Android - scrolling bitmap in custom view

I have a bitmap with the size of 400 x 70 pixels. I would like to scroll this bitmap up by one row and fill up row 70 with new pixels. I have tried to scroll the bitmap by copying it to an IntBuffer , copy it to another IntBuffer (starting at the second row) and the then write it back to the bitmap. This works but it takes a lot of CPU power and it is 开发者_如何学JAVAkind of slow. Is there any faster way to do this?

private Bitmap shift(Bitmap bitmap)
{
    buffer.rewind();
    buffer1.rewind();
    bitmap.copyPixelsToBuffer(buffer);
    buffer.position(bitmap.getWidth());
    buffer1.put(buffer.array(), bitmap.getWidth()*2, bitmap.getWidth() * bitmap.getHeight());
    buffer1.rewind();
    bitmap.copyPixelsFromBuffer(buffer1);

    return bitmap;
}

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This is one way to do it using canvas:

    canvas.drawBitmap(bgr, bgrPosition, 0, null); 
    canvas.drawBitmap(bgr, 0 - bgrW + bgrPosition, 0, null);

    //next value for the background's position 
    if ( (bgrPosition += bgrDx) > bgrW){
        bgrPosition = 0;
    }

bgrDx is the speed of scrolling try bgrDx = 1, while bgrW is the width of the bgr bitmap. This method repeats the image and produces an infinite scroll, however you would need to use a looped image (the same on both ends) to make the scroll look seamless. Perhaps you should experiment with this and see if it performs any better for you.