Android Bitmap Decode decodeSampledBitmapFromFile(String filename, int reqWidth, int reqHeight)

Description

decode Sampled Bitmap From File

Declaration

public static Bitmap decodeSampledBitmapFromFile(String filename,
            int reqWidth, int reqHeight) 

Method Source Code

//package com.java2s;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

public class Main {
    public static 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);/*w  ww.j  a v a 2 s  .  c  om*/

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

    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) {

            // Calculate ratios of height and width to requested height and width
            final int heightRatio = Math.round((float) height
                    / (float) reqHeight);
            final int widthRatio = Math.round((float) width
                    / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will guarantee a final image
            // with both dimensions larger than or equal to the requested height and width.
            inSampleSize = heightRatio < widthRatio ? heightRatio
                    : widthRatio;

            // 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;
    }
}

Related

1. decodeBitmap(String path, int displayWidth, int displayHeight)
2. decodeBitmap(String path, int maxImageSize)
3. decodeSampledBitmap(Uri uri, int reqWidth, int reqHeight, Activity act)
4. decodeBitmapFromAssets(Context context, String fileName)
5. decodeImageFile(String strImagePath, BitmapFactory.Options options, boolean checkOrientation)
6. decodeSampledBitmapFromByte(byte[] res, int reqWidth, int reqHeight)