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101 lines
2.4 KiB
JavaScript
101 lines
2.4 KiB
JavaScript
/**
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* Create a blob builder even when vendor prefixes exist
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*/
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var BlobBuilder = typeof BlobBuilder !== 'undefined' ? BlobBuilder :
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typeof WebKitBlobBuilder !== 'undefined' ? WebKitBlobBuilder :
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typeof MSBlobBuilder !== 'undefined' ? MSBlobBuilder :
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typeof MozBlobBuilder !== 'undefined' ? MozBlobBuilder :
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false;
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/**
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* Check if Blob constructor is supported
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*/
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var blobSupported = (function() {
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try {
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var a = new Blob(['hi']);
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return a.size === 2;
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} catch(e) {
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return false;
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}
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})();
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/**
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* Check if Blob constructor supports ArrayBufferViews
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* Fails in Safari 6, so we need to map to ArrayBuffers there.
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*/
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var blobSupportsArrayBufferView = blobSupported && (function() {
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try {
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var b = new Blob([new Uint8Array([1,2])]);
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return b.size === 2;
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} catch(e) {
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return false;
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}
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})();
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/**
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* Check if BlobBuilder is supported
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*/
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var blobBuilderSupported = BlobBuilder
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&& BlobBuilder.prototype.append
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&& BlobBuilder.prototype.getBlob;
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/**
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* Helper function that maps ArrayBufferViews to ArrayBuffers
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* Used by BlobBuilder constructor and old browsers that didn't
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* support it in the Blob constructor.
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*/
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function mapArrayBufferViews(ary) {
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return ary.map(function(chunk) {
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if (chunk.buffer instanceof ArrayBuffer) {
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var buf = chunk.buffer;
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// if this is a subarray, make a copy so we only
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// include the subarray region from the underlying buffer
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if (chunk.byteLength !== buf.byteLength) {
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var copy = new Uint8Array(chunk.byteLength);
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copy.set(new Uint8Array(buf, chunk.byteOffset, chunk.byteLength));
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buf = copy.buffer;
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}
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return buf;
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}
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return chunk;
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});
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}
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function BlobBuilderConstructor(ary, options) {
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options = options || {};
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var bb = new BlobBuilder();
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mapArrayBufferViews(ary).forEach(function(part) {
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bb.append(part);
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});
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return (options.type) ? bb.getBlob(options.type) : bb.getBlob();
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};
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function BlobConstructor(ary, options) {
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return new Blob(mapArrayBufferViews(ary), options || {});
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};
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if (typeof Blob !== 'undefined') {
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BlobBuilderConstructor.prototype = Blob.prototype;
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BlobConstructor.prototype = Blob.prototype;
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}
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module.exports = (function() {
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if (blobSupported) {
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return blobSupportsArrayBufferView ? Blob : BlobConstructor;
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} else if (blobBuilderSupported) {
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return BlobBuilderConstructor;
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} else {
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return undefined;
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}
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})();
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