opencv_contrib/modules/freetype

FreeType2 Wrapper Module

This FreeType2 wrapper module allows to draw strings with outlines and bitmaps.

Requested external libraries

harfbuzz is requested to convert UTF8 to gid(GlyphID).

freetype library is requested to rasterize given gid.

• harfbuzz https://www.freedesktop.org/wiki/Software/HarfBuzz/
• freetype https://www.freetype.org/

Usage

cv::Ptr<cv::freetype::FreeType2> ft2;
ft2 = cv::freetype::createFreeType2();
ft2->loadFontData(ttf_pathname, 0);
ft2->putText(mat, "hello world", cv::Point(20, 200),
             30, CV_RGB(0, 0, 0), cv::FILLED, cv::LINE_AA, true);

Option

• 2nd argument of loadFontData is used if font file has many font data.
• 3 drawing mode is available.
  • outline mode is used if lineWidth is larger than 0. (like original putText)
  • bitmap mode is used if lineWidth is less than 0.
    • 1bit bitmap mode is used if lineStyle is 4 or 8.
    • gray bitmap mode is used if lineStyle is 16.