Improve detail scene

app/src/main/java/com/hippo/scene/SceneView.java

@@ -17,6 +17,8 @@
 package com.hippo.scene;
 
 import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Path;
 import android.support.annotation.NonNull;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
@@ -27,6 +29,12 @@ public class SceneView extends AbsoluteLayout {
 
     private boolean mEnableTouch = true;
 
+    private Path mPath;
+    private float mRadius;
+    private float mCirclePercent = 1f;
+    private float mStartX = -1f;
+    private float mStartY = -1f;
+
     public SceneView(Context context) {
         super(context);
         init();
@@ -44,6 +52,7 @@ public class SceneView extends AbsoluteLayout {
 
     private void init() {
         setClickable(true);
+        mPath = new Path();
     }
 
     public void setEnableTouch(boolean enableTouch) {
@@ -64,4 +73,65 @@ public class SceneView extends AbsoluteLayout {
     public boolean dispatchGenericMotionEvent(@NonNull MotionEvent event) {
         return mEnableTouch && super.dispatchGenericMotionEvent(event);
     }
+
+    private void updateRadius() {
+        int width = getWidth();
+        int height = getHeight();
+        if ((mStartX  != -1f || mStartY != -1f) && width != 0 && height != 0) {
+            float h = Math.max(mStartX, width - mStartX);
+            float v = Math.max(mStartY, height - mStartY);
+            mRadius = (float) Math.hypot(h, v);
+        }
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int l, int t,
+            int r, int b) {
+        super.onLayout(changed, l, t, r, b);
+        updateRadius();
+    }
+
+    @Override
+    public void draw(@NonNull Canvas canvas) {
+        float circlePercent = mCirclePercent;
+        int saved = 0;
+
+        if (circlePercent != 1f && mRadius != 0f) {
+            mPath.rewind();
+            mPath.addCircle(mStartX, mStartY, circlePercent * mRadius, Path.Direction.CW);
+            saved = canvas.save();
+            canvas.clipPath(mPath);
+        }
+
+        super.draw(canvas);
+
+        if (circlePercent != 1f && mRadius != 0f && saved != 0) {
+            canvas.restoreToCount(saved);
+        }
+    }
+
+    @SuppressWarnings("unused")
+    public void setCirclePercent(float circlePercent) {
+        float largeCirclePercent = Math.max(mCirclePercent, circlePercent);
+        mCirclePercent = circlePercent;
+
+        if (largeCirclePercent == 1f) {
+            invalidate();
+        } else {
+            float radius = mRadius * largeCirclePercent;
+            invalidate((int) (mStartX - radius), (int) (mStartY - radius),
+                    (int) (mStartX + radius), (int) (mStartY + radius));
+        }
+    }
+
+    @SuppressWarnings("unused")
+    public float getCirclePercent() {
+        return mCirclePercent;
+    }
+
+    public void setStartPoint(float x, float y) {
+        mStartX = x;
+        mStartY = y;
+        updateRadius();
+    }
 }