Android Open Source - ImageGrabber Image Resizer

• Back to Image/resize  ↑

From Project

Back to project page ImageGrabber.

License

The source code is released under:

Apache License

Java Source Code

package com.herroworld.imagegrabber;
//w w w . ja  va 2 s . co  m
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

/**
 * A simple subclass of {@link ImageWorker} that resizes images from resources
 * given a target width and height. Useful for when the input images might be
 * too large to simply load directly into memory.
 */
public class ImageResizer extends ImageWorker {
    private static final String TAG = "ImageWorker";
    protected int mImageWidth;
    protected int mImageHeight;

    /**
     * Initialize providing a single target image size (used for both width and
     * height);
     * 
     * @param context
     * @param imageWidth
     * @param imageHeight
     */
    public ImageResizer(Context context, int imageWidth, int imageHeight) {
        super(context);
        setImageSize(imageWidth, imageHeight);
    }

    /**
     * Initialize providing a single target image size (used for both width and
     * height);
     * 
     * @param context
     * @param imageSize
     */
    public ImageResizer(Context context, int imageSize) {
        super(context);
        setImageSize(imageSize);
    }

    /**
     * Set the target image width and height.
     * 
     * @param width
     * @param height
     */
    public void setImageSize(int width, int height) {
        mImageWidth = width;
        mImageHeight = height;
    }

    /**
     * Set the target image size (width and height will be the same).
     * 
     * @param size
     */
    public void setImageSize(int size) {
        setImageSize(size, size);
    }

    /**
     * The main processing method. This happens in a background task. In this
     * case we are just sampling down the bitmap and returning it from a
     * resource.
     * 
     * @param resId
     * @return
     */
    private Bitmap processBitmap(int resId) {
        if (Utils.DEBUG) {
            Log.d(TAG, "processBitmap - " + resId);
        }
        return decodeSampledBitmapFromResource(
                mContext.getResources(), resId, mImageWidth, mImageHeight);
    }

    @Override
    protected Bitmap processBitmap(Object data, boolean forceFetch) {
        return processBitmap(Integer.parseInt(String.valueOf(data)));
    }

    /**
     * Decode and sample down a bitmap from resources to the requested width and
     * height.
     * 
     * @param res The resources object containing the image data
     * @param resId The resource id of the image data
     * @param reqWidth The requested width of the resulting bitmap
     * @param reqHeight The requested height of the resulting bitmap
     * @return A bitmap sampled down from the original with the same aspect
     *         ratio and dimensions that are equal to or greater than the
     *         requested width and height
     */
    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
            int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    /**
     * Decode and sample down a bitmap from a file to the requested width and
     * height.
     * 
     * @param filename The full path of the file to decode
     * @param reqWidth The requested width of the resulting bitmap
     * @param reqHeight The requested height of the resulting bitmap
     * @return A bitmap sampled down from the original with the same aspect
     *         ratio and dimensions that are equal to or greater than the
     *         requested width and height
     */
    public static synchronized Bitmap decodeSampledBitmapFromFile(String filename,
            int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filename, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFile(filename, options);
    }

    /**
     * Calculate an inSampleSize for use in a {@link BitmapFactory.Options}
     * object when decoding bitmaps using the decode* methods from
     * {@link BitmapFactory}. This implementation calculates the closest
     * inSampleSize that will result in the final decoded bitmap having a width
     * and height equal to or larger than the requested width and height. This
     * implementation does not ensure a power of 2 is returned for inSampleSize
     * which can be faster when decoding but results in a larger bitmap which
     * isn't as useful for caching purposes.
     * 
     * @param options An options object with out* params already populated (run
     *            through a decode* method with inJustDecodeBounds==true
     * @param reqWidth The requested width of the resulting bitmap
     * @param reqHeight The requested height of the resulting bitmap
     * @return The value to be used for inSampleSize
     */
    public static int calculateInSampleSize(BitmapFactory.Options options,
            int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            if (width > height) {
                inSampleSize = Math.round((float) height / (float) reqHeight);
            } else {
                inSampleSize = Math.round((float) width / (float) reqWidth);
            }

            // This offers some additional logic in case the image has a strange
            // aspect ratio. For example, a panorama may have a much larger
            // width than height. In these cases the total pixels might still
            // end up being too large to fit comfortably in memory, so we should
            // be more aggressive with sample down the image (=larger
            // inSampleSize).

            final float totalPixels = width * height;

            // Anything more than 2x the requested pixels we'll sample down
            // further.
            final float totalReqPixelsCap = reqWidth * reqHeight * 2;

            while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
                inSampleSize++;
            }
        }
        return inSampleSize;
    }
}

Java Source Code List

• Back to Image/resize  ↑