Crate agg

Expand description

Anti Grain Geometry - Rust implementation

Originally derived from version 2.4 of AGG

This crate implments the drawing / painting 2D algorithms developed in the Anti Grain Geometry C++ library. Quoting from the author in the documentation:

Anti-Grain Geometry is not a solid graphic library and it’s not very easy to use. I consider AGG as a “tool to create other tools”. It means that there’s no “Graphics” object or something like that, instead, AGG consists of a number of loosely coupled algorithms that can be used together or separately. All of them have well defined interfaces and absolute minimum of implicit or explicit dependencies.

§Anti-Aliasing and Subpixel Accuracy

One primary strenght of AGG are the combination of drawing with subpixel accuracy with anti-aliasing effects. There are many examples within the documentation and reproduced here.

§Drawing

There are multiple ways to put / draw pixels including:

Scanline Renderers
- Antialiased or Aliased (Binary)
Outline Renderer, possibly with Images
Raw Pixel Manipulation

§Scanline Renderer

The multitude of renderers here include render_scanlines, render_all_paths, render_scanlines_aa_solid and render_scanlines_bin_solid

  use agg::PixelData;
  use agg::Render;
  // Create a blank image 10x10 pixels
  let pix = agg::Pixfmt::<agg::Rgb8>::new(100,100);
  let mut ren_base = agg::RenderingBase::new(pix);
  ren_base.clear(agg::Rgba8::white());
  // Draw a polygon from (10,10) - (50,90) - (90,10)
  let mut ras = agg::RasterizerScanline::new();
  ras.move_to_d(10.0, 10.0);
  ras.line_to_d(50.0, 90.0);
  ras.line_to_d(90.0, 10.0);
  // Render the line to the image
  let mut ren = agg::RenderingScanlineAASolid::with_base(&mut ren_base);
  ren.color(&agg::Rgba8::black());
  agg::render_scanlines(&mut ras, &mut ren);
  // Save the image to a file
  agg::ppm::write_ppm(&ren_base.pixeldata(), 100,100,
                      "little_black_triangle.ppm").unwrap();

§Outline AntiAlias Renderer

   use agg::{Pixfmt,Rgb8,Rgba8,RenderingBase,SetColor};
   use agg::{RendererOutlineAA,RasterizerOutlineAA};
   use agg::PixelData;
   let pix = Pixfmt::<Rgb8>::new(100,100);
   let mut ren_base = agg::RenderingBase::new(pix);
   ren_base.clear( Rgba8::new(255, 255, 255, 255) );

   let mut ren = RendererOutlineAA::with_base(&mut ren_base);
   ren.color(agg::Rgba8::new(102,77,26,255));
   ren.profile.width(3.0);

   let mut path = agg::PathStorage::new();
   path.move_to(10.0, 10.0);
   path.line_to(50.0, 90.0);
   path.line_to(90.0, 10.0);

   let mut ras = RasterizerOutlineAA::with_renderer(&mut ren);
   ras.add_path(&path);
   agg::ppm::write_ppm(&ren_base.pixeldata(), 100,100,
         "outline_aa.ppm").unwrap();

§Primative Renderer

Render for primative shapes: lines, rectangles, and ellipses; filled or outlined.

   use agg::{Pixfmt,Rgb8,Rgba8,RenderingBase,SetColor};
   use agg::{RendererPrimatives,RasterizerOutline};
   use agg::PixelData;
   let pix = Pixfmt::<Rgb8>::new(100,100);
   let mut ren_base = agg::RenderingBase::new(pix);
   ren_base.clear( Rgba8::new(255, 255, 255, 255) );

   let mut ren = RendererPrimatives::with_base(&mut ren_base);
   ren.line_color(agg::Rgba8::new(0,0,0,255));

   let mut path = agg::PathStorage::new();
   path.move_to(10.0, 10.0);
   path.line_to(50.0, 90.0);
   path.line_to(90.0, 10.0);

   let mut ras = RasterizerOutline::with_primative(&mut ren);
   ras.add_path(&path);
   agg::ppm::write_ppm(&ren_base.pixeldata(), 100,100,
         "primative.ppm").unwrap();