如何以编程方式压缩图像

Question

I have 30 to 40 images in my resource folder. And I am currently using DrawBitpMap() to draw it in my screen. But It gives me an error "VM outOfMemeory error". So I tried to resize the images. Now my image resolution is 160x160. Now I don't get that error. it runs without any problem. So my question is, Is there anyway I could compress my images programmatically instead of manually resizing the images in resources?

Answer 1

try using this example

public class bitmaptest extends Activity {
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        LinearLayout linLayout = new LinearLayout(this);

        // load the origial BitMap (500 x 500 px)
        Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(), 
               R.drawable.android);

        int width = bitmapOrg.width();
        int height = bitmapOrg.height();
        int newWidth = 200;
        int newHeight = 200;

        // calculate the scale - in this case = 0.4f
        float scaleWidth = ((float) newWidth) / width;
        float scaleHeight = ((float) newHeight) / height;

        // createa matrix for the manipulation
        Matrix matrix = new Matrix();
        // resize the bit map
        matrix.postScale(scaleWidth, scaleHeight);
        // rotate the Bitmap
        matrix.postRotate(45);

        // recreate the new Bitmap
        Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0, 
                          width, height, matrix, true); 

        // make a Drawable from Bitmap to allow to set the BitMap 
        // to the ImageView, ImageButton or what ever
        BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);

        ImageView imageView = new ImageView(this);

        // set the Drawable on the ImageView
        imageView.setImageDrawable(bmd);

        // center the Image
        imageView.setScaleType(ScaleType.CENTER);

        // add ImageView to the Layout
        linLayout.addView(imageView, 
            new LinearLayout.LayoutParams(
                      LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
                )
        );

        // set LinearLayout as ContentView
        setContentView(linLayout);
    }
}

you can also do

Bitmap.createScaledBitmap(yourimage, 160, 160, true);

Answer 2

To compress an image in android, use the method compress from the class Bitmap .

But I believe you want to scale , rather than compress . There is a method in the same class to scale it.

Alternatively, instead of resizing the image every time it reads it, use ImageMagick in a batch file to resize them in a PC, and copy them to the res/ folder already resized.

Answer 3

这就是我解决这个问题的方法。

Bitmap originalImage= Bitmap.createScaledBitmap (BitmapFactory.decodeResource(getResources(), imageId), 160, 160, true);