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September 6, 2024 17:22
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A simple JavaScript to resize an image and create a blob out of it
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| window.resize = (function () { | |
| 'use strict'; | |
| function Resize() {} | |
| Resize.prototype = { | |
| init: function(outputQuality) { | |
| this.outputQuality = (outputQuality === 'undefined' ? 0.8 : outputQuality); | |
| }, | |
| photo: function(file, maxSize, outputType, callback) { | |
| var _this = this; | |
| var reader = new FileReader(); | |
| reader.onload = function (readerEvent) { | |
| _this.resize(readerEvent.target.result, maxSize, outputType, callback); | |
| } | |
| reader.readAsDataURL(file); | |
| }, | |
| resize: function(dataURL, maxSize, outputType, callback) { | |
| var _this = this; | |
| var image = new Image(); | |
| image.onload = function (imageEvent) { | |
| // Resize image | |
| var canvas = document.createElement('canvas'), | |
| width = image.width, | |
| height = image.height; | |
| if (width > height) { | |
| if (width > maxSize) { | |
| height *= maxSize / width; | |
| width = maxSize; | |
| } | |
| } else { | |
| if (height > maxSize) { | |
| width *= maxSize / height; | |
| height = maxSize; | |
| } | |
| } | |
| canvas.width = width; | |
| canvas.height = height; | |
| canvas.getContext('2d').drawImage(image, 0, 0, width, height); | |
| _this.output(canvas, outputType, callback); | |
| } | |
| image.src = dataURL; | |
| }, | |
| output: function(canvas, outputType, callback) { | |
| switch (outputType) { | |
| case 'file': | |
| canvas.toBlob(function (blob) { | |
| callback(blob); | |
| }, 'image/jpeg', 0.8); | |
| break; | |
| case 'dataURL': | |
| callback(canvas.toDataURL('image/jpeg', 0.8)); | |
| break; | |
| } | |
| } | |
| }; | |
| return Resize; | |
| }()); |
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how to use it?