core: add vectors and limits

Also fix a bug in the computation of group sizes, due to subscripts and
superscripts being counted before their final layout was decided.

README.md

@@ -24,7 +24,8 @@ List of currently supported elements:
 * Subscripts and superscripts (`_` and `^`)
 * Grouping parentheses, brackets and braces (`\left` and `\right`)
 * Grouping angle brackets, vertical lines, and dots (invisible)
-* Summation symbols
+* Sums, products and integrals (`\sum`, `\prod` and `\int`)
+* Vectors (`\vec`) and limits (`\lim`)
 
 Features that are partially implemented (and what is left to finish them):
 
@@ -40,7 +41,7 @@ See the `TODO.md` file for more features to come.
 First specify the platform you want to use :
 
 * `cli` is for command-line tests, with no visualization (PC)
-* `sdl2` is an SDL interface with visualization (font support coming) (PC)
+* `sdl2` is an SDL interface with visualization (PC)
 * `fx9860g` builds the library for fx-9860G targets (calculator)
 * `fxcg50` builds the library for fx-CG 50 targets (calculator)
 

TODO.md

@@ -1,11 +1,22 @@
-*  Write real error messages
 *  Support Unicode symbols (probably requires help from the font side, urgh)
+   Available blocks:
+   ->  U+0020 .. U+007F   (128)  ASCII
+   ->  U+00A0 .. U+00FF   (96)   Latin-1 Supplement
+   ->  U+0390 .. U+03CF   (64)   Greek
+   ->  U+2010 .. U+215F   (80)   General punctuation
+   ->  U+2070 .. U+209F   (48)   Subscripts and superscripts
+   ->  U+2160 .. U+217F   (32)   Roman numerals
+   ->  U+2190 .. U+21FF   (112)  Arrows
+   Blocks to come:
+   ->  U+2200 .. ?               Mathematical operators
+   ->  U+25A0 .. U+25FF   (96)   Geometric shapes
+
 *  Don't use TEX_LAYOUT_SPACING for everything, just make it the default
 *  Add a parameter to resolve as inline style or display style
-*  Support character-level spacing
+*  Parametrize character-level and word-level spacing
 *  Be more generic in what nodes have display mode by default
+*  Reduce horizontal spacing by using a proportional font
+*  Have a decent variable-height font system in gint
 
 *  Add square roots, and honor TEX_SQRT_SLANTED and TEX_SQRT_BAR_LENGTH
-*  Add vectors
-*  Add limits
 *  Add matrices

include/TeX/TeX.h

@@ -34,6 +34,15 @@
 
 /* Whether to place bounds above and below integrals (display mode) */
 #define TEX_INT_DISPLAY 0
+/* Height of the integral symbol */
+#define TEX_INT_HEIGHT 21
+
+/* Length of arrow extensions from the tip of a vector */
+#define TEX_VEC_ARROW_LENGTH 2
+/* Horizontal margin around vector */
+#define TEX_VEC_MARGIN 0
+/* Extra height between argument and vector */
+#define TEX_VEC_SPACING TEX_LAYOUT_SPACING
 
 /* Make the vertical part of the square root symbol slanted at low heights */
 #define TEX_SQRT_SLANTED 1

src/classes.c

@@ -243,11 +243,9 @@ void supsubscript_render(struct TeX_Node const * node, int x, int y,
 //---
 //	Summation symbol.
 //	* args: 0 (ignored)
-//	* flow: default
+//	* flow: display mode when available
 //
 //	Summation symbols are just nodes with a constant size and function.
-//	They are automatically placed in display mode except if the user asked
-//	for inline mode.
 //---
 
 void sum_size(struct TeX_Node *node)
@@ -271,9 +269,7 @@ void sum_render(__attribute__((unused)) struct TeX_Node const * node, int x,
 //---
 //	Product symbol.
 //	* args: 0 (ignored)
-//	* flow: default
-//
-//	Just like summation symbols, uses display mode by default.
+//	* flow: display mode when available
 //---
 
 void prod_size(struct TeX_Node *node)
@@ -302,8 +298,8 @@ void prod_render(__attribute__((unused)) struct TeX_Node const * node, int x,
 void int_size(struct TeX_Node *node)
 {
 	node->width = 5;
-	node->height = 19;
-	node->line = 9;
+	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)
@@ -317,6 +313,79 @@ void int_render(struct TeX_Node const * node, int x, int y, int 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.
+//
+//	------>  ] related to TEX_VEC_ARROW_LENGTH
+//	         ] TEX_VEC_SPACING
+//	   1
+//	|_| |_|
+//	TEX_VEC_MARGIN
+//---
+
+void vec_size(struct TeX_Node *node)
+{
+	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 */
+	render_flow(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_size(struct TeX_Node *node)
+{
+	int w, h;
+	TeX_size("lim", &w, &h);
+	node->width = w;
+	node->height = h;
+	node->line = node->height >> 1;
+}
+
+void lim_render(__attribute__((unused)) struct TeX_Node const * node, int x,
+	int y, int color)
+{
+	TeX_text("lim", x, y, color);
+}
+
 //---
 //	The class table and lookup functions
 //---
@@ -335,13 +404,15 @@ struct TeX_Class TeX_table[] = {
 	{ "\\sup", supsubscript_size, supsubscript_render },
 	{ "\\sub", supsubscript_size, supsubscript_render },
 
-	/* Large operator symbols */
+	/* Large operator symbols, integral */
 	{ "sum",   sum_size, sum_render },
 	{ "prod",  prod_size, prod_render },
-
-	/* Integral */
 	{ "int",   int_size, int_render },
 
+	/* Vectors, limits */
+	{ "vec",   vec_size, vec_render },
+	{ "lim",   lim_size, lim_render },
+
 	/* NULL terminator */
 	{ NULL },
 };

src/flow.c

@@ -221,11 +221,11 @@ void group_open(struct group *group, struct TeX_Node *left)
 }
 
 /* group_update(): Update a group with a new node */
-void group_update(struct group *group, struct TeX_Node *node)
+void group_update(struct group *group, struct chunk *chunk)
 {
 	/* Account for node displacement around baseline */
-	group->above = max(node->line - node->l, group->above);
-	group->below = max(node->height - node->line + node->l, group->below);
+	group->above = max(chunk->line, group->above);
+	group->below = max(chunk->height - chunk->line, group->below);
 }
 
 /* group_close(): Close a group with its right node */
@@ -259,10 +259,12 @@ void group_close(struct group *group, struct TeX_Node *right)
 //	Laying out flows
 //---
 
-static void update(struct chunk *c, int *x, int *above, int *below)
+static void update(struct chunk *c, struct group *g, int *x, int *above,
+	int *below)
 {
 	if(!chunk_set(c)) return;
 	chunk_compute(c);
+	group_update(g, c);
 
 	*x += c->width + TEX_LAYOUT_SPACING;
 	*above = max(*above, c->line - c->base->l);
@@ -290,7 +292,6 @@ void size_flow(struct TeX_Flow *flow)
 	{
 		char const *class = "";
 		size_node(node);
-		group_update(g, node);
 
 		if(node->type != TEX_NODECLASS_TEXT)
 			class = TeX_table[node->type - 1].name;
@@ -305,11 +306,13 @@ void size_flow(struct TeX_Flow *flow)
 			chunk_set_subscript(&c, node);
 			continue;
 		}
+		/* Leave the last chunk and make a new one */
+		update(&c, g, &x, &above, &below);
+
 		if(!strcmp(class, "left") && g-groups < TEX_LEFTRIGHT_NESTING)
 		{
 			g++;
 			group_open(g, node);
-			group_update(g, node);
 		}
 		if(!strcmp(class, "right") && g - groups > 0)
 		{
@@ -317,13 +320,12 @@ void size_flow(struct TeX_Flow *flow)
 			g--;
 		}
 
-		/* Leave the last chunk and make a new one */
-		update(&c, &x, &above, &below);
-
 		int mode = TEX_CHUNK_INLINE;
-		if(!strcmp(class, "sum") || !strcmp(class, "prod")
+		if(!strcmp(class, "sum")
+		|| !strcmp(class, "prod")
+		|| !strcmp(class, "lim")
 		#if TEX_INT_DISPLAY
-			|| !strcmp(class, "int")
+		|| !strcmp(class, "int")
 		#endif
 			)
 		{
@@ -335,7 +337,7 @@ void size_flow(struct TeX_Flow *flow)
 	}
 
 	/* Finish the last chunk */
-	update(&c, &x, &above, &below);
+	update(&c, g, &x, &above, &below);
 
 	flow->height = above + below;
 	flow->line   = above;

src/platform/sdl2.c

@@ -104,10 +104,6 @@ void intf_text(char const *str, int x, int y, int color)
 		SDL_RenderCopy(r, font, &src, &dst);
 		x += FONT_WIDTH + 1;
 	}
-
-//	SDL_Rect rect = { .x = x, .y = y };
-//	intf_size(str, &rect.w, &rect.h);
-//	SDL_RenderDrawRect(r, &rect);
 }
 
 //---
@@ -170,9 +166,9 @@ int main(void)
 {
 	char const * formula =
 	"\\frac{x^7\\left[X,Y\\right]+3\\left|\\frac{A}{B}\\right>}"
-	      "{\\prod_{k=1}^n\\left\\{\\frac{a_k+b_k}{k!}\\right\\}^5}"
-	" + \\sum_{k=1}^n\\frac{(b-a)^k}{k!}"
-	"+\\int_a^b\\frac{(b-t)^{n+1}}{n!}dt";
+	      "{\\lim_{x->0}\\left\\{\\frac{a_k+b_k}{k!}\\right\\}^5}"
+	" + \\int_a^b\\frac{\\left(b-t\\right)^{n+1}}{n!}dt"
+	" + \\vec{A}.\\vec{B}";
 
 	struct TeX_Flow *flow = TeX_parse(formula);
 	if(!flow) { puts("parsing error!"); return 1; }