feat: highlight an area when using "Overlay" function

blurry/src/main/java/jp/wasabeef/blurry/Blur.java

@@ -6,6 +6,7 @@
 import android.graphics.Paint;
 import android.graphics.PorterDuff;
 import android.graphics.PorterDuffColorFilter;
+import android.graphics.PorterDuffXfermode;
 import android.renderscript.Allocation;
 import android.renderscript.Element;
 import android.renderscript.RSRuntimeException;
@@ -49,7 +50,7 @@ public static Bitmap of(Context context, Bitmap source, BlurFactor factor) {
       return null;
     }
 
-    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+    Bitmap bitmap = Bitmap.createBitmap(context.getResources().getDisplayMetrics(), width, height, Bitmap.Config.ARGB_8888);
 
     Canvas canvas = new Canvas(bitmap);
     canvas.scale(1 / (float) factor.sampling, 1 / (float) factor.sampling);
@@ -66,6 +67,11 @@ public static Bitmap of(Context context, Bitmap source, BlurFactor factor) {
       bitmap = Blur.stack(bitmap, factor.radius, true);
     }
 
+    if (factor.hotRect != null) {
+      paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
+      canvas.drawBitmap(source, factor.hotRect, factor.hotRect, paint);
+    }
+
     if (factor.sampling == BlurFactor.DEFAULT_SAMPLING) {
       return bitmap;
     } else {

blurry/src/main/java/jp/wasabeef/blurry/BlurFactor.java

@@ -1,6 +1,7 @@
 package jp.wasabeef.blurry;
 
 import android.graphics.Color;
+import android.graphics.Rect;
 
 /**
  * Copyright (C) 2020 Wasabeef
@@ -28,4 +29,5 @@ class BlurFactor {
   public int radius = DEFAULT_RADIUS;
   public int sampling = DEFAULT_SAMPLING;
   public int color = Color.TRANSPARENT;
+  public Rect hotRect;
 }

blurry/src/main/java/jp/wasabeef/blurry/BlurTask.java

@@ -61,7 +61,7 @@ public void execute() {
     THREAD_POOL.execute(new Runnable() {
       @Override
       public void run() {
-        Context context = contextWeakRef.get();
+        final Context context = contextWeakRef.get();
         if (callback != null) {
           new Handler(Looper.getMainLooper()).post(new Runnable() {
             @Override

blurry/src/main/java/jp/wasabeef/blurry/Blurry.java

@@ -2,6 +2,7 @@
 
 import android.content.Context;
 import android.graphics.Bitmap;
+import android.graphics.Rect;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.view.View;
@@ -95,9 +96,23 @@ public BitmapComposer from(Bitmap bitmap) {
     }
 
     public void onto(final ViewGroup target) {
+      onto(target, null);
+    }
+
+    public void onto(final ViewGroup target, final View hotView) {
       factor.width = target.getMeasuredWidth();
       factor.height = target.getMeasuredHeight();
 
+      if (hotView != null) {
+        final int[] hotPos = new int[2];
+        hotView.getLocationOnScreen(hotPos);
+        final int[] targetPos = new int[2];
+        target.getLocationOnScreen(targetPos);
+        final int relativeX = hotPos[0] - targetPos[0];
+        final int relativeY = hotPos[1] - targetPos[1];
+        factor.hotRect = new Rect(relativeX, relativeY, hotView.getWidth() + relativeX, hotView.getHeight() + relativeY);
+      }
+
       if (async) {
         BlurTask task = new BlurTask(target, factor, new BlurTask.Callback() {
           @Override

build.gradle

@@ -10,7 +10,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.1.0-beta04'
+        classpath 'com.android.tools.build:gradle:4.2.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
       // TODO: Close JCenter on May 1st https://jfrog.com/blog/into-the-sunset-bintray-jcenter-gocenter-and-chartcenter/

example/src/main/java/jp/wasabeef/example/blurry/MainActivity.kt

@@ -59,7 +59,7 @@ class MainActivity : AppCompatActivity() {
             .sampling(2)
             .async()
             .animate(500)
-            .onto(findViewById<View>(R.id.content) as ViewGroup)
+            .onto(findViewById<View>(R.id.content) as ViewGroup, findViewById(R.id.hotView))
           Log.d(getString(R.string.app_name),
             "TIME " + (System.currentTimeMillis() - startMs).toString() + "ms")
         }

example/src/main/res/layout/activity_main.xml

@@ -68,5 +68,12 @@
     android:textSize="88sp"
     android:textStyle="bold" />
 
+  <View
+    android:id="@+id/hotView"
+    android:layout_width="match_parent"
+    android:layout_height="150dp"
+    android:layout_alignLeft="@id/spacer"
+    android:layout_marginTop="100dp" />
+
 </RelativeLayout>