Add SupportBlurTransformation which uses RenderScript support library. (#125)

* 	Add SupportBlurTransformation which uses RenderScript support library.

* 	Whoops -- forgot to change the imports.

* 	Fix type.

transformations/build.gradle

@@ -11,6 +11,9 @@ android {
     versionCode "git rev-list origin/master --count".execute().text.toInteger()
     versionName VERSION_NAME
 
+    renderscriptTargetApi TARGET_SDK_VERSION as int
+    renderscriptSupportModeEnabled true
+
     consumerProguardFiles 'proguard-rules.txt'
   }
 }

transformations/src/main/java/jp/wasabeef/glide/transformations/SupportBlurTransformation.java

@@ -0,0 +1,101 @@
+package jp.wasabeef.glide.transformations;
+
+/**
+ * Copyright (C) 2018 Wasabeef
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.os.Build;
+import android.support.v8.renderscript.RSRuntimeException;
+import android.support.annotation.NonNull;
+import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
+import java.security.MessageDigest;
+import jp.wasabeef.glide.transformations.internal.FastBlur;
+import jp.wasabeef.glide.transformations.internal.SupportRSBlur;
+
+public class SupportBlurTransformation extends BitmapTransformation {
+
+    private static final int VERSION = 1;
+    private static final String ID =
+            "jp.wasabeef.glide.transformations.SupportBlurTransformation." + VERSION;
+    private static final byte[] ID_BYTES = ID.getBytes(CHARSET);
+
+    private static int MAX_RADIUS = 25;
+    private static int DEFAULT_DOWN_SAMPLING = 1;
+
+    private int radius;
+    private int sampling;
+
+    public SupportBlurTransformation() {
+        this(MAX_RADIUS, DEFAULT_DOWN_SAMPLING);
+    }
+
+    public SupportBlurTransformation(int radius) {
+        this(radius, DEFAULT_DOWN_SAMPLING);
+    }
+
+    public SupportBlurTransformation(int radius, int sampling) {
+        this.radius = radius;
+        this.sampling = sampling;
+    }
+
+    @Override protected Bitmap transform(@NonNull Context context, @NonNull BitmapPool pool,
+                                         @NonNull Bitmap toTransform, int outWidth, int outHeight) {
+
+        int width = toTransform.getWidth();
+        int height = toTransform.getHeight();
+        int scaledWidth = width / sampling;
+        int scaledHeight = height / sampling;
+
+        Bitmap bitmap = pool.get(scaledWidth, scaledHeight, Bitmap.Config.ARGB_8888);
+
+        Canvas canvas = new Canvas(bitmap);
+        canvas.scale(1 / (float) sampling, 1 / (float) sampling);
+        Paint paint = new Paint();
+        paint.setFlags(Paint.FILTER_BITMAP_FLAG);
+        canvas.drawBitmap(toTransform, 0, 0, paint);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
+            try {
+                bitmap = SupportRSBlur.blur(context, bitmap, radius);
+            } catch (RSRuntimeException e) {
+                bitmap = FastBlur.blur(bitmap, radius, true);
+            }
+        } else {
+            bitmap = FastBlur.blur(bitmap, radius, true);
+        }
+
+        return bitmap;
+    }
+
+    @Override public String toString() {
+        return "SupportBlurTransformation(radius=" + radius + ", sampling=" + sampling + ")";
+    }
+
+    @Override public boolean equals(Object o) {
+        return o instanceof SupportBlurTransformation;
+    }
+
+    @Override public int hashCode() {
+        return ID.hashCode();
+    }
+
+    @Override public void updateDiskCacheKey(MessageDigest messageDigest) {
+        messageDigest.update(ID_BYTES);
+    }
+}

transformations/src/main/java/jp/wasabeef/glide/transformations/internal/SupportRSBlur.java

@@ -0,0 +1,70 @@
+package jp.wasabeef.glide.transformations.internal;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.os.Build;
+import android.support.v8.renderscript.Allocation;
+import android.support.v8.renderscript.Element;
+import android.support.v8.renderscript.RSRuntimeException;
+import android.support.v8.renderscript.RenderScript;
+import android.support.v8.renderscript.ScriptIntrinsicBlur;
+
+/**
+ * Copyright (C) 2018 Wasabeef
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class SupportRSBlur {
+
+    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
+    public static Bitmap blur(Context context, Bitmap bitmap, int radius) throws RSRuntimeException {
+        RenderScript rs = null;
+        Allocation input = null;
+        Allocation output = null;
+        ScriptIntrinsicBlur blur = null;
+        try {
+            rs = RenderScript.create(context);
+            rs.setMessageHandler(new RenderScript.RSMessageHandler());
+            input = Allocation.createFromBitmap(rs, bitmap, Allocation.MipmapControl.MIPMAP_NONE,
+                    Allocation.USAGE_SCRIPT);
+            output = Allocation.createTyped(rs, input.getType());
+            blur = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
+
+            blur.setInput(input);
+            blur.setRadius(radius);
+            blur.forEach(output);
+            output.copyTo(bitmap);
+        } finally {
+            if (rs != null) {
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                    RenderScript.releaseAllContexts();
+                } else {
+                    rs.destroy();
+                }
+            }
+            if (input != null) {
+                input.destroy();
+            }
+            if (output != null) {
+                output.destroy();
+            }
+            if (blur != null) {
+                blur.destroy();
+            }
+        }
+
+        return bitmap;
+    }
+}