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✏️ Editing: example2.cpp

// example2.cpp

// This file demonstrates how to render a coloured glyph with a differently
// coloured outline.
//
// Written Feb. 2009 by Erik Möller,
// with slight modifications by Werner Lemberg
//
// Public domain.
//
// Eric uses similar code in real applications; see
//
//   http://www.timetrap.se
//   http://www.emberwind.se
//
// for more.

#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_STROKER_H

#include <vector>
#include <fstream>
#include <iostream>

#ifdef _MSC_VER
#define MIN __min
#define MAX __max
#else
#define MIN std::min
#define MAX std::max
#endif

// Define some fixed size types.

typedef unsigned char uint8;
typedef unsigned short uint16;
typedef unsigned int uint32;

// Try to figure out what endian this machine is using. Note that the test
// below might fail for cross compilation; additionally, multi-byte
// characters are implementation-defined in C preprocessors.

#if (('1234' >> 24) == '1')
#elif (('4321' >> 24) == '1')
  #define BIG_ENDIAN
#else
  #error "Couldn't determine the endianness!"
#endif

// A simple 32-bit pixel.

union Pixel32
{
  Pixel32()
  : integer(0) { }
  Pixel32(uint8 bi, uint8 gi, uint8 ri, uint8 ai = 255)
  {
    b = bi;
    g = gi;
    r = ri;
    a = ai;
  }

uint32 integer;

struct
  {
#ifdef BIG_ENDIAN
    uint8 a, r, g, b;
#else // BIG_ENDIAN
    uint8 b, g, r, a;
#endif // BIG_ENDIAN
  };
};

struct Vec2
{
  Vec2() { }
  Vec2(float a, float b)
  : x(a), y(b) { }

float x, y;
};

struct Rect
{
  Rect() { }
  Rect(float left, float top, float right, float bottom)
  : xmin(left), xmax(right), ymin(top), ymax(bottom) { }

void Include(const Vec2 &r)
  {
    xmin = MIN(xmin, r.x);
    ymin = MIN(ymin, r.y);
    xmax = MAX(xmax, r.x);
    ymax = MAX(ymax, r.y);
  }

float Width() const { return xmax - xmin + 1; }
  float Height() const { return ymax - ymin + 1; }

float xmin, xmax, ymin, ymax;
};

// TGA Header struct to make it simple to dump a TGA to disc.

#if defined(_MSC_VER) || defined(__GNUC__)
#pragma pack(push, 1)
#pragma pack(1)               // Dont pad the following struct.
#endif

struct TGAHeader
{
  uint8   idLength,           // Length of optional identification sequence.
          paletteType,        // Is a palette present? (1=yes)
          imageType;          // Image data type (0=none, 1=indexed, 2=rgb,
                              // 3=grey, +8=rle packed).
  uint16  firstPaletteEntry,  // First palette index, if present.
          numPaletteEntries;  // Number of palette entries, if present.
  uint8   paletteBits;        // Number of bits per palette entry.
  uint16  x,                  // Horiz. pixel coord. of lower left of image.
          y,                  // Vert. pixel coord. of lower left of image.
          width,              // Image width in pixels.
          height;             // Image height in pixels.
  uint8   depth,              // Image color depth (bits per pixel).
          descriptor;         // Image attribute flags.
};

#if defined(_MSC_VER) || defined(__GNUC__)
#pragma pack(pop)
#endif

bool
WriteTGA(const std::string &filename,
         const Pixel32 *pxl,
         uint16 width,
         uint16 height)
{
  std::ofstream file(filename.c_str(), std::ios::binary);
  if (file)
  {
    TGAHeader header;
    memset(&header, 0, sizeof(TGAHeader));
    header.imageType  = 2;
    header.width = width;
    header.height = height;
    header.depth = 32;
    header.descriptor = 0x20;

file.write((const char *)&header, sizeof(TGAHeader));
    file.write((const char *)pxl, sizeof(Pixel32) * width * height);

return true;
  }
  return false;
}

// A horizontal pixel span generated by the FreeType renderer.

struct Span
{
  Span() { }
  Span(int _x, int _y, int _width, int _coverage)
  : x(_x), y(_y), width(_width), coverage(_coverage) { }

int x, y, width, coverage;
};

typedef std::vector<Span> Spans;

// Each time the renderer calls us back we just push another span entry on
// our list.

void
RasterCallback(const int y,
               const int count,
               const FT_Span * const spans,
               void * const user) 
{
  Spans *sptr = (Spans *)user;
  for (int i = 0; i < count; ++i) 
    sptr->push_back(Span(spans[i].x, y, spans[i].len, spans[i].coverage));
}

// Set up the raster parameters and render the outline.

void
RenderSpans(FT_Library &library,
            FT_Outline * const outline,
            Spans *spans) 
{
  FT_Raster_Params params;
  memset(&params, 0, sizeof(params));
  params.flags = FT_RASTER_FLAG_AA | FT_RASTER_FLAG_DIRECT;
  params.gray_spans = RasterCallback;
  params.user = spans;

FT_Outline_Render(library, outline, &params);
}

// Render the specified character as a colored glyph with a colored outline
// and dump it to a TGA.

void
WriteGlyphAsTGA(FT_Library &library,
                const std::string &fileName,
                wchar_t ch,
                FT_Face &face,
                int size,
                const Pixel32 &fontCol,
                const Pixel32 outlineCol,
                float outlineWidth)
{
  // Set the size to use.
  if (FT_Set_Char_Size(face, size << 6, size << 6, 90, 90) == 0)
  {
    // Load the glyph we are looking for.
    FT_UInt gindex = FT_Get_Char_Index(face, ch);
    if (FT_Load_Glyph(face, gindex, FT_LOAD_NO_BITMAP) == 0)
    {
      // Need an outline for this to work.
      if (face->glyph->format == FT_GLYPH_FORMAT_OUTLINE)
      {
        // Render the basic glyph to a span list.
        Spans spans;
        RenderSpans(library, &face->glyph->outline, &spans);

// Next we need the spans for the outline.
        Spans outlineSpans;

// Set up a stroker.
        FT_Stroker stroker;
        FT_Stroker_New(library, &stroker);
        FT_Stroker_Set(stroker,
                       (int)(outlineWidth * 64),
                       FT_STROKER_LINECAP_ROUND,
                       FT_STROKER_LINEJOIN_ROUND,
                       0);

FT_Glyph glyph;
        if (FT_Get_Glyph(face->glyph, &glyph) == 0)
        {
          FT_Glyph_StrokeBorder(&glyph, stroker, 0, 1);
          // Again, this needs to be an outline to work.
          if (glyph->format == FT_GLYPH_FORMAT_OUTLINE)
          {
            // Render the outline spans to the span list
            FT_Outline *o =
              &reinterpret_cast<FT_OutlineGlyph>(glyph)->outline;
            RenderSpans(library, o, &outlineSpans);
          }

// Clean up afterwards.
          FT_Stroker_Done(stroker);
          FT_Done_Glyph(glyph);

// Now we need to put it all together.
          if (!spans.empty())
          {
            // Figure out what the bounding rect is for both the span lists.
            Rect rect(spans.front().x,
                      spans.front().y,
                      spans.front().x,
                      spans.front().y);
            for (Spans::iterator s = spans.begin();
                 s != spans.end(); ++s)
            {
              rect.Include(Vec2(s->x, s->y));
              rect.Include(Vec2(s->x + s->width - 1, s->y));
            }
            for (Spans::iterator s = outlineSpans.begin();
                 s != outlineSpans.end(); ++s)
            {
              rect.Include(Vec2(s->x, s->y));
              rect.Include(Vec2(s->x + s->width - 1, s->y));
            }

#if 0
            // This is unused in this test but you would need this to draw
            // more than one glyph.
            float bearingX = face->glyph->metrics.horiBearingX >> 6;
            float bearingY = face->glyph->metrics.horiBearingY >> 6;
            float advance = face->glyph->advance.x >> 6;
#endif

// Get some metrics of our image.
            int imgWidth = rect.Width(),
                imgHeight = rect.Height(),
                imgSize = imgWidth * imgHeight;

// Allocate data for our image and clear it out to transparent.
            Pixel32 *pxl = new Pixel32[imgSize];
            memset(pxl, 0, sizeof(Pixel32) * imgSize);

// Loop over the outline spans and just draw them into the
            // image.
            for (Spans::iterator s = outlineSpans.begin();
                 s != outlineSpans.end(); ++s)
              for (int w = 0; w < s->width; ++w)
                pxl[(int)((imgHeight - 1 - (s->y - rect.ymin)) * imgWidth
                          + s->x - rect.xmin + w)] =
                  Pixel32(outlineCol.r, outlineCol.g, outlineCol.b,
                          s->coverage);

// Then loop over the regular glyph spans and blend them into
            // the image.
            for (Spans::iterator s = spans.begin();
                 s != spans.end(); ++s)
              for (int w = 0; w < s->width; ++w)
              {
                Pixel32 &dst =
                  pxl[(int)((imgHeight - 1 - (s->y - rect.ymin)) * imgWidth
                      + s->x - rect.xmin + w)];
                Pixel32 src = Pixel32(fontCol.r, fontCol.g, fontCol.b,
                                      s->coverage);
                dst.r = (int)(dst.r + ((src.r - dst.r) * src.a) / 255.0f);
                dst.g = (int)(dst.g + ((src.g - dst.g) * src.a) / 255.0f);
                dst.b = (int)(dst.b + ((src.b - dst.b) * src.a) / 255.0f);
                dst.a = MIN(255, dst.a + src.a);
              }

// Dump the image to disk.
            WriteTGA(fileName, pxl, imgWidth, imgHeight);

delete [] pxl;
          }
        }
      }
    }
  }
}

int
main(int argc,
     char **argv)
{
  if (argc != 3)
  {
    std::cerr << "Render letter `B' of given font as a TGA image.\n";
    std::cerr << "\n";
    std::cerr << "usage: example2 <font> <TGA-file>\n";
    return 1;
  }

// Initialize FreeType.
  FT_Library library;
  FT_Init_FreeType(&library);

// Open up a font file.
  std::ifstream fontFile(argv[1], std::ios::binary);
  if (fontFile)
  {
    // Read the entire file to a memory buffer.
    fontFile.seekg(0, std::ios::end);
    std::fstream::pos_type fontFileSize = fontFile.tellg();
    fontFile.seekg(0);
    unsigned char *fontBuffer = new unsigned char[fontFileSize];
    fontFile.read((char *)fontBuffer, fontFileSize);

// Create a face from a memory buffer.  Be sure not to delete the memory
    // buffer until you are done using that font as FreeType will reference
    // it directly.
    FT_Face face;
    FT_New_Memory_Face(library, fontBuffer, fontFileSize, 0, &face);

// Dump out a single glyph to a tga.
    WriteGlyphAsTGA(library,
                    argv[2],
                    L'B',
                    face,
                    100,
                    Pixel32(255, 90, 30),
                    Pixel32(255, 255, 255),
                    3.0f);

// Now that we are done it is safe to delete the memory.
    delete [] fontBuffer;
  }

// Clean up the library
  FT_Done_FreeType(library);

return 1;
}

// Local Variables: 
// coding: utf-8
// End:

MR SKB