cv::freetype::FreeTypeFont Class Reference

#include <freetypeFont.h>

Inheritance diagram for cv::freetype::FreeTypeFont:

Public Member Functions
virtual bool	loadFontData (String fontFileName, int idx)=0
	Load font data.
virtual bool	loadFontData (const FT_Byte *fontData, FT_Long fontDataSize, int idx)=0
virtual void	setSplitNumber (int num)=0
	Set Split Number from Bezier-curve to line.
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.
virtual Size	getTextSize (const String &text, int fontHeight, int thickness, CV_OUT int *baseLine)=0
	Calculates the width and height of a text string.

Detailed Description

Definition at line 54 of file freetypeFont.h.

Member Function Documentation

getTextSize()

virtual Size cv::freetype::FreeTypeFont::getTextSize ( const String &  text, int  fontHeight, int  thickness, CV_OUT 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;
 
cv::Ptr<cv::freetype::FreeType2> ft2;
ft2 = cv::freetype::createFreeType2();
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

	text	Input text string.
	fontHeight	Drawing font size by pixel unit.
	thickness	Thickness of lines used to render the text. See putText for details.
[out]	baseLine	y-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() [1/2]

virtual bool cv::freetype::FreeTypeFont::loadFontData ( const FT_Byte *  fontData, FT_Long  fontDataSize, int  idx  )

pure virtual

loadFontData() [2/2]

virtual bool cv::freetype::FreeTypeFont::loadFontData ( String  fontFileName, int  idx  )

pure virtual

Load font data.

The function loadFontData loads font data.

Parameters

fontFileName	FontFile Name
id	face_index to select a font faces in a single file.

putText()

virtual void cv::freetype::FreeTypeFont::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

img	Image.
text	Text string to be drawn.
org	Bottom-left/Top-left corner of the text string in the image.
fontHeight	Drawing font size by pixel unit.
color	Text color.
thickness	Thickness of the lines used to draw a text when negative, the glyph is filled. Otherwise, the glyph is drawn with this thickness.
line_type	Line type. See the line for details.
bottomLeftOrigin	When true, the image data origin is at the bottom-left corner. Otherwise, it is at the top-left corner.

setSplitNumber()

virtual void cv::freetype::FreeTypeFont::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

num	number of split points from bezier-curve to line

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

• include/freetypeFont.h