[wiki:Component SocLib Components General Index] 

= Component description =

This component is a common utility component.

This creates a frame buffer, it uses soclib-fb from the utilities for a SDL-based viewer window.

For now, the only supported mode are YUV-422 and YUV-420. This may change in the future.

User may directly modify a shared-memory buffer, and update it to screen on-demand.

= Component usage =

== Object ==

{{{
soclib::common::FbController *fb;
}}}

== Instanciation ==

{{{
    soclib::common::FbController(
        const std::string &basename,
        unsigned long width,
        unsigned long height,
        int subsampling );
}}}

 basename::
   The name of the created framebuffer window
 width::
   Width of the window
 height::
   Height of the window
 subsampling::
   YUV subsampling, valid values are 422 and 420

== Usage ==

{{{
    const unsigned long width = 320;
    const unsigned long height = 240;

    soclib::common::FbController fb("fb0", width, height, 422);

    ...

// sample setter function:

void set(soclib::common::FbController &fb, int line, int column, uint8_t y, uint8_t u, uint8_t v)
{
    uint8_t* buffer = (uint8_t*)fb.surface();
    const unsigned long width = fb.m_width;
    const unsigned long height = fb.m_height;

    buffer[                 line*width  +column  ] = y;
    buffer[width*height    +line*width/2+column/2] = u;
    buffer[width*height*3/2+line*width/2+column/2] = v;

    fb->update();
}
}}}