Following code can be used to scale images to given width and height with maintaining it's aspect ratio
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
public class BitmapSizeHelper {
public static enum ScalingLogic {
CROP, FIT
}
public static Bitmap getBitmapFromResources(Resources res, int resId,
int dstWidth, int dstHeight, ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth,
options.outHeight, dstWidth, dstHeight, scalingLogic);
Bitmap unscaledBitmap = BitmapFactory.decodeResource(res, resId,
options);
return unscaledBitmap;
}
public static Bitmap getBitmapFromPath(int targetW, int targetH,
String photopath, int dstWidth, int dstHeight,
ScalingLogic scalingLogic) {
Options options = new Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(photopath, options);
options.inJustDecodeBounds = false;
options.inSampleSize = calculateSampleSize(options.outWidth,
options.outHeight, dstWidth, dstHeight, scalingLogic);
Bitmap bitmap = BitmapFactory.decodeFile(photopath, options);
return bitmap;
}
public static int calculateSampleSize(int srcWidth, int srcHeight,
int dstWidth, int dstHeight, ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float) srcWidth / (float) srcHeight;
final float dstAspect = (float) dstWidth / (float) dstHeight;
if (srcAspect > dstAspect) {
return srcWidth / dstWidth;
} else {
return srcHeight / dstHeight;
}
} else {
final float srcAspect = (float) srcWidth / (float) srcHeight;
final float dstAspect = (float) dstWidth / (float) dstHeight;
if (srcAspect > dstAspect) {
return srcHeight / dstHeight;
} else {
return srcWidth / dstWidth;
}
}
}
public static Bitmap createScaledBitmap(Bitmap unscaledBitmap,
int dstWidth, int dstHeight, ScalingLogic scalingLogic) {
Rect srcRect = calculateSrcRect(unscaledBitmap.getWidth(),
unscaledBitmap.getHeight(), dstWidth, dstHeight, scalingLogic);
Rect dstRect = calculateDstRect(unscaledBitmap.getWidth(),
unscaledBitmap.getHeight(), dstWidth, dstHeight, scalingLogic);
Bitmap scaledBitmap = Bitmap.createBitmap(dstRect.width(),
dstRect.height(), Config.ARGB_8888);
Canvas canvas = new Canvas(scaledBitmap);
canvas.drawBitmap(unscaledBitmap, srcRect, dstRect, new Paint(
Paint.FILTER_BITMAP_FLAG));
return scaledBitmap;
}
public static Rect calculateSrcRect(int srcWidth, int srcHeight,
int dstWidth, int dstHeight, ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.CROP) {
final float srcAspect = (float) srcWidth / (float) srcHeight;
final float dstAspect = (float) dstWidth / (float) dstHeight;
if (srcAspect > dstAspect) {
final int srcRectWidth = (int) (srcHeight * dstAspect);
final int srcRectLeft = (srcWidth - srcRectWidth) / 2;
return new Rect(srcRectLeft, 0, srcRectLeft + srcRectWidth,
srcHeight);
} else {
final int srcRectHeight = (int) (srcWidth / dstAspect);
final int scrRectTop = (int) (srcHeight - srcRectHeight) / 2;
return new Rect(0, scrRectTop, srcWidth, scrRectTop
+ srcRectHeight);
}
} else {
return new Rect(0, 0, srcWidth, srcHeight);
}
}
public static Rect calculateDstRect(int srcWidth, int srcHeight,
int dstWidth, int dstHeight, ScalingLogic scalingLogic) {
if (scalingLogic == ScalingLogic.FIT) {
final float srcAspect = (float) srcWidth / (float) srcHeight;
final float dstAspect = (float) dstWidth / (float) dstHeight;
if (srcAspect > dstAspect) {
return new Rect(0, 0, dstWidth, (int) (dstWidth / srcAspect));
} else {
return new Rect(0, 0, (int) (dstHeight * srcAspect), dstHeight);
}
} else {
return new Rect(0, 0, dstWidth, dstHeight);
}
}
}
