HTML5 Canvas 按 id 选择图形教程

要使用 Konva 按 id 选择图形，可以配合 # 选择器使用 find() 方法。 find() 方法始终返回元素数组，即使预计它只返回一个元素。 如果只需要一个元素，可以使用 findOne() 方法。 find() 方法适用于任何节点，包括舞台、图层、组和图形。

**操作说明：**按下“Activate Rectangle”按钮，按 id 选择矩形并执行过渡。你也可以拖放该矩形。

Vanilla

import Konva from 'konva';

const stage = new Konva.Stage({
  container: 'container',
  width: window.innerWidth,
  height: window.innerHeight,
});

const layer = new Konva.Layer();
stage.add(layer);

// create a rectangle with id
const rect = new Konva.Rect({
  x: stage.width() / 2 - 25,
  y: stage.height() / 2 - 25,
  width: 50,
  height: 50,
  fill: 'red',
  id: 'myRect',
  draggable: true
});

layer.add(rect);

// add button
const button = document.createElement('button');
button.textContent = 'Activate Rectangle';
document.body.appendChild(button);

button.addEventListener('click', () => {
  // find rectangle by id and animate it
  const rectangle = layer.findOne('#myRect');
  rectangle.to({
    duration: 1,
    rotation: 360,
    fill: 'blue',
    easing: Konva.Easings.EaseInOut
  });
});

React

import { Stage, Layer, Rect } from 'react-konva';
import { useRef, useState } from 'react';

const App = () => {
  const [position, setPosition] = useState({
    x: window.innerWidth / 2 - 25,
    y: window.innerHeight / 2 - 25
  });
  const layerRef = useRef(null);

  const handleClick = () => {
    // find rectangle by id and animate it
    const rectangle = layerRef.current.findOne('#myRect');
    rectangle.to({
      duration: 1,
      rotation: 360,
      fill: 'blue',
      easing: Konva.Easings.EaseInOut
    });
  };

  const handleDragEnd = (e) => {
    setPosition({
      x: e.target.x(),
      y: e.target.y()
    });
  };

  return (
    <div>
      <button onClick={handleClick} style={{ marginBottom: '10px' }}>
        Activate Rectangle
      </button>
      <Stage width={window.innerWidth} height={window.innerHeight}>
        <Layer ref={layerRef}>
          <Rect
            x={position.x}
            y={position.y}
            width={50}
            height={50}
            fill="red"
            id="myRect"
            draggable
            onDragEnd={handleDragEnd}
          />
        </Layer>
      </Stage>
    </div>
  );
};

export default App;

Vue

<template>
  <div>
    <button @click="handleClick" style="margin-bottom: 10px">
      Activate Rectangle
    </button>
    <v-stage :config="stageSize">
      <v-layer ref="layerRef">
        <v-rect
          :config="rectConfig"
          @dragend="handleDragEnd"
        />
      </v-layer>
    </v-stage>
  </div>
</template>

<script setup>
import { ref } from 'vue';
import Konva from 'konva';

const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const position = ref({
  x: window.innerWidth / 2 - 25,
  y: window.innerHeight / 2 - 25
});

const rectConfig = ref({
  x: position.value.x,
  y: position.value.y,
  width: 50,
  height: 50,
  fill: 'red',
  id: 'myRect',
  draggable: true
});

const layerRef = ref(null);

const handleClick = () => {
  // find rectangle by id and animate it
  const rectangle = layerRef.value.getNode().findOne('#myRect');
  rectangle.to({
    duration: 1,
    rotation: 360,
    fill: 'blue',
    easing: Konva.Easings.EaseInOut
  });
};

const handleDragEnd = (e) => {
  const newPos = e.target.position();
  position.value = newPos;
  rectConfig.value.x = newPos.x;
  rectConfig.value.y = newPos.y;
};
</script>