osch / lua-lpugl

A minimal Lua-API for building GUIs using Cairo or OpenGL (see: https://github.com/osch/lua-lpugl#lpugl)

lpugl

LPugl is a minimal Lua-API for building GUIs. It is based on Pugl (PlUgin Graphics Library), a minimal portable API for embeddable GUIs.

LPugl provides only a very minimal API. See lwtk (Lua Widget Toolkit) for implementing GUI widgets on top of LPugl.

Like Pugl, LPugl does only have explicit context and no static data, so it's possible to have several instances within the same program and even within the same Lua main state. Therefore LPugl is especially suited for building GUIs for plugins or components within larger applications. For example see LDPF-Examples: here LPugl is used for the GUI of audio processing plugins with DPF (DISTRHO Plugin Framework).

Supported platforms:

• X11
• Windows
• Mac OS X

Supported rendering backends:

• Cairo (requires OOCairo)
• OpenGL

Thanks to the modular architecture of Pugl, more rendering backends could be possible in the future. Different rendering backends can be combined in one application and also in the same window by embedding different view objects.

LuaRocks modules:

• lpugl - platform specific base module
• lpugl_cairo - Cairo rendering backend module
• lpugl_opengl - OpenGL rendering backend module

Further reading:

• Documentation
• Examples

First Example

• Simple example for using the Cairo backend:

  local lpugl = require"lpugl_cairo"
  
  local world = lpugl.newWorld("Hello World App")
  local scale = world:getScreenScale()
  
  local view = world:newView 
  {
      title     = "Hello World Window",
      size      = {300*scale, 100*scale},
      resizable = true,
      
      eventFunc = function(view, event, ...)
          print(event, ...)
          if event == "EXPOSE" then
              local cairo = view:getDrawContext()
              local w, h  = view:getSize()
              cairo:set_source_rgb(0.9, 0.9, 0.9)
              cairo:rectangle(0, 0, w, h)
              cairo:fill()
              cairo:set_source_rgb(0, 0, 0)
              cairo:select_font_face("sans-serif", "normal", "normal")
              cairo:set_font_size(24*scale)
              local text = "Hello World!"
              local ext = cairo:text_extents(text)
              cairo:move_to((w - ext.width)/2, (h - ext.height)/2 + ext.height)
              cairo:show_text(text)
          elseif event == "CLOSE" then
              view:close()
          end
      end
  }
  view:show()
  
  while world:hasViews() do
      world:update()
  end