combining two png files in android

I have two png image files that I would like my android app to combine programmatically into one png image file and am wondering if it is possible to do so? if so, what I would like to do is just overlay them on each other to create one file.

the idea behind this is that I have a handful of png files, some with a portion of the image on the left with the rest transparent and the others wit开发者_开发知识库h an image on the right and the rest transparent. and based on user input it will combine the two to make one file to display. (and i cant just display the two images side by side, they need to be one file)

is this possible to do programmatically in android and how so?

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I've been trying to figure this out for a little while now.

Here's (essentially) the code I used to make it work.

// Get your images from their files
Bitmap bottomImage = BitmapFactory.decodeFile("myFirstPNG.png");
Bitmap topImage = BitmapFactory.decodeFile("myOtherPNG.png");

// As described by Steve Pomeroy in a previous comment, 
// use the canvas to combine them.
// Start with the first in the constructor..
Canvas comboImage = new Canvas(bottomImage);
// Then draw the second on top of that
comboImage.drawBitmap(topImage, 0f, 0f, null);

// comboImage is now a composite of the two. 

// To write the file out to the SDCard:
OutputStream os = null;
try {
    os = new FileOutputStream("/sdcard/DCIM/Camera/" + "myNewFileName.png");
    comboImage.compress(CompressFormat.PNG, 50, os)
} catch(IOException e) {
    e.printStackTrace();
}

EDIT :

there was a typo, So, I've changed

image.compress(CompressFormat.PNG, 50, os)

to

bottomImage.compress(CompressFormat.PNG, 50, os)

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You can do blending. This is not particular to Android. It's just universal image processing.

EDIT:

You may find these articles & samples & code useful:

http://www.jhlabs.com/ip/

http://kfb-android.blogspot.com/2009/04/image-processing-in-android.html

http://code.google.com/p/jjil/

Image Processing on Android

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I use this code

private class PhotoComposition extends AsyncTask<Object, Void, Boolean> {
    private String pathSave;//path save combined images

    @Override
    protected Boolean doInBackground(Object... objects) {

      List<String> images = (List<String>) objects[0]; //lsit of path iamges
      pathSave = (String) objects[1];//path save combined images
      if (images.size() == 0) {
        return false;
      }
      List<Bitmap> bitmaps = new ArrayList<>();
      for (int i = 0; i < images.size(); i++) {
        bitmaps.add(BitmapFactory.decodeFile( images.get(i)));
      }
      int width = findWidth(bitmaps);//Find the width of the composite image
      int height = findMaxHeight(bitmaps);//Find the height of the composite image

      Bitmap combineBitmap  = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);//create bitmap of composite image

      combineBitmap.eraseColor(Color.parseColor("#00000000")); //bcakgraound color of composite image

      Bitmap mutableCombineBitmap = combineBitmap.copy(Bitmap.Config.ARGB_8888, true);//create mutable bitmap to create canvas

      Canvas canvas = new Canvas(mutableCombineBitmap);// create canvas to add bitmaps

      float left = 0f;

      for (int i = 0; i < bitmaps.size(); i++) {
        canvas.drawBitmap(bitmaps.get(i), left, 0f, null);//Taking photos horizontally

        left += bitmaps.get(i).getWidth();//Take right to the size of the previous photo
      }

      OutputStream outputStream = null;
      try {
        outputStream = new FileOutputStream(pathSave);//path of save composite image
        mutableCombineBitmap.compress(Bitmap.CompressFormat.PNG, 80, outputStream);
      } catch (IOException e) {
        e.printStackTrace();
        return false;
      }
      return true;
    }


    @Override
    protected void onPostExecute(Boolean isSave) {
      if (isSave) {
        //iamge save on pathSave
        Log.i("PhotoComposition", "onPostExecute: " + pathSave);
      }
      super.onPostExecute(isSave);
    }

    private int findMaxHeight(List<Bitmap> bitmaps) {
      int maxHeight = Integer.MIN_VALUE;
      for (int i = 0; i < bitmaps.size(); i++) {
        if (bitmaps.get(i).getHeight() > maxHeight) {
          maxHeight = bitmaps.get(i).getHeight();
        }
      }
      return maxHeight;
    }

    private int findWidth(List<Bitmap> bitmaps) {
      int width = 0;
      for (int i = 0; i < bitmaps.size(); i++) {
        width += bitmaps.get(i).getWidth();
      }
      return width;
    }

USAGE

List<String> images = new ArrayList<>();
    images.add("/storage/emulated/0/imageOne.png");//path of image in storage
    images.add("/storage/emulated/0/imageTwo.png");
//   images.add("/storage/emulated/0/imageThree");
//   ... //add more images
    String pathSaveCombinedImage = "/storage/emulated/0/CombinedImage.png";//path save result image
  new PhotoComposition().execute(images, pathSaveCombinedImage);

And the result of using the above code will be as follows

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You may wish to look into the Canvas object, which would make it easy to do other drawing operations as well. You can just draw your bitmaps onto a canvas where you want them, then save the resulting bitmap.

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If they have transparent sections, then if you draw one on top of the other, only the non-transparent portions will overlap. It will be up to you to arrange the bitmaps however you like.

For the separate issue of re-saving your image to a png, use bitmap.compress().

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Try this .

public Bitmap mergeBitmap(Bitmap frame, Bitmap img){

    Bitmap bmOverlay = Bitmap.createBitmap(frame.getWidth(), frame.getHeight(), frame.getConfig());
    Canvas canvas = new Canvas(bmOverlay);
    canvas.drawBitmap(img, 0, 0, null);
    canvas.drawBitmap(frame, new Matrix(), null);

    return bmOverlay;

}

Returns a bitmap image

Pass two bitmap images to your function as shown below

Bitmap img= mergeBitmap(imgone, imagetwo);

See the entire post or also see merge multiple images in android programmatically