Android Bitmap save without transparent area

Question

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 pictur

Answer 1

I took @Alvaro Menezes's answer and improved it as a Kotlin extension function. I tweaked it a bit, changed some variable names for better readability and it adds more fixes to the issue mentioned by @Ahamadullah Saikat that throws an IllegalArgumentException

Note that reading pixels by line improve a lot the performances against reading this independently as the accepted answer suggest.

/**
 * Trims a bitmap borders of a given color.
 *
 */
fun Bitmap.trim(@ColorInt color: Int = Color.TRANSPARENT): Bitmap {

    var top = height
    var bottom = 0
    var right = width
    var left = 0

    var colored = IntArray(width, { color })
    var buffer = IntArray(width)

    for (y in bottom until top) {
        getPixels(buffer, 0, width, 0, y, width, 1)
        if (!Arrays.equals(colored, buffer)) {
            bottom = y
            break
        }
    }

    for (y in top - 1 downTo bottom) {
        getPixels(buffer, 0, width, 0, y, width, 1)
        if (!Arrays.equals(colored, buffer)) {
            top = y
            break
        }
    }

    val heightRemaining = top - bottom
    colored = IntArray(heightRemaining, { color })
    buffer = IntArray(heightRemaining)

    for (x in left until right) {
        getPixels(buffer, 0, 1, x, bottom, 1, heightRemaining)
        if (!Arrays.equals(colored, buffer)) {
            left = x
            break
        }
    }

    for (x in right - 1 downTo left) {
        getPixels(buffer, 0, 1, x, bottom, 1, heightRemaining)
        if (!Arrays.equals(colored, buffer)) {
            right = x
            break
        }
    }
    return Bitmap.createBitmap(this, left, bottom, right - left, top - bottom)
}