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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

CanvasRenderingContext2D .createRadialGradient() method of the Canvas 2D API creates a radial gradient using the size and coordinates of two circles.

此方法返回 CanvasGradient . To be applied to a shape, the gradient must first be assigned to the fillStyle or strokeStyle 特性。

注意： Gradient coordinates are global, i.e., relative to the current coordinate space. When applied to a shape, the coordinates are NOT relative to the shape's coordinates.

句法

CanvasGradient ctx.createRadialGradient(x0, y0, r0, x1, y1, r1);
					

createRadialGradient() method is specified by six parameters, three defining the gradient's start circle, and three defining the end circle.

参数

x0

The x-axis coordinate of the start circle.

y0

The y-axis coordinate of the start circle.

r0

The radius of the start circle. Must be non-negative and finite.

x1

The x-axis coordinate of the end circle.

y1

The y-axis coordinate of the end circle.

r1

The radius of the end circle. Must be non-negative and finite.

返回值

CanvasGradient

A radial CanvasGradient initialized with the two specified circles.

范例

Filling a rectangle with a radial gradient

This example initializes a radial gradient using the createRadialGradient() method. Three color stops between the gradient's two circles are then created. Finally, the gradient is assigned to the canvas context, and is rendered to a filled rectangle.

HTML

<canvas id="canvas" width="200" height="200"></canvas>
					

JavaScript

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
// Create a radial gradient
// The inner circle is at x=110, y=90, with radius=30
// The outer circle is at x=100, y=100, with radius=70
var gradient = ctx.createRadialGradient(110,90,30, 100,100,70);
// Add three color stops
gradient.addColorStop(0, 'pink');
gradient.addColorStop(.9, 'white');
gradient.addColorStop(1, 'green');
// Set the fill style and draw a rectangle
ctx.fillStyle = gradient;
ctx.fillRect(20, 20, 160, 160);
					

结果

规范

规范	状态	注释
HTML 实时标准 The definition of 'CanvasRenderingContext2D.createRadialGradient' 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
createRadialGradient	Chrome Yes	Edge 12	Firefox 1.5	IE Yes	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android 4	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes

图例

完整支持

完整支持

Gecko-specific notes

• Starting with Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1), specifying non-finite values now throws NOT_SUPPORTED_ERR 而不是 SYNTAX_ERR .
• Starting with Gecko 5.0 (Firefox 5.0 / Thunderbird 5.0 / SeaMonkey 2.2), specifying a negative radius correctly throws INDEX_SIZE_ERR .

另请参阅

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.createLinearGradient()

元数据

• 最后修改： 2019 年 3 月 23 日

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()