TeX/src/classes.c

//---
//	classes: Node classes used for mathematical notations
//---

#include <TeX/config.h>
#include <TeX/node.h>
#include <TeX/flow.h>
#include <TeX/env.h>
#include <TeX/classes.h>

#include <TeX/interface.h>
#include <TeX/defs.h>

#include <string.h>


/* Some quick macros to access parameters and their size */
#define args ((node)->args)
#define w(n) (args[n]->width)
#define h(n) (args[n]->height)
#define l(n) (args[n]->line)

//---
//	Text.
//	* args: 0 (can't have any)
//	* flow: normal
//---

void text_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	int w, h;
	TeX_size((char const *)node->text, &w, &h);

	node->width = w;
	node->height = h;
	node->line = h >> 1;
}

void text_render(struct TeX_Node const * node, int x, int y, int color)
{
	TeX_text((void *)node->text, x, y, color);
}

//---
//	Environment nodes.
//---

void env_layout(struct TeX_Node *node, int display)
{
	node->env->layout(node->env, display);

	node->width  = node->env->width;
	node->height = node->env->height;
	node->line   = node->env->line;
}

void env_render(struct TeX_Node const * node, int x, int y, int color)
{
	node->env->render(node->env, x, y, color);
}

//---
//	Fractions.
//	* args: 2 (<2 invalidate, >2 ignore)
//	* flow: normal
//
//	Graphical parameters:
//
//	TEX_FRACTION_SPACING:
//	  Spacing between bar and operands
//	TEX_FRACTION_BAR_THICKNESS:
//	  Thickness (pixels) of fraction bar
//	TEX_FRACTION_MARGIN:
//	  Additional bar length that extends beyond the operands
//
//	     1
//	          ] TEX_FRACTION_SPACING
//	  ####### ] TEX_FRACTION_BAR_THICKNESS
//	          ] TEX_FRACTION_SPACING
//	     2
//        |_| |_|
//	TEX_FRACTION_MARGIN
//---

void frac_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	/* Drop the fraction if there are less than two arguments */
	if(!args[1]) { node->hidden = 1; return; }

	int margin    = TEX_FRACTION_MARGIN;
	int thickness = TEX_FRACTION_BAR_THICKNESS;
	int spacing   = TEX_FRACTION_SPACING;

	node->width  = max(w(0), w(1)) + 2 * margin;
	node->height = h(0) + h(1) + 2 * spacing + thickness;
	node->line   = h(0) + spacing + thickness / 2;
}

void frac_render(struct TeX_Node const * node, int x, int y, int color)
{
	/* Fraction bar */
	for(int i = 0; i < TEX_FRACTION_BAR_THICKNESS; i++)
	{
		int y0 = y + h(0) + TEX_FRACTION_SPACING + i;
		TeX_line(x, y0, x + node->width - 1, y0, color);
	}

	/* First argument */
	TeX_flow_render(args[0],
		x + ((node->width - w(0)) >> 1),
		y,
		color);

	/* Second argument */
	TeX_flow_render(args[1],
		x + ((node->width - w(1)) >> 1),
		y + h(0) + 2*TEX_FRACTION_SPACING + TEX_FRACTION_BAR_THICKNESS,
		color);
}

//---
//	Left and right delimiters.
//	* args: 1 (<1 invalidate, >1 ignore)
//	* flow: adapt width and height to contents until matching delimiter
//
//	Left and right delimiters are resizable bracket-like elements used to
//	parenthesize or decorate terms. They serve a special flow purpose and
//	are matched together by the TeX_flow_layout() routine.
//
//	Graphical parameters:
//
//	TEX_LEFTRIGHT_ALIGNED:
//	  Forces the middle of the decoration to be aligned with the baseline
//	TEX_LEFTRIGHT_SYMMETRICAL:
//	  Makes the size of the delimiter symmetrical around the baseline
//	TEX_LEFTRIGHT_ANGLE_WIDTH:
//	  Width of the "<" and ">" angle delimiters
//
//	Default:       Aligned:      Aligned symmetrical:
//	 /  x           /  x                /  x
//       |  -           |  -                |  -
//      <   y           |  y                |  y
//       | ---         <  ---              <  ---
//	 \  z           \  z                |  z
//                                          |
//                                          \.
//
//	LaTeX's behavior on this is essentially centered symmetrical, but it
//	seems to resize the contents to make it smoother. Not possible here.
//---

void leftright_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	int width, height;
	TeX_size("#", &width, &height);

	/* TODO: Not the same on fxcg50 */
	node->width = 3;
	node->height = height;
	node->line = height >> 1;

	if(node->subtype == '<' || node->subtype == '>')
		node->width = TEX_LEFTRIGHT_ANGLE_WIDTH;
	if(node->subtype == '|')
		node->width = 1;
}

void leftright_render(struct TeX_Node const * node, int x, int y, int color)
{
	int h = node->height, w = node->width, l = node->line;

	switch(node->subtype)
	{
	case '(':
		TeX_pixel(x + 2, y, color);
		TeX_pixel(x + 1, y + 1, color);
		TeX_line(x, y + 2, x, y + h - 3, color);
		TeX_pixel(x + 1, y + h - 2, color);
		TeX_pixel(x + 2, y + h - 1, color);
		break;

	case ')':
		TeX_pixel(x, y, color);
		TeX_pixel(x + 1, y + 1, color);
		TeX_line(x + 2, y + 2, x + 2, y + h - 3, color);
		TeX_pixel(x + 1, y + h - 2, color);
		TeX_pixel(x, y + h - 1, color);
		break;

	case '[':
		TeX_pixel(x + 1, y, color);
		TeX_pixel(x + 2, y, color);
		TeX_line(x, y, x, y + h - 1, color);
		TeX_pixel(x + 1, y + h - 1, color);
		TeX_pixel(x + 2, y + h - 1, color);
		break;

	case ']':
		TeX_pixel(x, y, color);
		TeX_pixel(x + 1, y, color);
		TeX_line(x + 2, y, x + 2, y + h - 1, color);
		TeX_pixel(x, y + h - 1, color);
		TeX_pixel(x + 1, y + h - 1, color);
		break;

	case '{':
		TeX_pixel(x + 2, y, color);
		TeX_line(x + 1, y + 1, x + 1, y + l - 1, color);
		TeX_pixel(x, y + l, color);
		TeX_line(x + 1, y + l + 1, x + 1, y + h - 2, color);
		TeX_pixel(x + 2, y + h - 1, color);
		break;

	case '}':
		TeX_pixel(x, y, color);
		TeX_line(x + 1, y + 1, x + 1, y + l - 1, color);
		TeX_pixel(x + 2, y + l, color);
		TeX_line(x + 1, y + l + 1, x + 1, y + h - 2, color);
		TeX_pixel(x, y + h - 1, color);
		break;

	case '<':
		TeX_line(x, y + l, x + w - 1, y, color);
		TeX_line(x, y + l, x + w - 1, y + h - 1, color);
		break;

	case '>':
		TeX_line(x + w - 1, y + l, x, y, color);
		TeX_line(x + w - 1, y + l, x, y + h - 1, color);
		break;

	case '|':
		TeX_line(x, y, x, y + h - 1, color);
		break;
	}
}

//---
//	Superscripts and subscripts.
//	* args: 1 (<1 invalidate, >1 ignore)
//	* flow: elevated or lowered to extend the previous node
//
//	Superscript and subscripts are very common elements. The class itself
//	does nothing but name them and render its argument. The only special
//	thing about them is their behavior in a flow, which depends on the
//	context and is handled by flow functions in [TeX.c].
//
//	TODO: parameters for display mode (TEX_DISPLAY_SPACING)
//
//	Graphical parameters:
//
//	TEX_SUPERSCRIPT_DEPTH:
//	  Distance between bottom of superscript and top of base
//	TEX_SUBSCRIPT_ELEVATION:
//	  Distance between top of subscript and bottom of base
//	TEX_SUPERSCRIPT_SPACING:
//	  Horizontal spacing between superscript and base
//	TEX_SUBSCRIPT_SPACING:
//	  Horizontal spacing between subscript and base
//
//	          +-----+
//	          |     |
//	+------+  |  1  |  --,
//	| Base |  |     |    |  TEX_SUPERSCRIPT_DEPTH
//	|      |  +-----+  --'
//	+------+
//             >--< TEX_SUPERSCRIPT_SPACING
//
//	+------+
//	|      |  +-----+  --,
//	| Base |  |     |    |  TEX_SUBSCRIPT_ELEVATION
//	+------+  |  1  |  --'
//	          |     |
//	          +-----+
//             >--< TEX_SUBSCRIPT_SPACING
//---

void supsubscript_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	/* Invalidate node if no argument is provided */
	if(!args[0]) { node->hidden = 1; return; }

	node->width  = w(0);
	node->height = h(0);
	node->line   = l(0);
}

void supsubscript_render(struct TeX_Node const * node, int x, int y,
	int color)
{
	TeX_flow_render(args[0], x, y, color);
}

//---
//	Summation symbol.
//	* args: 0 (ignored)
//	* flow: display mode when available
//
//	Summation symbols are just nodes with a constant size and function.
//---

void sum_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	node->width = 9;
	node->height = 9;
	node->line = 4;
}

void sum_render(TEX_UNUSED struct TeX_Node const * node, int x, int y,
	int color)
{
	TeX_line(x, y, x + 8, y, color);
	TeX_line(x, y, x + 4, y + 4, color);
	TeX_line(x, y + 8, x + 4, y + 4, color);
	TeX_line(x, y + 8, x + 8, y + 8, color);
	TeX_pixel(x + 8, y + 1, color);
	TeX_pixel(x + 8, y + 7, color);
}

//---
//	Product symbol.
//	* args: 0 (ignored)
//	* flow: display mode when available
//---

void prod_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	node->width = 9;
	node->height = 9;
	node->line = 4;
}

void prod_render(TEX_UNUSED struct TeX_Node const * node, int x, int y,
	int color)
{
	TeX_line(x, y, x + 8, y, color);
	TeX_line(x + 1, y, x + 1, y + 8, color);
	TeX_line(x + 0, y + 8, x + 2, y + 8, color);
	TeX_line(x + 7, y, x + 7, y + 8, color);
	TeX_line(x + 6, y + 8, x + 8, y + 8, color);
}

//---
//	Integral symbol
//	* args: 0 (ignored)
//	* flow: default
//---

void int_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	node->width = 5;
	node->height = TEX_INT_HEIGHT;
	node->line = TEX_INT_HEIGHT >> 1;
}

void int_render(struct TeX_Node const * node, int x, int y, int color)
{
	int h = node->height;

	TeX_pixel(x + 3, y, color);
	TeX_pixel(x + 4, y + 1, color);
	TeX_line(x + 2, y + 1, x + 2, y + h - 2, color);
	TeX_pixel(x, y + h - 2, color);
	TeX_pixel(x + 1, y + h - 1, color);
}

//---
//	Vectors
//	* args: 1 (<1 invalidate, >1 ignore)
//	* flow: normal
//
//	This "\vec" command is an equivalent of "\overrightarrow" in LaTeX, it
//	covers its argument and extends.
//
//	Graphical parameters:
//
//	TEX_VEC_ARROW_LENGTH:
//	  Number of pixels that extend diagonally from the tip of the arrow.
//	TEX_VEC_SPACING:
//	  Number of pixels of spacing between argument and vector
//	TEX_VEC_MARGIN:
//	  Horizontal margin around the argument.
//
//	------>  ] 2 * TEX_VEC_ARROW_LENGTH + 1
//	         ] TEX_VEC_SPACING
//	   1
//	|_| |_|
//	TEX_VEC_MARGIN
//---

void vec_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	int arrow_height = 2 * TEX_VEC_ARROW_LENGTH + 1;

	node->width = w(0) + 2 * TEX_VEC_MARGIN;
	node->height = h(0) + TEX_VEC_SPACING + arrow_height;
	node->line = l(0) + TEX_VEC_SPACING + arrow_height;
}

void vec_render(struct TeX_Node const * node, int x, int y, int color)
{
	int length = TEX_VEC_ARROW_LENGTH;
	int arrow_height = 2 * length + 1;
	int w = node->width;

	/* Draw arrow */
	TeX_line(x, y + length, x + w - 1, y + length, color);
	TeX_line(x + w - 1, y + length, x + w - 1 - length, y, color);
	TeX_line(x + w - 1, y + length, x + w - 1 - length, y + 2 * length,
		color);

	/* First argument */
	TeX_flow_render(args[0],
		x + TEX_VEC_MARGIN,
		y + TEX_VEC_SPACING + arrow_height,
		color);
}

//---
//	Limit notation
//	* args: 0 (ignored)
//	* flow: display mode when available
//---

void lim_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	int w, h;
	TeX_size("lim", &w, &h);
	node->width = w;
	node->height = h;
	node->line = h >> 1;
}

void lim_render(TEX_UNUSED struct TeX_Node const * node, int x, int y,
	int color)
{
	TeX_text("lim", x, y, color);
}

//---
//	Square roots
//	* args: 1 (<1 invalidate, >1 ignore)
//	* flow: normal
//
//	Graphical parameters:
//
//	TEX_SQRT_SLANTED:
//	  Makes the vertical part of the square root slanted when it is small.
//	TEX_SQRT_SLANT_MAX:
//	  Maximum height consider small
//	TEX_SQRT_SLANT_LENGTH:
//	  Horizontal size occupied by the slanted part.
//	TEX_SQRT_BAR_LENGTH:
//	  Length of the top-right bar marking the end of the argument (or 0)
//	TEX_SQRT_TIP_LENGTH:
//	  Length of tip starting at the bottom left of the square root
//	TEX_SQRT_MARGIN:
//	  Margin around argument
//
//	If TEX_SQRT_SLANTED != 0 and height(1) <= TEX_SQRT_SLANT_MAX:
//
//	  TEX_SQRT_TIP_LENGTH
//	   |         _______    v
//	   |        /       |   |  TEX_SQRT_BAR_LENGTH
//	   |   v   /    1       ^
//	   +-->| \/
//	       ^  <->
//	   TEX_SQRT_SLANT_LENGTH
//
//	All other cases:
//
//	  TEX_SQRT_TIP_LENGTH
//	   |        _______    v
//	   |       |       |   |  TEX_SQRT_BAR_LENGTH
//	   |   v   |   1       ^
//	   +-->|  \|
//             ^
//---

void sqrt_layout(struct TeX_Node *node, TEX_UNUSED int display)
{
	/* Invalidate the node if no argument is present */
	if(!args[0]) { node->hidden = 1; return; }

	int slanted = TEX_SQRT_SLANTED && h(0) <= TEX_SQRT_SLANT_MAX;

	node->width = w(0) + 2 * TEX_SQRT_MARGIN + TEX_SQRT_TIP_LENGTH;
	node->width += (TEX_SQRT_BAR_LENGTH > 0);
	node->width += (slanted ? TEX_SQRT_SLANT_LENGTH : 1);

	node->height = h(0) + TEX_SQRT_MARGIN + 1;
	node->line = l(0) + TEX_SQRT_MARGIN + 1;
}

void sqrt_render(struct TeX_Node const * node, int x, int y, int color)
{
	int slanted = TEX_SQRT_SLANTED && h(0) <= TEX_SQRT_SLANT_MAX;
	int w = node->width;
	int h = node->height;

	int tip = TEX_SQRT_TIP_LENGTH;
	TeX_line(x, y + h - tip - 1, x + tip, y + h - 1, color);

	int bar_length = (slanted ? TEX_SQRT_SLANT_LENGTH : 1);
	TeX_line(x + tip + bar_length - 1, y, x + tip, y + h - 1, color);

	int base = tip + bar_length;
	TeX_line(x + base, y, x + w - 1, y, color);
	TeX_line(x + w - 1, y, x + w - 1, y + TEX_SQRT_BAR_LENGTH, color);

	TeX_flow_render(args[0],
		x + base + TEX_SQRT_MARGIN,
		y + 1 + TEX_SQRT_MARGIN,
		color);
}

//---
//	The class table and lookup functions
//---

/* Default sub- and superscript mode for integrals depends on config */
#if TEX_INT_DISPLAY
#define INT_MODE TEX_FLOW_PREFER_DISPLAY
#else
#define INT_MODE TEX_FLOW_INLINE
#endif

static struct TeX_Class const class_table[] = {
	/* Text and environments */
	{ "\\text", text_layout, text_render, -1 },
	{ "\\end",  env_layout, env_render, -1 },

	/* Fractions */
	{ "frac",   frac_layout, frac_render, TEX_FLOW_INLINE },

	/* Size-aware opening and closing elements */
	{ "left",   leftright_layout, leftright_render, TEX_FLOW_INLINE },
	{ "right",  leftright_layout, leftright_render, TEX_FLOW_INLINE },

	/* Superscripts and subscripts */
	{ "\\sup",  supsubscript_layout, supsubscript_render, -1 },
	{ "\\sub",  supsubscript_layout, supsubscript_render, -1 },

	/* Large operator symbols, integral */
	{ "sum",    sum_layout, sum_render, TEX_FLOW_PREFER_DISPLAY },
	{ "prod",   prod_layout, prod_render, TEX_FLOW_PREFER_DISPLAY },
	{ "int",    int_layout, int_render, INT_MODE },

	/* Vectors, limits */
	{ "vec",    vec_layout, vec_render, TEX_FLOW_INLINE },
	{ "lim",    lim_layout, lim_render, TEX_FLOW_DISPLAY },

	/* Square root */
	{ "sqrt",   sqrt_layout, sqrt_render, TEX_FLOW_INLINE },

	/* NULL terminator */
	{ NULL },
};

/* TeX_class_find(): Find a class using a command name */
int TeX_class_find(char const *name)
{
	/* TODO: Do a binary search instead of a linear one */
	for(int i = 1; class_table[i].name; i++)
	{
		if(!strcmp(class_table[i].name, name)) return i;
	}

	return -1;
}

/* TeX_class_of(): Get the class pointer of a node */
struct TeX_Class const *TeX_class_of(struct TeX_Node const * node)
{
	return &class_table[node->type];
}