Implement clipping rectangle for ReactNativeART

Reviewed By: sebmarkbage, taomin

Differential Revision: D3140869

fb-gh-sync-id: 0da27705c4cfca7a1fcae12eed11a7335a62631f
fbshipit-source-id: 0da27705c4cfca7a1fcae12eed11a7335a62631f

Libraries/ART/ARTGroup.h

@@ -14,4 +14,6 @@
 
 @interface ARTGroup : ARTNode <ARTContainer>
 
+@property (nonatomic, assign) CGRect clipping;
+
 @end

Libraries/ART/ARTGroup.m

@@ -13,7 +13,10 @@
 
 - (void)renderLayerTo:(CGContextRef)context
 {
-// TO-DO: Clipping rectangle
+
+  if (!CGRectIsEmpty(self.clipping)) {
+    CGContextClipToRect(context, self.clipping);
+  }
 
   for (ARTNode *node in self.subviews) {
     [node renderTo:context];

Libraries/ART/ReactNativeART.js

@@ -227,13 +227,7 @@ var ClippingRectangle = React.createClass({
     var y = extractNumber(props.y, 0);
     var w = extractNumber(props.width, 0);
     var h = extractNumber(props.height, 0);
-    var clipping = new Path()
-      .moveTo(x, y)
-      .line(w, 0)
-      .line(0, h)
-      .line(w, 0)
-      .close()
-      .toJSON();
+    var clipping = [x, y, w, h];
     // The current clipping API requires x and y to be ignored in the transform
     var propsExcludingXAndY = merge(props);
     delete propsExcludingXAndY.x;

Libraries/ART/ViewManagers/ARTGroupManager.m

@@ -10,6 +10,7 @@
 #import "ARTGroupManager.h"
 
 #import "ARTGroup.h"
+#import "RCTConvert+ART.h"
 
 @implementation ARTGroupManager
 
@@ -20,4 +21,6 @@ RCT_EXPORT_MODULE()
   return [ARTGroup new];
 }
 
+RCT_EXPORT_VIEW_PROPERTY(clipping, CGRect)
+
 @end

ReactAndroid/src/main/java/com/facebook/react/views/art/ARTGroupShadowNode.java

@@ -9,14 +9,33 @@
 
 package com.facebook.react.views.art;
 
+import javax.annotation.Nullable;
+
 import android.graphics.Canvas;
 import android.graphics.Paint;
+import android.graphics.RectF;
+import android.graphics.Region;
+
+import com.facebook.react.bridge.JSApplicationIllegalArgumentException;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.uimanager.annotations.ReactProp;
 
 /**
  * Shadow node for virtual ARTGroup view
  */
 public class ARTGroupShadowNode extends ARTVirtualNode {
 
+  protected @Nullable RectF mClipping;
+
+  @ReactProp(name = "clipping")
+  public void setClipping(@Nullable ReadableArray clippingDims) {
+    float[] clippingData = PropHelper.toFloatArray(clippingDims);
+    if (clippingData != null) {
+      mClipping = createClipping(clippingData);
+      markUpdated();
+    }
+  }
+
   @Override
   public boolean isVirtual() {
     return true;
@@ -26,7 +45,16 @@ public class ARTGroupShadowNode extends ARTVirtualNode {
     opacity *= mOpacity;
     if (opacity > MIN_OPACITY_FOR_DRAW) {
       saveAndSetupCanvas(canvas);
-      // TODO(6352006): apply clipping (iOS doesn't do it yet, it seems to cause issues)
+
+      if (mClipping != null) {
+        canvas.clipRect(
+          mClipping.left * mScale,
+          mClipping.top * mScale,
+          mClipping.right * mScale,
+          mClipping.bottom * mScale,
+          Region.Op.REPLACE);
+      }
+
       for (int i = 0; i < getChildCount(); i++) {
         ARTVirtualNode child = (ARTVirtualNode) getChildAt(i);
         child.draw(canvas, paint, opacity);
@@ -36,4 +64,21 @@ public class ARTGroupShadowNode extends ARTVirtualNode {
       restoreCanvas(canvas);
     }
   }
+
+  /**
+   * Creates a {@link RectF} from an array of dimensions
+   * (e.g. [x, y, width, height])
+   *
+   * @param data the array of dimensions
+   * @return the {@link RectF} that can used to clip the canvas
+   */
+  private static RectF createClipping(float[] data) {
+    if (data.length != 4) {
+      throw new JSApplicationIllegalArgumentException(
+          "Clipping should be array of length 4 (e.g. [x, y, width, height])");
+    }
+    RectF clippingRect = new RectF(
+      data[0], data[1], data[0] + data[2], data[1] + data[3]);
+    return clippingRect;
+  }
 }