Difference between revisions of "Evas"

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Some engines are deprecated, broken or need some work, they include Cairo, GLEW, Qtopia and possible more.
 
Some engines are deprecated, broken or need some work, they include Cairo, GLEW, Qtopia and possible more.
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[[Category:enlightenment]]

Latest revision as of 22:45, 27 October 2011

Evas is an object-oriented 2D canvas that uses retained renderer mode. It's part of Enlightenment Foundation Libraries. It's written in C but bindings for Python and Ruby exists.

Evas main goals are to be easy to use and optimized. The latter is one of its strongest points: it's very light on memory, blit functions are optimized in C and MMX, SSE or Altivec where possible. It can use rendering threads, splitting independent work among threads, reaching about sqrt(N-cores) improvements. Since it can know what changed from one frame to another, it can do employ dirty-rectangle optimizations to avoid repainting unchanged areas and will also merge dirty rectangles to avoid painting the same area twice (NP problem, solved with a good heuristic). There are also engines that use hardware acceleration, like OpenGL, DirectFB and XRender/X11. Evas ships with native 16bpp engines targeted at embedded systems.

Documentation

  • API (Doxygen)
  • Evas is base of Edje, so its documentations can serve as guide as well.

Features

  • Optimized for raster and bitmaps
  • Basic Primitives:
    • Rectangles, Lines and Polygons
    • Gradients: includes different modes like linear, radial and more, with different configurations, stop points and even semi-transparent colors.
    • Images: includes different scaling methods, like nearest or smooth super and super-sampled. It can do image tiling and handles border properties so scale will scale them properly. Can load images from PNG, JPEG, TIFF, PPM, SVG and more.
    • Text: include effects as shadow (hard and soft), outline and glow. Can use fontconfig for font discovery, uses freetype rendering by default. Supports UTF-8.
    • Text Block: handles wrapping and tags to change properties. Supports edit and password mode.
  • Advanced Primivies:
    • Smart Objects: objects without visual, they are used to hold other objects (like groups) and its methods are user-defined, so on resize you can rearrange its children, for example.
    • Box: smart object that can layout a sequence of children in some way. It's extensible, but by default lots of layouts are provided like vertical, horizontal, stack, flow.
    • Table: smart object that layout children in a table, supports row and column spanning.
  • Operations include stacking, rectangular clipping, moving and resizing.
  • It's not tied to any main loop, you must call its render routines and feed events. Ecore_Evas is a helper to ease that process with Ecore main loop and its engines (X11, Xcb, DirectFB...)

Engines

Working engines:

  • 32 bits per pixel native engines (can downscale to 1bpp, with optional dithering):
    • Software Buffer
    • Software X11 and XCB
    • XRender X11 and XCB
    • OpenGL X11
    • Software Linux Framebuffer
    • DirectFB
    • Software SDL
    • Software Win32 GDI
    • Software WindowsCE
    • Software DirectDraw (Windows)
    • Direct3d (Windows)
    • Quartz (MacOS X)
  • 16 bits per pixel:
    • Software 16-X11
    • Software 16-DirectDraw
    • Software 16-WindowsCE
    • Software 16-SDL

Some engines are deprecated, broken or need some work, they include Cairo, GLEW, Qtopia and possible more.