occur as normal, only the final step of rendering on the GPU to the
+     * display will be skipped.
+     *
+     * This can be toggled on and off at will, so screenshot tests can also run in this same
+     * environment by toggling drawing back on and forcing a frame to be drawn such as by calling
+     * view#invalidate(). Once drawn and the screenshot captured, this can then be turned back off.
+     *
+     * Backported from android T.
+     *
+     * @hide
+     */
+    // TODO: Add link to androidx's Screenshot library for help with this
+    @UnsupportedAppUsage
+    public static void setDrawingEnabled(boolean drawingEnabled) {
+        nSetDrawingEnabled(drawingEnabled);
+    }
+
     private static final class DestroyContextRunnable implements Runnable {
         private final long mNativeInstance;
 
@@ -1393,4 +1441,8 @@ public class HardwareRenderer {
 
     private static native void nInitDisplayInfo(int width, int height, float refreshRate,
             int wideColorDataspace, long appVsyncOffsetNanos, long presentationDeadlineNanos);
+
+    private static native void nSetDrawingEnabled(boolean drawingEnabled);
+
+    private static native boolean nIsDrawingEnabled();
 }

libs/hwui/Properties.cpp

@@ -88,6 +88,9 @@ bool Properties::enableWebViewOverlays = false;
 
 StretchEffectBehavior Properties::stretchEffectBehavior = StretchEffectBehavior::ShaderHWUI;
 
+bool Properties::drawingEnabled = true;
+OverrideDrawingEnabled Properties::overrideDrawingEnabled = OverrideDrawingEnabled::Default;
+
 bool Properties::load() {
     bool prevDebugLayersUpdates = debugLayersUpdates;
     bool prevDebugOverdraw = debugOverdraw;
@@ -141,6 +144,11 @@ bool Properties::load() {
 
     enableWebViewOverlays = base::GetBoolProperty(PROPERTY_WEBVIEW_OVERLAYS_ENABLED, false);
 
+    drawingEnabled = base::GetBoolProperty(PROPERTY_DRAWING_ENABLED, true);
+    if (!drawingEnabled) {
+        enableRTAnimations = false;
+    }
+
     return (prevDebugLayersUpdates != debugLayersUpdates) || (prevDebugOverdraw != debugOverdraw);
 }
 
@@ -210,5 +218,18 @@ void Properties::overrideRenderPipelineType(RenderPipelineType type, bool inUnit
     sRenderPipelineType = type;
 }
 
+void Properties::setDrawingEnabled(bool newDrawingEnabled) {
+    overrideDrawingEnabled =
+            newDrawingEnabled ? OverrideDrawingEnabled::On : OverrideDrawingEnabled::Off;
+    enableRTAnimations = newDrawingEnabled;
+}
+
+bool Properties::isDrawingEnabled() {
+    if (overrideDrawingEnabled == OverrideDrawingEnabled::Default) {
+        return drawingEnabled;
+    }
+    return overrideDrawingEnabled == OverrideDrawingEnabled::On;
+}
+
 }  // namespace uirenderer
 }  // namespace android

libs/hwui/Properties.h

@@ -187,6 +187,12 @@ enum DebugLevel {
  */
 #define PROPERTY_WEBVIEW_OVERLAYS_ENABLED "debug.hwui.webview_overlays_enabled"
 
+/**
+ * Property for globally GL drawing state. Can be overridden per process with
+ * setDrawingEnabled.
+ */
+#define PROPERTY_DRAWING_ENABLED "debug.hwui.drawing_enabled"
+
 ///////////////////////////////////////////////////////////////////////////////
 // Misc
 ///////////////////////////////////////////////////////////////////////////////
@@ -208,6 +214,8 @@ enum class StretchEffectBehavior {
     UniformScale  // Uniform scale stretch everywhere
 };
 
+enum class OverrideDrawingEnabled { Default, On, Off };
+
 /**
  * Renderthread-only singleton which manages several static rendering properties. Most of these
  * are driven by system properties which are queried once at initialization, and again if init()
@@ -301,6 +309,12 @@ public:
         stretchEffectBehavior = behavior;
     }
 
+    // Represents if GL drawing is enabled. Should only be false in headless testing environments
+    static bool drawingEnabled;
+    static OverrideDrawingEnabled overrideDrawingEnabled;
+    static bool isDrawingEnabled();
+    static void setDrawingEnabled(bool enable);
+
 private:
     static StretchEffectBehavior stretchEffectBehavior;
     static ProfileType sProfileType;

libs/hwui/jni/android_graphics_HardwareRenderer.cpp

@@ -817,6 +817,14 @@ static void android_view_ThreadedRenderer_initDisplayInfo(JNIEnv*, jclass, jint
     DeviceInfo::setPresentationDeadlineNanos(presentationDeadlineNanos);
 }
 
+static void android_view_ThreadedRenderer_setDrawingEnabled(JNIEnv*, jclass, jboolean enabled) {
+    Properties::setDrawingEnabled(enabled);
+}
+
+static jboolean android_view_ThreadedRenderer_isDrawingEnabled(JNIEnv*, jclass) {
+    return Properties::isDrawingEnabled();
+}
+
 // ----------------------------------------------------------------------------
 // HardwareRendererObserver
 // ----------------------------------------------------------------------------
@@ -953,6 +961,9 @@ static const JNINativeMethod gMethods[] = {
         {"preload", "()V", (void*)android_view_ThreadedRenderer_preload},
         {"isWebViewOverlaysEnabled", "()Z",
          (void*)android_view_ThreadedRenderer_isWebViewOverlaysEnabled},
+        {"nSetDrawingEnabled", "(Z)V", (void*)android_view_ThreadedRenderer_setDrawingEnabled},
+        {"nIsDrawingEnabled", "()Z", (void*)android_view_ThreadedRenderer_isDrawingEnabled},
+
 };
 
 static JavaVM* mJvm = nullptr;

libs/hwui/renderthread/CanvasContext.cpp

@@ -256,7 +256,7 @@ void CanvasContext::setStopped(bool stopped) {
 }
 
 void CanvasContext::allocateBuffers() {
-    if (mNativeSurface) {
+    if (mNativeSurface && Properties::isDrawingEnabled()) {
         ANativeWindow_tryAllocateBuffers(mNativeSurface->getNativeWindow());
     }
 }
@@ -480,7 +480,8 @@ nsecs_t CanvasContext::draw() {
     SkRect dirty;
     mDamageAccumulator.finish(&dirty);
 
-    if (dirty.isEmpty() && Properties::skipEmptyFrames && !surfaceRequiresRedraw()) {
+    if (!Properties::isDrawingEnabled() ||
+        (dirty.isEmpty() && Properties::skipEmptyFrames && !surfaceRequiresRedraw())) {
         mCurrentFrameInfo->addFlag(FrameInfoFlags::SkippedFrame);
         if (auto grContext = getGrContext()) {
             // Submit to ensure that any texture uploads complete and Skia can

libs/hwui/renderthread/CanvasContext.h

@@ -90,9 +90,17 @@ public:
      *         and false otherwise (e.g. cache limits have been exceeded).
      */
     bool pinImages(std::vector<SkImage*>& mutableImages) {
+        if (!Properties::isDrawingEnabled()) {
+            return true;
+        }
         return mRenderPipeline->pinImages(mutableImages);
     }
-    bool pinImages(LsaVector<sk_sp<Bitmap>>& images) { return mRenderPipeline->pinImages(images); }
+    bool pinImages(LsaVector<sk_sp<Bitmap>>& images) {
+        if (!Properties::isDrawingEnabled()) {
+            return true;
+        }
+        return mRenderPipeline->pinImages(images);
+    }
 
     /**
      * Unpin any image that had be previously pinned to the GPU cache