user1066874 user1066874 - 2 months ago 30
Android Question

Android Bitmap save without transparent area

I want to save bitmap without transparent area.

Bitmap has large transparent pixel.

So i want to remove that

How can i do this?

I cant add picture so explain with symbols.

I dont want to crop function.
I hope use filter

┌────────────────────────┐

│ transparent area

│ ┌────────┐

│ crop this

└────────┘

└────────────────────────┘

Answer

To find the non-transparent area of your bitmap, iterate across the bitmap in x and y and find the min and max of the non-transparent region. Then crop the bitmap to those co-ordinates.

Bitmap CropBitmapTransparency(Bitmap sourceBitmap)
{
    int minX = sourceBitmap.getWidth();
    int minY = sourceBitmap.getHeight();
    int maxX = -1;
    int maxY = -1;
    for(int y = 0; y < sourceBitmap.getHeight(); y++)
    {
        for(int x = 0; x < sourceBitmap.getWidth(); x++)
        {
            int alpha = (sourceBitmap.getPixel(x, y) >> 24) & 255;
            if(alpha > 0)   // pixel is not 100% transparent
            {
                if(x < minX)
                    minX = x;
                if(x > maxX)
                    maxX = x;
                if(y < minY)
                    minY = y;
                if(y > maxY)
                    maxY = y;
            }
        }
    }
    if((maxX < minX) || (maxY < minY))
        return null; // Bitmap is entirely transparent

    // crop bitmap to non-transparent area and return:
    return Bitmap.createBitmap(sourceBitmap, minX, minY, (maxX - minX) + 1, (maxY - minY) + 1);
}
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