node-pngjs-draw

Adds basic drawing functionnalities to pngjs node module.

Install

``sh
$ npm install --save pngjs-draw
`

Example

`js
var fs = require('fs');
var drawing = require('pngjs-draw');
var png = drawing(require('pngjs').PNG);

fs.createReadStream("blue.png")
.pipe(new png({ filterType: 4 }))
.on('parsed', function() {
// Draws a pixel with transparent green
this.drawPixel(150,200, this.colors.black())

// Draws a line with transparent red
this.drawLine(0,0,200,200, this.colors.red(50))

// Draws a rectangle with transparent black
this.fillRect(150,150,75,20, this.colors.black(100))

// Draws a filled rectangle with transparent white
this.fillRect(50,50,100,100, this.colors.white(100))

// Draws a text with custom color
this.drawText(20,20, "Hello world !", this.colors.new(255,100,10))

// Writes file
this.pack().pipe(fs.createWriteStream('blue.out.png'));
});
`

Documentation

$3

Draws the pixel at the given coordinates with the given color.

* {int} x The x coordinate of the pixel
* {int} y The y coordinate of the pixel
* {Array(byte)} color The color used to paint the pixel

$3

Draws a line beetween two points with the given color.

* {int} x0 The x coordinate of the start
* {int} y0 The y coordinate of the start
* {int} x1 The x coordinate of the end
* {int} y1 The y coordinate of the end
* {Array(byte)} color The color used to paint the line

$3

Draws a stroked rectangle with the given color.

* {int} x The top left x coordinate of the rectangle
* {int} y The top left y coordinate of the rectangle
* {int} width The width of the rectangle
* {int} height The height of the rectangle
* {Array(byte)} color The color used to paint strokes of the rectangle

$3

Draws a filled rectangle with the given color.

* {int} x The top left x coordinate of the rectangle
* {int} y The top left y coordinate of the rectangle
* {int} width The width of the rectangle
* {int} height The height of the rectangle
* {Array(byte)} color The color used to fill the rectangle

$3

Draw a text to the image.

* {int} x The top left x coordinate of the string
* {int} y The top left y coordinate of the string
* {string} text The string value
* {Array(byte)} color The color used used as foreground
* {Object} font The font used to render the string (optional)
* {Object} text The string value

return {int} The length in pixel of the rendered string

$3

Measure the rendered text length with the given font.

* {string} text The string value
* {Array(byte)} color The color used used as foreground
* {Object} font The font used to render the string (optional)

return {int} The length in pixel of the rendered string

$3

[,,,]

A color is a javascript array containing Red/Green/Blue/Alpha byte components.

PNG.prototype.colors.new = function(r,g,b,a)

The new method generates an array with the provided components.

Default values :

* r: 0
* g: 0
* b: 0
* a: 255

`
PNG.prototype.colors.red = function(a)
PNG.prototype.colors.greed = function(a)
PNG.prototype.colors.blue = function(a)
PNG.prototype.colors.black = function(a)
PNG.prototype.colors.white = function(a)
`

Helper methods for creating base colors are also available.

$3

In order to use a custom font, you must first generate a font module from an image presenting all the supported characters.

For more details, take a look at these files :
* build-font.js
fonts/
custom-font/`

Roadmap / Ideas

* More shapes (circles, polygons)
* Rotations
* Multi-lines texts

Copyright and license

MIT © Aloïs Deniel