431 lines
8.9 KiB
C
431 lines
8.9 KiB
C
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/*
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* A very simple font cache and rasterizer that uses FreeType
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* to draw fonts from a single OpenGL texture. The code uses
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* a linear-probe hashtable, and writes new glyphs into
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* the texture using glTexSubImage2D. When the texture fills
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* up, or the hash table gets too crowded, the cache is emptied.
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*
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* This is designed to be used for horizontal text only,
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* and draws unhinted text with subpixel accurate metrics
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* and kerning. As such, you should always call the drawing
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* function with an orthogonal transform that maps units
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* to pixels accurately.
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*/
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#include "gl-app.h"
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#include <string.h>
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#include <math.h>
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#include <stdlib.h>
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#include <stdio.h>
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#define PADDING 1 /* set to 0 to save some space but disallow arbitrary transforms */
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#define MAXGLYPHS 4093 /* prime number for hash table goodness */
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#define CACHESIZE 1024
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#define XPRECISION 4
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#define YPRECISION 1
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struct key
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{
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fz_font *font;
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float size;
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short gid;
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unsigned char subx;
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unsigned char suby;
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};
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struct glyph
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{
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char lsb, top, w, h;
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short s, t;
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};
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struct table
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{
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struct key key;
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struct glyph glyph;
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};
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static struct table g_table[MAXGLYPHS];
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static int g_table_load = 0;
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static unsigned int g_cache_tex = 0;
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static int g_cache_w = CACHESIZE;
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static int g_cache_h = CACHESIZE;
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static int g_cache_row_y = 0;
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static int g_cache_row_x = 0;
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static int g_cache_row_h = 0;
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static fz_font *g_font = NULL;
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static void clear_font_cache(void)
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{
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#if PADDING > 0
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unsigned char *zero = malloc(g_cache_w * g_cache_h);
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memset(zero, 0, g_cache_w * g_cache_h);
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glBindTexture(GL_TEXTURE_2D, g_cache_tex);
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glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, g_cache_w, g_cache_h, GL_ALPHA, GL_UNSIGNED_BYTE, zero);
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free(zero);
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#endif
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memset(g_table, 0, sizeof(g_table));
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g_table_load = 0;
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g_cache_row_y = PADDING;
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g_cache_row_x = PADDING;
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g_cache_row_h = 0;
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}
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void ui_init_fonts(void)
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{
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const unsigned char *data;
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int size;
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glGenTextures(1, &g_cache_tex);
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glBindTexture(GL_TEXTURE_2D, g_cache_tex);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, g_cache_w, g_cache_h, 0, GL_ALPHA, GL_UNSIGNED_BYTE, NULL);
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clear_font_cache();
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data = fz_lookup_builtin_font(ctx, "Charis SIL", 0, 0, &size);
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if (!data)
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data = fz_lookup_builtin_font(ctx, "Times", 0, 0, &size);
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g_font = fz_new_font_from_memory(ctx, NULL, data, size, 0, 0);
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}
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void ui_finish_fonts(void)
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{
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clear_font_cache();
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fz_drop_font(ctx, g_font);
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}
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static unsigned int hashfunc(struct key *key)
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{
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unsigned char *buf = (unsigned char *)key;
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unsigned int len = sizeof(struct key);
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unsigned int h = 0;
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while (len--)
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h = *buf++ + (h << 6) + (h << 16) - h;
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return h;
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}
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static unsigned int lookup_table(struct key *key)
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{
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unsigned int pos = hashfunc(key) % MAXGLYPHS;
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while (1)
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{
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if (!g_table[pos].key.font) /* empty slot */
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return pos;
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if (!memcmp(key, &g_table[pos].key, sizeof(struct key))) /* matching slot */
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return pos;
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pos = (pos + 1) % MAXGLYPHS;
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}
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}
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static struct glyph *lookup_glyph(fz_font *font, float size, int gid, float *xp, float *yp)
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{
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fz_matrix trm, subpix_trm;
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unsigned char subx, suby;
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fz_pixmap *pixmap;
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struct key key;
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unsigned int pos;
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int w, h;
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/* match fitz's glyph cache quantization */
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trm = fz_scale(size, -size);
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trm.e = *xp;
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trm.f = *yp;
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fz_subpixel_adjust(ctx, &trm, &subpix_trm, &subx, &suby);
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*xp = trm.e;
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*yp = trm.f;
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/*
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* Look it up in the table
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*/
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memset(&key, 0, sizeof key);
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key.font = font;
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key.size = size;
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key.gid = gid;
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key.subx = subx;
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key.suby = suby;
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pos = lookup_table(&key);
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if (g_table[pos].key.font)
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return &g_table[pos].glyph;
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/*
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* Render the bitmap
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*/
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glEnd();
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pixmap = fz_render_glyph_pixmap(ctx, font, gid, &subpix_trm, NULL, 8);
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w = pixmap->w;
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h = pixmap->h;
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/*
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* Find an empty slot in the texture
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*/
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if (g_table_load == (MAXGLYPHS * 3) / 4)
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{
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puts("font cache table full, clearing cache");
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clear_font_cache();
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pos = lookup_table(&key);
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}
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if (h + PADDING > g_cache_h || w + PADDING > g_cache_w)
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return NULL;
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if (g_cache_row_x + w + PADDING > g_cache_w)
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{
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g_cache_row_y += g_cache_row_h + PADDING;
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g_cache_row_x = PADDING;
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g_cache_row_h = 0;
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}
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if (g_cache_row_y + h + PADDING > g_cache_h)
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{
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puts("font cache texture full, clearing cache");
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clear_font_cache();
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pos = lookup_table(&key);
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}
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/*
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* Copy bitmap into texture
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*/
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memcpy(&g_table[pos].key, &key, sizeof(struct key));
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g_table[pos].glyph.w = pixmap->w;
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g_table[pos].glyph.h = pixmap->h;
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g_table[pos].glyph.lsb = pixmap->x;
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g_table[pos].glyph.top = -pixmap->y;
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g_table[pos].glyph.s = g_cache_row_x;
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g_table[pos].glyph.t = g_cache_row_y;
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g_table_load ++;
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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glPixelStorei(GL_UNPACK_ROW_LENGTH, pixmap->w);
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glTexSubImage2D(GL_TEXTURE_2D, 0, g_cache_row_x, g_cache_row_y, w, h,
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GL_ALPHA, GL_UNSIGNED_BYTE, pixmap->samples);
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glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
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fz_drop_pixmap(ctx, pixmap);
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glBegin(GL_QUADS);
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g_cache_row_x += w + PADDING;
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if (g_cache_row_h < h + PADDING)
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g_cache_row_h = h + PADDING;
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return &g_table[pos].glyph;
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}
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static float ui_draw_glyph(fz_font *font, float size, int gid, float x, float y)
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{
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struct glyph *glyph;
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float s0, t0, s1, t1, xc, yc;
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glyph = lookup_glyph(font, size, gid, &x, &y);
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if (!glyph)
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return 0;
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s0 = (float) glyph->s / g_cache_w;
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t0 = (float) glyph->t / g_cache_h;
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s1 = (float) (glyph->s + glyph->w) / g_cache_w;
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t1 = (float) (glyph->t + glyph->h) / g_cache_h;
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xc = floorf(x) + glyph->lsb;
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yc = floorf(y) - glyph->top + glyph->h;
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glTexCoord2f(s0, t0); glVertex2f(xc, yc - glyph->h);
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glTexCoord2f(s1, t0); glVertex2f(xc + glyph->w, yc - glyph->h);
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glTexCoord2f(s1, t1); glVertex2f(xc + glyph->w, yc);
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glTexCoord2f(s0, t1); glVertex2f(xc, yc);
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return fz_advance_glyph(ctx, font, gid, 0) * size;
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}
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float ui_measure_character(int c)
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{
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fz_font *font;
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int gid = fz_encode_character_with_fallback(ctx, g_font, c, 0, 0, &font);
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return fz_advance_glyph(ctx, font, gid, 0) * ui.fontsize;
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}
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static float ui_draw_character_imp(float x, float y, int c)
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{
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fz_font *font;
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int gid = fz_encode_character_with_fallback(ctx, g_font, c, 0, 0, &font);
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return ui_draw_glyph(font, ui.fontsize, gid, x, y);
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}
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static void ui_begin_text(void)
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{
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glBindTexture(GL_TEXTURE_2D, g_cache_tex);
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glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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glEnable(GL_BLEND);
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glEnable(GL_TEXTURE_2D);
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glBegin(GL_QUADS);
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}
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static void ui_end_text(void)
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{
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glEnd();
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glDisable(GL_TEXTURE_2D);
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glDisable(GL_BLEND);
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}
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void ui_draw_string(float x, float y, const char *str)
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{
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int c;
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ui_begin_text();
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while (*str)
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{
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str += fz_chartorune(&c, str);
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x += ui_draw_character_imp(x, y + ui.baseline, c);
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}
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ui_end_text();
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}
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void ui_draw_string_part(float x, float y, const char *s, const char *e)
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{
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int c;
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ui_begin_text();
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while (s < e)
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{
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s += fz_chartorune(&c, s);
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x += ui_draw_character_imp(x, y + ui.baseline, c);
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}
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ui_end_text();
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}
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void ui_draw_character(float x, float y, int c)
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{
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ui_begin_text();
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ui_draw_character_imp(x, y + ui.baseline, c);
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ui_end_text();
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}
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float ui_measure_string(const char *str)
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{
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int c;
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float x = 0;
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while (*str)
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{
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str += fz_chartorune(&c, str);
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x += ui_measure_character(c);
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}
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return x;
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}
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float ui_measure_string_part(const char *s, const char *e)
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{
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int c;
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float w = 0;
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while (s < e)
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{
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s += fz_chartorune(&c, s);
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w += ui_measure_character(c);
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}
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return w;
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}
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int ui_break_lines(char *a, struct line *lines, int maxlines, int width, int *maxwidth)
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{
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char *next, *space = NULL, *b = a;
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int c, n = 0;
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float space_x, x = 0, w = 0;
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if (maxwidth)
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*maxwidth = 0;
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while (*b)
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{
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next = b + fz_chartorune(&c, b);
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if (c == '\r' || c == '\n')
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{
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if (lines && n < maxlines)
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{
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lines[n].a = a;
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lines[n].b = b;
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}
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++n;
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if (maxwidth && *maxwidth < x)
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*maxwidth = x;
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a = next;
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x = 0;
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space = NULL;
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}
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else
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{
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if (c == ' ')
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{
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space = b;
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space_x = x;
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}
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w = ui_measure_character(c);
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if (x + w > width)
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{
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if (space)
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{
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if (lines && n < maxlines)
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{
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lines[n].a = a;
|
||
|
|
lines[n].b = space;
|
||
|
|
}
|
||
|
|
++n;
|
||
|
|
if (maxwidth && *maxwidth < space_x)
|
||
|
|
*maxwidth = space_x;
|
||
|
|
a = next = space + 1;
|
||
|
|
x = 0;
|
||
|
|
space = NULL;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
if (lines && n < maxlines)
|
||
|
|
{
|
||
|
|
lines[n].a = a;
|
||
|
|
lines[n].b = b;
|
||
|
|
}
|
||
|
|
++n;
|
||
|
|
if (maxwidth && *maxwidth < x)
|
||
|
|
*maxwidth = x;
|
||
|
|
a = b;
|
||
|
|
x = w;
|
||
|
|
space = NULL;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
x += w;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
b = next;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (lines && n < maxlines)
|
||
|
|
{
|
||
|
|
lines[n].a = a;
|
||
|
|
lines[n].b = b;
|
||
|
|
}
|
||
|
|
++n;
|
||
|
|
if (maxwidth && *maxwidth < x)
|
||
|
|
*maxwidth = x;
|
||
|
|
return n < maxlines ? n : maxlines;
|
||
|
|
}
|
||
|
|
|
||
|
|
void ui_draw_lines(float x, float y, struct line *lines, int n)
|
||
|
|
{
|
||
|
|
int i;
|
||
|
|
for (i = 0; i < n; ++i)
|
||
|
|
{
|
||
|
|
ui_draw_string_part(x, y, lines[i].a, lines[i].b);
|
||
|
|
y += ui.lineheight;
|
||
|
|
}
|
||
|
|
}
|