XYPieChart is an simple and easy-to-use pie chart for iOS app. It started from a Potion Project which needs an animated pie graph without interaction. All animation was implemented in the drawRect: method. After played with BTSPieChart, really like its code structure, it’s clean, has well named functions, structure like a UITableView. XYPieChart rewrote the code, based on CALayers for the animation. Compared to BTSPieChart, XYPieChart is a prettier version, it has a simpler insert/delete slices algorithm, different design of slice selection, more flexible to customize.
A graphics card can render 3D graphics hundreds of times faster than a CPU and graphics cards are used to accelerate compositing of windows on the desktop for a many-fold performance increase.
Despite the advantages of graphics cards in these areas, 2D geometry on the Mac is normally generated by the CPU in main memory. You can opt to have your program drawn on the graphics card instead but this option is off by default. This 2D on the graphics card drawing is named QuartzGL.
QuartzGL works by generating an an OpenGL ARB_fragment_program (pixel buffer drawing commands) and performing on the graphics card what would ordinarily be performed on the CPU.