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

PNG.prototype.drawPixel

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

PNG.prototype.drawLine

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

PNG.prototype.drawRect

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

PNG.prototype.fillRect

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

PNG.prototype.drawText

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

PNG.prototype.measureString

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

Creating colors

[<R>,<G>,<B>,<A>] 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.

Custom fonts

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