TeX/include/TeX/classes.h

//---
//	class: Node classes
//---

#include <TeX/node.h>

/* TeX_Class
   Essentially the prototype of a node class, which implements the layout and
   rendering function of a fixed mathematical construct. */
struct TeX_Class
{
	/* Most of the time this name appears in the formula using the "\name"
	   notation, but some classes (superscript, parentheses, matrices...)
	   have special syntax and their names are hardcoded. To avoid
	   conflicts, built-in class names start with a backslash. */
	char const *name;

	/* layout()
	   This function must calculate the width, height and base line of the
	   node and store the results in the structure fields. It is allowed to
	   access the .width, .height and .line fields of its children because
	   they will have had their size calculated beforehand.

	   This TeX module provides classes with a primitive function that
	   calculates the size of raw strings:
	     #include <TeX/interface.h>
	     void TeX_size(char const *str, int *width, int *height);

	   @node     A node of the described class, for size calculation
	   @display  Whether we use full-size display instead of inline mode */
	void (*layout)(struct TeX_Node *node, int display);

	/* render()
	   This function must render the given node at the provided (x, y)
	   coordinates. The (x, y) point is the top-left corner of the bounding
	   box of the expression and is inside the box (ie. it can be drawn
	   to). This function must honor the size estimates provided by
	   calculate_size() and not draw outside the bounding box.

	   This TeX module provides three primitive functions for rendering:
	     #include <TeX/interface.h>
	     void TeX_pixel(int x, int y, int color);
	     void TeX_line(int x1, int y1, int x2, int y2, int color);
	     void TeX_text(char const *str, int x, int y, int color);

	   @node   A node of the described class, for rendering
	   @x      Horizontal coordinate of the requested rendering position
	   @y      Vertical coordinate of the requested rendering position
	   @color  Requested rendering color */
	void (*render)(struct TeX_Node const * node, int x, int y, int color);

	/* Sub- and superscript mode, see <TeX/flow.h> for available modes */
	int mode;
};

/* TeX_class_find(): Find a class using a command name
   @name  Command name
   Returns a positive class id representing the requested TeX_Class object (if
   a class with this name is found in the table, a negative number otherwise.
   This function never returns 0, which is reserved for TEX_NODECLASS_TEXT. */
int TeX_class_find(char const *name);

/* TeX_class_of(): Get the class pointer of a node */
struct TeX_Class const *TeX_class_of(struct TeX_Node const * node);