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