The Basic Principles of GDI

I l @ ve RuBoard

The Basic Principles of GDI+

Like its predecessor GDI, GDI+ is an immediate mode graphics system. This means that as you send commands to the graphic interface, effects are seen on the device surface or in the display memory immediately. The other kind of graphics system, retained mode graphics, usually maintain hierarchies of objects that know how to paint themselves .

GDI+ uses brushes and pens to paint on the graphics surface, just like GDI did. Unlike GDI, though, you can use any graphical object on any surface at any time. GDI required you to create a graphics object, select it for use in a Device Context (DC), use the object, deselect it from the DC, and then destroy the object. If you didn't do it in that order, you could get system resource leaks that would eventually cause all the memory in your system to be allocated away and the system would need a reboot. GDI+ is altogether friendlier to use because you don't have to worry about selecting and deselecting objects in the right order.

As you might expect, the evolution of GDI+ reflects many of the recent changes in graphics card capabilities. Additions to your graphics arsenal include Alpha Blending or image transparency, antialiasing, transformations like rotation and scaling, plus many new innovations in the areas of color correction and region manipulation.

I l @ ve RuBoard