I am new for freetype library, and trying to following the tutorial to render text into opencv mat.
And I have some problem on non-monospace font face like Ubuntu Regular.
"g++ -o test_ubuntu_regular test_freetype.cpp `pkg-config opencv --cflags --libs` -I/usr/include/freetype2 -lfreetype"
"g++ -o test_ubuntu_regular_mono test_freetype.cpp `pkg-config opencv --cflags --libs` -I/usr/include/freetype2 -lfreetype -D_USE_MONO_"
I also try to use kerning to solve the problem but the delta vector always return (0,0).
Thanks for yours kindly help.
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#include <string>
#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <ft2build.h>
#include FT_FREETYPE_H
using namespace std;
using namespace cv;
int main(int arch, char* argv[])
{
///Setup test font, font size, and string
#ifndef _USE_MONO_
string test_font = "Ubuntu-R.ttf";
#else
string test_font = "UbuntuMono-R.ttf";
#endif
string test_string = "jjj abcdefghijklmnopqrstuvwxyz jjj";
int height = 32;
FT_UInt status;
///Initialize library
FT_Library library;
status = FT_Init_FreeType(&library);
if (status)
{
cout<<"Freetype library initialization failed"<<endl;
return 1;
}
///Load font face
FT_Face face;
status = FT_New_Face(library, test_font.c_str(), 0, &face);
if (status)
{
cout<<"Freetype load font face failed"<<endl;
return 1;
}
///Set font size
status = FT_Set_Pixel_Sizes(face, 0, height);
if (status)
{
cout<<"Freetype set size failed"<<endl;
return 1;
}
///Render to text_image
Mat text_image;
int max_height=0;
FT_GlyphSlot slot=face->glyph;
for (size_t t=0; t<test_string.size(); t++)
{
///Load and render character
status = FT_Load_Char(face, test_string[t], FT_LOAD_RENDER );
if (status)
{
cout<<"Freetype load char \""<<test_string[t]<<"\" failed"<<endl;
continue;
}
///Compute max height of character image for concat them
max_height = max(max_height, height-slot->bitmap_top+slot->bitmap.rows);
///Create character image
Mat char_image=Mat::zeros(max_height, slot->advance.x/64, CV_8UC1);
for (int y=height-slot->bitmap_top, j=0; j<slot->bitmap.rows; y++, j++)
{
uchar* scanline = char_image.ptr<uchar>(y);
for (int x=slot->bitmap_left, i=0; i<slot->bitmap.width; x++, i++)
{
if (x>=char_image.cols)
{
continue;
}
scanline[x] |= slot->bitmap.buffer[j*slot->bitmap.pitch+i];
}
}
///Concat character image to text image
if (text_image.empty())
{
text_image=char_image;
}
else
{
if (max_height>text_image.rows)
{
copyMakeBorder(text_image, text_image, 0, max_height-text_image.rows, 0, 0, BORDER_CONSTANT, Scalar(0));
}
hconcat(text_image, char_image, text_image);
}
}
#ifndef _USE_MONO_
imwrite("ubuntu-regular.png", text_image);
#else
imwrite("ubuntu-regular-mono.png", text_image);
#endif
}
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ubuntu-regular.png
ubuntu-regular-mono.png