<template>
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<div class="el-color-alpha-slider" :class="{ 'is-vertical': vertical }">
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<div class="el-color-alpha-slider__bar"
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@click="handleClick"
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ref="bar"
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:style="{
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background: background
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}">
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</div>
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<div class="el-color-alpha-slider__thumb"
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ref="thumb"
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:style="{
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left: thumbLeft + 'px',
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top: thumbTop + 'px'
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}">
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</div>
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</div>
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</template>
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<script>
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import draggable from '../draggable';
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export default {
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name: 'el-color-alpha-slider',
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props: {
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color: {
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required: true
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},
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vertical: Boolean
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},
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watch: {
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'color._alpha'() {
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this.update();
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},
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'color.value'() {
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this.update();
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}
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},
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methods: {
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handleClick(event) {
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const thumb = this.$refs.thumb;
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const target = event.target;
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if (target !== thumb) {
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this.handleDrag(event);
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}
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},
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handleDrag(event) {
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const rect = this.$el.getBoundingClientRect();
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const { thumb } = this.$refs;
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if (!this.vertical) {
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let left = event.clientX - rect.left;
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left = Math.max(thumb.offsetWidth / 2, left);
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left = Math.min(left, rect.width - thumb.offsetWidth / 2);
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this.color.set('alpha', Math.round((left - thumb.offsetWidth / 2) / (rect.width - thumb.offsetWidth) * 100));
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} else {
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let top = event.clientY - rect.top;
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top = Math.max(thumb.offsetHeight / 2, top);
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top = Math.min(top, rect.height - thumb.offsetHeight / 2);
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this.color.set('alpha', Math.round((top - thumb.offsetHeight / 2) / (rect.height - thumb.offsetHeight) * 100));
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}
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},
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getThumbLeft() {
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if (this.vertical) return 0;
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const el = this.$el;
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const alpha = this.color._alpha;
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if (!el) return 0;
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const thumb = this.$refs.thumb;
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return Math.round(alpha * (el.offsetWidth - thumb.offsetWidth / 2) / 100);
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},
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getThumbTop() {
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if (!this.vertical) return 0;
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const el = this.$el;
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const alpha = this.color._alpha;
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if (!el) return 0;
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const thumb = this.$refs.thumb;
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return Math.round(alpha * (el.offsetHeight - thumb.offsetHeight / 2) / 100);
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},
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getBackground() {
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if (this.color && this.color.value) {
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const { r, g, b } = this.color.toRgb();
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return `linear-gradient(to right, rgba(${r}, ${g}, ${b}, 0) 0%, rgba(${r}, ${g}, ${b}, 1) 100%)`;
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}
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return null;
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},
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update() {
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this.thumbLeft = this.getThumbLeft();
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this.thumbTop = this.getThumbTop();
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this.background = this.getBackground();
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}
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},
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data() {
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return {
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thumbLeft: 0,
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thumbTop: 0,
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background: null
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};
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},
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mounted() {
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const { bar, thumb } = this.$refs;
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const dragConfig = {
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drag: (event) => {
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this.handleDrag(event);
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},
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end: (event) => {
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this.handleDrag(event);
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}
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};
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draggable(bar, dragConfig);
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draggable(thumb, dragConfig);
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this.update();
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}
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};
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</script>
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