利用freetype轉出bitmap點陣字

rasters是利用freetype將特定字型文字轉成bitmap字串。

bool rasters(const wchar_t texts[], Bitmap *bitmap)
{
    if(texts[0] == '\0') {
        return true;
    }

    FT_Library library;
    if (FT_Init_FreeType(&library)) {
        return false;
    }

    FT_Face face;
    if(FT_New_Face(library, "C:/WINDOWS/Fonts/MINGLIU.TTC", 0, &face)) {
        FT_Done_FreeType(library);
        return false;
    }

    int pixalWidth = 36;
    int pixalHeight = 36;
    if(FT_Set_Pixel_Sizes(face, pixalWidth, pixalHeight)) {
        FT_Done_Face(face);
        FT_Done_FreeType(library);
        return false;
    }

    FT_Select_Charmap(face, FT_ENCODING_UNICODE);
    for(int i=0; i<wcslen(texts); i++) {
        unsigned int ucode = texts[i];
        FT_UInt glyph_index = FT_Get_Char_Index(face, ucode);
        if(!glyph_index) {
            continue;
        }

        if (FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT)) {
            continue;
        }
        if (face->glyph->format != FT_GLYPH_FORMAT_BITMAP) {
            if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_MONO)) {
                continue;
            }
        }

        Bitmap font = {    face->glyph->bitmap_left,
                        face->glyph->bitmap_top - face->glyph->bitmap.rows,
                        face->glyph->bitmap.width,
                        face->glyph->bitmap.rows,
                        face->glyph->bitmap.pitch,
                        face->glyph->bitmap.buffer
                      };
        combinetext(bitmap, &font);
    }

    FT_Done_Face(face);
    FT_Done_FreeType(library);

    return true;
}

參考資料：
使用freetype2从ttf字库中提取任意大点阵字体
透過 FreeType 繪製 Unicode ASCII Art

完整程式

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <ft2build.h>
#include FT_FREETYPE_H

typedef struct Bitmap_ {
    int             x;
    int             y;
    unsigned int    width;
    unsigned int    height;
    unsigned int    pitch;
    unsigned char*  data;

} Bitmap;

void printtext(Bitmap *bitmap)
{
    for(int j=0; j<bitmap->height; j++) {
        for(int i=0; i<bitmap->pitch; i++) {
            for(int k=7; k>=0; k--){
                if(7-k+i*8 == bitmap->width)
                    break;
                printf("%c", (bitmap->data[i+j*bitmap->pitch] & 0x1<<k)?'1':'0');
            }
        }
        printf("\n");
    }
}

void combinetext(Bitmap *bitmap, Bitmap *font)
{
    int x1 = bitmap->x;
    int y1 = bitmap->y;
    unsigned int width1 = bitmap->width;
    unsigned int height1 = bitmap->height;
    unsigned int pitch1 = bitmap->pitch;
    unsigned char* data1 = bitmap->data;

    int x2 = x1 + width1 + font->x;
    int y2 = font->y;
    unsigned int width2 = font->width;
    unsigned int height2 = font->height;
    unsigned int pitch2 = font->pitch;
    unsigned char* data2 = font->data;

    int x3 = x1;
    if(x1 > x2) {
        x3 = x2;
    }
    unsigned int width3 = width1 + font->x + width2;
    int y3 = y1;
    unsigned int height3 = height1;
    if(y1 > y2) {
        y3 = y2;
        height3 += (y1 - y2);
    }
    if(y1+height1 < y2+height2) {
        height3 += (y2+height2) - (y1+height1);
    }
    unsigned int pitch3 = width3/8;
    if(width3 % 8 != 0) {
        pitch3 += 1;
    }

    int size3 = pitch3 * height3;
    unsigned char *data3 = calloc(size3, sizeof(unsigned char));
    int shiftX1 = 0;
    int shiftY1 = (height3+y3) - (height1+y1);
    for(int j=0; j<height1; j++) {
        int nj = j+shiftY1;
        for(int i=0; i<pitch1; i++) {
            int n = shiftX1/8+i+nj*pitch3;
            unsigned char data = data1[i+j*pitch1];
            int shift = shiftX1%8;
            if(shift == 0) {
                data3[n] |= data;
            } else {
                data3[n] |= (0x7f & data>>shift);
                data3[n+1] |= data<<(8-shift);
            }
        }
    }
    int shiftX2 = x2-x3;
    int shiftY2 = (height3+y3) - (height2+y2);
    for(int j=0; j<height2; j++) {
        int nj = j+shiftY2;
        for(int i=0; i<pitch2; i++) {
            int n = shiftX2/8+i+nj*pitch3;
            unsigned char data = data2[i+j*pitch2];
            int shift = shiftX2%8;
            if(shift == 0) {
                data3[n] |= data;
            } else {
                data3[n] |= (0x7f & data>>shift);
                data3[n+1] |= data<<(8-shift);
            }
        }
    }
    free(bitmap->data);

    bitmap->x = x3;
    bitmap->y = y3;
    bitmap->width = width3;
    bitmap->height = height3;
    bitmap->pitch = pitch3;
    bitmap->data = data3;
}

bool rasters(const wchar_t texts[], Bitmap *bitmap)
{
    if(texts[0] == '\0') {
        return true;
    }

    FT_Library library;
    if (FT_Init_FreeType(&library)) {
        return false;
    }

    FT_Face face;
    if(FT_New_Face(library, "C:/WINDOWS/Fonts/MINGLIU.TTC", 0, &face)) {
        FT_Done_FreeType(library);
        return false;
    }

    int pixalWidth = 24;
    int pixalHeight = 24;
    if(FT_Set_Pixel_Sizes(face, pixalWidth, pixalHeight)) {
        FT_Done_Face(face);
        FT_Done_FreeType(library);
        return false;
    }

    FT_Select_Charmap(face, FT_ENCODING_UNICODE);
    for(int i=0; i<wcslen(texts); i++) {
        unsigned int ucode = texts[i];
        FT_UInt glyph_index = FT_Get_Char_Index(face, ucode);
        if(!glyph_index) {
            continue;
        }

        if (FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT)) {
            continue;
        }
        if (face->glyph->format != FT_GLYPH_FORMAT_BITMAP) {
            if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_MONO)) {
                continue;
            }
        }

        Bitmap font = {    face->glyph->bitmap_left,
                        face->glyph->bitmap_top - face->glyph->bitmap.rows,
                        face->glyph->bitmap.width,
                        face->glyph->bitmap.rows,
                        face->glyph->bitmap.pitch,
                        face->glyph->bitmap.buffer
                      };
        combinetext(bitmap, &font);
    }

    FT_Done_Face(face);
    FT_Done_FreeType(library);

    return true;
}

int main(int argc, char *argv[])
{
    unsigned char *array = calloc(1, sizeof(unsigned char));
    //unsigned char array[1] = {0};
    Bitmap bitmap = {0, 0, 0, 0, 0, array};
    if(rasters(L"新年快樂", &bitmap)) {
        printtext(&bitmap);
    } else {
        printf("error");
    }
    return EXIT_SUCCESS;
}