Large mouse events refactoring and cleanup

js/input/UMouseWheel.js

@@ -0,0 +1,47 @@
+export default class UMouseWheel {
+
+    /**
+     * 
+     * @param {HTMLElement} target 
+     * @param {import("../UEBlueprint").default} blueprint 
+     * @param {Object} options 
+     */
+    constructor(target, blueprint, options) {
+        this.target = target
+        this.blueprint = blueprint
+        this.looseTarget = options?.looseTarget ?? true
+        this.movementSpace = this.blueprint?.getGridDOMElement() ?? document
+        let self = this
+
+        this.mouseWheelHandler = function (e) {
+            e.preventDefault()
+            if (!self.looseTarget && e.target != e.currentTarget) {
+                return
+            }
+            let scaleCorrection = 1 / self.blueprint.getScale()
+            let offset = [e.offsetX, e.offsetY]
+            if (self.looseTarget) {
+                /*
+                 * Compensating for having used the mouse wheel over a descendant of the target (the element listened for the 'wheel' event).
+                 * We are interested to get the location relative to the listened target, not the exact target that caused the event.
+                 */
+                const targetOffset = e.target.getBoundingClientRect()
+                const currentTargetOffset = e.currentTarget.getBoundingClientRect()
+                offset = [
+                    offset[0] + targetOffset.x * scaleCorrection - currentTargetOffset.x * scaleCorrection,
+                    offset[1] + targetOffset.y * scaleCorrection - currentTargetOffset.y * scaleCorrection
+                ]
+            }
+            self.wheel(Math.sign(e.deltaY), offset)
+        }
+
+        this.movementSpace.addEventListener('wheel', this.mouseWheelHandler, false)
+        // Prevent movement space from being scrolled
+        this.movementSpace.parentElement?.addEventListener('wheel', e => e.preventDefault())
+    }
+
+    /* Subclasses will override the following method */
+    wheel(location, variation) {
+
+    }
+}