< by the people in Jim McCann's [Textiles Lab](https://textiles-lab.github.io/) at CMU.<br >
As a summary, DAT files are [Run-Length-Encoded](https://en.wikipedia.org/wiki/Run-length_encoding) images.
Your main interface will be
* [datfile.js](images/datfile.js) for writing and reading DAT files
* [dat2png.js](images/dat2png.js) for visualizing DAT files
To use any of these, you need [Node.js](https://nodejs.org/en/).<br>
To install the visualization script dependencies, see [node-canvas](https://github.com/Automattic/node-canvas) (it's typically more than just `npm install canvas`).<br>
To install the conversion code, you need [png-js](https://github.com/devongovett/png.js).
**Note**: the visualization code was using version 1.6.11 of node-canvas.<br>
The new Canvas 2 API may / likely does not work.
The visualization script transforms a DAT file into a PNG image. Its usage is as follows:
```bash
./dat2png.js file.dat [file.png] [scale=1] [text=0]
```
Arguments:
* Input file (DAT)
* Output file (PNG), defaulting to DAT with extension replaced with `.png`
* Scale factor: for useful visualiztion, use a larger number, e.g. 10
* Text: boolean value for whether to display the instruction number in each cell (requires large scale to be readable)
Here are a few examples using `datfile.js`.
The corresponding images used `./dat2png.js file.dat file.png 10 1`.
# Pattern1.js
* [pattern1.js](images/pattern1.js)
```js
const DATFile = require('./datfile.js');
let dat = new DATFile();
dat.allocatePixels(20, 20);
for(let x = 0; x < 20; ++x){
for(let y = 0; y < 20; ++y){
dat.setPixel(y, x, 1 + (y % 2));
}
}
dat.write('pattern1.dat');
```
# Test1.js
* [test1.js](images/test1.js)
```js
const DATFile = require('./datfile.js');
let dat = new DATFile();
dat.allocateLines(10, 10, true);
for(let i = 0; i < 10; ++i){
dat.setLine(i + 3, 1 + (i%2), { R3: 6 }, i % 2 ? 'right' : 'left');
}
dat.setLineDirections();
dat.setCarrierPositions();
dat.write('test1.dat');
```
# Test2.js
* [test2.js](images/test2.js)
```js
const DATFile = require('./datfile.js');
let dat = new DATFile();
dat.create(10);
dat.writePreamble(); // newline=true (because streaming from create)
for(let i = 0; i < 10; ++i){
dat.setLine(dat.current, 1 + (i%2), { R3: 6 }, i % 2 ? 'right' : 'left', true);
}
dat.writePostamble();
dat.setLineDirections();
dat.setCarrierPositions();
dat.write('test2.dat');
```
# Test3.js
* [test3.js](images/test3.js)
```js
const DATFile = require('./datfile.js');
let dat = new DATFile();
dat.create(10);
dat.writePreamble(); // newline=true (because streaming from create)
// create welt for hookup
for(let i = 1; i < 10; i += 2)
dat.setValue(dat.current, i, 11); // tuck
dat.setValue(dat.current, 0, 216); // float
dat.setLineOptions(dat.current, { R3: 5, R10: 5, R15: 10 });
dat.newLine();
for(let i = 0; i < 10; i+= 2)
dat.setValue(dat.current, i, 11); // tuck
dat.setValue(dat.current, 9, 216); // float
dat.setLineOptions(dat.current, { R3: 5, R6: 33 });
dat.newLine();
// knitting
for(let i = 0; i < 2; ++i)
dat.setLine(dat.current, 51, { R3: 5, R6: 5 });
// cutting
dat.setSegment(dat.current, 9, [16], { R3: 255, R6: 5, R15: 90 }); // R15=90 for end of yarn init
// knitting
for(let i = 0; i < 2; ++i)
dat.setLine(dat.current, 51, { R3: 5, R5: i == 0 ? 2 : 0, R6: 5 }); // reset carrier (R5) on first line
// transfer + knitting
for(let i = 0; i < 3; ++i){
// transfer
dat.setSegment(dat.current, 4, [20, 20], { R5: 1 });
dat.setSegment(dat.current, 4, [30], { L2: 1, L4: 10, R5: 1 });
dat.setSegment(dat.current, 5, [30], { L4: 11, R5: 1 });
// knit
dat.setLine(dat.current, 51, { R3: 5, R6: 5 });
dat.setLine(dat.current, 51, { R3: 5, R6: 5 });
}
// end knitting
dat.setLine(dat.current, 51, { R3: 5, R6: 5 });
dat.setLine(dat.current, 51, { R3: 5, R6: 5, R10: 105, R15: 20 });
dat.writePostamble();
dat.setLineDirections();
dat.setCarrierPositions();
dat.write('test3.dat');
```
# Drawing Your Own Program
You can also draw your program as PNG and then convert it to DAT.<br>
The required scripts for conversion are:
* [png2dat.js](images/png2dat.js) for translating PNG to DAT files
* [datfile.js](images/datfile.js) (library used by png2dat)
The script `png2dat.js` takes as input a png file, and and optional output dat target.
```bash
./png2dat.js file.png [file.dat]
```
For writing anything reasonable, make sure to work with the necessary colormap so the color numbers map directly to the instructions that are in the reference documents of the introduction.
You can download and modify the following 20x20 pattern (should be likely up-scaled):
# Miscellaneous Resources
[Accessibility](http://accessibility.mit.edu/) @ [MIT](http://web.mit.edu) [CSAIL](http://csail.mit.edu)
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