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Simplify calculating hash from file with chunked-file-reader
The chunked-file-reader comes with the functionality of reading a file in chunks, so we can simplify the file example a lot by offloading this logic to that package. I think this will make it much more approachable for people wanting to reuse that code. The chunked-file-reader package uses `readAsArrayBuffer()`, and we cannot use it for tests that use `readAsBinaryString()`. Also, chunked-file-reader always uses `File.prototype.slice`, but I think that's ok now, since `blob.mozSlice()` is only needed for Firefox 12 and earlier, though I don't on which version did Safari start supporting `File.prototype.slice` (I tested that it works on Safari 11 which is the current latest version). Closes satazor#48
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| (function(root, factory){ | ||
| if(typeof define === 'function' && define.amd) | ||
| { | ||
| define(factory); | ||
| } | ||
| else if(typeof exports === 'object' && typeof module != 'undefined') | ||
| { | ||
| module.exports= factory(); | ||
| } | ||
| else | ||
| { | ||
| this.ChunkedFileReader= factory(); | ||
| } | ||
| }(this, function(){ | ||
| 'use strict'; | ||
|
|
||
| /** | ||
| * Create a new instance of ChunkedFileReader. | ||
| * | ||
| * @class ChunkedFileReader | ||
| * @constructor | ||
| * @param opts {object} The options. | ||
| * Valid options are: | ||
| * maxChunkSize - Maximum chunk size | ||
| */ | ||
| var ChunkedFileReader= function(opts){ | ||
| opts || (opts= {}); | ||
|
|
||
| this.maxChunkSize= (opts.maxChunkSize || 256 * 1024); | ||
| this.listeners= {}; | ||
| }; | ||
|
|
||
| /** | ||
| * Subscribe a event. | ||
| * | ||
| * @method subscribe | ||
| * @param eventName {string} The event name to be subscribed | ||
| * @param listener {function} The listener function to be invoked on events | ||
| * @param thisObj {any} The `this' object to be used for invoking listener function | ||
| */ | ||
| ChunkedFileReader.prototype.subscribe= function(eventName, listener, thisObj){ | ||
| this.listeners[eventName]= (this.listeners[eventName] || []); | ||
| this.listeners[eventName].push({ | ||
| ctx: thisObj, | ||
| fun: listener | ||
| }); | ||
| }; | ||
|
|
||
| /** | ||
| * **Internal use** | ||
| * | ||
| * @method publish | ||
| * @param eventName {string} The event name | ||
| * @param eventArgs {object} The event args to be passed each listeners | ||
| */ | ||
| ChunkedFileReader.prototype.publish= function(eventName, eventArgs){ | ||
| (this.listeners[eventName] || []).forEach(function(listener){ | ||
| listener.fun.call(listener.ctx, eventArgs); | ||
| }, this); | ||
| }; | ||
|
|
||
| /** | ||
| * Read chunks from File object. | ||
| * | ||
| * It produces some events:<br> | ||
| * <ul> | ||
| * <li>"begin" - On started file reading.</li> | ||
| * <li>"progress" - On progress changed.</li> | ||
| * <li>"chunk" - On read a chunk.</li> | ||
| * <li>"end" - On Finished reading.</li> | ||
| * </ul> | ||
| * | ||
| * @method readChunks | ||
| * @param input {blob} The Blob (File) object | ||
| */ | ||
| ChunkedFileReader.prototype.readChunks= function(input){ | ||
| var chunkSize= Math.min(this.maxChunkSize, input.size); | ||
| var remainingBytes= input.size; | ||
| var nchunks= (remainingBytes % chunkSize === 0) | ||
| ? remainingBytes / chunkSize | ||
| : parseInt(remainingBytes / chunkSize) + 1; | ||
|
|
||
| var pos= 0; | ||
| var reader= new FileReader(input); | ||
| var seq= 1; | ||
| var that= this; | ||
| reader.onloadend= function(evt){ | ||
| if(evt.target.readyState !== FileReader.DONE) | ||
| { | ||
| return; | ||
| } | ||
|
|
||
| that.publish('progress', { | ||
| nchunks: nchunks, | ||
| done: seq, | ||
| done_ratio: (seq / nchunks) | ||
| }); | ||
| that.publish('chunk', { | ||
| seq: seq, | ||
| nchunks: nchunks, | ||
| chunk: evt.target.result | ||
| }); | ||
| ++seq; | ||
|
|
||
| pos+= chunkSize; | ||
| remainingBytes-= chunkSize; | ||
| if(remainingBytes < chunkSize) | ||
| { | ||
| chunkSize= remainingBytes; | ||
| } | ||
| if(remainingBytes > 0) | ||
| { | ||
| reader.readAsArrayBuffer(input.slice(pos, pos + chunkSize)); | ||
| } | ||
| else | ||
| { | ||
| that.publish('end', { | ||
| nchunks: nchunks, | ||
| }); | ||
| } | ||
| }; | ||
|
|
||
| this.publish('begin', { | ||
| nchunks: nchunks | ||
| }); | ||
|
|
||
| reader.readAsArrayBuffer(input.slice(pos, pos + chunkSize)); | ||
| }; | ||
| return ChunkedFileReader; | ||
| })); |
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