TextRenderer Class Reference

TextRenderer enables quick and easy string rendering in OpenGL applications. More...

#include <easy3d/renderer/text_renderer.h>

Public Types
enum	Align { ALIGN_LEFT , ALIGN_RIGHT , ALIGN_CENTER }
	Horizontal alignment. More...

Public Member Functions
	TextRenderer (float dpi_scale=1.0f, int texture_size=512, bool mipmaps=false)
	Constructor.
	~TextRenderer ()
bool	add_font (const std::string &font_file)
	Add a font from a file. This function must be called at least once to add a font.
std::size_t	num_fonts () const
	The number of available fonts.
const std::vector< std::string > &	font_names () const
	The names of available fonts.
float	draw (const std::string &text, float x, float y, float font_size, int font_id=0, const vec3 &font_color=vec3(0, 0, 0), bool upper_left=true) const
	Draw the text.
Rect	draw (const std::string &text, float x, float y, float font_size, Align align, int font_id=0, const vec3 &font_color=vec3(0, 0, 0), float line_spacing=0.0f, bool upper_left=true) const
	Draw multi-line text with alignment support. This method produces line breaks for text with "\n".
void	set_character_spacing (float spacing)
	Set the spacing between consecutive characters. The default character spacing is 0.
float	character_spacing () const
	Query the spacing between consecutive characters.
void	set_kerning (bool kerning)
	Set kerning.
bool	kerning () const
	Query the kerning behavior. Kerning is disabled by default.
float	font_height (float font_size) const
	Query the height of the font.
float	string_width (const std::string &str, float font_size) const
	Query the width of a string (treated as if with no space between characters).
float	string_height (const std::string &str, float font_size) const
	Query the height of a string.
Rect	string_bounding_rect (const std::string &str, float x, float y, float font_size) const
	Query the bounding rectangle of a string (treated as if with no space between characters).

Detailed Description

TextRenderer enables quick and easy string rendering in OpenGL applications.

It supports truetype (TTF) fonts and Unicode strings. All glyphs are cached in OpenGL textures and font rasterization is done using 'stb_truetype.h.' TextRenderer allows you to:

• switch between fonts;
• change character spacing;
• enable/disable kerning;

  Todo

  For a large number of strings/characters, it is necessary to separate buffer creation and rendering.

  Performance evaluation.

Examples

Tutorial_309_TextRendering/main.cpp.

Member Enumeration Documentation

Align

enum Align

Horizontal alignment.

Enumerator
ALIGN_LEFT	Align text to the left.
ALIGN_RIGHT	Align text to the right.
ALIGN_CENTER	Align text to the center.

Constructor & Destructor Documentation

TextRenderer()

TextRenderer ( float dpi_scale = 1.0f, int texture_size = 512, bool mipmaps = false )

explicit

Constructor.

Parameters

dpi_scale	The DPI scale factor.
texture_size	The size of the font textures. Suggested values are 512, 1024, 2048 ...
mipmaps	True to create mipmaps for the font textures.

~TextRenderer()

~TextRenderer

(

)

Destructor.

Member Function Documentation

add_font()

bool add_font

(

const std::string &

font_file

)

Add a font from a file. This function must be called at least once to add a font.

Parameters

font_file

The font file (.ttf, etc.).

Returns

True if the font was successfully added, false otherwise.

character_spacing()

float character_spacing

(

)

const

Query the spacing between consecutive characters.

Returns

The spacing between consecutive characters.

draw() [1/2]

Rect draw	(	const std::string &	text,
		float	x,
		float	y,
		float	font_size,
		Align	align,
		int	font_id = 0,
		const vec3 &	font_color = vec3(0, 0, 0),
		float	line_spacing = 0.0f,
		bool	upper_left = true ) const

Draw multi-line text with alignment support. This method produces line breaks for text with "\n".

Parameters

text	The string to be drawn.
x	The x-coordinate of the starting position, relative to the left edge of the content area.
y	The y-coordinate of the starting position. If upper_left is true, this position is relative to the top edge of the content area. Otherwise, it is relative to the bottom edge of the content area.
font_size	The font size.
align	Specifies how the lines are aligned.
font_id	The id of the font used to draw the text, which is generated by calling to add_font(). 0 is the first font, 1 is the second, etc.
font_color	The font color.
line_spacing	The line spacing, which is a ratio relative to line height. A zero value means no extra space between lines.
upper_left	True to define the origin in the upper left corner of the content area. Otherwise, it is defined in the bottom left corner of the content area.

Returns

The region occupied by the text.

draw() [2/2]

float draw	(	const std::string &	text,
		float	x,
		float	y,
		float	font_size,
		int	font_id = 0,
		const vec3 &	font_color = vec3(0, 0, 0),
		bool	upper_left = true ) const

Draw the text.

Parameters

text	The string to be drawn.
x	The x-coordinate of the starting position, relative to the left edge of the content area.
y	The y-coordinate of the starting position. If upper_left is true, this position is relative to the top edge of the content area. Otherwise, it is relative to the bottom edge of the content area.
font_size	The font size.
font_id	The id of the font used to draw the text, which is generated by calling to add_font(). 0 is the first font, 1 is the second, etc.
font_color	The font color.
upper_left	True to define the origin in the upper left corner of the content area. Otherwise, it is defined in the bottom left corner of the content area.

Returns

The end position of the x-coordinate. This allows you to draw another string after the previous one.

Note

This function will draw the text in one line and thus line breaks (i.e., "\n") will be ignored.

font_height()

float font_height

(

float

font_size

)

const

Query the height of the font.

Parameters

font_size

The font size.

Returns

The height of the font in pixels.

font_names()

const std::vector< std::string > & font_names ( ) const

inline

The names of available fonts.

Returns

A const reference to the vector of font names.

kerning()

bool kerning

(

)

const

Query the kerning behavior. Kerning is disabled by default.

Returns

The kerning behavior.

num_fonts()

std::size_t num_fonts ( ) const

inline

The number of available fonts.

Returns

The number of available fonts.

set_character_spacing()

void set_character_spacing

(

float

spacing

)

Set the spacing between consecutive characters. The default character spacing is 0.

Parameters

spacing

The expected character spacing.

set_kerning()

void set_kerning

(

bool

kerning

)

Set kerning.

Parameters

kerning

The expected kerning behavior.

string_bounding_rect()

Rect string_bounding_rect	(	const std::string &	str,
		float	x,
		float	y,
		float	font_size ) const

Query the bounding rectangle of a string (treated as if with no space between characters).

Parameters

str	The string to measure.
x	The x-coordinate of the starting position, relative to the left edge of the content area.
y	The y-coordinate of the starting position, relative to the top edge of the content area.
font_size	The font size.

Returns

The bounding rectangle of the string (in pixels).

string_height()

float string_height	(	const std::string &	str,
		float	font_size ) const

Query the height of a string.

Parameters

str	The string to measure.
font_size	The font size.

Returns

The height of the string in pixels.

string_width()

float string_width	(	const std::string &	str,
		float	font_size ) const

Query the width of a string (treated as if with no space between characters).

Useful to position a string. For example, with the string width, its X-center can be computed as: viewer_width * 0.5 - string_width * 0.5.

Parameters

str	The string to measure.
font_size	The font size.

Returns

The width of the string in pixels.

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

• G:/3_code/Easy3D/easy3d/renderer/text_renderer.h
• G:/3_code/Easy3D/easy3d/renderer/text_renderer.cpp