4coder/win32_ft_font.cpp

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// NOTE(allen): Thanks to insofaras.
// This is copy-pasted from some work he
// did to get free type working on linux.
// Once it is working on both sides it might
// be possible to pull some parts out as
// portable FT rendering.
#undef internal
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_LCD_FILTER_H
#define internal static
internal u32
next_pow_of_2(u32 v){
--v;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
return ++v;
}
#define NUM_GLYPHS 128
#define ENABLE_LCD_FILTER 0
internal b32
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win32_ft_font_load(Partition *part, Render_Font *rf, char *name, i32 pt_size, i32 tab_width){
Temp_Memory temp = begin_temp_memory(part);
char* filename = push_array(part, char, 256);
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String str = make_string(filename, 0, 256);
sysshared_to_binary_path(&str, name);
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memset(rf, 0, sizeof(*rf));
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//TODO(inso): put stuff in linuxvars / init in main
FT_Library ft;
FT_Face face;
b32 use_lcd_filter = 0;
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FT_Init_FreeType(&ft);
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//NOTE(inso): i'm not sure the LCD filter looks better, and it doesn't work perfectly with the coloring stuff
#if ENABLE_LCD_FILTER
if(FT_Library_SetLcdFilter(ft, FT_LCD_FILTER_DEFAULT) == 0){
puts("LCD Filter on");
use_lcd_filter = 1;
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
}
#endif
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FT_New_Face(ft, filename, 0, &face);
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// set size & metrics
FT_Size_RequestRec_ size = {};
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size.type = FT_SIZE_REQUEST_TYPE_NOMINAL;
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size.height = pt_size << 6;
FT_Request_Size(face, &size);
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rf->loaded = 1;
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rf->ascent = CEIL32 (face->size->metrics.ascender / 64.0f);
rf->descent = FLOOR32 (face->size->metrics.descender / 64.0f);
rf->advance = CEIL32 (face->size->metrics.max_advance / 64.0f);
rf->height = CEIL32 (face->size->metrics.height / 64.0f);
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rf->line_skip = rf->height - (rf->ascent - rf->descent);
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rf->height -= rf->line_skip;
rf->line_skip = 0;
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int max_glyph_w = face->size->metrics.x_ppem;
int max_glyph_h = rf->height;
int tex_width = 64;
int tex_height = 0;
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// estimate upper bound on texture width
do {
tex_width *= 2;
float glyphs_per_row = ceilf(tex_width / (float) max_glyph_w);
float rows = ceilf(NUM_GLYPHS / glyphs_per_row);
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tex_height = CEIL32(rows * (max_glyph_h + 2));
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} while(tex_height > tex_width);
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tex_height = next_pow_of_2(tex_height);
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int pen_x = 0;
int pen_y = 0;
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u32* pixels = push_array(part, u32, tex_width * tex_height);
memset(pixels, 0, tex_width * tex_height * sizeof(u32));
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// XXX: test if AUTOHINT looks better or not
const u32 ft_extra_flags = use_lcd_filter ? FT_LOAD_TARGET_LCD : FT_LOAD_FORCE_AUTOHINT;
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for(int i = 0; i < NUM_GLYPHS; ++i){
if(FT_Load_Char(face, i, FT_LOAD_RENDER | ft_extra_flags) != 0) continue;
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int w = face->glyph->bitmap.width;
int h = face->glyph->bitmap.rows;
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// lcd filter produces RGB bitmaps, need to account for the extra components
if(use_lcd_filter){
w /= 3;
}
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// move to next line if necessary
if(pen_x + w >= tex_width){
pen_x = 0;
pen_y += (max_glyph_h + 2);
}
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// set all this stuff the renderer needs
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Glyph_Data* c = rf->glyphs + i;
c->x0 = (f32)(pen_x);
c->y0 = (f32)(pen_y);
c->x1 = (f32)(pen_x + w);
c->y1 = (f32)(pen_y + h + 1);
c->xoff = (f32)(face->glyph->bitmap_left);
c->yoff = (f32)(rf->ascent - face->glyph->bitmap_top);
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c->xoff2 = w + c->xoff;
c->yoff2 = h + c->yoff + 1;
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rf->advance_data[i] = (f32)(face->glyph->advance.x >> 6);
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rf->glyphs[i].exists = 1;
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int pitch = face->glyph->bitmap.pitch;
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// write to texture atlas
for(int j = 0; j < h; ++j){
for(int i = 0; i < w; ++i){
int x = pen_x + i;
int y = pen_y + j;
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if(use_lcd_filter){
u8 r = face->glyph->bitmap.buffer[j * pitch + i * 3];
u8 g = face->glyph->bitmap.buffer[j * pitch + i * 3 + 1];
u8 b = face->glyph->bitmap.buffer[j * pitch + i * 3 + 2];
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u8 a = (u8)ROUND32((r + g + b) / 3.0f);
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pixels[y * tex_width + x] = (a << 24) | (r << 16) | (g << 8) | b;
} else {
pixels[y * tex_width + x] = face->glyph->bitmap.buffer[j * pitch + i] * 0x1010101;
}
}
}
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pen_x = CEIL32(c->x1 + 1);
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}
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Glyph_Data space_glyph = rf->glyphs[' '];
f32 space_width = rf->advance_data[' '];
rf->glyphs['\r'] = space_glyph;
rf->advance_data['\r'] = space_width*tab_width;
rf->glyphs['\n'] = space_glyph;
rf->advance_data['\n'] = space_width*tab_width;
rf->glyphs['\t'] = space_glyph;
rf->advance_data['\t'] = space_width*tab_width;
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FT_Done_FreeType(ft);
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tex_height = next_pow_of_2(pen_y + max_glyph_h + 2);
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rf->tex_width = tex_width;
rf->tex_height = tex_height;
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// upload texture
glGenTextures(1, &rf->tex);
glBindTexture(GL_TEXTURE_2D, rf->tex);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
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if(use_lcd_filter){
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_width, tex_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
} else {
glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, tex_width, tex_height, 0, GL_ALPHA, GL_UNSIGNED_INT, pixels);
}
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glBindTexture(GL_TEXTURE_2D, 0);
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end_temp_memory(temp);
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return 1;
}