API Reference

Before reading further, make sure you’ve understood the Basic Concepts.

• Types
  • Data Types
  • Input types
  • Literal Helper Macros
• Functions
  • Miscellaneous
  • Initializers, Releasers and Reallocators
  • Drawing
  • Printers
  • Sprite Operations
  • Object Operations
  • Pen Operations
  • Movement
  • Sensors

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Implementation Details

Warning

VisualT is currently broken on big endian systems. The issue will be fixed in the following updates.

Restrict qualifier

The restrict keyword basically means that the qualified pointer must be unique among the function parameters. In VisualT’s API, its meaning is extended to “the referenced base Object must be unique among the function parameters”. That’s to indicate that multiple pointers to instances created from a common base Object aren’t allowed either.
This in important to keep in mind when dealing with allocators and releasers, like vtRelease(). Instances are a more advanced “implicit feature” of VisualT, and should only be used by users familiar with C.

Strict Aliasing

VisualT expects uint8_t to be a type compatible with char, in order to respect the strict aliasing rule. If, in your implementation, uint8_t is not equivalent to char, try to disable strict aliasing (-fno-strict-aliasing) and see what happens. If you spot erroneous behavior, create an issue and we’ll look into it.

Signedness

Variables in the source default to signed integers. Unsigned integers are used, when possible, to avoid unsigned->signed casts when dealing with unsigned public types.
Public types, when reasonable, use unsignedness as a self-explanatory semantic indicator, like VTObj.length, which supports >0 values only.
VTObj.width, instead, is also a >0 type, but it’s expressed by a signed type, because it’s frequent used in calculations involving other signed types like x and y positions.