渲染字形后，将FreeType位图清零

Question

I've created a repository that has the most basic way to reproduce my issue. I use Cmake to build and it's set up to statically link freetype into my executable.

FreeType is a submodule, so you can clone it all at once with:

git clone --recurse-submodules https://github.com/jeffw387/freetype_minimum_test

or if you prefer just clone freetype from git into the externals directory.

I'm currently testing on Ubuntu.

I can initialize FreeType, create a face from the font, and load a glyph from a character code with the FT_LOAD_RENDER flag all without errors.

Then when I inspect the bitmap buffer, it's zero-initialized on every row. I used gdb from within VS Code in order to inspect the buffer, but before that I also tried copying out the data line by line.

The font I'm testing with is a free font I found online, but I was able to test it in Libre Office and it seems to work just fine.

Can anyone spot a problem with the code? If anyone is willing I'd love to know if this repo creates the same issue on their machine.

Here's my cpp file for easy viewing:

#include <ft2build.h>
#include FT_FREETYPE_H
#include <iostream>
#include <vector>

int main() {
  FT_Library library{};
  if (FT_Init_FreeType(&library)) {
    std::cout << "Error initializing FreeType.";
  }

  FT_Face face{};
  auto faceResult = FT_New_Face(library, "Anke.ttf", 0, &face);
  if (faceResult) {
    std::cout << "Error creating face.";
  }

  if ((face->face_flags & FT_FACE_FLAG_SCALABLE) != FT_FACE_FLAG_SCALABLE) {
    std::cout << "Error: font is not scalable.";
  }

  if (FT_Set_Pixel_Sizes(face, 0, 50)) {
    std::cout << "Error setting font pixel size.";
  }

  if (FT_Load_Char(face, 'P', FT_LOAD_RENDER)) {
    std::cout << "Error loading or rendering glyph.";
  }
  auto bmp = face->glyph->bitmap;

  return 0;
}

Answer 1

I've done some further testing and it seems like there was a problem with my freetype fork. I haven't gone to the trouble of figuring out what it was, but in any case now that I've tried it with a fresh clone from https://github.com/aseprite/freetype2 it works.