javascript - Creating a PNG from uncompressed raw PNG data -

i using android screenshot library capture screenshots. want show screenshot in web browser.

i have written small socket app on pc connects android phone , encode captured screenshot base64.

string base64 = base64.getencoder().encodetostring(bytes); 

this base64 being sent web page on websocket. below html/js code should draw image on canvas. have stored base64 image data in text file test purpose.

<div style="background: aqua; width: 500px; height: 660px;">      <canvas style="width: 480px; height: 640px;" id="sim">     </canvas> </div>  <script type="text/javascript">     var ctx;     var width = 480;     var height = 640;      (function start() {         ctx = document.getelementbyid("sim").getcontext("2d");         loadfromfile();     })();      function loadimage(data) {          var image = new image();         image.onload = function() {             //this part never executes             ctx.drawimage(image, 0, 0);             console.log("images loaded!");         }          image.src = "data:image/png;base64," + data;     }      function loadfromfile() {         //please data **https://app.box.com/s/e19ww51fd37h4sy8getjnag31ud6tpp9**         var file = "imagefile.txt";          var rawfile = new xmlhttprequest();         rawfile.open("get", file, true);          rawfile.onreadystatechange = function() {             if (rawfile.readystate === 4) {                 if (rawfile.status === 200 || rawfile.status == 0) {                     var data = rawfile.responsetext;                     console.log("data loaded: " + data.length);                      loadimage(data);                 }             }         }         rawfile.send(null);     } </script> 

for convenience, here jsfiddle of same code.

please point right algorithm how generate png raw uncompressed data. code sample great ;)

thanks

public static string encodetobase64(bitmap image) { bitmap immagex=image; bytearrayoutputstream baos = new bytearrayoutputstream();   immagex.compress(bitmap.compressformat.jpeg, 100, baos); byte[] b = baos.tobytearray(); string imageencoded = base64.encodetostring(b,base64.default);  log.e("look", imageencoded); return imageencoded; }  public static bitmap decodebase64(string input)   { byte[] decodedbyte = base64.decode(input, 0); return bitmapfactory.decodebytearray(decodedbyte, 0, decodedbyte.length); }