Created
May 26, 2017 15:28
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Scale Image to fit on canvas
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>JS Bin</title> | |
| </head> | |
| <body> | |
| <canvas id='cv'></canvas> | |
| <button id='other'>other image</button> | |
| </body> | |
| </html> |
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| //Source: https://stackoverflow.com/questions/23104582/scaling-an-image-to-fit-on-canvas | |
| var canvas=document.getElementById('cv'); | |
| var ctx= canvas.getContext('2d'); | |
| var img = new Image(); | |
| img.onload= drawImageScaled.bind(null, img, ctx); | |
| function drawImageScaled(img, ctx) { | |
| var canvas = ctx.canvas ; | |
| var hRatio = canvas.width / img.width ; | |
| var vRatio = canvas.height / img.height ; | |
| var ratio = Math.min ( hRatio, vRatio ); | |
| var centerShift_x = ( canvas.width - img.width*ratio ) / 2; | |
| var centerShift_y = ( canvas.height - img.height*ratio ) / 2; | |
| ctx.clearRect(0,0,canvas.width, canvas.height); | |
| ctx.drawImage(img, 0,0, img.width, img.height, | |
| centerShift_x,centerShift_y,img.width*ratio, img.height*ratio); | |
| } | |
| img.src = 'http://s1.dmcdn.net/BhdSy/526x297-KuG.jpg'; | |
| document.getElementById('other').onclick = function() { | |
| img = new Image(); | |
| img.onload= drawImageScaled.bind(null, img, ctx); | |
| img.src = | |
| 'http://www.pliagedepapier.com/gallery/albums/userpics/12780/DogEvie-JasonKuG.jpg'; | |
| } |
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