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65 lines
1.9 KiB
65 lines
1.9 KiB
9 years ago
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//TODO: replace with cdn url
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module.exports = function Tesseract(url=location.href+'build/tesseract.worker.js'){
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var blob = new Blob(["importScripts('"+url+"');"])
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var worker = new Worker(window.URL.createObjectURL(blob));
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var bigworker = false
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var jobCounter = 0
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var handlers = {}
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function runAsync(action, args){
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var jobId = jobCounter++
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handlers[jobId] = {}
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var message = {jobId, action, args}
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console.log(message)
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worker.postMessage(message)
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return {
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then (f){ handlers[jobId].result = f; return this},
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error (f){ handlers[jobId].error = f; return this},
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progress(f){ handlers[jobId].progress = f; return this}
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}
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}
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worker.onmessage = function(e){
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var {jobId, progress, error, result} = e.data
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var handler = handlers[jobId]
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if(progress && handler.progress) handler.progress(progress);
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if(error && handler.error) handler.error(error);
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if(result && handler.result) handler.result(result);
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}
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function convertToImageData(image){
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if(image.getContext) image = image.getContext('2d');
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else if(image.tagName == "IMG" || image.tagName == "VIDEO"){
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var c = document.createElement('canvas');
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c.width = image.naturalWidth || image.videoWidth;
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c.height = image.naturalHeight || image.videoHeight;
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var ctx = c.getContext('2d');
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ctx.drawImage(image, 0, 0);
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image = ctx;
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}
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if(image.getImageData) image = image.getImageData(0, 0, image.canvas.width, image.canvas.height);
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return image
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}
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runAsync('init', {mem: (1<<24) * 6})
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return {
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detect(image){
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return runAsync('detect', {image: convertToImageData(image)})
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},
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recognize(image, options='eng'){
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if (typeof options === 'string') options = {lang: options};
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else options.lang = options.lang || 'eng';
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if (!bigworker && ['chi_sim', 'chi_tra', 'jpn'].indexOf(options.lang) != -1){
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runAsync('init', {mem: (1<<24) * 10})
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bigworker = true
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}
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return runAsync('recognize', {options, image: convertToImageData(image)})
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}
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}
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}
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