Preliminary accessibility support for CropView

Making accessibility nodes for the top and bottom boundaries. They don't
do anything yet, just informational labeling.

Bug: 180062481
Test: Explore UI with switch access and talkback
Change-Id: Icc05fd865c70d32239e955745f1496bbd117529c

packages/SystemUI/res/values/strings.xml

@@ -247,6 +247,10 @@
     <string name="screenshot_dismiss_description">Dismiss screenshot</string>
     <!-- Content description indicating that the view is a preview of the screenshot that was just taken [CHAR LIMIT=NONE] -->
     <string name="screenshot_preview_description">Screenshot preview</string>
+    <!-- Content description for the top boundary of the screenshot being cropped [CHAR LIMIT=NONE] -->
+    <string name="screenshot_top_boundary">Top boundary</string>
+    <!-- Content description for the bottom boundary of the screenshot being cropped [CHAR LIMIT=NONE] -->
+    <string name="screenshot_bottom_boundary">Bottom boundary</string>
 
     <!-- Notification title displayed for screen recording [CHAR LIMIT=50]-->
     <string name="screenrecord_name">Screen Recorder</string>

packages/SystemUI/src/com/android/systemui/screenshot/CropView.java

@@ -24,15 +24,21 @@ import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
+import android.graphics.Rect;
+import android.os.Bundle;
 import android.util.AttributeSet;
+import android.util.IntArray;
 import android.util.Log;
 import android.util.MathUtils;
 import android.view.MotionEvent;
 import android.view.View;
+import android.view.accessibility.AccessibilityEvent;
+import android.view.accessibility.AccessibilityNodeInfo;
 
 import androidx.annotation.Nullable;
 import androidx.interpolator.view.animation.FastOutSlowInInterpolator;
 
+import com.android.internal.widget.ExploreByTouchHelper;
 import com.android.systemui.R;
 
 /**
@@ -80,6 +86,8 @@ public class CropView extends View {
         t.recycle();
         // 48 dp touchable region around each handle.
         mCropTouchMargin = 24 * getResources().getDisplayMetrics().density;
+
+        setAccessibilityDelegate(new AccessibilityHelper());
     }
 
     @Override
@@ -231,6 +239,87 @@ public class CropView extends View {
         return CropBoundary.NONE;
     }
 
+    private class AccessibilityHelper extends ExploreByTouchHelper {
+
+        private static final int TOP_HANDLE_ID = 1;
+        private static final int BOTTOM_HANDLE_ID = 2;
+
+        AccessibilityHelper() {
+            super(CropView.this);
+        }
+
+        @Override
+        protected int getVirtualViewAt(float x, float y) {
+            if (Math.abs(y - fractionToPixels(mTopCrop)) < mCropTouchMargin) {
+                return TOP_HANDLE_ID;
+            }
+            if (Math.abs(y - fractionToPixels(mBottomCrop)) < mCropTouchMargin) {
+                return BOTTOM_HANDLE_ID;
+            }
+            return ExploreByTouchHelper.INVALID_ID;
+        }
+
+        @Override
+        protected void getVisibleVirtualViews(IntArray virtualViewIds) {
+            virtualViewIds.add(TOP_HANDLE_ID);
+            virtualViewIds.add(BOTTOM_HANDLE_ID);
+        }
+
+        @Override
+        protected void onPopulateEventForVirtualView(int virtualViewId, AccessibilityEvent event) {
+            switch(virtualViewId) {
+                case TOP_HANDLE_ID:
+                    event.setContentDescription(
+                            getResources().getString(R.string.screenshot_top_boundary));
+                    break;
+                case BOTTOM_HANDLE_ID:
+                    event.setContentDescription(
+                            getResources().getString(R.string.screenshot_bottom_boundary));
+                    break;
+            }
+        }
+
+        @Override
+        protected void onPopulateNodeForVirtualView(int virtualViewId,
+                AccessibilityNodeInfo node) {
+            switch(virtualViewId) {
+                case TOP_HANDLE_ID:
+                    node.setContentDescription(
+                            getResources().getString(R.string.screenshot_top_boundary));
+                    setNodePositions(mTopCrop, node);
+                    break;
+                case BOTTOM_HANDLE_ID:
+                    node.setContentDescription(
+                            getResources().getString(R.string.screenshot_bottom_boundary));
+                    setNodePositions(mBottomCrop, node);
+                    break;
+            }
+
+            // TODO: need to figure out the full set of actions to support here.
+            node.addAction(
+                    AccessibilityNodeInfo.AccessibilityAction.ACTION_CLICK);
+            node.setClickable(true);
+            node.setFocusable(true);
+        }
+
+        @Override
+        protected boolean onPerformActionForVirtualView(
+                int virtualViewId, int action, Bundle arguments) {
+            return false;
+        }
+
+        private void setNodePositions(float fraction, AccessibilityNodeInfo node) {
+            int pixels = fractionToPixels(fraction);
+            Rect rect = new Rect(0, (int) (pixels - mCropTouchMargin),
+                    getWidth(), (int) (pixels + mCropTouchMargin));
+            node.setBoundsInParent(rect);
+            int[] pos = new int[2];
+            getLocationOnScreen(pos);
+            rect.offset(pos[0], pos[1]);
+            node.setBoundsInScreen(rect);
+        }
+    }
+
     /**
      * Listen for crop motion events and state.
      */