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camera.js
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camera.js
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let canvas = document.querySelector("canvas")
let c = canvas.getContext("2d")
export let currentZoom = 1;
let isDragging = false;
let dragStartPosition = { x: 0, y: 0 };
export let currentTransformedCursor;
function onMouseDown(event) {
event.preventDefault();
console.log(event)
if(event.buttons==2){
isDragging = true;
dragStartPosition = getTransformedPoint(event.offsetX, event.offsetY);
}
}
function getTransformedPoint(x, y) {
const originalPoint = new DOMPoint(x, y);
return c.getTransform().invertSelf().transformPoint(originalPoint);
}
function onMouseMove(event) {
currentTransformedCursor = getTransformedPoint(event.offsetX, event.offsetY)
if (isDragging) {
c.translate(currentTransformedCursor.x - dragStartPosition.x, currentTransformedCursor.y - dragStartPosition.y);
}
}
function onMouseUp() {
isDragging = false;
}
function onWheel(event) {
let zoom = event.deltaY < 0 ? 1.1 : 0.9;
currentZoom += Number((1-zoom).toFixed(1))
if(currentZoom > 15){
currentZoom = 15
zoom = 1
}
c.translate(currentTransformedCursor.x, currentTransformedCursor.y);
c.scale(zoom, zoom);
c.translate(-currentTransformedCursor.x, -currentTransformedCursor.y);
event.preventDefault();
}
canvas.addEventListener('mousedown', onMouseDown);
canvas.addEventListener('mousemove', onMouseMove);
canvas.addEventListener('mouseup', onMouseUp);
canvas.addEventListener('wheel', onWheel);