355 lines
9.4 KiB
Vue
355 lines
9.4 KiB
Vue
<template>
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<div
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id="image-viewer"
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ref="viewer"
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:class="{opened: link !== null}"
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@wheel="onMouseWheel"
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@touchstart.passive="onTouchStart"
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@click="onClick"
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>
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<template v-if="link !== null">
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<button class="close-btn" aria-label="Close"></button>
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<a class="open-btn" :href="link.link" target="_blank" rel="noopener"></a>
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<img
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ref="image"
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:src="link.thumb"
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alt=""
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:style="computeImageStyles"
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@load="onImageLoad"
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@mousedown="onImageMouseDown"
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@touchstart.passive="onImageTouchStart"
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/>
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</template>
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</div>
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</template>
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<script>
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import Mousetrap from "mousetrap";
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export default {
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name: "ImageViewer",
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data() {
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return {
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link: null,
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position: {
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x: 0,
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y: 0,
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},
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transform: {
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x: 0,
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y: 0,
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scale: 0,
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},
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};
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},
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computed: {
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computeImageStyles() {
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// Sub pixels may cause the image to blur in certain browsers
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// round it down to prevent that
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const transformX = Math.floor(this.transform.x);
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const transformY = Math.floor(this.transform.y);
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return {
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left: `${this.position.x}px`,
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top: `${this.position.y}px`,
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transform: `translate3d(${transformX}px, ${transformY}px, 0) scale3d(${this.transform.scale}, ${this.transform.scale}, 1)`,
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};
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},
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},
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watch: {
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link() {
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// TODO: history.pushState
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if (this.link === null) {
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return;
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}
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this.$root.$on("resize", this.correctPosition);
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},
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},
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mounted() {
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Mousetrap.bind("esc", this.closeViewer);
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},
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destroyed() {
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Mousetrap.unbind("esc", this.closeViewer);
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},
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methods: {
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closeViewer() {
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if (this.link === null) {
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return;
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}
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this.$root.$off("resize", this.correctPosition);
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this.link = null;
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},
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onImageLoad() {
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this.prepareImage();
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},
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prepareImage() {
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const viewer = this.$refs.viewer;
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const image = this.$refs.image;
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const width = viewer.offsetWidth;
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const height = viewer.offsetHeight;
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const scale = Math.min(1, width / image.width, height / image.height);
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this.position.x = Math.floor(-image.naturalWidth / 2);
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this.position.y = Math.floor(-image.naturalHeight / 2);
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this.transform.scale = Math.max(scale, 0.1);
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this.transform.x = width / 2;
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this.transform.y = height / 2;
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},
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calculateZoomShift(newScale, x, y, oldScale) {
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const imageWidth = this.$refs.image.width;
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const centerX = this.$refs.viewer.offsetWidth / 2;
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const centerY = this.$refs.viewer.offsetHeight / 2;
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return {
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x:
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centerX -
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((centerX - (y - (imageWidth * x) / 2)) / x) * newScale +
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(imageWidth * newScale) / 2,
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y:
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centerY -
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((centerY - (oldScale - (imageWidth * x) / 2)) / x) * newScale +
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(imageWidth * newScale) / 2,
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};
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},
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correctPosition() {
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const image = this.$refs.image;
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const widthScaled = image.width * this.transform.scale;
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const heightScaled = image.height * this.transform.scale;
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const containerWidth = this.$refs.viewer.offsetWidth;
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const containerHeight = this.$refs.viewer.offsetHeight;
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if (widthScaled < containerWidth) {
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this.transform.x = containerWidth / 2;
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} else if (this.transform.x - widthScaled / 2 > 0) {
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this.transform.x = widthScaled / 2;
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} else if (this.transform.x + widthScaled / 2 < containerWidth) {
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this.transform.x = containerWidth - widthScaled / 2;
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}
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if (heightScaled < containerHeight) {
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this.transform.y = containerHeight / 2;
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} else if (this.transform.y - heightScaled / 2 > 0) {
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this.transform.y = heightScaled / 2;
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} else if (this.transform.y + heightScaled / 2 < containerHeight) {
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this.transform.y = containerHeight - heightScaled / 2;
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}
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},
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// Reduce multiple touch points into a single x/y/scale
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reduceTouches(touches) {
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let totalX = 0;
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let totalY = 0;
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let totalScale = 0;
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for (let i = 0; i < touches.length; i++) {
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const x = touches[i].clientX;
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const y = touches[i].clientY;
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totalX += x;
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totalY += y;
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for (let i2 = 0; i2 < touches.length; i2++) {
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if (i !== i2) {
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const x2 = touches[i2].clientX;
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const y2 = touches[i2].clientY;
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totalScale += Math.sqrt((x - x2) * (x - x2) + (y - y2) * (y - y2));
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}
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}
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}
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if (totalScale === 0) {
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totalScale = 1;
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}
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return {
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x: totalX / touches.length,
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y: totalY / touches.length,
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scale: totalScale / touches.length,
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};
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},
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onTouchStart(e) {
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// prevent sidebar touchstart event, we don't want to interact with sidebar while in image viewer
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e.stopImmediatePropagation();
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},
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// Touch image manipulation:
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// 1. Move around by dragging it with one finger
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// 2. Change image scale by using two fingers
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onImageTouchStart(e) {
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const image = this.$refs.image;
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let touch = this.reduceTouches(e.touches);
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let currentTouches = e.touches;
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let touchEndFingers = 0;
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const currentTransform = {
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x: touch.x,
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y: touch.y,
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scale: touch.scale,
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};
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const startTransform = {
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x: this.transform.x,
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y: this.transform.y,
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scale: this.transform.scale,
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};
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const touchMove = (moveEvent) => {
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touch = this.reduceTouches(moveEvent.touches);
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if (currentTouches.length !== moveEvent.touches.length) {
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currentTransform.x = touch.x;
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currentTransform.y = touch.y;
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currentTransform.scale = touch.scale;
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startTransform.x = this.transform.x;
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startTransform.y = this.transform.y;
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startTransform.scale = this.transform.scale;
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}
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const deltaX = touch.x - currentTransform.x;
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const deltaY = touch.y - currentTransform.y;
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const deltaScale = touch.scale / currentTransform.scale;
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currentTouches = moveEvent.touches;
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touchEndFingers = 0;
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const newScale = Math.min(3, Math.max(0.1, startTransform.scale * deltaScale));
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const fixedPosition = this.calculateZoomShift(
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newScale,
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startTransform.scale,
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startTransform.x,
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startTransform.y
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);
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this.transform.x = fixedPosition.x + deltaX;
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this.transform.y = fixedPosition.y + deltaY;
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this.transform.scale = newScale;
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this.correctPosition();
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};
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const touchEnd = (endEvent) => {
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const changedTouches = endEvent.changedTouches.length;
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if (currentTouches.length > changedTouches + touchEndFingers) {
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touchEndFingers += changedTouches;
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return;
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}
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// todo: this is swipe to close, but it's not working very well due to unfinished delta calculation
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/* if (
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this.transform.scale <= 1 &&
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endEvent.changedTouches[0].clientY - startTransform.y <= -70
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) {
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return this.closeViewer();
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}*/
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this.correctPosition();
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image.removeEventListener("touchmove", touchMove, {passive: true});
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image.removeEventListener("touchend", touchEnd, {passive: true});
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};
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image.addEventListener("touchmove", touchMove, {passive: true});
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image.addEventListener("touchend", touchEnd, {passive: true});
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},
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// Image mouse manipulation:
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// 1. Mouse wheel scrolling will zoom in and out
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// 2. If image is zoomed in, simply dragging it will move it around
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onImageMouseDown(e) {
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// todo: ignore if in touch event currently?
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// only left mouse
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if (e.which !== 1) {
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return;
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}
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e.stopPropagation();
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e.preventDefault();
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const viewer = this.$refs.viewer;
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const image = this.$refs.image;
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const startX = e.clientX;
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const startY = e.clientY;
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const startTransformX = this.transform.x;
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const startTransformY = this.transform.y;
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const widthScaled = image.width * this.transform.scale;
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const heightScaled = image.height * this.transform.scale;
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const containerWidth = viewer.offsetWidth;
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const containerHeight = viewer.offsetHeight;
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const centerX = this.transform.x - widthScaled / 2;
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const centerY = this.transform.y - heightScaled / 2;
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let movedDistance = 0;
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const mouseMove = (moveEvent) => {
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moveEvent.stopPropagation();
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moveEvent.preventDefault();
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const newX = moveEvent.clientX - startX;
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const newY = moveEvent.clientY - startY;
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movedDistance = Math.max(movedDistance, Math.abs(newX), Math.abs(newY));
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if (centerX < 0 || widthScaled + centerX > containerWidth) {
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this.transform.x = startTransformX + newX;
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}
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if (centerY < 0 || heightScaled + centerY > containerHeight) {
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this.transform.y = startTransformY + newY;
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}
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this.correctPosition();
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};
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const mouseUp = (upEvent) => {
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this.correctPosition();
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if (movedDistance < 2 && upEvent.button === 0) {
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this.closeViewer();
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}
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image.removeEventListener("mousemove", mouseMove);
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image.removeEventListener("mouseup", mouseUp);
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};
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image.addEventListener("mousemove", mouseMove);
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image.addEventListener("mouseup", mouseUp);
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},
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// If image is zoomed in, holding ctrl while scrolling will move the image up and down
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onMouseWheel(e) {
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// if image viewer is closing (css animation), you can still trigger mousewheel
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// TODO: Figure out a better fix for this
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if (this.link === null) {
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return;
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}
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e.preventDefault(); // TODO: Can this be passive?
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if (e.ctrlKey) {
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this.transform.y += e.deltaY;
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} else {
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const delta = e.deltaY > 0 ? 0.1 : -0.1;
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const newScale = Math.min(3, Math.max(0.1, this.transform.scale + delta));
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const fixedPosition = this.calculateZoomShift(
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newScale,
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this.transform.scale,
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this.transform.x,
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this.transform.y
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);
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this.transform.scale = newScale;
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this.transform.x = fixedPosition.x;
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this.transform.y = fixedPosition.y;
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}
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this.correctPosition();
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},
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onClick(e) {
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// If click triggers on the image, ignore it
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if (e.target === this.$refs.image) {
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return;
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}
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this.closeViewer();
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},
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},
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};
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</script>
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