[BottomSheetBehavior] Broken hidden->collapsed animation, setPeekHeight animation

Description: Changing BottomSheet state when one is laid out should lead to state change animation. However changing state from hidden to collapsed breaks animation totally in certain cases (makes it appear as expanded -> collapsed). setPeekHeight is affected as well due to the same reason (leads to no visible animation, peek height is changed due to layout)

Source code:

// Issue for hidden -> collapsed
behavior.isHideable = true
behavior.state = BottomSheetBehavior.STATE_HIDDEN
// await layout

behavior.isHideable = false // animates only if no onLayoutChild happens between setHideable and settleToState

// The same issue for setPeekHeight
behavior.isHideable = true
behavior.state = BottomSheetBehavior.STATE_HIDDEN
// await layout

setPeekHeight(123, true) // animates only if no onLayoutChild happens between setPeekHeight and settleToState

Possible workaround for both is ugly as hell:

if (view.parent.isLayoutRequested) {
    view.post(animateCollapse)
    return
}
behavior.isHideable = false
behavior.state = BottomSheetBehavior.STATE_COLLAPSED

Thoughts:

This seem to work correctly prior to 46366ad4356b57180eac048cec9994c796a5ca66 (onLayoutChild change with hideable check) There are several culprits to me:

• hideable is set prior to layout (whereas state - once view is actually laid out)
• peekHeight is set prior to layout as well
• settleToStatePendingLayout awaits parent being laid out, however onLayoutChild could pass several times affecting child’s mTop
• onLayoutChild affect child’s mTop and startSettlingAnimation either won’t animate or animate incorrectly

Android API version: any

Material Library version: 1.2.1

Device: any

[prathameshmm02]

I can confirm, it’s still an issue as stated by the author. When BottomSheet is first hidden then if tried to unhide it by setting isHideable to false, it jumps to the expanded state then to the collapsed state but according to the setHideable method and normally, it should be in collapsed state.

public void setHideable(boolean hideable) {
    if (this.hideable != hideable) {
      this.hideable = hideable;
      if (!hideable && state == STATE_HIDDEN) {
        // Lift up to collapsed state
        setState(STATE_COLLAPSED);
      }
      updateAccessibilityActions();
    }
  }

[paulfthomas]

Closing the issue due to no further info available, please feel free to reopen it with more details.