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#include "../../include/mgl/graphics/font.h"
#include <stdio.h>
#define STB_TRUETYPE_IMPLEMENTATION
#include "../../external/stb_truetype.h"
/* TODO: Use correct atlas padding after resize. Its incorrect because padding from previous size doesn't accumulate */
/* Need padding so filtering doesn't touch pixels in another glyphs area */
#define GLYPH_PADDING 2
#define GLYPH_UPSAMPLE 1
int mgl_font_load_from_file(mgl_font *self, const mgl_memory_mapped_file *mapped_file, unsigned int character_size) {
self->texture.id = 0;
self->font_atlas.width = 0;
self->font_atlas.height = 0;
self->font_atlas.prev_width = 0;
self->font_atlas.prev_height = 0;
self->font_atlas.pointer_position = (mgl_vec2i){ GLYPH_PADDING, GLYPH_PADDING };
self->font_atlas.render_section = MGL_ATLAS_SECTION_INITIAL;
self->character_size = character_size;
mgl_font_char_map_init(&self->char_map);
self->current_line_max_height = 0;
self->font_info = NULL;
self->font_info = malloc(sizeof(stbtt_fontinfo));
if(!self->font_info) {
fprintf(stderr, "Error: failed to load font, error: out of memory\n");
return -1;
}
/* TODO: Handle font offset with ttc */
if(!stbtt_InitFont(self->font_info, mapped_file->data, stbtt_GetFontOffsetForIndex(mapped_file->data, 0))) {
fprintf(stderr, "Error: failed to load font, error: stbtt_InitFont failed\n");
mgl_font_unload(self);
return -1;
}
if(mgl_texture_init(&self->texture) != 0) {
mgl_font_unload(self);
return -1;
}
/* TODO: Use stbtt_GetCodepointSDF */
return 0;
}
void mgl_font_unload(mgl_font *self) {
mgl_texture_unload(&self->texture);
mgl_font_char_map_deinit(&self->char_map);
self->current_line_max_height = 0;
free(self->font_info);
self->font_info = NULL;
}
static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width) {
if(self->font_atlas.pointer_position.x + glyph_width + GLYPH_PADDING >= self->font_atlas.width) {
if(self->font_atlas.pointer_position.y + self->current_line_max_height + GLYPH_PADDING >= self->font_atlas.height && self->font_atlas.render_section != MGL_ATLAS_SECTION_RIGHT) {
/*
Texture atlas looks like this with glyphs filling the texture:
|----|
|ABCD|
|EFGH|
|----|
And then texture atlas gets resized:
|----|----| |
|ABCD| | <-| 1. The right side gets filled in with new glyphs.
|EDFG| | <-|
|----|----| |
| | | |
| | | |
| | | |
|----|----| |
|
^^^^^^^^^^^ |
---------------|
2. The bottom side gets filled in with new glyphs after the right side is filled with glyphs.
*/
/* Texture overflow, enlargen the font atlas! */
/* TODO: Create a new texture and copy the texture content instead of rendering all glyphs again */
if(mgl_texture_resize(&self->texture, self->font_atlas.width * 2, self->font_atlas.height * 2, NULL) == 0) {
self->font_atlas.prev_width = self->font_atlas.width;
self->font_atlas.prev_height = self->font_atlas.height;
self->font_atlas.width *= 2;
self->font_atlas.height *= 2;
self->font_atlas.render_section = MGL_ATLAS_SECTION_RIGHT;
self->font_atlas.pointer_position.x = self->font_atlas.prev_width;
self->font_atlas.pointer_position.y = GLYPH_PADDING;
mgl_font_char_map_clear_rendered(&self->char_map);
mgl_font_glyph glyph_dummy;
mgl_font_char_iterator font_char_it = mgl_font_char_map_begin(&self->char_map);
while(font_char_it.value) {
mgl_font_get_glyph(self, font_char_it.value->key, &glyph_dummy);
mgl_font_char_iterator_next(&font_char_it);
}
} else {
fprintf(stderr, "Error: failed to resize font atlas\n");
}
} else if(self->font_atlas.render_section == MGL_ATLAS_SECTION_RIGHT && self->font_atlas.pointer_position.y + self->current_line_max_height + GLYPH_PADDING >= self->font_atlas.prev_height) {
self->font_atlas.render_section = MGL_ATLAS_SECTION_BOTTOM;
self->font_atlas.pointer_position.x = GLYPH_PADDING;
self->font_atlas.pointer_position.y = self->font_atlas.prev_height;
} else {
if(self->font_atlas.render_section != MGL_ATLAS_SECTION_RIGHT) {
self->font_atlas.pointer_position.x = GLYPH_PADDING;
} else {
self->font_atlas.pointer_position.x = self->font_atlas.prev_width;
}
self->font_atlas.pointer_position.y += self->current_line_max_height + GLYPH_PADDING;
}
self->current_line_max_height = 0;
}
}
int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph) {
if(self->font_atlas.width == 0) {
const int initial_atlas_size = 128;
/* TODO: Scale by character size */
mgl_texture_load_options load_options = {
.compressed = false,
.pixel_coordinates = true
};
if(mgl_texture_load_from_memory(&self->texture, NULL, initial_atlas_size, initial_atlas_size, MGL_IMAGE_FORMAT_ALPHA, &load_options) == 0) {
/*fprintf(stderr, "Error: failed to create font atlas texture, error: mgl_texture_load_from_memory failed\n");*/
self->font_atlas.width = initial_atlas_size;
self->font_atlas.height = initial_atlas_size;
}
}
mgl_font_char_entry *existing_char_entry = mgl_font_char_map_get(&self->char_map, codepoint);
if(existing_char_entry) {
*glyph = existing_char_entry->value;
if(existing_char_entry->rendered)
return 0;
}
/*
TODO: Maybe somehow use multiple textures? that would be needed when using a lot of glyphs (such as when using chinese fonts).
TODO: Map texture buffer and rasterize the glyph directly into the texture.
*/
const int glyph_index = stbtt_FindGlyphIndex(self->font_info, codepoint);
if(glyph_index == 0) {
memset(glyph, 0, sizeof(mgl_font_glyph));
return -1;
}
const float font_scale = stbtt_ScaleForPixelHeight(self->font_info, self->character_size*GLYPH_UPSAMPLE);
int advance = 0;
int lsb;
stbtt_GetGlyphHMetrics(self->font_info, glyph_index, &advance, &lsb);
const float glyph_advance = font_scale * advance;
int x0, y0, x1, y1;
stbtt_GetGlyphBitmapBox(self->font_info, glyph_index, font_scale, font_scale, &x0, &y0, &x1, &y1);
int width = x1 - x0;
int height = y1 - y0;
int xoff = x0;
int yoff = y0;
/* TODO: Use stbtt_MakeGlyphBitmapSubpixelPrefilter instead for better text quality */
const size_t pixels_size = (width + GLYPH_PADDING * 2) * (height + GLYPH_PADDING * 2);
unsigned char *pixels = malloc(pixels_size);
if(pixels) {
/* TODO: Is this needed? */
/*memset(pixels, 0, pixels_size);*/
stbtt_MakeGlyphBitmapSubpixel(self->font_info, pixels, width, height, width, font_scale, font_scale, GLYPH_PADDING, GLYPH_PADDING, glyph_index);
}
mgl_vec2i render_offset;
if(existing_char_entry) {
render_offset = existing_char_entry->render_offset;
} else {
mgl_font_handle_new_render_position(self, width);
render_offset.x = self->font_atlas.pointer_position.x;
render_offset.y = self->font_atlas.pointer_position.y;
mgl_font_glyph new_glyph;
new_glyph.position = (mgl_vec2i){ xoff/GLYPH_UPSAMPLE, yoff/GLYPH_UPSAMPLE };
new_glyph.size = (mgl_vec2i){ width/GLYPH_UPSAMPLE, height/GLYPH_UPSAMPLE };
new_glyph.texture_position = (mgl_vec2i){ render_offset.x, render_offset.y };
new_glyph.texture_size = (mgl_vec2i){ width, height };
new_glyph.advance = glyph_advance/GLYPH_UPSAMPLE;
*glyph = new_glyph;
if(mgl_font_char_map_insert(&self->char_map, codepoint, &new_glyph, &existing_char_entry) != 0) {
free(pixels);
memset(glyph, 0, sizeof(mgl_font_glyph));
return 0;
}
existing_char_entry->render_offset = render_offset;
if(height > self->current_line_max_height)
self->current_line_max_height = height;
self->font_atlas.pointer_position.x += width + GLYPH_PADDING;
}
existing_char_entry->rendered = true;
if(!pixels) {
if(codepoint == ' ' || codepoint == '\t') {
return 0;
} else {
memset(glyph, 0, sizeof(mgl_font_glyph));
return -1;
}
}
const int res = mgl_texture_update(&self->texture, pixels, render_offset.x, render_offset.y, width, height, MGL_IMAGE_FORMAT_ALPHA);
free(pixels);
return res;
}
int mgl_font_get_kerning(const mgl_font *self, uint32_t prev_codepoint, uint32_t codepoint) {
return 0;
/* TODO: */
/*return stbtt_GetCodepointKernAdvance(self->font_info, prev_codepoint, codepoint);*/
}
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