I would like to load a cropped version of a bitmap image into a Bitmap object, without loading the original bitmap as well.
Is this at all possible without writing custom loading routines to handle the raw data?
Thanks, Sandor
5 Answers
It's actually very straightforward to do. Use
Bitmap yourBitmap = Bitmap.createBitmap(sourceBitmap, x to start from, y to start from, width, height)
Update: use BitmapRegionDecoder
2 Comments
Schermvlieger
Thanks Steve, but that would require me to load in the sourceBitmap first, and I am trying to avoid doing that, since it is too large to fit in memory, and I want to work with a bitmap that has not been downsampled.
Steve Haley
Oops, you're right, I didn't read that part of your question properly. I'm not sure then how to do this without downsampling. In fact a very similar problem is on my own figure-out-how-to-do list as well!
try this
InputStream istream = null;
try {
istream = this.getContentResolver().openInputStream(yourBitmapUri);
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
BitmapRegionDecoder decoder = null;
try {
decoder = BitmapRegionDecoder.newInstance(istream, false);
} catch (IOException e) {
e.printStackTrace();
}
Bitmap bMap = decoder.decodeRegion(new Rect(istream, x to start from, y to start from, x to end with, y to end with), null);
imageView.setImageBitmap(bMap);
1 Comment
Renjith
oops..sorry.. one more thing this method is intented for sdk version 2.3 or above...
@RKN
Your method can also throw OutOfMemoryError exception - if cropped bitmap exceeds VM.
My method combines Yours and protection against this exeption: (l, t, r, b - % of image)
Bitmap cropBitmap(ContentResolver cr, String file, float l, float t, float r, float b)
{
try
{
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
// First decode with inJustDecodeBounds=true to check dimensions
BitmapFactory.decodeFile(file, options);
int oWidth = options.outWidth;
int oHeight = options.outHeight;
InputStream istream = cr.openInputStream(Uri.fromFile(new File(file)));
BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(istream, false);
if (decoder != null)
{
options = new BitmapFactory.Options();
int startingSize = 1;
if ((r - l) * oWidth * (b - t) * oHeight > 2073600)
startingSize = (int) ((r - l) * oWidth * (b - t) * oHeight / 2073600) + 1;
for (options.inSampleSize = startingSize; options.inSampleSize <= 32; options.inSampleSize++)
{
try
{
return decoder.decodeRegion(new Rect((int) (l * oWidth), (int) (t * oHeight), (int) (r * oWidth), (int) (b * oHeight)), options);
}
catch (OutOfMemoryError e)
{
Continue with for loop if OutOfMemoryError occurs
}
}
}
else
return null;
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
return null;
}
and returns max available bitmap or null
1 Comment
TWiStErRob
What if
startingSize > 32 initially because the input image is so big?Use RapidDecoder.
And simply do this
import rapid.decoder.BitmapDecoder;
Rect bounds = new Rect(left, top, right, bottom);
Bitmap bitmap = BitmapDecoder.from(getResources(), R.drawable.image)
.region(bounds).decode();
It requires Android 2.2 or above.
Comments
You can load the scaled version of bitmap with out fully loading the bitmap using following algorithm
- Calculate the maximum possible inSampleSize that still yields an image larger than your target.
- Load the image using BitmapFactory.decodeFile(file, options), passing inSampleSize as an option.
- Resize to the desired dimensions using Bitmap.createScaledBitmap().
Check the following post Android: Resize a large bitmap file to scaled output file for further details.
