Text Rendering using TrueType Font | C++

Rendering Text

In order to render text, the Rendering subsystem requires the implementation of Aspose.Font.Rendering.IGlyphOutlinePainter interface to draw glyph. This can be achieved using the following steps.

  1. Implement the IGlyphOutlinePainter methods by creating a class GlyphOutlinePainter which requires object of type System.Drawing.Drawing2D.GraphicsPath for graphic drawing objectives. The implementation is as illustrated below.

     1For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-C
      2RenderingText::GlyphOutlinePainter::GlyphOutlinePainter(System::SharedPtr<System::Drawing::Drawing2D::GraphicsPath> path)
      3{
      4    _path = path;
      5}
      6
      7void RenderingText::GlyphOutlinePainter::MoveTo(System::SharedPtr<Aspose::Font::RenderingPath::MoveTo> moveTo)
      8{
      9    _path->CloseFigure();
     10    _currentPoint.set_X((float)moveTo->get_X());
     11    _currentPoint.set_Y((float)moveTo->get_Y());
     12}
     13
     14void RenderingText::GlyphOutlinePainter::LineTo(System::SharedPtr<Aspose::Font::RenderingPath::LineTo> lineTo)
     15{
     16    float x = (float)lineTo->get_X();
     17    float y = (float)lineTo->get_Y();
     18    _path->AddLine(_currentPoint.get_X(), _currentPoint.get_Y(), x, y);
     19    _currentPoint.set_X(x);
     20    _currentPoint.set_Y(y);
     21}
     22
     23void RenderingText::GlyphOutlinePainter::CurveTo(System::SharedPtr<Aspose::Font::RenderingPath::CurveTo> curveTo)
     24{
     25    float x3 = (float)curveTo->get_X3();
     26    float y3 = (float)curveTo->get_Y3();
     27    
     28    _path->AddBezier(_currentPoint.get_X(), _currentPoint.get_Y(), (float)curveTo->get_X1(), (float)curveTo->get_Y1(), (float)curveTo->get_X2(), (float)curveTo->get_Y2(), x3, y3);
     29    
     30    _currentPoint.set_X(x3);
     31    _currentPoint.set_Y(y3);
     32}
     33
     34void RenderingText::GlyphOutlinePainter::ClosePath()
     35{
     36    _path->CloseFigure();
     37}
     38
     39System::Object::shared_members_type Aspose::Font::Examples::WorkingWithTrueTypeAndOpenTypeFonts::RenderingText::GlyphOutlinePainter::GetSharedMembers()
     40{
     41    auto result = System::Object::GetSharedMembers();
     42    
     43    result.Add("Aspose::Font::Examples::WorkingWithTrueTypeAndOpenTypeFonts::RenderingText::GlyphOutlinePainter::_path", this->_path);
     44    result.Add("Aspose::Font::Examples::WorkingWithTrueTypeAndOpenTypeFonts::RenderingText::GlyphOutlinePainter::_currentPoint", this->_currentPoint);
     45    
     46    return result;
     47}

  2. Create method DrawText() which draws specified text into System.Drawing.Bitmap object and saves resultant bitmap on Disc. This will include the following steps:

Auxillary steps for this strategy

Implementation of DrawText method is as shown below.

  1. create utility method to calculate font width to image width as shown in the code sample below
1For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-C
2double RenderingText::FontWidthToImageWith(double width, int32_t fontSourceResulution, double fontSize, double dpi /* = 300*/)
3{
4    double resolutionCorrection = dpi / 72;
5    // 72 is font's internal dpi
6    return (width / fontSourceResulution) * fontSize * resolutionCorrection;
7}

Calling the Rendering Text functionality

To use the above implementations, the following sample code can be executed from the Main method of a console based application.

 1For complete examples and data files, please go to https://github.com/aspose-font/Aspose.Font-for-C
 2System::String dataDir = RunExamples::GetDataDir_Data();
 3    
 4System::String fileName1 = dataDir + u"Montserrat-Bold.ttf";
 5//Font file name with full path
 6System::SharedPtr<FontDefinition> fd1 = System::MakeObject<FontDefinition>(Aspose::Font::FontType::TTF, System::MakeObject<FontFileDefinition>(u"ttf", System::MakeObject<FileSystemStreamSource>(fileName1)));
 7System::SharedPtr<TtfFont> ttfFont1 = System::DynamicCast_noexcept<Aspose::Font::Ttf::TtfFont>(Aspose::Font::Font::Open(fd1));
 8    
 9System::String fileName2 = dataDir + u"Lora-Bold.ttf";
10//Font file name with full path
11System::SharedPtr<FontDefinition> fd2 = System::MakeObject<FontDefinition>(Aspose::Font::FontType::TTF, System::MakeObject<FontFileDefinition>(u"ttf", System::MakeObject<FileSystemStreamSource>(fileName2)));
12System::SharedPtr<TtfFont> ttfFont2 = System::DynamicCast_noexcept<Aspose::Font::Ttf::TtfFont>(Aspose::Font::Font::Open(fd2));
13    
14DrawText(u"Hello world", ttfFont1, 14, System::Drawing::Brushes::get_White(), System::Drawing::Brushes::get_Black(), dataDir + u"hello1_montserrat_out.jpg");
15DrawText(u"Hello world", ttfFont2, 14, System::Drawing::Brushes::get_Yellow(), System::Drawing::Brushes::get_Red(), dataDir + u"hello2_lora_out.jpg");

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