Kotlin - scaling canvas performance issues

Question

Am making an Android game using Kotlin. I followed this tutorial:

https://www.tutorialkart.com/kotlin-android/get-started-with-android-game-development/

I wanted to add zoom in/out functionality to my canvas. This is how i did it in the draw event:

override fun draw(canvas: Canvas) {
    super.draw(canvas)

    canvas.scale(GameView.viewScreenWidth/GameView.viewPortWidth, GameView.viewScreenHeight/GameView.viewPortHeight)
    canvas.translate(-GameView.viewX, -GameView.viewY)
    for(instance in this.instances) {
        instance.draw(canvas) //these are all instances in my game
    }
}

What i'm essentially doing is looping through all of my instances' draw events, and drawing them on the screen. I have about 80 calls to canvas.drawBitmap that look like this:

spriteNumber = /* what ever number i currently need */
canvas.drawBitmap(this.spriteCache[spriteNumber], x.toFloat(), y.toFloat(), null)

The problem is that with each new canvas.drawBitmap call i get a drop in FPS. 80 calls = about 15 FPS. if I comment out the canvas.drawBitmap call, i have 60 FPS.

Also, if i comment out canvas.scale(GameView.viewScreenWidth/GameView.viewPortWidth, GameView.viewScreenHeight/GameView.viewPortHeight), then i also get 60 FPS.

How do i draw 80 sprites on the screen and scale the canvas while not going down to 15 FPS per second?

All bitmaps are scaled to desired width/height inside the constructor, and stored as cache. I dont create any bitmaps anywhere else.

Did you try finding the bottleneck with the various profiling tools? developer.android.com/studio/profile/android-profiler — Enselic
canvas.drawBitmap was the bottle neck. Although, this was only true when a scale to the canvas was applied — Boriss
Got it. The canvas was software accelerated. Hardware accelerating it fixed the problem — Boriss

Boriss Boriss · Accepted Answer · 2019-11-18T16:17:43

The canvas was software accelerated. Hardware accelerating it fixed the problem. I'm getting around 60 FPS as expected.

Kotlin - scaling canvas performance issues

1 Answers