I don’t think the “Multitouch: Panning, zooming, rotating” example does quite what the gif implies <...

# compose

[Chris Fillmore]

I don’t think the “Multitouch: Panning, zooming, rotating” example does quite what the gif implies
https://developer.android.com/jetpack/compose/gestures#multitouch

[Chris Fillmore]

In particular, I don’t think there is single-touch input, only multi-touch. Also, the origin of rotation does not seem to travel with the translation

[Chris Fillmore]

This sample also rotates around a fixed origin
https://developer.android.com/reference/kotlin/androidx/compose/foundation/gestures/package-summary#(androidx.compose.ui.i[…]olean,kotlin.Function4)

[Chris Fillmore]

At least as far as I can tell

[Chris Fillmore]

Oof, nevermind. Looks like my problem was including the centroid, when I didn’t need to

[Chris Fillmore]

Although, as a separate issue, I should mention that I needed to use two separate graphicsLayer blocks, like this

Modifier
  .graphicsLayer {
    // apply translation here
  }
  .pointerInput(...)
  .graphicsLayer {
    // apply rotation here
  }

Without separate blocks, the pointer input doesn’t translate.

It may be worth pointing that out in the docs?

[Albert Chang]

You must apply them before the pointer input modifier, yes, but you should be able to apply all the transformations in the first graphics layer block.