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这是我想在 Vue.js 中实现的行为这是我正在尝试制作的 Js fiddle 示例： https ://jsfiddle.net/richardcwc/ukqhf54k/

//Canvas
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
//Variables
var canvasx = $(canvas).offset().left;
var canvasy = $(canvas).offset().top;
var last_mousex = last_mousey = 0;
var mousex = mousey = 0;
var mousedown = false;

//Mousedown
$(canvas).on('mousedown', function(e) {
    last_mousex = parseInt(e.clientX-canvasx);
    last_mousey = parseInt(e.clientY-canvasy);
    mousedown = true;
});

//Mouseup
$(canvas).on('mouseup', function(e) {
    mousedown = false;
});

//Mousemove
$(canvas).on('mousemove', function(e) {
    mousex = parseInt(e.clientX-canvasx);
    mousey = parseInt(e.clientY-canvasy);
    if(mousedown) {
        ctx.clearRect(0,0,canvas.width,canvas.height); //clear canvas
        ctx.beginPath();
        var width = mousex-last_mousex;
        var height = mousey-last_mousey;
        ctx.rect(last_mousex,last_mousey,width,height);
        ctx.strokeStyle = 'black';
        ctx.lineWidth = 10;
        ctx.stroke();
    }
    //Output
    $('#output').html('current: '+mousex+', '+mousey+'<br/>last: '+last_mousex+', '+last_mousey+'<br/>mousedown: '+mousedown);
});

我正在使用一个名为Konva.js的库。现在我可以使用 Konva.js 在 Vue.js 中自由绘图了。但是当我尝试用 mousemove 绘制矩形时。它不能正常工作。我不确定是什么导致了这个问题。谢谢你的帮助！这是我在 代码沙盒上的工作

这是我在工作中发现的行为。它仅在鼠标移动事件和鼠标单击事件之后绘制矩形。

4

1 回答 1

5 
<template>
  <v-stage
    ref="stage"
    :config="stageSize"
    @mousemove="handleMouseMove"
    @mouseDown="handleMouseDown"
    @mouseUp="handleMouseUp"
  >
    <v-layer ref="layer">
      <v-text
        ref="text"
        :config="{
          x: 10,
          y: 10,
          fontSize: 20,
          text: text,
          fill: 'black',
        }"
      />
      <v-rect
        v-for="(rec, index) in recs"
        :key="index"
        :config="{
          x: Math.min(rec.startPointX, rec.startPointX + rec.width),
          y: Math.min(rec.startPointY, rec.startPointY + rec.height),
          width: Math.abs(rec.width),
          height: Math.abs(rec.height),
          fill: 'rgb(0,0,0,0)',
          stroke: 'black',
          strokeWidth: 3,
        }"
      />
    </v-layer>
  </v-stage>
</template>

<script>
const width = window.innerWidth;
const height = window.innerHeight;

export default {
  data() {
    return {
      stageSize: {
        width: width,
        height: height,
      },
      text: "Try to draw a rectangle",
      lines: [],
      isDrawing: false,
      recs: [],
    };
  },
  methods: {
    handleMouseDown(event) {
      this.isDrawing = true;
      const pos = this.$refs.stage.getNode().getPointerPosition();
      this.setRecs([
        ...this.recs,
        { startPointX: pos.x, startPointY: pos.y, width: 0, height: 0 },
      ]);
    },
    handleMouseUp() {
      this.isDrawing = false;
    },
    setRecs(element) {
      this.recs = element;
    },
    handleMouseMove(event) {
      // no drawing - skipping
      if (!this.isDrawing) {
        return;
      }
      // console.log(event);
      const point = this.$refs.stage.getNode().getPointerPosition();
      // handle  rectangle part
      let curRec = this.recs[this.recs.length - 1];
      curRec.width = point.x - curRec.startPointX;
      curRec.height = point.y - curRec.startPointY;
    },
  },
};
</script>

演示：https ://codesandbox.io/s/vue-konva-drawings-rectangles-ivjtu?file=/src/App.vue

于 2020-11-09T15:41:10.657 回答