Btukfyl

I am trying to draw a border on an image with a squircle mask using a Picasso Transformation. The squircle mask is a VectorDrawable.

I think the easiest and most flexible way to do this is to first draw a larger squircle of a desired border color using canvas.drawPaint. Then draw a smaller squircle using the photo bitmap using canvas.drawBitmap. I can draw them both separately, I can scale the bitmap and draw it with the mask successfully, but any time I try to combine the two it loses the mask on the canvas.drawBitmap call. Any ideas on what I could be doing wrong?

I have tried loads of blend mode options but I don't think that is the issue.

override fun transform(source: Bitmap): Bitmap {

    val width = source.width

    val height = source.height

    val borderWidth = 100



    val output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)

    val canvas = Canvas(output)



    //Draw a full size, red squircle

    val paint = Paint()

    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)

    paint.color = Color.RED

    val mask = context.getDrawable(maskID)

    mask.setBounds(0, 0, width, height)

    mask.draw(canvas)

    canvas.drawPaint(paint)



    //Draw a masked, scaled down bitmap of the photo on top

    val bitmapPaint = Paint()

    bitmapPaint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)

    val bitmapMask = context.getDrawable(maskID)

    bitmapMask.setBounds(borderWidth / 2, borderWidth / 2, width - borderWidth / 2, height - borderWidth / 2)

    bitmapMask.draw(canvas)



    val sourceDrawable = source.toDrawable(context.resources)

    sourceDrawable.setBounds(borderWidth / 2, borderWidth / 2, width - borderWidth / 2, height - borderWidth / 2)

    canvas.drawBitmap(sourceDrawable.bitmap, null,

           Rect(borderWidth / 2, borderWidth / 2, width - borderWidth / 2, height - borderWidth / 2),

           bitmapPaint)



    source.recycle()



    return output

}

Result:

If I comment out the call to drawBitmap I get this result (which is nearly there!):

UPDATED 27/11/2018

I've solved the problem by drawing the picture on a temp canvas with desired mask, then drawing the result bitmap over the main canvas. The source code and visual result are included here:

MaskTransformation.kt

import android.content.Context

import android.graphics.*

import android.graphics.drawable.BitmapDrawable

import android.support.annotation.DrawableRes

import android.support.v4.content.ContextCompat

import com.squareup.picasso.Transformation





class MaskTransformation(

    private val context: Context,

    @DrawableRes private val maskID: Int

) : Transformation {



    override fun key(): String {

        return "mask"

    }



    override fun transform(source: Bitmap): Bitmap {

        val width = source.width

        val height = source.height

        val borderWidth = 400



        val output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)

        val canvas = Canvas(output)



        //Draw a full size, red squircle

        val paint = Paint()

        paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)

        paint.color = Color.RED

        val mask = ContextCompat.getDrawable(context, maskID)!!

        mask.setBounds(0, 0, width, height)

        mask.draw(canvas)

        canvas.drawPaint(paint)



        //Draw a masked, scaled down bitmap of the photo on top

        val maskingPaint = Paint()

        maskingPaint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_IN)

        val maskDrawable = ContextCompat.getDrawable(context, maskID)!!

        maskDrawable.setBounds(borderWidth / 2, borderWidth / 2, width - borderWidth / 2, height - borderWidth / 2)



        val overlayBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)

        val overlayCanvas = Canvas(overlayBitmap)

        maskDrawable.draw(overlayCanvas)



        val pictureBitmap = Bitmap.createBitmap(width - borderWidth, height - borderWidth, Bitmap.Config.ARGB_8888)

        val pictureCanvas = Canvas(pictureBitmap)



        val sourceDrawable = BitmapDrawable(context.resources, source)

        sourceDrawable.setBounds(borderWidth / 2, borderWidth / 2, width - borderWidth / 2, height - borderWidth / 2)

        pictureCanvas.drawBitmap(

            sourceDrawable.bitmap,

            null,

            Rect(0, 0, width - borderWidth, height - borderWidth),

            Paint()

        )



        overlayCanvas.drawBitmap(pictureBitmap, (borderWidth / 2).toFloat(), (borderWidth / 2).toFloat(), maskingPaint)



        canvas.drawBitmap(overlayBitmap, 0f, 0f, Paint())



        source.recycle()



        return output

    }



}

MainActivity.kt

import android.os.Bundle

import android.support.v7.app.AppCompatActivity

import com.squareup.picasso.Picasso

import kotlinx.android.synthetic.main.activity_main.*



class MainActivity : AppCompatActivity() {



    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)



        Picasso.get()

            .load(R.drawable.img_aminography)

            .transform(MaskTransformation(this, R.drawable.ic_squircle))

            .into(imageView)



    }

}

ic_squircle.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"

        android:width="24dp"

        android:height="24dp"

        android:viewportWidth="32"

        android:viewportHeight="32">



    <path android:fillColor="#000000"

          android:pathData="M31.2,14.3v3.5c0,9.8,-5.9,13.5,-13.4,13.5h-3.5c-7.7,0,-13.5,-3.4,-13.5,-13.5v-3.5c0,-10.8,6,-13.5,13.5,-13.5h3.5C25.2,0.8,31.2,4.1,31.2,14.3"/>



</vector>

.

Visual Result