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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

setLineDash() method of the Canvas 2D API's CanvasRenderingContext2D interface sets the line dash pattern used when stroking lines. It uses an array of values that specify alternating lengths of lines and gaps which describe the pattern.

注意： To return to using solid lines, set the line dash list to an empty array.

句法

ctx.setLineDash(segments);
					

参数

segments

数组 of numbers that specify distances to alternately draw a line and a gap (in coordinate space units). If the number of elements in the array is odd, the elements of the array get copied and concatenated. For example, [5, 15, 25] will become [5, 15, 25, 5, 15, 25] . If the array is empty, the line dash list is cleared and line strokes return to being solid.

返回值

undefined .

范例

基本范例

此范例使用 setLineDash() method to draw a dashed line above a solid line.

HTML

<canvas id="canvas"></canvas>
					

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
// Dashed line
ctx.beginPath();
ctx.setLineDash([5, 15]);
ctx.moveTo(0, 50);
ctx.lineTo(300, 50);
ctx.stroke();
// Solid line
ctx.beginPath();
ctx.setLineDash([]);
ctx.moveTo(0, 100);
ctx.lineTo(300, 100);
ctx.stroke();
					

结果

Some common patterns

This example illustrates a variety of common line dash patterns.

HTML

<canvas id="canvas"></canvas>
					

JavaScript

drawDashedLine() function created below makes the drawing of multiple dashed lines simple. It receives a pattern array as its only parameter.

function drawDashedLine(pattern) {
  ctx.beginPath();
  ctx.setLineDash(pattern);
  ctx.moveTo(0, y);
  ctx.lineTo(300, y);
  ctx.stroke();
  y += 20;
}
const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
let y = 15;
drawDashedLine([]);
drawDashedLine([1, 1]);
drawDashedLine([10, 10]);
drawDashedLine([20, 5]);
drawDashedLine([15, 3, 3, 3]);
drawDashedLine([20, 3, 3, 3, 3, 3, 3, 3]);
drawDashedLine([12, 3, 3]);  // Equals [12, 3, 3, 12, 3, 3]
					

结果

规范

规范	状态	注释
HTML 实时标准 The definition of 'CanvasRenderingContext2D.setLineDash' in that specification.	实时标准

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
setLineDash	Chrome 23	Edge 12	Firefox 27	IE 11	Opera 15	Safari 6.1	WebView Android ≤37	Chrome Android 25	Firefox Android 27	Opera Android 14	Safari iOS 7	Samsung Internet Android 1.5

图例

完整支持

完整支持

另请参阅

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.getLineDash()
• CanvasRenderingContext2D.lineDashOffset

元数据

• 最后修改： Apr 3, 2020

相关话题

1. CanvasRenderingContext2D
2. 特性

   1. canvas
   2. currentTransform
   3. direction
   4. fillStyle
   5. filter
   6. font
   7. globalAlpha
   8. globalCompositeOperation
   9. imageSmoothingEnabled
   10. imageSmoothingQuality
   11. lineCap
   12. lineDashOffset
   13. lineJoin
   14. lineWidth
   15. miterLimit
   16. shadowBlur
   17. shadowColor
   18. shadowOffsetX
   19. shadowOffsetY
   20. strokeStyle
   21. textAlign
   22. textBaseline
3. 方法

   1. addHitRegion()
   2. arc()
   3. arcTo()
   4. beginPath()
   5. bezierCurveTo()
   6. clearHitRegions()
   7. clearRect()
   8. clip()
   9. closePath()
   10. createImageData()
   11. createLinearGradient()
   12. createPattern()
   13. createRadialGradient()
   14. drawFocusIfNeeded()
   15. drawImage()
   16. drawWidgetAsOnScreen()
   17. drawWindow()
   18. ellipse()
   19. fill()
   20. fillRect()
   21. fillText()
   22. getImageData()
   23. getLineDash()
   24. getTransform()
   25. isPointInPath()
   26. isPointInStroke()
   27. lineTo()
   28. measureText()
   29. moveTo()
   30. putImageData()
   31. quadraticCurveTo()
   32. rect()
   33. removeHitRegion()
   34. resetTransform()
   35. restore()
   36. rotate()
   37. save()
   38. scale()
   39. scrollPathIntoView()
   40. setLineDash()
   41. setTransform()
   42. stroke()
   43. strokeRect()
   44. strokeText()
   45. transform()
   46. translate()