CoordinatorLayout.Behavior中blocksInteractionBelow()失效，getScrimOpacity()未覆盖按钮求助

Let’s tackle these two frustrating CoordinatorLayout issues head-on, with practical fixes tied to the core behavior logic you referenced earlier:

1. Getting blocksInteractionBelow() to Actually Block Interactions #

Returning true from this method should intercept all touches for views below your CoordinatorLayout child, but it often fails due to easy-to-miss setup details:

• Double-check your Behavior attachment: Make sure the child view in your XML has app:layout_behavior pointing directly to your custom Behavior class (no typos in the full package name!).
• Add explicit touch interception: Sometimes the default logic doesn’t catch all touch events. Override onInterceptTouchEvent() to enforce the block when blocksInteractionBelow() is true:

  override fun onInterceptTouchEvent(
      parent: CoordinatorLayout,
      child: V,
      event: MotionEvent
  ): Boolean {
      // Prioritize blocking interactions if our flag is set
      return blocksInteractionBelow() || super.onInterceptTouchEvent(parent, child, event)
  }
  

• Verify view ordering/elevation: If your child view is positioned behind the views you want to block, blocksInteractionBelow() can’t do anything. Ensure your child has a higher elevation or is placed later in the layout hierarchy.

2. Making getScrimOpacity() Cover Buttons Properly #

The scrim effect relies on two key pieces: a non-zero opacity value and correct drawing ordering. Here’s how to fix it:

• Override getScrimOpacity() with a valid value: The default implementation returns 0.0f (no scrim), so you need to return something between 0.0f and 1.0f (e.g., 0.5f for a 50% transparent overlay):

  override fun getScrimOpacity(): Float {
      // 50% opacity scrim to signal blocked interactions
      return 0.5f
  }
  

• Adjust scrim color and elevation: Buttons or custom views might have higher elevation than the default scrim. Override getScrimColor() to use a semi-transparent color, and ensure your CoordinatorLayout child has enough elevation to bring the scrim above other elements:

  override fun getScrimColor(parent: CoordinatorLayout, child: V): Int {
      // Dark, semi-transparent scrim that stands out over buttons
      return Color.argb(128, 0, 0, 0)
  }
  

• Test with a built-in Behavior first: If your custom code is acting up, try using BottomSheetBehavior temporarily—if the scrim works there, the issue is in your custom Behavior implementation, not the layout setup.

A Quick Recap of the Core Logic #

As you noted before, returning true from blocksInteractionBelow() is the most direct way to block all interactions below a CoordinatorLayout child. Pairing this with a non-zero getScrimOpacity() is critical—it gives users a clear visual cue that interactions are blocked, so they don’t think the app is frozen. Nail down these two methods, plus the touch interception and view ordering checks, and your issues should be resolved.

内容的提问来源于stack exchange，提问作者j2esu