Dump a BMP file 2 an array of arrays (of arrays)

Hi,

I've been trying to dump a bmp file in to an array as follows:
an array of 32 arrays of 32 arrays of 4 byte values, but have not been able to make it work, I would appreciate any help, this is what I've been trying:

The first 54 bytes have header information:

var img = new Array();
function rcolor(x){
    return (TONES*x/256);
}

function readbmp(myfile){
    try{
        var i=0;
        var k=0;
        var x=0;
        var flag=0;
        var px = new Array();
        px[0] = 0;
        px[1] = 0;
        px[2] = 0;
        px[3] = 0;
        var line=new Array();
        if (myfile.length==4096){
            flag=4;
        }
        else {
            flag =3;
        }
        for (var byte in myfile){
            z= myfile[byte];
            console.log(z);
            k+=1;
            if(k==1){
                px[0]=myfile[byte];
            }
            if(k==2){
                px[1]=myfile[byte];
            }
            if(k==3){
                px[2]=myfile[byte];
            }
            if(k==4){
                px[3]=myfile[byte];
            }
            if(k==flag){
                k=0;
                line.push(px);
                x+=1;
                if(x==32){
                    img.push(line);
                    line.splice(0, line.length); 
                    x=0;
                }
  
            }
        }
        console.log(img);
        return x;
    }
    catch(err){
        return 0;
    }
}

var image = require("fs").readFile("GIF/wizardcity00­001.bmp", "binary");
image = image.substr(54,image.length);
readbmp(image);

I would really appreciate any help.

Bests

One thing you're going to need to do is use Uint32Arrays. An array of 32 32 entry simple arrays will take up a bit over 2048 memory units, which is more than the espruino board has. Even with typed arrays, that's going to be like 500-something memory units.

Tryed several things always running out of memory, un the end I used a unit8array and stored everything on a 4096 lineal array and I will have to calculate the positions every time

So you have it working now?

You should have some luck using 32 x Uint32Arrays (or Uint8Arrays)?

In the end I dumped the 32 X 32 bmp into Uint32Arrays, here is the code:

var image = require("fs").readFile("GIF/blue.bmp", "binary");
image = image.substr(54,image.length);
if (image.length==4096){
  var bytes = new Uint8Array(4096);
  for (var j=0;j<4096;j++){ 
    //bytes[j]=Math.round(image[j].charCodeA­t()*TONES/256);
    bytes[j]=image[j].charCodeAt();
    //console.log(image[j].charCodeAt());
  }
}
if (image.length==3072){
  var c = 0;
  var bytes = new Uint8Array(4096);
  for (var j=0;j<3072;j++){
    if ((c+1)%4==0){
      bytes[c]=128;
      c+=1;
    } else {
      //bytes[j]=Math.round(image[j].charCodeA­t()*TONES/256);
      bytes[c]=image[j].charCodeAt();
      
      //console.log(image[j].charCodeAt());
    }
    c+=1;
  }
}

Could you please modify your post, as it looks broken :)

You can extract colour data from bmp into Uint8Array on desktop computer, then using atob convert into binary string, and save into a file.
Then it will be much easier and faster to load it from SD card on Espruino from that file (binary string) using atob, speed should spike dramatically.

I just edited the post - you just need to highlight the code and click the 'code' button.

You can actually set the value of the Uint8Array to the string with a simple:

bytes.set(image);

Which could be a bit faster for the first case.

Thanks @moka - If anyone's interested there's a little bit on how to do this at the bottom of http://www.espruino.com/Graphics

Having said that, a module to load Bitmaps off the SD card would be pretty cool :)