When should we use LAYER_TYPE_HARDWARE

Question

After reading on http://developer.android.com/guide/topics/graphics/hardware-accel.html , my understanding on 3 different type of layering techniques are (Assume the device has GPU)

LAYER_TYPE_SOFTWARE - Draw is performed by software on software's off-screen bitmap memory. Software's off-screen bitmap will then transferred to GPU. GPU render the bitmap on screen.
LAYER_TYPE_NONE - GPU will draw directly on screen.
LAYER_TYPE_HARDWARE - Draw is performed by GPU on GPU's off-screen bitmap memory. GPU's off-screen bitmap will then render to screen by GPU.

When to use LAYER_TYPE_SOFTWARE

My understanding certain draw operation isn't supported by GPU like setShadowLayer. Hence, we need to switch to LAYER_TYPE_SOFTWARE, so that draw will be performed by software.

However, since there's software's off-screen bitmap memory transferred to GPU operation, things may appear slower.

When to use LAYER_TYPE_NONE

I think this is the default settings in most of the devices. So, I assume we should use this technique most of the time.

When to use LAYER_TYPE_HARDWARE

I have no idea when to use this technique. Any example will be very much appreciated, on when we should apply LAYER_TYPE_HARDWARE technique.

p/s Also, my understanding on LAYER_TYPE_... may appear wrong. Kindly correct me, if you find any mistake. Thank you.

LAYER_TYPE_HARDWARE: The view is rendered in hardware into a hardware texture ,if the application is hardware accelerated. If the application is not hardware accelerated,this layer type behaves the same as LAYER_TYPE_SOFTWARE. — Radhey, Nov 26 '14 at 14:20

score 4 · Answer 1 · answered Oct 29 '18 at 19:43

When to use LAYER_TYPE_HARDWARE

When I want to draw a text that cutout the parent view (allowing you to see through it) I use:

setLayerType(View.LAYER_TYPE_HARDWARE, null)

For example in my custom view:

init {
    setLayerType(View.LAYER_TYPE_HARDWARE, null)
}

private val textPaint = TextPaint(ANTI_ALIAS_FLAG).apply {
    textSize = size
    xfermode = PorterDuffXfermode(PorterDuff.Mode.CLEAR)
}

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
    createTextLayout(MeasureSpec.getSize(widthMeasureSpec))
    setMeasuredDimension(widthMeasureSpec, heightMeasureSpec)
}

private fun createTextLayout(textWidth: Int) {
    textLayout = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        StaticLayout.Builder
                .obtain(text, 0, text.length, textPaint, textWidth)
                .setAlignment(Layout.Alignment.ALIGN_CENTER)
                .build()
    } else {
        StaticLayout(text, textPaint, textWidth, Layout.Alignment.ALIGN_CENTER, 1f, 0f, true)
    }
}

...

override fun onDraw(canvas: Canvas?) {
    canvas?.drawCircle(width / 2f, height / 2f, width / 2f, circlePaint)

    canvas?.withTranslation(
            x = width / 2f - textLayout.width / 2f,
            y = height / 2f - textLayout.height / 2f
    ) {
        textLayout.draw(canvas)
    }
}

The result:

And without setting LAYER_TYPE_HARDWARE:

It would be helpful to explain why you're doing that in this case. — michalbrz, Oct 29 '21 at 12:35

score 2 · Answer 2 · answered Jan 14 '19 at 09:00

2

Basically its like a drawing cache. if your custom view is expensive to render/draw but the content doesn't change too much often then i'd use the flag. otherwise your just stressing out the device to cache for no reason.

answered Jan 14 '19 at 09:00

j2emanue

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score 1 · Answer 3 · answered Dec 07 '21 at 10:02

You should use most of the times LAYER_TYPE_HARDWARE as it is more efficient. But must take into account that not all Canvas Drawing Operations are supported with LAYER_TYPE_HARDWARE on specific API levels. So, you may need to switch to LAYER_TYPE_SOFTWARE if you need to do some unsupported drawing by hardware acceleration.

List of draw support operations across API levels: Link

Next link describes extensively hardware acceleration, which will hint you when to use it or not: Link

When should we use LAYER_TYPE_HARDWARE

When to use LAYER_TYPE_SOFTWARE

When to use LAYER_TYPE_NONE

When to use LAYER_TYPE_HARDWARE

3 Answers3