CircleTransform for Picasso in Kotlin

CircleTransform.kt

/*
 * Copyright 2014 Julian Shen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.picassodemo;

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;

import com.squareup.picasso.Transformation;

/**
 * Originally created by julian on 13/6/21.
 */
import android.graphics.*
import com.squareup.picasso.Transformation

class CircleTransform : Transformation {

    private var x: Int = 0
    private var y: Int = 0

    override fun transform(source: Bitmap): Bitmap {
        val size = Math.min(source.width, source.height)

        x = (source.width - size) / 2
        y = (source.height - size) / 2

        val squaredBitmap = Bitmap.createBitmap(source, x, y, size, size)
        if (squaredBitmap !== source) source.recycle()
        val bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888)

        val canvas = Canvas(bitmap)
        val paint = Paint()
        val shader = BitmapShader(squaredBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP)
        paint.shader = shader
        paint.isAntiAlias = true

        val r = size / 2f
        canvas.drawCircle(r, r, r, paint)

        squaredBitmap.recycle()
        return bitmap
    }

    override fun key() = "circle(x=$x,y=$y)"
}