/
using_base64.html
188 lines (143 loc) · 5.82 KB
/
using_base64.html
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<html>
<head>
</head>
<body>
<img id="ItemPreview" src="" />
<script>
function Length(url)
{
var http = new XMLHttpRequest();
http.open('HEAD', url);
http.onreadystatechange = function() {
if (this.readyState == this.DONE) {
console.log(this);
length = this.getResponseHeader('Content-Length');
// console.log(this);
get_image(this.responseURL, length)
}
};
http.send();
}
// var length = 0;
length = Length("binary");
// console.log(length);
// get_image("output", length);
// console.log("Length = "+length);
window["content1"] = ""
window["content2"] = ""
window["content3"] = ""
function get_part(url, start_index, end_index, variable_name){
var xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET",url,true);
// console.log("LENGTTH ="+length);
console.log("Start_part ="+start_index);
console.log("end_part ="+end_index);
// xmlhttp.responseType = 'arraybuffer';
xmlhttp.setRequestHeader("Range", "bytes="+start_index+"-"+end_index);
xmlhttp.send();
xmlhttp.addEventListener("readystatechange", function () {
if (xmlhttp.readyState == xmlhttp.DONE) {
var response = xmlhttp.response;
// var response = new Uint8Array(xmlhttp.response)
// console.log(xmlhttp.response.length);
console.log("LENGTH of "+variable_name+" = "+response.length);
// console.log(variable_name)
window[variable_name] = response;
if (window['content1'] != "" && window['content2'] != "" && window['content3'] != ""){
// content = content1+content2+content3
// content = _appendBuffer(window['content1'], window['content2']);
// content = _appendBuffer(window['content'], window['content3']);
// var b64encoded1 = btoa(String.fromCharCode.apply(null, content1));
// var b64encoded2 = btoa(String.fromCharCode.apply(null, content2));
// var b64encoded3 = btoa(String.fromCharCode.apply(null, content3));
// document.getElementById("ItemPreview").src = "data:image/png;base64," + b64encoded1 + b64encoded2 + b64encoded3;
document.getElementById("ItemPreview").src = "data:image/png;base64," + content1 + content2 + content3;
}
}
});
// var something = new ArrayBuffer(xmlhttp.response)
// var view = new Int32Array(buffer);
// return new Uint8Array(xmlhttp.response)
}
var _appendBuffer = function(buffer1, buffer2) {
var tmp = new Uint8Array(buffer1.byteLength + buffer2.byteLength);
tmp.set(new Uint8Array(buffer1), 0);
tmp.set(new Uint8Array(buffer2), buffer1.byteLength);
return tmp;
};
function get_image(url, length){
var start_part_1 = 0;
var end_part_1 = Math.floor(length/3) - 2;
// if (end_part_1%3 != 0){
// end_part_1 = end_part_1 + (3 - end_part_1%3);
// }
get_part(url, start_part_1, end_part_1, "content1");
console.log(content1);
var start_part_2 = end_part_1+1;
var end_part_2 = start_part_2 + end_part_1;
// var content2 = new Uint8Array(request.response);
get_part(url, start_part_2, end_part_2, "content2") //--> returns only the partial content
var start_part_3 = end_part_2+1;
var end_part_3 = length-1;
get_part(url, start_part_3, end_part_3, "content3") //--> returns only the partial content
// var start_part_4 = end_part_3;
// var end_part_4 = start_part_4 + end_part_1;
// console.log("Start_part 2 ="+start_part_4);
// console.log("end_part2 ="+end_part_4);
// // var content3 = new Uint8Array(request.response);
// content4 = xmlhttp.response; //--> returns only the partial content
// var start_part_5 = end_part_4;
// var end_part_5 = length -1;
// console.log("Start_part 2 ="+start_part_5);
// console.log("end_part2 ="+end_part_5);
// // var content3 = new Uint8Array(request.response);
// content5 = xmlhttp.response; //--> returns only the partial content
// image_64 = window.btoa(unescape(encodeURIComponent(content1 + content2 + content3)));
// console.log(image_64);
// content = content1+content2+content3
// image_64 = content
// console.log(content.length);
// image_64 = base64ArrayBuffer(content);
// document.getElementById("ItemPreview").src = "data:image/png;base64," + image_64;
}
function base64ArrayBuffer(arrayBuffer) {
var base64 = ''
var encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
var bytes = new Uint8Array(arrayBuffer)
var byteLength = bytes.byteLength
var byteRemainder = byteLength % 3
var mainLength = byteLength - byteRemainder
var a, b, c, d
var chunk
// Main loop deals with bytes in chunks of 3
for (var i = 0; i < mainLength; i = i + 3) {
// Combine the three bytes into a single integer
chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2]
// Use bitmasks to extract 6-bit segments from the triplet
a = (chunk & 16515072) >> 18 // 16515072 = (2^6 - 1) << 18
b = (chunk & 258048) >> 12 // 258048 = (2^6 - 1) << 12
c = (chunk & 4032) >> 6 // 4032 = (2^6 - 1) << 6
d = chunk & 63 // 63 = 2^6 - 1
// Convert the raw binary segments to the appropriate ASCII encoding
base64 += encodings[a] + encodings[b] + encodings[c] + encodings[d]
}
// Deal with the remaining bytes and padding
if (byteRemainder == 1) {
chunk = bytes[mainLength]
a = (chunk & 252) >> 2 // 252 = (2^6 - 1) << 2
// Set the 4 least significant bits to zero
b = (chunk & 3) << 4 // 3 = 2^2 - 1
base64 += encodings[a] + encodings[b] + '=='
} else if (byteRemainder == 2) {
chunk = (bytes[mainLength] << 8) | bytes[mainLength + 1]
a = (chunk & 64512) >> 10 // 64512 = (2^6 - 1) << 10
b = (chunk & 1008) >> 4 // 1008 = (2^6 - 1) << 4
// Set the 2 least significant bits to zero
c = (chunk & 15) << 2 // 15 = 2^4 - 1
base64 += encodings[a] + encodings[b] + encodings[c] + '='
}
return base64
}
</script>
</body>
</html>