From 48728d6d192d0d0a694af04cec1b2a0862a56eb6 Mon Sep 17 00:00:00 2001
From: Dmitry Gladkov <dmitry.gladkov@gmail.com>
Date: Wed, 20 Jan 2016 14:11:24 +0200
Subject: [PATCH] optimize render performance for rounded corners on Android

---
 .../BV/LinearGradient/LinearGradientView.java | 31 +++++++++++++------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/android/src/main/java/com/BV/LinearGradient/LinearGradientView.java b/android/src/main/java/com/BV/LinearGradient/LinearGradientView.java
index 9fd4350..45b7d58 100644
--- a/android/src/main/java/com/BV/LinearGradient/LinearGradientView.java
+++ b/android/src/main/java/com/BV/LinearGradient/LinearGradientView.java
@@ -6,7 +6,7 @@ import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.LinearGradient;
 import android.graphics.Paint;
-import android.graphics.Rect;
+import android.graphics.Path;
 import android.graphics.RectF;
 import android.graphics.Shader;
 import android.view.View;
@@ -14,6 +14,8 @@ import android.view.View;
 public class LinearGradientView extends View {
 
     private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+    private Path mPathForBorderRadius;
+    private RectF mTempRectForBorderRadius;
     private LinearGradient mShader;
 
     private float[] mLocations;
@@ -60,12 +62,14 @@ public class LinearGradientView extends View {
 
     public void setBorderRadius(float borderRadius) {
         mBorderRadius = borderRadius;
+        updatePath();
         drawGradient();
     }
 
     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         mSize = new int[]{w, h};
+        updatePath();
         drawGradient();
     }
 
@@ -82,18 +86,27 @@ public class LinearGradientView extends View {
         invalidate();
     }
 
+    private void updatePath() {
+        if (mPathForBorderRadius == null) {
+            mPathForBorderRadius = new Path();
+            mTempRectForBorderRadius = new RectF();
+        }
+        mPathForBorderRadius.reset();
+        mTempRectForBorderRadius.set(0f, 0f, (float) mSize[0], (float) mSize[1]);
+        mPathForBorderRadius.addRoundRect(
+            mTempRectForBorderRadius,
+            mBorderRadius,
+            mBorderRadius,
+            Path.Direction.CW);
+    }
+
     @Override
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);
-        if (mBorderRadius != 0f) {
-            RectF clipBounds = new RectF(canvas.getClipBounds());
-            canvas.drawRoundRect(
-                clipBounds,
-                mBorderRadius,
-                mBorderRadius,
-                mPaint);
-        } else {
+        if (mPathForBorderRadius == null) {
             canvas.drawPaint(mPaint);
+        } else {
+            canvas.drawPath(mPathForBorderRadius, mPaint);
         }
     }
 }