Creates a bitmap by either down sampling from the thumbnail in EXIF or the full image.

Description

Demo Code

/*//from   w ww  .j a v a 2  s . c  om
 * Copyright (C) 2009 The Android Open Source Project
 *
 * 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.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.media.ExifInterface;
import android.media.MediaMetadataRetriever;
import android.net.Uri;
import android.os.ParcelFileDescriptor;
import android.provider.BaseColumns;
import android.provider.MediaStore.Images;
import android.provider.MediaStore.Images.Thumbnails;
import android.util.Log;
import java.io.FileInputStream;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.OutputStream;

public class Main{
    private static final String TAG = "ThumbnailUtils";
    private static final int UNCONSTRAINED = -1;
    /**
     * Creates a bitmap by either downsampling from the thumbnail in EXIF or the full image.
     * The functions returns a SizedThumbnailBitmap,
     * which contains a downsampled bitmap and the thumbnail data in EXIF if exists.
     */
    private static void createThumbnailFromEXIF(String filePath,
            int targetSize, int maxPixels,
            SizedThumbnailBitmap sizedThumbBitmap) {
        if (filePath == null)
            return;

        ExifInterface exif = null;
        byte[] thumbData = null;
        try {
            exif = new ExifInterface(filePath);
            if (exif != null) {
                thumbData = exif.getThumbnail();
            }
        } catch (IOException ex) {
            Log.w(TAG, ex);
        }

        BitmapFactory.Options fullOptions = new BitmapFactory.Options();
        BitmapFactory.Options exifOptions = new BitmapFactory.Options();
        int exifThumbWidth = 0;
        int fullThumbWidth = 0;

        // Compute exifThumbWidth.
        if (thumbData != null) {
            exifOptions.inJustDecodeBounds = true;
            BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length,
                    exifOptions);
            exifOptions.inSampleSize = computeSampleSize(exifOptions,
                    targetSize, maxPixels);
            exifThumbWidth = exifOptions.outWidth
                    / exifOptions.inSampleSize;
        }

        // Compute fullThumbWidth.
        fullOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filePath, fullOptions);
        fullOptions.inSampleSize = computeSampleSize(fullOptions,
                targetSize, maxPixels);
        fullThumbWidth = fullOptions.outWidth / fullOptions.inSampleSize;

        // Choose the larger thumbnail as the returning sizedThumbBitmap.
        if (thumbData != null && exifThumbWidth >= fullThumbWidth) {
            int width = exifOptions.outWidth;
            int height = exifOptions.outHeight;
            exifOptions.inJustDecodeBounds = false;
            sizedThumbBitmap.mBitmap = BitmapFactory.decodeByteArray(
                    thumbData, 0, thumbData.length, exifOptions);
            if (sizedThumbBitmap.mBitmap != null) {
                sizedThumbBitmap.mThumbnailData = thumbData;
                sizedThumbBitmap.mThumbnailWidth = width;
                sizedThumbBitmap.mThumbnailHeight = height;
            }
        } else {
            fullOptions.inJustDecodeBounds = false;
            sizedThumbBitmap.mBitmap = BitmapFactory.decodeFile(filePath,
                    fullOptions);
        }
    }
    private static int computeSampleSize(BitmapFactory.Options options,
            int minSideLength, int maxNumOfPixels) {
        int initialSize = computeInitialSampleSize(options, minSideLength,
                maxNumOfPixels);

        int roundedSize;
        if (initialSize <= 8) {
            roundedSize = 1;
            while (roundedSize < initialSize) {
                roundedSize <<= 1;
            }
        } else {
            roundedSize = (initialSize + 7) / 8 * 8;
        }

        return roundedSize;
    }
    private static int computeInitialSampleSize(
            BitmapFactory.Options options, int minSideLength,
            int maxNumOfPixels) {
        double w = options.outWidth;
        double h = options.outHeight;

        int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 : (int) Math
                .ceil(Math.sqrt(w * h / maxNumOfPixels));
        int upperBound = (minSideLength == UNCONSTRAINED) ? 128
                : (int) Math.min(Math.floor(w / minSideLength),
                        Math.floor(h / minSideLength));

        if (upperBound < lowerBound) {
            // return the larger one when there is no overlapping zone.
            return lowerBound;
        }

        if ((maxNumOfPixels == UNCONSTRAINED)
                && (minSideLength == UNCONSTRAINED)) {
            return 1;
        } else if (minSideLength == UNCONSTRAINED) {
            return lowerBound;
        } else {
            return upperBound;
        }
    }
}
Creates a bitmap by either down sampling from the thumbnail in EXIF or the full image. - Android Graphics

Description

Demo Code

Related Tutorials
