Fit.LAYOUT artboard size incorrect when onMeasure is deferred or state machine animates artboard width

[mfazekas]

Description

Fit.LAYOUT artboard size is incorrect under two conditions:

1. layoutScaleFactorAutomatic defaults to 1.0 and is only set to device density in onMeasure(). Since the view hasn't been measured yet when setRiveFile() is called, resizeArtboard() computes pixelWidth / 1.0 instead of pixelWidth / density — the artboard ends up density× too wide. iOS avoids this by initializing the scale factor at view init time. Originally reported in rive-nitro-react-native#206, simple workaround possible by setting layoutScaleFactor to density before setRiveFile.

2. When a state machine animates the artboard width: keyframes overwrite m_Width every frame via CoreRegistry::setDouble(artboard, widthPropertyKey, ...) during advance(). Since resizeArtboard() only runs once (one-shot requireArtboardResize flag), the artboard stays at the keyframe value.

For reference, the iOS runtime approaches this differently: it initializes scale factor at view init time and re-applies artboard dimensions every frame in drawRive rather than using a one-shot flag. It also re-applies on size change in drawableSizeDidChange. Not saying this is necessarily the right approach for Android, but it avoids both issues above.

Versions, Device, and Other Information

• Rive Android Runtime Version: 11.3.2
• Rive API: Legacy (View-based)
• Device: Android API 35 emulator (1080x2220, 440dpi), also reported on OnePlus CPH2719, Samsung Galaxy Fold 3
• App Minimum SDK Level: 21
• App Target SDK Level: 36
• Frequency: Issue 1 — 100% when setRiveFile is called before onMeasure. Issue 2 — 9/10 with layout_test.riv.

Reproduction Steps

Issue 1 (scale factor default): Any .riv with Fit.LAYOUT. The view hasn't been measured when setRiveFile is called, so layoutScaleFactorAutomatic is still 1.0. Confirmed via logcat:

configure: reload=true fit=LAYOUT viewSize=0x0px
configure post-setRiveFile: artboardW=1920.0 artboardH=1080.0
onLayout: artboardW=1920.0 artboardH=1080.0  ← still intrinsic size after layout

Reproduced in bare Android by suppressing onMeasure:

✗ Artboard 1080 dp ≠ View 393 dp (2.8x too wide!)

The 2.75x factor matches exactly the device density — 1080px / 1.0 instead of 1080px / 2.75.

Issue 2 (keyframe overwrite): layout_test.riv with Fit.LAYOUT — the state machine animates the artboard width property, overwriting the value set by resizeArtboard() every frame. Reproduced 9/10 launches.

Source .riv/.rev File

• Issue 1: Any .riv with Fit.LAYOUT (tested with GradientBorder.riv from user's repro)
• Issue 2: layout_test.riv from rive-android example app

Expected Behavior

Artboard dimensions should match viewWidth / density for Fit.LAYOUT.

Screenshots

Additional context

For reference, iOS handles this in:

• RiveView.swift L38-44 — scale factor initialized at view init
• drawRive L446-452 — artboard dimensions re-applied every frame
• drawableSizeDidChange L490-501 — re-applied on size change