A wired example of Canvas be cut off by very long .clip() path
Discussion can be found at StackOverflow.
Last active
May 14, 2021 04:11
-
-
Save hijiangtao/4769c61573ebd2b068d6065930fbd65d to your computer and use it in GitHub Desktop.
A wired example of Canvas be cut off by very long `.clip()` path
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <title>Wired Cut off Canvas</title> | |
| <Style> | |
| body { | |
| background-color: gray; | |
| } | |
| #canvas { | |
| position: absolute; | |
| x: 2px; | |
| y: 2px; | |
| } | |
| #canvas2 { | |
| position: absolute; | |
| x: 754px; | |
| y: 2px; | |
| } | |
| </Style> | |
| </head> | |
| <body> | |
| <canvas id="canvas"></canvas> | |
| <canvas id="canvas2"></canvas> | |
| <script src="./index.js"></script> | |
| </body> | |
| </html> |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| class BaseCanvas { | |
| constructor() { | |
| this.canvas = document.getElementById('canvas'); | |
| this.ctx = this.canvas.getContext('2d'); | |
| this.canvas2 = document.getElementById('canvas2'); | |
| this.ctx2 = this.canvas.getContext('2d'); | |
| this.config = { | |
| width: 750, | |
| height: 20000, | |
| rectWidth: 680, | |
| rectHeight: 18000, | |
| } | |
| } | |
| updateCanvas() { | |
| const { width, height, rectWidth, rectHeight } = this.config; | |
| this.canvas.height = height; | |
| this.canvas.width = width; | |
| this.drawBackground(); | |
| const x = (width - rectWidth) / 2; | |
| const y = x; | |
| this.drawClipContent(x, y, rectWidth, rectHeight, 20, () => { | |
| this.ctx.fillStyle = '#FFF'; | |
| this.ctx.fillRect(x, y, rectWidth, rectHeight); | |
| // some other logics here | |
| // ... | |
| }); | |
| } | |
| drawBackground() { | |
| this.ctx.fillStyle = '#4997FE'; | |
| this.ctx.fillRect(0, 0, this.config.width, this.config.height); | |
| } | |
| drawClipContent( | |
| x, | |
| y, | |
| width, | |
| height, | |
| radius, | |
| contentFn | |
| ) { | |
| this.ctx.save(); | |
| this.ctx.beginPath(); | |
| this.ctx.translate(x, y); | |
| this.drawRoundRectPath(width, height, radius, true); | |
| this.ctx.closePath(); | |
| this.ctx.clip(); | |
| if (contentFn) { | |
| this.ctx.translate(-x, -y); | |
| contentFn(); | |
| } | |
| this.ctx.restore(); | |
| } | |
| drawClipContent2( | |
| x, | |
| y, | |
| width, | |
| height, | |
| radius, | |
| contentFn | |
| ) { | |
| this.ctx.save(); | |
| this.ctx.translate(x, y); | |
| this.ctx.beginPath(); | |
| this.drawRoundRectPath(width, height, radius, true); | |
| this.ctx.closePath(); | |
| this.ctx.clip(); | |
| if (contentFn) { | |
| this.ctx.translate(-x, -y); | |
| this.ctx.fillStyle = '#FFF'; | |
| this.ctx.fillRect(x, y, rectWidth, rectHeight); | |
| } | |
| this.ctx.restore(); | |
| } | |
| drawRoundRectPath(width, height, radius) { | |
| const topLeftRadius = radius; | |
| const topRightRadius = radius; | |
| const bottomLeftRadius = radius; | |
| const bottomRightRadius = radius; | |
| this.ctx.arc(width - bottomRightRadius, height - bottomRightRadius, bottomRightRadius, 0, Math.PI / 2); | |
| this.ctx.lineTo(bottomLeftRadius, height); | |
| this.ctx.arc(bottomLeftRadius, height - bottomLeftRadius, bottomLeftRadius, Math.PI / 2, Math.PI); | |
| this.ctx.lineTo(0, topLeftRadius); | |
| this.ctx.arc(topLeftRadius, topLeftRadius, topLeftRadius, Math.PI, (Math.PI * 3) / 2); | |
| this.ctx.lineTo(width - topRightRadius, 0); | |
| this.ctx.arc(width - topRightRadius, topRightRadius, topRightRadius, (Math.PI * 3) / 2, Math.PI * 2); | |
| this.ctx.lineTo(width, height - topRightRadius); | |
| } | |
| } | |
| // calling | |
| const ins = new BaseCanvas(); | |
| ins.updateCanvas(); |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment