OpenCV  3.4.7-dev
Open Source Computer Vision
Public Member Functions | List of all members
cv::freetype::FreeType2 Class Referenceabstract

#include <opencv2/freetype.hpp>

Inheritance diagram for cv::freetype::FreeType2:
cv::Algorithm

Public Member Functions

virtual Size getTextSize (const String &text, int fontHeight, int thickness, int *baseLine)=0
 Calculates the width and height of a text string. More...
 
virtual void loadFontData (String fontFileName, int id)=0
 Load font data. More...
 
virtual void putText (InputOutputArray img, const String &text, Point org, int fontHeight, Scalar color, int thickness, int line_type, bool bottomLeftOrigin)=0
 Draws a text string. More...
 
virtual void setSplitNumber (int num)=0
 Set Split Number from Bezier-curve to line. More...
 
- Public Member Functions inherited from cv::Algorithm
 Algorithm ()
 
virtual ~Algorithm ()
 
virtual void clear ()
 Clears the algorithm state. More...
 
virtual bool empty () const
 Returns true if the Algorithm is empty (e.g. in the very beginning or after unsuccessful read. More...
 
virtual String getDefaultName () const
 
virtual void read (const FileNode &fn)
 Reads algorithm parameters from a file storage. More...
 
virtual void save (const String &filename) const
 
virtual void write (FileStorage &fs) const
 Stores algorithm parameters in a file storage. More...
 
void write (const Ptr< FileStorage > &fs, const String &name=String()) const
 simplified API for language bindings This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
 

Additional Inherited Members

- Static Public Member Functions inherited from cv::Algorithm
template<typename _Tp >
static Ptr< _Tp > load (const String &filename, const String &objname=String())
 Loads algorithm from the file. More...
 
template<typename _Tp >
static Ptr< _Tp > loadFromString (const String &strModel, const String &objname=String())
 Loads algorithm from a String. More...
 
template<typename _Tp >
static Ptr< _Tp > read (const FileNode &fn)
 Reads algorithm from the file node. More...
 
- Protected Member Functions inherited from cv::Algorithm
void writeFormat (FileStorage &fs) const
 

Member Function Documentation

§ getTextSize()

virtual Size cv::freetype::FreeType2::getTextSize ( const String text,
int  fontHeight,
int  thickness,
int *  baseLine 
)
pure virtual

Calculates the width and height of a text string.

The function getTextSize calculates and returns the approximate size of a box that contains the specified text. That is, the following code renders some text, the tight box surrounding it, and the baseline: :

String text = "Funny text inside the box";
int fontHeight = 60;
int thickness = -1;
int linestyle = 8;
Mat img(600, 800, CV_8UC3, Scalar::all(0));
int baseline=0;
ft2->loadFontData( "./mplus-1p-regular.ttf", 0 );
Size textSize = ft2->getTextSize(text,
fontHeight,
thickness,
&baseline);
if(thickness > 0){
baseline += thickness;
}
// center the text
Point textOrg((img.cols - textSize.width) / 2,
(img.rows + textSize.height) / 2);
// draw the box
rectangle(img, textOrg + Point(0, baseline),
textOrg + Point(textSize.width, -textSize.height),
Scalar(0,255,0),1,8);
// ... and the baseline first
line(img, textOrg + Point(0, thickness),
textOrg + Point(textSize.width, thickness),
Scalar(0, 0, 255),1,8);
// then put the text itself
ft2->putText(img, text, textOrg, fontHeight,
Scalar::all(255), thickness, linestyle, true );
Parameters
textInput text string.
fontHeightDrawing font size by pixel unit.
thicknessThickness of lines used to render the text. See putText for details.
[out]baseLiney-coordinate of the baseline relative to the bottom-most text point.
Returns
The size of a box that contains the specified text.
See also
cv::putText

§ loadFontData()

virtual void cv::freetype::FreeType2::loadFontData ( String  fontFileName,
int  id 
)
pure virtual

Load font data.

The function loadFontData loads font data.

Parameters
fontFileNameFontFile Name
idface_index to select a font faces in a single file.

§ putText()

virtual void cv::freetype::FreeType2::putText ( InputOutputArray  img,
const String text,
Point  org,
int  fontHeight,
Scalar  color,
int  thickness,
int  line_type,
bool  bottomLeftOrigin 
)
pure virtual

Draws a text string.

The function putText renders the specified text string in the image. Symbols that cannot be rendered using the specified font are replaced by "Tofu" or non-drawn.

Parameters
imgImage.
textText string to be drawn.
orgBottom-left/Top-left corner of the text string in the image.
fontHeightDrawing font size by pixel unit.
colorText color.
thicknessThickness of the lines used to draw a text when negative, the glyph is filled. Otherwise, the glyph is drawn with this thickness.
line_typeLine type. See the line for details.
bottomLeftOriginWhen true, the image data origin is at the bottom-left corner. Otherwise, it is at the top-left corner.

§ setSplitNumber()

virtual void cv::freetype::FreeType2::setSplitNumber ( int  num)
pure virtual

Set Split Number from Bezier-curve to line.

The function setSplitNumber set the number of split points from bezier-curve to line. If you want to draw large glyph, large is better. If you want to draw small glyph, small is better.

Parameters
numnumber of split points from bezier-curve to line

The documentation for this class was generated from the following file: