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class CropManager {
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constructor(canvas, ctx) {
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this.canvas = canvas;
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this.ctx = ctx;
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this.backgroundZoom = 1;
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this.backgroundPanX = 0;
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this.backgroundPanY = 0;
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this.isPanning = false;
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this.lastPanX = 0;
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this.lastPanY = 0;
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this.lastTouchDistance = 0;
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// Bind event handlers
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this.handleBackgroundZoom = this.handleBackgroundZoom.bind(this);
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this.handleBackgroundPanStart = this.handleBackgroundPanStart.bind(this);
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this.handleBackgroundPan = this.handleBackgroundPan.bind(this);
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this.handleBackgroundPanEnd = this.handleBackgroundPanEnd.bind(this);
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this.handleTouchStart = this.handleTouchStart.bind(this);
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this.handleTouchMove = this.handleTouchMove.bind(this);
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}
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resetStates() {
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this.backgroundZoom = 1;
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this.backgroundPanX = 0;
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this.backgroundPanY = 0;
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this.isPanning = false;
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this.lastPanX = 0;
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this.lastPanY = 0;
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this.lastTouchDistance = 0;
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}
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isCropMode() {
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return this.canvas.parentNode.classList.contains('crop-mode');
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}
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exitCropMode() {
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this.canvas.parentNode.classList.remove('crop-mode');
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setCanvasTitle("");
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this.canvas.removeEventListener('wheel', this.handleBackgroundZoom);
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this.canvas.removeEventListener('mousedown', this.handleBackgroundPanStart);
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this.canvas.removeEventListener('mousemove', this.handleBackgroundPan);
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this.canvas.removeEventListener('mouseup', this.handleBackgroundPanEnd);
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this.canvas.removeEventListener('mouseleave', this.handleBackgroundPanEnd);
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this.canvas.removeEventListener('touchstart', this.handleTouchStart);
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this.canvas.removeEventListener('touchmove', this.handleTouchMove);
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this.canvas.removeEventListener('touchend', this.handleBackgroundPanEnd);
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this.canvas.removeEventListener('touchcancel', this.handleBackgroundPanEnd);
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}
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initializeCrop() {
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const imageFile = document.getElementById('imageFile');
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if (imageFile.files.length == 0) {
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fillCanvas('white');
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return;
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}
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this.exitCropMode();
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this.resetStates();
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this.canvas.style.backgroundImage = `url(${URL.createObjectURL(imageFile.files[0])})`;
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this.canvas.style.backgroundSize = '100%';
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this.canvas.style.backgroundPosition = '';
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this.canvas.style.backgroundRepeat = 'no-repeat';
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// add event listeners for zoom and pan
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this.canvas.addEventListener('wheel', this.handleBackgroundZoom);
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this.canvas.addEventListener('mousedown', this.handleBackgroundPanStart);
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this.canvas.addEventListener('mousemove', this.handleBackgroundPan);
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this.canvas.addEventListener('mouseup', this.handleBackgroundPanEnd);
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this.canvas.addEventListener('mouseleave', this.handleBackgroundPanEnd);
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// Touch events for mobile devices
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this.canvas.addEventListener('touchstart', this.handleTouchStart);
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this.canvas.addEventListener('touchmove', this.handleTouchMove);
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this.canvas.addEventListener('touchend', this.handleBackgroundPanEnd);
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this.canvas.addEventListener('touchcancel', this.handleBackgroundPanEnd);
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// Make the canvas transparent
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this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
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setCanvasTitle("裁剪模式: 可用鼠标滚轮或双指触摸缩放图片");
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this.canvas.parentNode.classList.add('crop-mode');
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}
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finishCrop(callback) {
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const imageFile = document.getElementById('imageFile');
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if (imageFile.files.length == 0) return;
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const image = new Image();
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image.onload = () => {
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URL.revokeObjectURL(image.src);
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const fieldsetRect = this.canvas.getBoundingClientRect();
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const scale = (image.width / fieldsetRect.width) / this.backgroundZoom;
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const sx = -this.backgroundPanX * scale;
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const sy = -this.backgroundPanY * scale;
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const sWidth = fieldsetRect.width * scale;
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const sHeight = fieldsetRect.height * scale;
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fillCanvas('white');
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this.ctx.drawImage(image, sx, sy, sWidth, sHeight, 0, 0, this.canvas.width, this.canvas.height);
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this.exitCropMode();
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if (callback) callback();
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};
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image.src = URL.createObjectURL(imageFile.files[0]);
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}
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handleTouchStart(e) {
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e.preventDefault();
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if (e.touches.length === 1) {
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this.handleBackgroundPanStart(e.touches[0]);
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} else if (e.touches.length === 2) {
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this.isPanning = false; // Stop panning when zooming
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this.lastTouchDistance = this.getTouchDistance(e.touches);
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}
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}
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handleTouchMove(e) {
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e.preventDefault();
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if (this.isPanning && e.touches.length === 1) {
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this.handleBackgroundPan(e.touches[0]);
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} else if (e.touches.length === 2) {
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const newDist = this.getTouchDistance(e.touches);
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if (this.lastTouchDistance > 0) {
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const zoomFactor = newDist / this.lastTouchDistance;
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this.backgroundZoom *= zoomFactor;
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this.backgroundZoom = Math.max(0.1, Math.min(5, this.backgroundZoom)); // Limit zoom range
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this.updateBackgroundTransform();
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}
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this.lastTouchDistance = newDist;
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}
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}
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handleBackgroundZoom(e) {
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e.preventDefault();
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const zoomFactor = e.deltaY > 0 ? 0.9 : 1.1;
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this.backgroundZoom *= zoomFactor;
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this.backgroundZoom = Math.max(0.1, Math.min(5, this.backgroundZoom)); // Limit zoom range
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this.updateBackgroundTransform();
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}
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handleBackgroundPanStart(e) {
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this.isPanning = true;
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this.lastPanX = e.clientX;
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this.lastPanY = e.clientY;
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this.canvas.style.cursor = 'grabbing';
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}
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handleBackgroundPan(e) {
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if (this.isPanning) {
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const deltaX = e.clientX - this.lastPanX;
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const deltaY = e.clientY - this.lastPanY;
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this.backgroundPanX += deltaX;
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this.backgroundPanY += deltaY;
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this.lastPanX = e.clientX;
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this.lastPanY = e.clientY;
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this.updateBackgroundTransform();
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}
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}
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handleBackgroundPanEnd() {
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this.isPanning = false;
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this.lastTouchDistance = 0; // Reset touch distance
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this.canvas.style.cursor = 'grab';
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}
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updateBackgroundTransform() {
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this.canvas.style.backgroundSize = `${100 * this.backgroundZoom}%`;
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this.canvas.style.backgroundPosition = `${this.backgroundPanX}px ${this.backgroundPanY}px`;
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}
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getTouchDistance(touches) {
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const touch1 = touches[0];
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const touch2 = touches[1];
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return Math.sqrt(
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Math.pow(touch2.clientX - touch1.clientX, 2) +
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Math.pow(touch2.clientY - touch1.clientY, 2)
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);
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}
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initCropTools() {
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document.getElementById('crop-zoom-in').addEventListener('click', (e) => {
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e.preventDefault();
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this.handleBackgroundZoom({ preventDefault: () => { }, deltaY: -1 });
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});
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document.getElementById('crop-zoom-out').addEventListener('click', (e) => {
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e.preventDefault();
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this.handleBackgroundZoom({ preventDefault: () => { }, deltaY: 1 });
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});
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document.getElementById('crop-move-left').addEventListener('click', (e) => {
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e.preventDefault();
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this.backgroundPanX -= 10;
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this.updateBackgroundTransform();
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});
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document.getElementById('crop-move-right').addEventListener('click', (e) => {
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e.preventDefault();
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this.backgroundPanX += 10;
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this.updateBackgroundTransform();
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});
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document.getElementById('crop-move-up').addEventListener('click', (e) => {
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e.preventDefault();
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this.backgroundPanY -= 10;
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this.updateBackgroundTransform();
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});
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document.getElementById('crop-move-down').addEventListener('click', (e) => {
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e.preventDefault();
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this.backgroundPanY += 10;
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this.updateBackgroundTransform();
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});
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}
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}
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Reference in New Issue
Block a user