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December 21, 2022 15:36
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Rescaling Canvas to Parent Element Size
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width"> | |
| <title>JS Bin</title> | |
| <style> | |
| html, body { | |
| margin: 0; | |
| width: 100%; | |
| height: 100%; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <canvas id="canvas"></canvas> | |
| <script> | |
| const canvasElement = document.getElementById('canvas'); | |
| const c = canvasElement.getContext('2d'); | |
| let rafPending = false; | |
| const raf = (f) => { | |
| if (rafPending) { | |
| return; | |
| } | |
| rafPending = true; | |
| window.requestAnimationFrame(() => { | |
| rafPending = false; | |
| f(); | |
| }); | |
| }; | |
| const setCanvasSizeFromParent = () => { | |
| const dpr = window.devicePixelRatio || 1; | |
| const w = c.canvas.parentElement.clientWidth * dpr; | |
| const h = c.canvas.parentElement.clientHeight * dpr; | |
| c.canvas.width = w; | |
| c.canvas.height = h; | |
| c.canvas.style.width = `${w}px`; | |
| c.canvas.style.height = `${h}px`; | |
| c.scale(dpr, dpr); | |
| c.beginPath(); | |
| c.moveTo(0, 0); | |
| c.lineTo(c.canvas.width, c.canvas.height); | |
| c.stroke(); | |
| }; | |
| window.addEventListener('resize', () => { | |
| raf(setCanvasSizeFromParent); | |
| }); | |
| raf(setCanvasSizeFromParent); | |
| </script> | |
| </body> | |
| </html> |
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