Develop Reference

Using matrix.postRotate() to rotate a bitmap and add it to a canvas

I am trying to rotate a bitmap and add it to a canvas. The code seems straightforward, however the image is not being rotated. I can't use canvas.rotate() since I am layering images and do not want the first image to be rotated. I have verified that the rotation degree is correct with tattoo.getRotation(), and I have also tried this with a hard coded degree but that doesn't work either.
public static Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
Matrix matrix1 = new Matrix();
matrix1.setScale(imageView.getScaleX(), imageView.getScaleY());
matrix1.setTranslate(imageView.getX(), imageView.getY());
canvas.drawBitmap(bmp1, matrix1, null);
Matrix matrix2 = new Matrix();
matrix2.setTranslate(tattoo.getX(), tattoo.getY());
matrix2.postRotate(tattoo.getRotation());
matrix2.setScale(tattoo.getScaleX(), tattoo.getScaleY());
canvas.drawBitmap(bmp2, matrix2, null);
return bmOverlay;
}

How to overlay bitmap over another bitmap at particular XY position

I am working on a project where I have used canvas and user can touch move one bitmap overlay to another bitmap. When user presses save button then both bitmaps should merge and become a single bitmap. I have done all things and now merging two bitmap at XY position remains. During my research I found following code.
private Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, new Matrix(), null);
canvas.drawBitmap(bmp2, new Matrix(), null);
return bmOverlay;
}
But this code overlay bitmap at (0,0) location. I want to overlay bitmap at my given location. Please suggest some solution. Thanks in advance.

Use below code
private Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, new Matrix(), null);
canvas.drawBitmap(bmp2, x,y, null);
return bmOverlay;
}
Where x and y are actual positions where you have to draw the overlay bitmap.

draw over a white bitmap another bitmap

I'm trying to draw over a white painted bitmap another bitmap with doodles, but the result is always white:
Bitmap myBitmap = mBitmap;
Canvas canvas = new Canvas(myBitmap);
Paint paint = new Paint(Paint.FILTER_BITMAP_FLAG);
canvas.drawColor(0xffffffff);
canvas.drawBitmap(mBitmap, 0, 0, paint);
myBitmap.compress(CompressFormat.PNG, 100, output);
How i can make white as background, and paintings as foreground in the picture?

answering my own question for futur askers:
Bitmap bmOverlay = Bitmap.createBitmap(mBitmap.getWidth(), mBitmap.getHeight(), mBitmap.getConfig());
Bitmap bmp2 = Bitmap.createBitmap(mBitmap.getWidth(), mBitmap.getHeight(), mBitmap.getConfig());
Canvas canvas = new Canvas(bmOverlay);
bmp2.eraseColor(0xffffffff);
canvas.drawBitmap(bmp2, new Matrix(), null);
canvas.drawBitmap(mBitmap, new Matrix(), null);
bmOverlay is the final bitmap we want.

Overlay 2 bitmaps of different sizes, into one the size of the screen

I have 2 bitmaps, one is: width 720 x 404 height. the other is 1280x550
I used this function:
public Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Bitmap bmp2new = getResizedBitmap(bmp2, bmp1.getHeight(), bmp1.getWidth(), bmp2.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, new Matrix(), null);
canvas.drawBitmap(bmp2new, 0, 0, null);
return bmOverlay;
}
Now it shows me both. overlayed. Now the first one, is a screen capture from a video, and the second is the canvas i draw on. The problem is that if i draw something on something thats on the margin of the screen, it will be overlayed incorrectly (an offset) because, my video is stretched to be the same as the seconc picture.
What can i do, to put both pictures, but the screen capture to start with an offset of a couple of pixels, so it will be correctly placed?
I tried:
int left = (int)((bmp2.getWidth() - (bmp1.getWidth()*(bmp2.getHeight()/bmp1.getHeight())))/2.0);
Bitmap bmp1new = getResizedBitmap(bmp1, bmp2.getHeight(), ((bmp2.getWidth() - (bmp1.getWidth()*(bmp2.getHeight()/bmp1.getHeight())) , bmp1.getConfig());
Bitmap bmptest = Bitmap.createBitmap(bmp1new, left, 0,bmp1new.getWidth() - left, bmp1new.getHeight());
But had no luck, and now I'm even more confused

it worked with this:
public Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp2.getWidth(), bmp2.getHeight(), bmp1.getConfig());
float left =(bmp2.getWidth() - (bmp1.getWidth()*((float)bmp2.getHeight()/(float)bmp1.getHeight())))/(float)2.0;
float bmp1newW = bmp1.getWidth()*((float)bmp2.getHeight()/(float)bmp1.getHeight());
Bitmap bmp1new = getResizedBitmap(bmp1, bmp2.getHeight(), (int)bmp1newW , bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1new, left ,0 , null);
canvas.drawBitmap(bmp2, new Matrix(), null);
return bmOverlay;
}

capturing image from camera and overlaying another bitmap before we save it

here tempdata is the data captured from camera, savephoto(Bitmap) is a method am using to save the image taken from camera, and it is executing accurately ,,
BUt on [2]
i am overlaying another bitmap ,, and when i am calling the savephoto(p)
it is creating an empty file in the memorycard ...
not saving any image.
how can i overlay the two bitmap on top of each other
[1]File Imgname = Environment.getExternalStorageDirectory();
Bitmap bmp = BitmapFactory.decodeByteArray(tempdata,0,tempdata.length);
imv.setImageBitmap(bmp);
savePhoto(bmp);
[2]Bitmap bmp2 = BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);
Bitmap b = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(b);
canvas.drawBitmap(bmp, 0,0, null);
canvas.drawBitmap(bmp2, 50, 50, null);
savePhoto(b);
any help will be greatly appreciated
thanx

you can do like this after getting after getting bitmap from camera (assume bitmap1) and your bitmap to overlay on top of bitmap1 (assume bitmap2)
call this overlayMark() with your bitmaps it will return overlay bitmap that is your required bitmap . you can save that bitmap..
private Bitmap overlayMark(Bitmap bmp1, Bitmap bmp2) {
int bh = originalBitmap.getHeight();
int bw = originalBitmap.getWidth();
Bitmap bmOverlay = Bitmap.createBitmap(bw,bh,Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, 0, 0, null);
canvas.drawBitmap(bmp2, 0,0, null);
return bmOverlay;
}