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DisplayingBitmaps / src / com.example.android.displayingbitmaps / util /

ImageResizer.java

       
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        /*
       
       
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        * Copyright (C) 2012 The Android Open Source Project
       
       
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        *
       
       
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        * Licensed under the Apache License, Version 2.0 (the "License");
       
       
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        * you may not use this file except in compliance with the License.
       
       
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        * You may obtain a copy of the License at
       
       
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        *
       
       
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        *      http://www.apache.org/licenses/LICENSE-2.0
       
       
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        *
       
       
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        * Unless required by applicable law or agreed to in writing, software
       
       
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        * distributed under the License is distributed on an "AS IS" BASIS,
       
       
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        * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       
       
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        * See the License for the specific language governing permissions and
       
       
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        * limitations under the License.
       
       
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        */
       
       
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        package com.example.android.displayingbitmaps.util;
       
       
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        import android.annotation.TargetApi;
       
       
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        import android.content.Context;
       
       
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        import android.content.res.Resources;
       
       
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        import android.graphics.Bitmap;
       
       
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        import android.graphics.BitmapFactory;
       
       
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        import android.os.Build;
       
       
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        import com.example.android.common.logger.Log;
       
       
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        import com.example.android.displayingbitmaps.BuildConfig;
       
       
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        import java.io.FileDescriptor;
       
       
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        /**
       
       
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        * A simple subclass of {@link ImageWorker} that resizes images from resources given a target width
       
       
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        * and height. Useful for when the input images might be too large to simply load directly into
       
       
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        * memory.
       
       
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        */
       
       
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        public class ImageResizer extends ImageWorker {
       
       
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        private static final String TAG = "ImageResizer";
       
       
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        protected int mImageWidth;
       
       
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        protected int mImageHeight;
       
       
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        /**
       
       
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        * Initialize providing a single target image size (used for both width and height);
       
       
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        *
       
       
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        * @param context
       
       
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        * @param imageWidth
       
       
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        * @param imageHeight
       
       
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        */
       
       
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        public ImageResizer(Context context, int imageWidth, int imageHeight) {
       
       
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        super(context);
       
       
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        setImageSize(imageWidth, imageHeight);
       
       
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        }
       
       
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        /**
       
       
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        * Initialize providing a single target image size (used for both width and height);
       
       
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        *
       
       
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        * @param context
       
       
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        * @param imageSize
       
       
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        */
       
       
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        public ImageResizer(Context context, int imageSize) {
       
       
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        super(context);
       
       
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        setImageSize(imageSize);
       
       
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        }
       
       
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        /**
       
       
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        * Set the target image width and height.
       
       
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        *
       
       
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        * @param width
       
       
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        * @param height
       
       
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        */
       
       
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        public void setImageSize(int width, int height) {
       
       
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        mImageWidth = width;
       
       
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        mImageHeight = height;
       
       
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        }
       
       
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        /**
       
       
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        * Set the target image size (width and height will be the same).
       
       
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        *
       
       
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        * @param size
       
       
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        */
       
       
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        public void setImageSize(int size) {
       
       
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        setImageSize(size, size);
       
       
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        }
       
       
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        /**
       
       
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        * The main processing method. This happens in a background task. In this case we are just
       
       
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        * sampling down the bitmap and returning it from a resource.
       
       
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        *
       
       
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        * @param resId
       
       
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        * @return
       
       
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        */
       
       
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        private Bitmap processBitmap(int resId) {
       
       
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        if (BuildConfig.DEBUG) {
       
       
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        Log.d(TAG, "processBitmap - " + resId);
       
       
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        }
       
       
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        return decodeSampledBitmapFromResource(mResources, resId, mImageWidth,
       
       
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        mImageHeight, getImageCache());
       
       
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        }
       
       
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        @Override
       
       
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        protected Bitmap processBitmap(Object data) {
       
       
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        return processBitmap(Integer.parseInt(String.valueOf(data)));
       
       
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        }
       
       
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        /**
       
       
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        * Decode and sample down a bitmap from resources to the requested width and height.
       
       
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        *
       
       
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        * @param res The resources object containing the image data
       
       
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        * @param resId The resource id of the image data
       
       
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        * @param reqWidth The requested width of the resulting bitmap
       
       
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        * @param reqHeight The requested height of the resulting bitmap
       
       
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        * @param cache The ImageCache used to find candidate bitmaps for use with inBitmap
       
       
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        * @return A bitmap sampled down from the original with the same aspect ratio and dimensions
       
       
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        *         that are equal to or greater than the requested width and height
       
       
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        */
       
       
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        public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
       
       
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        int reqWidth, int reqHeight, ImageCache cache) {
       
       
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        // First decode with inJustDecodeBounds=true to check dimensions
       
       
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        final BitmapFactory.Options options = new BitmapFactory.Options();
       
       
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        options.inJustDecodeBounds = true;
       
       
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        BitmapFactory.decodeResource(res, resId, options);
       
       
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        // Calculate inSampleSize
       
       
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        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
       
       
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        // If we're running on Honeycomb or newer, try to use inBitmap
       
       
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        if (Utils.hasHoneycomb()) {
       
       
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        addInBitmapOptions(options, cache);
       
       
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        }
       
       
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        // Decode bitmap with inSampleSize set
       
       
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        options.inJustDecodeBounds = false;
       
       
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        return BitmapFactory.decodeResource(res, resId, options);
       
       
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        }
       
       
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        /**
       
       
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        * Decode and sample down a bitmap from a file to the requested width and height.
       
       
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        *
       
       
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        * @param filename The full path of the file to decode
       
       
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        * @param reqWidth The requested width of the resulting bitmap
       
       
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        * @param reqHeight The requested height of the resulting bitmap
       
       
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        * @param cache The ImageCache used to find candidate bitmaps for use with inBitmap
       
       
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        * @return A bitmap sampled down from the original with the same aspect ratio and dimensions
       
       
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        *         that are equal to or greater than the requested width and height
       
       
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        */
       
       
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        public static Bitmap decodeSampledBitmapFromFile(String filename,
       
       
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        int reqWidth, int reqHeight, ImageCache cache) {
       
       
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        // First decode with inJustDecodeBounds=true to check dimensions
       
       
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        final BitmapFactory.Options options = new BitmapFactory.Options();
       
       
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        options.inJustDecodeBounds = true;
       
       
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        BitmapFactory.decodeFile(filename, options);
       
       
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        // Calculate inSampleSize
       
       
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        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
       
       
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        // If we're running on Honeycomb or newer, try to use inBitmap
       
       
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        if (Utils.hasHoneycomb()) {
       
       
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        addInBitmapOptions(options, cache);
       
       
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        }
       
       
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        // Decode bitmap with inSampleSize set
       
       
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        options.inJustDecodeBounds = false;
       
       
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        return BitmapFactory.decodeFile(filename, options);
       
       
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        }
       
       
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        /**
       
       
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        * Decode and sample down a bitmap from a file input stream to the requested width and height.
       
       
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        *
       
       
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        * @param fileDescriptor The file descriptor to read from
       
       
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        * @param reqWidth The requested width of the resulting bitmap
       
       
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        * @param reqHeight The requested height of the resulting bitmap
       
       
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        * @param cache The ImageCache used to find candidate bitmaps for use with inBitmap
       
       
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        * @return A bitmap sampled down from the original with the same aspect ratio and dimensions
       
       
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        *         that are equal to or greater than the requested width and height
       
       
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        */
       
       
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        public static Bitmap decodeSampledBitmapFromDescriptor(
       
       
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        FileDescriptor fileDescriptor, int reqWidth, int reqHeight, ImageCache cache) {
       
       
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        // First decode with inJustDecodeBounds=true to check dimensions
       
       
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        final BitmapFactory.Options options = new BitmapFactory.Options();
       
       
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        options.inJustDecodeBounds = true;
       
       
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        BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);
       
       
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        // Calculate inSampleSize
       
       
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        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
       
       
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        // Decode bitmap with inSampleSize set
       
       
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        options.inJustDecodeBounds = false;
       
       
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        // If we're running on Honeycomb or newer, try to use inBitmap
       
       
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        if (Utils.hasHoneycomb()) {
       
       
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        addInBitmapOptions(options, cache);
       
       
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        }
       
       
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        return BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);
       
       
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        }
       
       
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        @TargetApi(Build.VERSION_CODES.HONEYCOMB)
       
       
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        private static void addInBitmapOptions(BitmapFactory.Options options, ImageCache cache) {
       
       
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        // inBitmap only works with mutable bitmaps so force the decoder to
       
       
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        // return mutable bitmaps.
       
       
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        options.inMutable = true;
       
       
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        if (cache != null) {
       
       
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        // Try and find a bitmap to use for inBitmap
       
       
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        Bitmap inBitmap = cache.getBitmapFromReusableSet(options);
       
       
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        if (inBitmap != null) {
       
       
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        options.inBitmap = inBitmap;
       
       
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        }
       
       
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        }
       
       
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        }
       
       
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        /**
       
       
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        * Calculate an inSampleSize for use in a {@link android.graphics.BitmapFactory.Options} object when decoding
       
       
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        * bitmaps using the decode* methods from {@link android.graphics.BitmapFactory}. This implementation calculates
       
       
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        * the closest inSampleSize that is a power of 2 and will result in the final decoded bitmap
       
       
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        * having a width and height equal to or larger than the requested width and height.
       
       
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        *
       
       
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        * @param options An options object with out* params already populated (run through a decode*
       
       
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        *            method with inJustDecodeBounds==true
       
       
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        * @param reqWidth The requested width of the resulting bitmap
       
       
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        * @param reqHeight The requested height of the resulting bitmap
       
       
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        * @return The value to be used for inSampleSize
       
       
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        */
       
       
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        public static int calculateInSampleSize(BitmapFactory.Options options,
       
       
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        int reqWidth, int reqHeight) {
       
       
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        // Raw height and width of image
       
       
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        final int height = options.outHeight;
       
       
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        final int width = options.outWidth;
       
       
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        int inSampleSize = 1;
       
       
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        if (height > reqHeight || width > reqWidth) {
       
       
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        final int halfHeight = height / 2;
       
       
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        final int halfWidth = width / 2;
       
       
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        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
       
       
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        // height and width larger than the requested height and width.
       
       
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        while ((halfHeight / inSampleSize) > reqHeight
       
       
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        && (halfWidth / inSampleSize) > reqWidth) {
       
       
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        inSampleSize *= 2;
       
       
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        }
       
       
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        // This offers some additional logic in case the image has a strange
       
       
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        // aspect ratio. For example, a panorama may have a much larger
       
       
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        // width than height. In these cases the total pixels might still
       
       
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        // end up being too large to fit comfortably in memory, so we should
       
       
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        // be more aggressive with sample down the image (=larger inSampleSize).
       
       
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        long totalPixels = width * height / inSampleSize;
       
       
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        // Anything more than 2x the requested pixels we'll sample down further
       
       
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        final long totalReqPixelsCap = reqWidth * reqHeight * 2;
       
       
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        while (totalPixels > totalReqPixelsCap) {
       
       
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        inSampleSize *= 2;
       
       
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        totalPixels /= 2;
       
       
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        }
       
       
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        }
       
       
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        return inSampleSize;
       
       
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        }
       
       
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        }