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class ZoomManager {
constructor(horizontalZoom, verticalZoom) {
this.x = 0
this.y = 0
this.scaleX = 1
this.scaleY = 1
this.horizontalZoom = horizontalZoom
this.verticalZoom = verticalZoom
}
/**
* Convert world coordinates to screen coordinates.
*
* @param {number} worldX - The x-coordinate in world space.
* @param {number} worldY - The y-coordinate in world space.
* @returns {Array} The screen coordinates [screenX, screenY].
*/
worldToScreen(worldX, worldY) {
let screenX = (worldX - this.x) * this.scaleX
let screenY = (worldY - this.y) * this.scaleY
return {
x: screenX,
y: screenY
}
}
/**
* Convert screen coordinates to world coordinates.
*
* @param {number} screenX - The x-coordinate on the screen.
* @param {number} screenY - The y-coordinate on the screen.
* @returns {Array} The world coordinates [worldX, worldY].
*/
screenToWorld(screenX, screenY) {
let worldX = screenX / this.scaleX + this.x
let worldY = screenY / this.scaleY + this.y
return {
x: worldX,
y: worldY
}
}
/**
* Recalculates zoom based on mouse wheel event.
* @param {MouseEvent} event - The mouse wheel event object.
*/
recalculate(event) {
// Get mouse position
const pos = {
x: event.clientX,
y: event.clientY
}
// Calculate world coordinates before zoom
let beforeZoom, afterZoom
beforeZoom = this.screenToWorld(pos.x, pos.y)
// Adjust zoom scale based on mouse wheel delta
if (this.horizontalZoom)
this.scaleX -= (10 * this.scaleX) / event.deltaY;
if (this.verticalZoom)
this.scaleY -= (10 * this.scaleY) / event.deltaY;
// Calculate world coordinates after zoom
afterZoom = this.screenToWorld(pos.x, pos.y)
// Adjust zoom position to keep zoom centered around mouse position
this.x += beforeZoom.x - afterZoom.x
this.y += beforeZoom.y - afterZoom.y
// Reset zoom if it goes below 1
if (this.scaleX < 1 || this.scaleY < 1) {
this.x = 0
this.y = 0
this.scaleX = 1
this.scaleY = 1
}
}
}

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