Use Bitmap for thumb instead of Image

app/src/main/java/com/hippo/ehviewer/BitmapHelper.java

@@ -0,0 +1,58 @@
+/*
+ * 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.ehviewer;
+
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import com.hippo.conaco.ValueHelper;
+import com.hippo.conaco.ValueHolder;
+import com.hippo.yorozuya.io.InputStreamPipe;
+
+import java.io.IOException;
+
+public class BitmapHelper implements ValueHelper<Bitmap> {
+
+    @Nullable
+    @Override
+    public Bitmap decode(@NonNull InputStreamPipe isPipe) {
+        try {
+            isPipe.obtain();
+            return BitmapFactory.decodeStream(isPipe.open());
+        } catch (IOException e) {
+            return null;
+        } finally {
+            isPipe.close();
+            isPipe.release();
+        }
+    }
+
+    @Override
+    public int sizeOf(@NonNull String key, @NonNull Bitmap value) {
+        return value.getByteCount();
+    }
+
+    @Override
+    public void onRemove(@NonNull String key, @NonNull ValueHolder<Bitmap> oldValue) {}
+
+    @Override
+    public boolean useMemoryCache(@NonNull String key, ValueHolder<Bitmap> holder) {
+        return true;
+    }
+}