rendering a text buffer

5 files changed, 86 insertions, 21 deletions

diff --git a/buffer.c b/buffer.c
index 78fcc1a..8641eb1 100644
--- a/buffer.c
+++ b/buffer.c
@@ -3,7 +3,9 @@
 // blocks of a few thousand bytes. Block boundaries are not necessarily
 // on character boundaries, so one block might have part of a UTF-8 character
 // with the next block having the rest.
+#include "unicode.h"
 #include "util.c"
+#include "text.h"
 
 #define TEXT_BLOCK_MAX_SIZE 400
 // Once two adjacent blocks are at most this big, combine them into
@@ -114,3 +116,57 @@ void text_buffer_free(TextBuffer *buffer) {
 	}
 	free(blocks);
 }
+
+// Render the text buffer in the given rectangle
+void text_buffer_render(TextBuffer *buffer, Font *font, float box_x, float box_y, float box_w, float box_h) {
+	mbstate_t mbstate = {0};
+	uint nblocks = buffer->nblocks;
+	TextBlock *blocks = buffer->blocks;
+	text_chars_begin(font);
+	TextRenderState text_state = {
+		.x = box_x, .y = box_y,
+		.edge_right = box_x+box_w,
+		.edge_bottom = box_y+box_h
+	};
+
+	for (uint block_idx = 0; block_idx < nblocks; ++block_idx) {
+		TextBlock *block = &blocks[block_idx];
+		char *p = block->contents, *end = p + block->len;
+		while (p != end) {
+			char32_t c;
+			size_t n = mbrtoc32(&c, p, (size_t)(end - p), &mbstate);
+			if (n == 0) {
+				// null character
+				c = UNICODE_BOX_CHARACTER;
+				++p;
+			} else if (n == (size_t)(-3)) {
+				// no bytes consumed, but a character was produced
+			} else if (n == (size_t)(-2)) {
+				// incomplete character at end of block.
+				c = 0;
+				p = end;
+			} else if (n == (size_t)(-1)) {
+				// invalid UTF-8
+				c = UNICODE_BOX_CHARACTER;
+				++p;
+			} else {
+				p += n;
+			}
+			switch (c) {
+			case L'\n':
+				text_state.x = box_x;
+				text_state.y -= text_font_char_height(font);
+				break;
+			case L'\r': break; // for CRLF line endings
+			case L'\t':
+				for (int i = 0; i < 4; ++i)
+					text_render_char(font, L' ', &text_state);
+				break;
+			default:
+				text_render_char(font, c, &text_state);
+				break;
+			}
+		}
+	}
+	text_chars_end(font);
+}
diff --git a/main.c b/main.c
index 063f7eb..f2812f5 100644
--- a/main.c
+++ b/main.c
@@ -38,7 +38,8 @@ int main(void) {
 	if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) < 0)
 		die("%s", SDL_GetError());
 
-	SDL_Window *window = SDL_CreateWindow("ted", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 1280, 720, SDL_WINDOW_SHOWN|SDL_WINDOW_OPENGL);
+	SDL_Window *window = SDL_CreateWindow("ted", SDL_WINDOWPOS_UNDEFINED, 
+		SDL_WINDOWPOS_UNDEFINED, 1280, 720, SDL_WINDOW_SHOWN|SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
 	if (!window)
 		die("%s", SDL_GetError());
 
@@ -51,7 +52,7 @@ int main(void) {
 
 	SDL_GL_SetSwapInterval(1); // vsync
 
-	Font *font = text_font_load("assets/font.ttf", 24);
+	Font *font = text_font_load("assets/font.ttf", 16);
 	if (!font) {
 		die("Couldn't load font: %s", text_get_err());
 	}
@@ -81,6 +82,7 @@ int main(void) {
 
 		int window_width = 0, window_height = 0;
 		SDL_GetWindowSize(window, &window_width, &window_height);
+		float window_widthf = (float)window_width, window_heightf = (float)window_height;
 
 		// set up GL
 		glEnable(GL_BLEND);
@@ -93,7 +95,8 @@ int main(void) {
 		glClear(GL_COLOR_BUFFER_BIT);
 
 		glColor3f(1,1,1);
-		text_render(font, "hellσ! öθ☺", 50, 50);
+		//text_render(font, "hellσ! öθ☺", 50, 50);
+		text_buffer_render(&text_buffer, font, 50, window_heightf-50, window_widthf-100, window_heightf-100);
 		if (text_has_err()) {
 			printf("Text error: %s\n", text_get_err());
 			break;
diff --git a/text.c b/text.c
index 258af36..ddd7cdc 100644
--- a/text.c
+++ b/text.c
@@ -1,5 +1,6 @@
 #include "base.h"
 #include "text.h"
+#include "unicode.h"
 #define STB_TRUETYPE_IMPLEMENTATION
 #define STBTT_STATIC
 no_warn_start
@@ -8,7 +9,6 @@ no_warn_end
 #include <stdlib.h>
 #include <GL/gl.h>
 
-#define UNICODE_CODE_POINTS 0x110000 // number of Unicode code points
 // We split up code points into a bunch of pages, so we don't have to load all of the font at
 // once into one texture.
 #define CHAR_PAGE_SIZE 2048
@@ -136,9 +136,9 @@ Font *text_font_load(char const *ttf_filename, float font_size) {
 	return font;
 }
 
-typedef struct {
-	float x, y;
-} TextRenderState;
+float text_font_char_height(Font *font) {
+	return font->char_height;
+}
 
 static void text_render_with_page(Font *font, int page) {
 	if (font->curr_page != page) {
@@ -164,14 +164,14 @@ void text_chars_end(Font *font) {
 	font->curr_page = -1;
 }
 
-static void text_render_char_internal(Font *font, char32_t c, TextRenderState *state) {
+void text_render_char(Font *font, char32_t c, TextRenderState *state) {
 	if (c >= 0x30000 && c < 0xE0000){
 		// these Unicode code points are currently unassigned. replace them with a Unicode box.
 		// (specifically, we don't want to use extra memory for pages which
 		// won't even have any valid characters in them)
-		c = 0x2610;
+		c = UNICODE_BOX_CHARACTER;
 	}
-	if (c >= UNICODE_CODE_POINTS) c = 0x2610; // code points this big should never appear in valid Unicode
+	if (c >= UNICODE_CODE_POINTS) c = UNICODE_BOX_CHARACTER; // code points this big should never appear in valid Unicode
 	uint page = c / CHAR_PAGE_SIZE;
 	uint index = c % CHAR_PAGE_SIZE;
 	text_render_with_page(font, (int)page);
@@ -191,13 +191,6 @@ static void text_render_char_internal(Font *font, char32_t c, TextRenderState *s
 	}
 }
 
-void text_render_char(Font *font, char32_t c, float *x, float *y) {
-	TextRenderState state = {*x, *y};
-	text_render_char_internal(font, c, &state);
-	*x = state.x;
-	*y = state.y;
-}
-
 static void text_render_internal(Font *font, char const *text, float *x, float *y) {
 	mbstate_t mbstate = {0};
 	TextRenderState render_state = {*x, *y};
@@ -208,18 +201,18 @@ static void text_render_internal(Font *font, char const *text, float *x, float *
 		size_t ret = mbrtoc32(&c, text, (size_t)(end - text), &mbstate);
 		if (ret == 0) break;
 		if (ret == (size_t)(-2)) { // incomplete multi-byte character
-			text_render_char_internal(font, '?', &render_state);
+			text_render_char(font, '?', &render_state);
 			text = end; // done reading text
 		} else if (ret == (size_t)(-1)) {
 			// invalid UTF-8; skip this byte
-			text_render_char_internal(font, '?', &render_state);
+			text_render_char(font, '?', &render_state);
 			++text;
 		} else {
 			if (ret != (size_t)(-3))
 				text += ret; // character consists of `ret` bytes
 			switch (c) {
 			default:
-				text_render_char_internal(font, (char32_t)c, &render_state);
+				text_render_char(font, (char32_t)c, &render_state);
 				break;
 			}
 		}
diff --git a/text.h b/text.h
index ad18ef3..45cc6bb 100644
--- a/text.h
+++ b/text.h
@@ -10,6 +10,12 @@
 
 typedef struct Font Font;
 
+typedef struct {
+	float x, y;
+	// points at which the text should be cut off in the x and y directions
+	float edge_right, edge_bottom;
+} TextRenderState;
+
 extern bool text_has_err(void);
 // Get the current error. Errors will NOT be overwritten with newer errors.
 extern char const *text_get_err(void);
@@ -17,6 +23,8 @@ extern char const *text_get_err(void);
 extern void text_clear_err(void);
 // Load a TTF font found in ttf_filename with the given font size (character pixel height)
 extern Font *text_font_load(char const *ttf_filename, float font_size);
+// Height of a character of this font in pixels.
+extern float text_font_char_height(Font *font);
 // Render some UTF-8 text to the screen (simple interface).
 extern void text_render(Font *font, char const *text, float x, float y);
 // Get the dimensions of some text.
@@ -26,7 +34,7 @@ extern void text_chars_begin(Font *font);
 // Finish writing characters.
 extern void text_chars_end(Font *font);
 // Render a single character.
-extern void text_render_char(Font *font, char32_t c, float *x, float *y);
+extern void text_render_char(Font *font, char32_t c, TextRenderState *state);
 // Free memory used by font.
 extern void text_font_free(Font *font);
 
diff --git a/unicode.h b/unicode.h
new file mode 100644
index 0000000..387c08d
--- /dev/null
+++ b/unicode.h
@@ -0,0 +1,5 @@
+#ifndef UNICODE_H_
+#define UNICODE_H_
+#define UNICODE_BOX_CHARACTER 0x2610
+#define UNICODE_CODE_POINTS 0x110000 // number of Unicode code points
+#endif