Canvas 右键上下文菜单——为 Canvas 图形创建自定义菜单

需要为 Canvas 图形显示上下文菜单吗？

如需显示上下文菜单，必须：

1. 监听 Canvas 容器（舞台）的 contextmenu 事件
2. 阻止浏览器默认行为，以隐藏原生上下文菜单
3. 使用 Konva 工具或常规 HTML 创建自定义上下文菜单。

操作说明：双击舞台以创建圆形。右键单击图形，打开上下文菜单。

Vanilla

import Konva from 'konva';

// Create a div to use as a context menu
const menuNode = document.createElement('div');
menuNode.id = 'menu';
menuNode.style.display = 'none';
menuNode.style.position = 'fixed';
menuNode.style.width = '60px';
menuNode.style.backgroundColor = 'white';
menuNode.style.boxShadow = '0 0 5px grey';
menuNode.style.borderRadius = '3px';

// Create buttons for the menu
const pulseButton = document.createElement('button');
pulseButton.textContent = 'Pulse';
pulseButton.style.width = '100%';
pulseButton.style.backgroundColor = 'white';
pulseButton.style.border = 'none';
pulseButton.style.margin = '0';
pulseButton.style.padding = '10px';

const deleteButton = document.createElement('button');
deleteButton.textContent = 'Delete';
deleteButton.style.width = '100%';
deleteButton.style.backgroundColor = 'white';
deleteButton.style.border = 'none';
deleteButton.style.margin = '0';
deleteButton.style.padding = '10px';

// Add hover effects
pulseButton.addEventListener('mouseover', () => {
  pulseButton.style.backgroundColor = 'lightgray';
});
pulseButton.addEventListener('mouseout', () => {
  pulseButton.style.backgroundColor = 'white';
});

deleteButton.addEventListener('mouseover', () => {
  deleteButton.style.backgroundColor = 'lightgray';
});
deleteButton.addEventListener('mouseout', () => {
  deleteButton.style.backgroundColor = 'white';
});

// Add buttons to menu
menuNode.appendChild(pulseButton);
menuNode.appendChild(deleteButton);
document.body.appendChild(menuNode);

// Set up the stage
const width = window.innerWidth;
const height = window.innerHeight;

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

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

// add default shape
const shape = new Konva.Circle({
  x: stage.width() / 2,
  y: stage.height() / 2,
  radius: 50,
  fill: 'red',
  shadowBlur: 10,
});
layer.add(shape);

let currentShape;

// Setup the menu functionality
pulseButton.addEventListener('click', () => {
  currentShape.to({
    scaleX: 2,
    scaleY: 2,
    onFinish: () => {
      currentShape.to({ scaleX: 1, scaleY: 1 });
    },
  });
});

deleteButton.addEventListener('click', () => {
  currentShape.destroy();
});

// Hide menu on document click
window.addEventListener('click', () => {
  menuNode.style.display = 'none';
});

// Add double click event to create new shapes
stage.on('dblclick dbltap', function () {
  // add a new shape
  const newShape = new Konva.Circle({
    x: stage.getPointerPosition().x,
    y: stage.getPointerPosition().y,
    radius: 10 + Math.random() * 30,
    fill: Konva.Util.getRandomColor(),
    shadowBlur: 10,
  });
  layer.add(newShape);
});

// Add context menu event
stage.on('contextmenu', function (e) {
  // prevent default behavior
  e.evt.preventDefault();
  if (e.target === stage) {
    // if we are on empty place of the stage we will do nothing
    return;
  }
  currentShape = e.target;
  // show menu
  menuNode.style.display = 'initial';
  const containerRect = stage.container().getBoundingClientRect();
  menuNode.style.top =
    containerRect.top + stage.getPointerPosition().y + 4 + 'px';
  menuNode.style.left =
    containerRect.left + stage.getPointerPosition().x + 4 + 'px';
});

React

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

const App = () => {
  const [circles, setCircles] = useState([
    {
      id: 'initial-circle',
      x: window.innerWidth / 2,
      y: window.innerHeight / 2,
      radius: 50,
      fill: 'red',
      shadowBlur: 10
    }
  ]);
  const [menuPosition, setMenuPosition] = useState({ x: 0, y: 0 });
  const [showMenu, setShowMenu] = useState(false);
  const [selectedId, setSelectedId] = useState(null);
  const stageRef = useRef(null);
  const width = window.innerWidth;
  const height = window.innerHeight;

  // Create and cleanup context menu
  useEffect(() => {
    // Hide menu on window click
    const handleWindowClick = () => {
      setShowMenu(false);
    };
    window.addEventListener('click', handleWindowClick);
    
    return () => {
      window.removeEventListener('click', handleWindowClick);
    };
  }, []);

  // Handle double click to create a new circle
  const handleDblClick = (e) => {
    const stage = e.target.getStage();
    const pointerPosition = stage.getPointerPosition();
    const newCircle = {
      id: Date.now().toString(),
      x: pointerPosition.x,
      y: pointerPosition.y,
      radius: 10 + Math.random() * 30,
      fill: getRandomColor(),
      shadowBlur: 10
    };
    setCircles([...circles, newCircle]);
  };

  // Handle context menu for circles
  const handleContextMenu = (e) => {
    e.evt.preventDefault();
    if (e.target === e.target.getStage()) {
      return;
    }
    
    const stage = e.target.getStage();
    const containerRect = stage.container().getBoundingClientRect();
    const pointerPosition = stage.getPointerPosition();
    
    setMenuPosition({
      x: containerRect.left + pointerPosition.x + 4,
      y: containerRect.top + pointerPosition.y + 4
    });
    
    setShowMenu(true);
    setSelectedId(e.target.id());
    e.cancelBubble = true;
  };

  // Menu action handlers
  const handlePulse = () => {
    const newCircles = circles.map(circle => {
      if (circle.id === selectedId) {
        return {
          ...circle,
          scaleX: 2,
          scaleY: 2,
          animation: 'pulse'
        };
      }
      return circle;
    });
    setCircles(newCircles);
    
    // Reset scale after animation
    setTimeout(() => {
      const resetCircles = circles.map(circle => {
        if (circle.id === selectedId) {
          return {
            ...circle,
            scaleX: 1,
            scaleY: 1,
            animation: null
          };
        }
        return circle;
      });
      setCircles(resetCircles);
    }, 300);
  };

  const handleDelete = () => {
    const newCircles = circles.filter(circle => circle.id !== selectedId);
    setCircles(newCircles);
    setShowMenu(false);
  };

  // Utility function for random color
  const getRandomColor = () => {
    const letters = '0123456789ABCDEF';
    let color = '#';
    for (let i = 0; i < 6; i++) {
      color += letters[Math.floor(Math.random() * 16)];
    }
    return color;
  };

  return (
    <div style={{ position: 'relative' }}>
      <Stage
        width={width}
        height={height}
        onDblClick={handleDblClick}
        onDblTap={handleDblClick}
        onContextMenu={handleContextMenu}
        ref={stageRef}
      >
        <Layer>
          {circles.map((circle) => (
            <Circle
              key={circle.id}
              id={circle.id}
              x={circle.x}
              y={circle.y}
              radius={circle.radius}
              fill={circle.fill}
              shadowBlur={circle.shadowBlur}
              scaleX={circle.scaleX || 1}
              scaleY={circle.scaleY || 1}
            />
          ))}
        </Layer>
      </Stage>
      
      {/* Context Menu */}
      {showMenu && (
        <div
          style={{
            position: 'fixed',
            top: menuPosition.y,
            left: menuPosition.x,
            width: '60px',
            backgroundColor: 'white',
            boxShadow: '0 0 5px grey',
            borderRadius: '3px',
            zIndex: 10
          }}
          onClick={(e) => e.stopPropagation()}
        >
          <button
            style={{
              width: '100%',
              backgroundColor: 'white',
              border: 'none',
              margin: 0,
              padding: '10px',
              cursor: 'pointer'
            }}
            onMouseOver={(e) => e.target.style.backgroundColor = 'lightgray'}
            onMouseOut={(e) => e.target.style.backgroundColor = 'white'}
            onClick={handlePulse}
          >
            Pulse
          </button>
          <button
            style={{
              width: '100%',
              backgroundColor: 'white',
              border: 'none',
              margin: 0,
              padding: '10px',
              cursor: 'pointer'
            }}
            onMouseOver={(e) => e.target.style.backgroundColor = 'lightgray'}
            onMouseOut={(e) => e.target.style.backgroundColor = 'white'}
            onClick={handleDelete}
          >
            Delete
          </button>
        </div>
      )}
    </div>
  );
};

export default App;

Vue

<template>
  <div style="position: relative">
    <v-stage
      ref="stageRef"
      :config="stageConfig"
      @dblclick="handleDblClick"
      @dbltap="handleDblClick"
      @contextmenu="handleContextMenu"
    >
      <v-layer>
        <v-circle
          v-for="circle in circles"
          :key="circle.id"
          :config="{
            id: circle.id,
            x: circle.x,
            y: circle.y,
            radius: circle.radius,
            fill: circle.fill,
            shadowBlur: circle.shadowBlur,
            scaleX: circle.scaleX || 1,
            scaleY: circle.scaleY || 1,
          }"
        />
      </v-layer>
    </v-stage>
    
    <!-- Context Menu -->
    <div
      v-if="showMenu"
      :style="{
        position: 'fixed',
        top: menuPosition.y + 'px',
        left: menuPosition.x + 'px',
        width: '60px',
        backgroundColor: 'white',
        boxShadow: '0 0 5px grey',
        borderRadius: '3px',
        zIndex: 10
      }"
      @click.stop
    >
      <button
        :style="{
          width: '100%',
          backgroundColor: 'white',
          border: 'none',
          margin: 0,
          padding: '10px',
          cursor: 'pointer'
        }"
        @mouseover="e => e.target.style.backgroundColor = 'lightgray'"
        @mouseout="e => e.target.style.backgroundColor = 'white'"
        @click="handlePulse"
      >
        Pulse
      </button>
      <button
        :style="{
          width: '100%',
          backgroundColor: 'white',
          border: 'none',
          margin: 0,
          padding: '10px',
          cursor: 'pointer'
        }"
        @mouseover="e => e.target.style.backgroundColor = 'lightgray'"
        @mouseout="e => e.target.style.backgroundColor = 'white'"
        @click="handleDelete"
      >
        Delete
      </button>
    </div>
  </div>
</template>

<script setup>
import { ref, onMounted, onUnmounted } from 'vue';

const stageRef = ref(null);
const stageConfig = {
  width: window.innerWidth,
  height: window.innerHeight
};

// State for circles and context menu
const circles = ref([
  {
    id: 'initial-circle',
    x: window.innerWidth / 2,
    y: window.innerHeight / 2,
    radius: 50,
    fill: 'red',
    shadowBlur: 10
  }
]);
const menuPosition = ref({ x: 0, y: 0 });
const showMenu = ref(false);
const selectedId = ref(null);

// Create and cleanup context menu
onMounted(() => {
  window.addEventListener('click', handleWindowClick);
});

onUnmounted(() => {
  window.removeEventListener('click', handleWindowClick);
});

// Hide menu on window click
const handleWindowClick = () => {
  showMenu.value = false;
};

// Handle double click to create a new circle
const handleDblClick = (e) => {
  const stage = e.target.getStage();
  const pointerPosition = stage.getPointerPosition();
  const newCircle = {
    id: Date.now().toString(),
    x: pointerPosition.x,
    y: pointerPosition.y,
    radius: 10 + Math.random() * 30,
    fill: getRandomColor(),
    shadowBlur: 10
  };
  circles.value.push(newCircle);
};

// Handle context menu for circles
const handleContextMenu = (e) => {
  e.evt.preventDefault();
  if (e.target === e.target.getStage()) {
    return;
  }
  
  const stage = e.target.getStage();
  const containerRect = stage.container().getBoundingClientRect();
  const pointerPosition = stage.getPointerPosition();
  
  menuPosition.value = {
    x: containerRect.left + pointerPosition.x + 4,
    y: containerRect.top + pointerPosition.y + 4
  };
  
  showMenu.value = true;
  selectedId.value = e.target.id();
  e.cancelBubble = true;
};

// Menu action handlers
const handlePulse = () => {
  circles.value = circles.value.map(circle => {
    if (circle.id === selectedId.value) {
      return {
        ...circle,
        scaleX: 2,
        scaleY: 2
      };
    }
    return circle;
  });
  
  // Reset scale after animation
  setTimeout(() => {
    circles.value = circles.value.map(circle => {
      if (circle.id === selectedId.value) {
        return {
          ...circle,
          scaleX: 1,
          scaleY: 1
        };
      }
      return circle;
    });
  }, 300);
};

const handleDelete = () => {
  circles.value = circles.value.filter(circle => circle.id !== selectedId.value);
  showMenu.value = false;
};

// Utility function for random color
const getRandomColor = () => {
  const letters = '0123456789ABCDEF';
  let color = '#';
  for (let i = 0; i < 6; i++) {
    color += letters[Math.floor(Math.random() * 16)];
  }
  return color;
};
</script>