improve documentation for godoc

README.md

@@ -1,19 +1,20 @@
 draw2d
 ======
 
-This package (written in [go](http://golang.org)) provides an API to draw 2d vector forms on [images](http://golang.org/pkg/image).
+Package draw2d is a pure [go](http://golang.org) 2D vector graphics library with support for multiple output devices such as [images](http://golang.org/pkg/image) (draw2d), pdf documents (draw2dpdf) and opengl (draw2dopengl), which can also be used on the google app engine.
 This library is inspired by [postscript](http://www.tailrecursive.org/postscript) and [HTML5 canvas](http://www.w3.org/TR/2dcontext/).
 
+See the [documentation](http://godoc.org/github.com/llgcode/draw2d) for more details.
+
 The package depends on [freetype-go](http://code.google.com/p/freetype-go) package for its rasterization algorithm.
 
+Installation
+------------
 
-Using
------
-
-Install [golang](http://golang.org/doc/install) and get `draw2d` 
+Install [golang](http://golang.org/doc/install). To install or update the package draw2d on your system, run:
 
 ```
-go get github.com/llgcode/draw2d
+go get -u github.com/llgcode/draw2d
 ```
 
 and start coding using one of the [Samples](https://github.com/llgcode/draw2d.samples).

draw2d.go

@@ -1,5 +1,68 @@
 // Copyright 2010 The draw2d Authors. All rights reserved.
 // created: 13/12/2010 by Laurent Le Goff
 
-// Package draw2d provides a Graphic Context that can draw vector form on canvas.
+// Package draw2d is a pure go 2D vector graphics library with support
+// for multiple output devices such as images (draw2d), pdf documents
+// (draw2dpdf) and opengl (draw2dopengl), which can also be used on the
+// google app engine.
+//
+// Features
+//
+// Operations in draw2d include stroking and filling polygons, arcs,
+// Bézier curves, drawing images and text rendering with truetype fonts.
+// All drawing operations can be transformed by affine transformations
+// (scale, rotation, translation).
+//
+// Installation
+//
+// To install or update the package on your system, run:
+//   go get -u github.com/llgcode/draw2d
+//
+// Quick Start
+//
+// Package draw2d itself provides a graphic context that can draw vector
+// graphics and text on an image canvas. The following Go code
+// generates a simple drawing and saves it to an image file:
+//   // Initialize the graphic context on an RGBA image
+//   dest := image.NewRGBA(image.Rect(0, 0, 297, 210.0))
+//   gc := draw2d.NewGraphicContext(dest)
+//
+//   // Set some properties
+//   gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
+//   gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
+//   gc.SetLineWidth(5)
+//
+//   // Draw a closed shape
+//   gc.MoveTo(10, 10) // should always be called first for a new path
+//   gc.LineTo(100, 50)
+//   gc.QuadCurveTo(100, 10, 10, 10)
+//   gc.Close()
+//   gc.FillStroke()
+//
+//   // Save to file
+//   draw2d.SaveToPngFile(fn, dest)
+//
+// There are more examples here:
+// https://github.com/llgcode/draw2d.samples
+//
+// Drawing on pdf documents is provided by the draw2dpdf package.
+// Drawing on opengl is provided by the draw2dgl package.
+// See subdirectories at the bottom of this page.
+//
+// Acknowledgments
+//
+// Laurent Le Goff wrote this library, inspired by postscript and
+// HTML5 canvas. He implemented the image and opengl backend. Also
+// he created a pure go Postscripter interpreter which can draw to a
+// draw2d graphic context (https://github.com/llgcode/ps). Stani
+// Michiels implemented the pdf backend.
+//
+// The package depends on freetype-go package for its rasterization
+// algorithm.
+//
+// Packages using draw2d
+//
+// - https://github.com/llgcode/ps
+//
+// - https://github.com/gonum/plot
 package draw2d

draw2dgl/doc.go

@@ -0,0 +1,3 @@
+// Package draw2dgl provides a graphic context that can draw vector
+// graphics and text on OpenGL.
+package draw2dgl

draw2dpdf/doc.go

@@ -1,5 +1,39 @@
 // Copyright 2015 The draw2d Authors. All rights reserved.
 // created: 26/06/2015 by Stani Michiels
 
-// Package draw2dpdf provides a Graphic Context that can draw vector form on pdf file.
+// Package draw2dpdf provides a graphic context that can draw vector
+// graphics and text on pdf file.
+//
+// Quick Start
+//
+// The following Go code generates a simple drawing and saves it to a
+// pdf document:
+//   // Initialize the graphic context on an RGBA image
+//   dest := draw2dpdf.NewPdf("L", "mm", "A4")
+//   gc := draw2d.NewGraphicContext(dest)
+//
+//   // Set some properties
+//   gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
+//   gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
+//   gc.SetLineWidth(5)
+//
+//   // Draw a closed shape
+//   gc.MoveTo(10, 10) // should always be called first for a new path
+//   gc.LineTo(100, 50)
+//   gc.QuadCurveTo(100, 10, 10, 10)
+//   gc.Close()
+//   gc.FillStroke()
+//
+//   // Save to file
+//   draw2dpdf.SaveToPdfFile(fn, dest)
+//
+// There are more examples here:
+// https://github.com/llgcode/draw2d.samples
+//
+// Drawing on images is provided by the draw2d package.
+// Drawing on opengl is provided by the draw2dgl package.
+//
+// Acknowledgments
+//
+// The pdf backend uses https://github.com/jung-kurt/gofpdf
 package draw2dpdf

draw2dpdf/gc_test.go

@@ -1,35 +0,0 @@
-package draw2dpdf
-
-import (
-	"fmt"
-	"image/color"
-
-	"github.com/llgcode/draw2d"
-	"github.com/jung-kurt/gofpdf"
-)
-
-func ExampleGraphicContext() {
-	// Initialize the graphic context on a pdf document
-	pdf := gofpdf.New("P", "mm", "A4", "../font")
-	pdf.AddPage()
-	gc := NewGraphicContext(pdf)
-
-	// some properties
-	gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
-	gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
-	gc.SetLineCap(draw2d.RoundCap)
-	gc.SetLineWidth(5)
-
-	// draw something
-	gc.MoveTo(10, 10) // should always be called first for a new path
-	gc.LineTo(100, 50)
-	gc.QuadCurveTo(100, 10, 10, 10)
-	gc.Close()
-	gc.FillStroke()
-	fmt.Println(gc.LastPoint())
-
-	// draw2dpdf.SaveToPdfFile("example.pdf", pdf)
-
-	// Output:
-	// 10 10
-}