Click Handling and Actions in RemoteCompose

RemoteCompose provides a flexible click system based on modifiers that can trigger both internal state changes and host-side callbacks.

Click Propagation Process

Click events follow a similar propagation path to touch events but are specifically triggered on the "up" phase of a gesture if the movement threshold hasn't been exceeded.

1. Root Dispatch (CoreDocument)

When a user clicks, CoreDocument.onClick(x, y) is called with root-relative coordinates.

2. Backward Search (Component)

The document iterates through its component tree in reverse drawing order (top-to-bottom). For each component:

• It checks if the point (x, y) is within the component's bounds via contains(x, y).
• If contained, it recursively calls onClick on its children.
• If no child handles the click, it dispatches to its own onClick handlers (usually via ComponentModifiers).

3. Local Transformation

Before reaching a ClickModifierOperation, the coordinates are transformed:

• Root Space: Used for initial hit detection.
• Content Space: Passed to children and modifiers, accounting for parent scrolling and padding.

Click Modifiers (ClickModifierOperation)

The primary way to make a component interactive is by adding a click modifier.

Interaction Features

• Ripple Animation: Triggers a visual feedback ripple at the exact touch location. The ripple uses Easing.CUBIC_STANDARD and animates both color and radius over 1000ms.
• Haptic Feedback: Automatically triggers a host haptic effect (type 3) upon a successful click.
• Role & Semantics: Identifies the component as a Role.BUTTON for accessibility services (e.g., TalkBack).

Actions

A ClickModifierOperation acts as a container for one or more ActionOperations.

Action Type	Description
ValueChange	Updates a RemoteCompose variable (Float, String, or Boolean). Useful for toggling states like isExpanded or clickCount.
HostAction	Sends a metadata string back to the host application (Android/iOS). This is used for navigation or triggering native logic.
Custom Actions	Can be implemented to perform complex sequences, such as multiple variable updates or conditional logic.

Interaction with Scrolling

The system ensures that clicks and scrolls don't conflict:

1. Threshold: If a touch move exceeds a small distance threshold (e.g., 5-10 pixels), the gesture is "captured" by a scroll parent.
2. Cancellation: Once captured by a scroll, any pending click animations or actions on child components are cancelled.
3. Consumption: If a click is handled by a child, the event returns true, stopping further propagation to parent click handlers.