ded/src/free_glyph.c at fbbd9c7d80b873da278c519fedc6fd3b64b9c474 · tsoding/ded · GitHub

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#include <assert.h>
#include <stdbool.h>
#include "./free_glyph.h"
#define TAB_SIZE 4

void free_glyph_atlas_init(Free_Glyph_Atlas *atlas, FT_Face face)
{
    // TODO: Introduction of SDF font slowed down the start up time
    // We need to investigate what's up with that
    FT_Int32 load_flags = FT_LOAD_RENDER;
    for (int i = 32; i < 128; ++i) {
        if (FT_Load_Char(face, i, load_flags)) {
            fprintf(stderr, "ERROR: could not load glyph of a character with code %d\n", i);
            exit(1);
        }

        atlas->atlas_width += face->glyph->bitmap.width;
        if (atlas->atlas_height < face->glyph->bitmap.rows) {
            atlas->atlas_height = face->glyph->bitmap.rows;
        }

        load_flags = FT_LOAD_RENDER | FT_LOAD_TARGET_(FT_RENDER_MODE_SDF);
    }

    glActiveTexture(GL_TEXTURE0);
    glGenTextures(1, &atlas->glyphs_texture);
    glBindTexture(GL_TEXTURE_2D, atlas->glyphs_texture);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexImage2D(
        GL_TEXTURE_2D,
        0,
        GL_RED,
        (GLsizei) atlas->atlas_width,
        (GLsizei) atlas->atlas_height,
        0,
        GL_RED,
        GL_UNSIGNED_BYTE,
        NULL);

    int x = 0;
    load_flags = FT_LOAD_RENDER;
    for (int i = 32; i < 128; ++i) {
        if (FT_Load_Char(face, i, load_flags)) {
            fprintf(stderr, "ERROR: could not load glyph of a character with code %d\n", i);
            exit(1);
        }

        if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL)) {
            fprintf(stderr, "ERROR: could not render glyph of a character with code %d\n", i);
            exit(1);
        }

        atlas->metrics[i].ax = face->glyph->advance.x >> 6;
        atlas->metrics[i].ay = face->glyph->advance.y >> 6;
        atlas->metrics[i].bw = face->glyph->bitmap.width;
        atlas->metrics[i].bh = face->glyph->bitmap.rows;
        atlas->metrics[i].bl = face->glyph->bitmap_left;
        atlas->metrics[i].bt = face->glyph->bitmap_top;
        atlas->metrics[i].tx = (float) x / (float) atlas->atlas_width;

        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
        glTexSubImage2D(
            GL_TEXTURE_2D,
            0,
            x,
            0,
            face->glyph->bitmap.width,
            face->glyph->bitmap.rows,
            GL_RED,
            GL_UNSIGNED_BYTE,
            face->glyph->bitmap.buffer);
        x += face->glyph->bitmap.width;
        load_flags = FT_LOAD_RENDER | FT_LOAD_TARGET_(FT_RENDER_MODE_SDF);
    }

    // tab hack
    load_flags = FT_LOAD_RENDER;
    int i = '\t';
    if (FT_Load_Char(face, 32, load_flags)) {
        fprintf(stderr, "ERROR: could not load glyph of a character with code %d\n", i);
        exit(1);
    }

    if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL)) {
        fprintf(stderr, "ERROR: could not render glyph of a character with code %d\n", i);
        exit(1);
    }

    atlas->metrics[i].ax = (face->glyph->advance.x >> 6) * TAB_SIZE;
    atlas->metrics[i].ay = face->glyph->advance.y >> 6;
    atlas->metrics[i].bw = face->glyph->bitmap.width * TAB_SIZE;
    atlas->metrics[i].bh = face->glyph->bitmap.rows;
    atlas->metrics[i].bl = face->glyph->bitmap_left;
    atlas->metrics[i].bt = face->glyph->bitmap_top;
    atlas->metrics[i].tx = (float) 0 / (float) atlas->atlas_width;
}

float free_glyph_atlas_cursor_pos(const Free_Glyph_Atlas *atlas, const char *text, size_t text_size, Vec2f pos, size_t col)
{
    for (size_t i = 0; i < text_size; ++i) {
        if (i == col) {
            return pos.x;
        }

        size_t glyph_index = text[i];
        if (glyph_index >= GLYPH_METRICS_CAPACITY) {
            glyph_index = '?';
        }

        Glyph_Metric metric = atlas->metrics[glyph_index];
        pos.x += metric.ax;
        pos.y += metric.ay;
    }

    return pos.x;
}

void free_glyph_atlas_measure_line_sized(Free_Glyph_Atlas *atlas, const char *text, size_t text_size, Vec2f *pos)
{
    for (size_t i = 0; i < text_size; ++i) {
        size_t glyph_index = text[i];
        // TODO: support for glyphs outside of ASCII range
        if (glyph_index >= GLYPH_METRICS_CAPACITY) {
            glyph_index = '?';
        }
        Glyph_Metric metric = atlas->metrics[glyph_index];

        pos->x += metric.ax;
        pos->y += metric.ay;
    }
}

void free_glyph_atlas_render_line_sized(Free_Glyph_Atlas *atlas, Simple_Renderer *sr, const char *text, size_t text_size, Vec2f *pos, Vec4f color)
{
    for (size_t i = 0; i < text_size; ++i) {
        size_t glyph_index = text[i];
        // TODO: support for glyphs outside of ASCII range
        if (glyph_index >= GLYPH_METRICS_CAPACITY) {
            glyph_index = '?';
        }
        Glyph_Metric metric = atlas->metrics[glyph_index];
        float x2 = pos->x + metric.bl;
        float y2 = -pos->y - metric.bt;
        float w  = metric.bw;
        float h  = metric.bh;

        pos->x += metric.ax;
        pos->y += metric.ay;

        simple_renderer_image_rect(
            sr,
            vec2f(x2, -y2),
            vec2f(w, -h),
            vec2f(metric.tx, 0.0f),
            vec2f(metric.bw / (float) atlas->atlas_width, metric.bh / (float) atlas->atlas_height),
            color);
    }
}