Pointer

Overview

The Pointer API provides a single interface for handling both mouse and touch inputs to maximize cross-platform compatibility.

API

`pointer`

Handles mouse and touch events simultaneously for easy cross-platform functionality.

pub fn pointer() -> Pointer

Pointer

pub struct Pointer {
    /// The x position of the mouse cursor or most recent touch event
    x: i32,
    /// The y position of the mouse cursor or most recent touch event
    y: i32,
    /// The state of the left mouse button or touch
    state: Button,
    /// The scroll delta
    scroll: (i32, i32),
}

Usage

Reading Pointer Position & State

let p = pointer();
 
// World‐space position (accounts for camera zoom & pan)
let (world_x, world_y) = p.xy();
 
// Fixed‐canvas position (e.g. for UI)
let (canvas_x, canvas_y) = p.xy_fixed();
 
// Button & touch states
if p.just_pressed() {
    // Fired at the instant the button/touch goes down
}
if p.pressed() {
    // True every frame the button/touch is held
}
if p.just_released() {
    // Fired at the instant the button/touch goes up
}
if p.released() {
    // True every frame the button/touch is up
}
 
// Scroll wheel or two‐finger swipe delta
let (scroll_dx, scroll_dy) = p.scroll_delta();

The best way to detect a button "click/press" is to use the just_pressed() method AND one of the intersection techniques described in the following sections. For example...

let left_half_of_screen = bounds::canvas().adjust_width_by_fraction(0.5);
let p = pointer();
if p.just_pressed() && p.xy().intersects_bounds(left_half_of_screen) {
    // Detected a click/press on the left half of the screen
}

Hit-Testing Arbitrary Rectangles

World-space regions

// Suppose you have an in-world sprite at (50, 30) sized 100×20:
if p.intersects(50, 30, 100, 20) {
    // Pointer is over that sprite in world coordinates
}

Fixed UI elements

// A button drawn at (10,10) sized 200×50 in screen space:
if p.intersects_fixed(10, 10, 200, 50) {
    // Pointer is over that UI button
}

Hit-Testing Bounds

The (i32, i32) tuple implements the IntersectBounds trait to make detecting Bounds intersection more ergonomic/flexible.

World-space bounds intersection

let pointer_world_xy = p.xy();
let pointer_fixed_xy = p.xy_fixed();
let some_bounds = Bounds::new(100, 100, 64, 64);
 
if pointer_world_xy.intersects_bounds(some_bounds) {
    // Pointer position relative to the camera is inside `some_bounds`
}
if pointer_fixed_xy.intersects_bounds(some_bounds) {
    // Pointer position relative to the canvas is inside `some_bounds`
}