C# – displaying an image from a bitmap variable using codebehind

To fix the OutOfMemory error, you should do something like this:

BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;
Bitmap preview_bitmap = BitmapFactory.decodeStream(is, null, options);

This inSampleSize option reduces memory consumption.

Here's a complete method. First it reads image size without decoding the content itself. Then it finds the best inSampleSize value, it should be a power of 2, and finally the image is decoded.

// Decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
    try {
        // Decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f), null, o);

        // The new size we want to scale to
        final int REQUIRED_SIZE=70;

        // Find the correct scale value. It should be the power of 2.
        int scale = 1;
        while(o.outWidth / scale / 2 >= REQUIRED_SIZE && 
              o.outHeight / scale / 2 >= REQUIRED_SIZE) {
            scale *= 2;
        }

        // Decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
    } catch (FileNotFoundException e) {}
    return null;
}

You can use jQuery's attr() function. For example, if your img tag has an id attribute of 'my_image', you would do this:

<img id="my_image" src="first.jpg"/>

Then you can change the src of your image with jQuery like this:

$("#my_image").attr("src","second.jpg");

To attach this to a click event, you could write:

$('#my_image').on({
    'click': function(){
        $('#my_image').attr('src','second.jpg');
    }
});

To rotate the image, you could do this:

$('img').on({
    'click': function() {
         var src = ($(this).attr('src') === 'img1_on.jpg')
            ? 'img2_on.jpg'
            : 'img1_on.jpg';
         $(this).attr('src', src);
    }
});