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app/src/main/java/com/hippo/drawable/BitmapPool.java

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+/*
+ * Copyright 2016 Hippo Seven
+ *
+ * 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.
+ */
+
+package com.hippo.drawable;
+
+import android.graphics.Bitmap;
+import android.support.annotation.Nullable;
+import android.util.Log;
+
+import java.lang.ref.WeakReference;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+class BitmapPool {
+
+    private static final String TAG = BitmapPool.class.getSimpleName();
+
+    private final Set<WeakReference<Bitmap>> mReusableBitmapSet = new LinkedHashSet<>();
+
+    public synchronized void put(@Nullable Bitmap bitmap) {
+        if (bitmap != null) {
+            mReusableBitmapSet.add(new WeakReference<>(bitmap));
+        }
+    }
+
+    @Nullable
+    public synchronized Bitmap get(int width, int height) {
+        final Iterator<WeakReference<Bitmap>> iterator = mReusableBitmapSet.iterator();
+        Bitmap item;
+        while (iterator.hasNext()) {
+            item = iterator.next().get();
+            if (item != null) {
+                if (item.getWidth() == width && item.getHeight() == height) {
+                    // Remove from reusable set so it can't be used again.
+                    iterator.remove();
+                    return item;
+                }
+            } else {
+                // Remove from the set if the reference has been cleared or
+                // it can't be used.
+                iterator.remove();
+            }
+        }
+
+        // Can not find reusable bitmap
+        try {
+            return Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        } catch (OutOfMemoryError e) {
+            Log.e(TAG, "Out of memory");
+            return null;
+        }
+    }
+}