Replace stb's BakeBitmapFont with AGG based font's renderer

src/font_render_capi.cpp

@@ -1,27 +0,0 @@
-#include "font_render_capi.h"
-
-#include "font_render_lcd.h"
-
-FontRenderer *FontRendererNew(unsigned int flags, float gamma) {
-    bool hinting  = ((flags&FONT_RENDERER_HINTING)  != 0);
-    bool kerning  = ((flags&FONT_RENDERER_KERNING)  != 0);
-    bool subpixel = ((flags&FONT_RENDERER_SUBPIXEL) != 0);
-    font_renderer_lcd *font_renderer = new font_renderer_lcd(hinting, kerning, subpixel, (double) gamma);
-    return (FontRenderer *) font_renderer;
-}
-
-int FontRendererLoadFont(FontRenderer *fr_, const char *filename) {
-    font_renderer_lcd *font_renderer = (font_renderer_lcd *) fr_;
-    bool success = font_renderer->load_font(filename);
-    return (success ? 0 : 1);
-}
-
-int FontRendererDrawText(FontRenderer *fr_, RenColor *pixels, int width, int height, int pitch, const char *text, float text_size, int x, int y, RenColor color) {
-    // FIXME: it works below as long as font_renderer_lcd use a BGRA32 pixel format
-    font_renderer_lcd *font_renderer = (font_renderer_lcd *) fr_;
-    agg::rendering_buffer ren_buf((agg::int8u *) pixels, width, height, -pitch);
-    const agg::rgba8 agg_color(color.r, color.g, color.b);
-    double xd = x, yd = (height - y - text_size);
-    font_renderer->render_text(ren_buf, (double) text_size, agg_color, xd, yd, text);
-    return int(xd);
-}

src/font_render_capi.h

@@ -1,26 +0,0 @@
-#include <stdint.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include "renderer.h"
-
-struct FontRenderer_;
-typedef struct FontRenderer_ FontRenderer;
-
-enum {
-    FONT_RENDERER_HINTING  = 1 << 0,
-    FONT_RENDERER_KERNING  = 1 << 1,
-    FONT_RENDERER_SUBPIXEL = 1 << 2,
-
-    FONT_RENDERER_DEFAULT = FONT_RENDERER_HINTING | FONT_RENDERER_KERNING | FONT_RENDERER_SUBPIXEL,
-};
-
-FontRenderer *FontRendererNew(unsigned int flags, float gamma);
-int FontRendererLoadFont(FontRenderer *, const char *filename);
-int FontRendererDrawText(FontRenderer *fr_, RenColor *pixels, int width, int height, int pitch, const char *text, float text_size, int x, int y, RenColor color);
-
-#ifdef __cplusplus
-}
-#endif

src/font_renderer.cpp

@@ -0,0 +1,84 @@
+#include "font_renderer.h"
+
+#include "font_renderer_alpha.h"
+
+FontRenderer *FontRendererNew(unsigned int flags) {
+    bool hinting = ((flags & FONT_RENDERER_HINTING) != 0);
+    bool kerning = ((flags & FONT_RENDERER_KERNING) != 0);
+    font_renderer_alpha *font_renderer = new font_renderer_alpha(hinting, kerning);
+    return (FontRenderer *) font_renderer;
+}
+
+int FontRendererLoadFont(FontRenderer *fr_, const char *filename) {
+    font_renderer_alpha *font_renderer = (font_renderer_alpha *) fr_;
+    bool success = font_renderer->load_font(filename);
+    return (success ? 0 : 1);
+}
+
+int FontRendererGetFontHeight(FontRenderer *fr_, float size) {
+    font_renderer_alpha *font_renderer = (font_renderer_alpha *) fr_;
+    double ascender, descender;
+    font_renderer->get_font_vmetrics(ascender, descender);
+    int face_height = font_renderer->get_face_height();
+
+    float scale = font_renderer->scale_for_em_to_pixels(size);
+    return int((ascender - descender) * face_height * scale + 0.5);
+}
+
+int FontRendererBakeFontBitmap(FontRenderer *fr_, int font_height,
+    void *pixels, int pixels_width, int pixels_height,
+    int first_char, int num_chars, GlyphBitmapInfo *glyphs)
+{
+    font_renderer_alpha *font_renderer = (font_renderer_alpha *) fr_;
+
+    const int pixel_size = 1;
+    memset(pixels, 0x00, pixels_width * pixels_height * pixel_size);
+
+    double ascender, descender;
+    font_renderer->get_font_vmetrics(ascender, descender);
+
+    const int ascender_px  = int(ascender  * font_height + 0.5);
+    const int descender_px = int(descender * font_height + 0.5);
+
+    const int pad_y = font_height * 2 / 10;
+    const int y_step = font_height + 2 * pad_y;
+
+    agg::rendering_buffer ren_buf((agg::int8u *) pixels, pixels_width, pixels_height, -pixels_width * pixel_size);
+    int x = 0, y = pixels_height;
+    int res = 0;
+    const agg::alpha8 text_color(0xff);
+    for (int i = 0; i < num_chars; i++) {
+        int codepoint = first_char + i;
+        if (x + font_height > pixels_width) {
+            x = 0;
+            y -= y_step;
+        }
+        if (y - font_height - 2 * pad_y < 0) {
+            res = -1;
+            break;
+        }
+        const int y_baseline = y - pad_y - font_height;
+
+        double x_next = x, y_next = y_baseline;
+        font_renderer->render_codepoint(ren_buf, font_height, text_color, x_next, y_next, codepoint);
+        int x_next_i = int(x_next + 0.5);
+        GlyphBitmapInfo& glyph_info = glyphs[i];
+        glyph_info.x0 = x;
+        glyph_info.y0 = pixels_height - (y_baseline + ascender_px  + pad_y);
+        glyph_info.x1 = x_next_i;
+        glyph_info.y1 = pixels_height - (y_baseline + descender_px - pad_y);
+        glyph_info.xoff = 0;
+        glyph_info.yoff = -ascender * font_height;
+        glyph_info.xadvance = x_next - x;
+#if 0
+        fprintf(stderr,
+            "glyph codepoint %3d (ascii: %1c), BOX (%3d, %3d) (%3d, %3d), "
+            "OFFSET (%.5g, %.5g), X ADVANCE %.5g\n",
+            codepoint, i,
+            glyph_info.x0, glyph_info.y0, glyph_info.x1, glyph_info.y1,
+            glyph_info.xoff, glyph_info.yoff, glyph_info.xadvance);
+#endif
+        x = x_next_i;
+    }
+    return res;
+}

src/font_renderer.h

@@ -0,0 +1,34 @@
+#ifndef FONT_RENDERER_H
+#define FONT_RENDERER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Mirrors stbtt_bakedchar.
+struct GlyphBitmapInfo_ {
+  unsigned short x0, y0, x1, y1;
+  float xoff, yoff, xadvance;
+};
+typedef struct GlyphBitmapInfo_ GlyphBitmapInfo;
+
+struct FontRenderer_;
+typedef struct FontRenderer_ FontRenderer;
+
+enum {
+    FONT_RENDERER_HINTING  = 1 << 0,
+    FONT_RENDERER_KERNING  = 1 << 1,
+};
+
+FontRenderer *FontRendererNew(unsigned int flags);
+int FontRendererLoadFont(FontRenderer *, const char *filename);
+int FontRendererGetFontHeight(FontRenderer *, float size);
+int FontRendererBakeFontBitmap(FontRenderer *, int font_height,
+    void *pixels, int pixels_width, int pixels_height,
+    int first_char, int num_chars, GlyphBitmapInfo *glyph_info); 
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/meson.build

@@ -5,7 +5,7 @@ lite_sources = [
     'api/system.c',
     'renderer.c',
     'agg_font_freetype.cpp',
-    'font_render_capi.cpp',
+    'font_renderer.cpp',
     'rencache.c',
     'main.c',
 ]

src/renderer.c

@@ -4,7 +4,7 @@
 #include <math.h>
 #include "stb_truetype.h"
 #include "renderer.h"
-#include "font_render_capi.h"
+#include "font_renderer.h"
 
 #define MAX_GLYPHSET 256
 
@@ -13,15 +13,16 @@ struct RenImage {
   int width, height;
 };
 
-typedef struct {
+struct GlyphSetA {
   RenImage *image;
-  stbtt_bakedchar glyphs[256];
+  GlyphBitmapInfo glyphs[256];
-} GlyphSet;
+};
+typedef struct GlyphSetA GlyphSetA;
 
 struct RenFont {
   void *data;
   stbtt_fontinfo stbfont;
-  GlyphSet *sets[MAX_GLYPHSET];
+  GlyphSetA *sets[MAX_GLYPHSET];
   float size;
   int height;
   FontRenderer *renderer;
@@ -107,8 +108,8 @@ void ren_free_image(RenImage *image) {
 }
 
 
-static GlyphSet* load_glyphset(RenFont *font, int idx) {
+static GlyphSetA* load_glyphset(RenFont *font, int idx) {
-  GlyphSet *set = check_alloc(calloc(1, sizeof(GlyphSet)));
+  GlyphSetA *set = check_alloc(calloc(1, sizeof(GlyphSetA)));
 
   /* init image */
   int width = 128;
@@ -116,13 +117,9 @@ static GlyphSet* load_glyphset(RenFont *font, int idx) {
 retry:
   set->image = ren_new_image(width, height);
 
-  /* load glyphs */
+  int res = FontRendererBakeFontBitmap(font->renderer, font->height,
-  float s =
+    (void *) set->image->pixels, width, height,
-    stbtt_ScaleForMappingEmToPixels(&font->stbfont, 1) /
+    idx << 8, 256, set->glyphs);
-    stbtt_ScaleForPixelHeight(&font->stbfont, 1);
-  int res = stbtt_BakeFontBitmap(
-    font->data, 0, font->size * s, (void*) set->image->pixels,
-    width, height, idx * 256, 256, set->glyphs);
 
   /* retry with a larger image buffer if the buffer wasn't large enough */
   if (res < 0) {
@@ -132,6 +129,7 @@ retry:
     goto retry;
   }
 
+  // TODO: consider if this is still needed.
   /* adjust glyph yoffsets and xadvance */
   int ascent, descent, linegap;
   stbtt_GetFontVMetrics(&font->stbfont, &ascent, &descent, &linegap);
@@ -152,7 +150,7 @@ retry:
 }
 
 
-static GlyphSet* get_glyphset(RenFont *font, int codepoint) {
+static GlyphSetA* get_glyphset(RenFont *font, int codepoint) {
   int idx = (codepoint >> 8) % MAX_GLYPHSET;
   if (!font->sets[idx]) {
     font->sets[idx] = load_glyphset(font, idx);
@@ -184,20 +182,22 @@ RenFont* ren_load_font(const char *filename, float size) {
   int ok = stbtt_InitFont(&font->stbfont, font->data, 0);
   if (!ok) { goto fail; }
 
+  // FIXME: remove, font's height is recalculated using new FontRenderer.
   /* get height and scale */
   int ascent, descent, linegap;
   stbtt_GetFontVMetrics(&font->stbfont, &ascent, &descent, &linegap);
   float scale = stbtt_ScaleForMappingEmToPixels(&font->stbfont, size);
   font->height = (ascent - descent + linegap) * scale + 0.5;
 
-  /* make tab and newline glyphs invisible */
+  font->renderer = FontRendererNew(FONT_RENDERER_HINTING);
-  stbtt_bakedchar *g = get_glyphset(font, '\n')->glyphs;
-  g['\t'].x1 = g['\t'].x0;
-  g['\n'].x1 = g['\n'].x0;
-
-  font->renderer = FontRendererNew(FONT_RENDERER_HINTING|FONT_RENDERER_SUBPIXEL, 1.8);
   // FIXME check for errors
   FontRendererLoadFont(font->renderer, filename);
+  font->height = FontRendererGetFontHeight(font->renderer, size);
+
+  /* make tab and newline glyphs invisible */
+  GlyphBitmapInfo *g = get_glyphset(font, '\n')->glyphs;
+  g['\t'].x1 = g['\t'].x0;
+  g['\n'].x1 = g['\n'].x0;
 
   return font;
 
@@ -211,7 +211,7 @@ fail:
 
 void ren_free_font(RenFont *font) {
   for (int i = 0; i < MAX_GLYPHSET; i++) {
-    GlyphSet *set = font->sets[i];
+    GlyphSetA *set = font->sets[i];
     if (set) {
       ren_free_image(set->image);
       free(set);
@@ -223,7 +223,7 @@ void ren_free_font(RenFont *font) {
 
 
 void ren_set_font_tab_width(RenFont *font, int n) {
-  GlyphSet *set = get_glyphset(font, '\t');
+  GlyphSetA *set = get_glyphset(font, '\t');
   set->glyphs['\t'].xadvance = n;
 }
 
@@ -234,8 +234,8 @@ int ren_get_font_width(RenFont *font, const char *text) {
   unsigned codepoint;
   while (*p) {
     p = utf8_to_codepoint(p, &codepoint);
-    GlyphSet *set = get_glyphset(font, codepoint);
+    GlyphSetA *set = get_glyphset(font, codepoint);
-    stbtt_bakedchar *g = &set->glyphs[codepoint & 0xff];
+    GlyphBitmapInfo *g = &set->glyphs[codepoint & 0xff];
     x += g->xadvance;
   }
   return x;
@@ -334,17 +334,13 @@ void ren_draw_image(RenImage *image, RenRect *sub, int x, int y, RenColor color)
 
 
 int ren_draw_text(RenFont *font, const char *text, int x, int y, RenColor color) {
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
-  RenColor *pixels = (RenColor*) surf->pixels;
-  return FontRendererDrawText(font->renderer, pixels, surf->w, surf->h, surf->pitch, text, font->height * 0.8, x, y, color);
-#if 0
   RenRect rect;
   const char *p = text;
   unsigned codepoint;
   while (*p) {
     p = utf8_to_codepoint(p, &codepoint);
-    GlyphSet *set = get_glyphset(font, codepoint);
+    GlyphSetA *set = get_glyphset(font, codepoint);
-    stbtt_bakedchar *g = &set->glyphs[codepoint & 0xff];
+    GlyphBitmapInfo *g = &set->glyphs[codepoint & 0xff];
     rect.x = g->x0;
     rect.y = g->y0;
     rect.width = g->x1 - g->x0;
@@ -353,5 +349,4 @@ int ren_draw_text(RenFont *font, const char *text, int x, int y, RenColor color)
     x += g->xadvance;
   }
   return x;
-#endif
 }