aw: Add stencil test to WebView System Shell

This CL adds checkbox to animation tests inside WebView system shell
that enables external stencil by adding rounded corners clip path to
WebView.

Bug: 956709

Change-Id: Ia918bf2fa6af522bdda90d559eddf24c48172dbc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2075970
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745068}

android_webview/tools/system_webview_shell/BUILD.gn

@@ -33,6 +33,7 @@ android_apk("system_webview_shell_apk") {
     "apk/src/org/chromium/webview_shell/WebViewPackageHelper.java",
     "apk/src/org/chromium/webview_shell/WebViewThreadTestActivity.java",
     "apk/src/org/chromium/webview_shell/WebViewTracingActivity.java",
+    "apk/src/org/chromium/webview_shell/WebViewWithClipPath.java",
   ]
   android_manifest = "apk/AndroidManifest.xml"
   target_sdk_version = 29

android_webview/tools/system_webview_shell/apk/res/layout/activity_webview_animation_test.xml

@@ -34,6 +34,12 @@
             android:checked="false"
             android:text="@string/layer_button" />
     </LinearLayout>
+    <CheckBox
+        android:id="@+id/use_stencil"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:checked="false"
+        android:text="@string/stencil_button" />
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content">
@@ -56,7 +62,7 @@
         android:layout_width="match_parent"
         android:layout_height="0dip"
         android:layout_weight="1">
-        <WebView
+        <org.chromium.webview_shell.WebViewWithClipPath
             android:id="@+id/webview"
             android:layout_width="300dp"
             android:layout_height="300dp"

android_webview/tools/system_webview_shell/apk/res/values/strings.xml

@@ -32,6 +32,7 @@
     <string name="layer_button">Layer</string>
     <string name="rotate_button">Rotate</string>
     <string name="scale_button">Scale</string>
+    <string name="stencil_button">Rounded corner</string>
     <string name="translate_button">Translate</string>
 
     <!--  activity_web_platform_tests strings -->

android_webview/tools/system_webview_shell/apk/src/org/chromium/webview_shell/WebViewAnimationTestActivity.java

@@ -9,7 +9,6 @@ import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.WindowManager;
-import android.webkit.WebView;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.SeekBar;
@@ -66,7 +65,7 @@ public class WebViewAnimationTestActivity extends Activity {
             + "  </body>"
             + "</html>";
 
-    private WebView mWebView;
+    private WebViewWithClipPath mWebView;
     private boolean mIsWindowHardwareAccelerated;
 
     /** Called when the activity is first created. */
@@ -74,7 +73,7 @@ public class WebViewAnimationTestActivity extends Activity {
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_webview_animation_test);
-        mWebView = (WebView) findViewById(R.id.webview);
+        mWebView = (WebViewWithClipPath) findViewById(R.id.webview);
 
         mIsWindowHardwareAccelerated =
                 (getWindow().getAttributes().flags
@@ -115,10 +114,15 @@ public class WebViewAnimationTestActivity extends Activity {
                     @Override
                     public void onStopTrackingTouch(SeekBar seekBar) {}
                 });
-        CheckBox checkBox = ((CheckBox) findViewById(R.id.use_layer));
-        checkBox.setOnCheckedChangeListener(
+        CheckBox layerCheckBox = ((CheckBox) findViewById(R.id.use_layer));
+        layerCheckBox.setOnCheckedChangeListener(
                 (CompoundButton arg0, boolean checked) -> { setWebViewLayer(checked); });
-        setWebViewLayer(checkBox.isChecked());
+        setWebViewLayer(layerCheckBox.isChecked());
+
+        CheckBox stencilCheckBox = ((CheckBox) findViewById(R.id.use_stencil));
+        stencilCheckBox.setOnCheckedChangeListener(
+                (CompoundButton arg0, boolean checked) -> { setUseExternalStencil(checked); });
+        setUseExternalStencil(stencilCheckBox.isChecked());
     }
 
     private void runTranslate() {
@@ -154,4 +158,8 @@ public class WebViewAnimationTestActivity extends Activity {
             mWebView.setLayerType(View.LAYER_TYPE_NONE, null);
         }
     }
+
+    private void setUseExternalStencil(boolean useStecil) {
+        mWebView.setEnableClipPath(useStecil);
+    }
 }

android_webview/tools/system_webview_shell/apk/src/org/chromium/webview_shell/WebViewWithClipPath.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.webview_shell;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Path;
+import android.graphics.RectF;
+import android.util.AttributeSet;
+import android.webkit.WebView;
+
+/**
+ * WebView subclass that can add Clip to canvas inside onDraw to trigger External Stencil behaviour.
+ */
+public class WebViewWithClipPath extends WebView {
+    private Path mClipPath;
+    private boolean mShouldClip;
+
+    public WebViewWithClipPath(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public void setEnableClipPath(boolean shouldClip) {
+        this.mShouldClip = shouldClip;
+        invalidate();
+    }
+
+    @Override
+    protected void onSizeChanged(int newWidth, int newHeight, int oldWidth, int oldHeight) {
+        int radius = 150;
+
+        mClipPath = new Path();
+        mClipPath.addRoundRect(
+                new RectF(0, 0, newWidth, newHeight), radius, radius, Path.Direction.CW);
+
+        super.onSizeChanged(newWidth, newHeight, oldWidth, oldHeight);
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        if (mShouldClip && mClipPath != null) {
+            canvas.translate(getScrollX(), getScrollY());
+            canvas.clipPath(mClipPath);
+            canvas.translate(-getScrollX(), -getScrollY());
+        }
+        super.onDraw(canvas);
+    }
+}