TG Namespace Reference

The namespace within which all functionality is placed. More...

Classes
class	Font
	A class to hold the information about the font used for text rendering. More...
class	Image
	A simple class to hold a 2D image using datatype specified as ValueType template parameter. More...
class	magnify
	Adapter class to magnify an image. More...
class	Plot
	A class to provide plotting capabilities. More...
class	Rescale
	Adapter class to rescale intensities of image to colourmap indices. More...

Typedefs
using	ctype = unsigned char
	the data type to use to store intensities:
using	ColourMap = std::vector<std::array<ctype,3>>
	The data structure used to hold a colourmap.

Functions
ColourMap	gray (int number=101)
	convenience function to generate a ready-made grayscale colourmap
ColourMap	hot (int number=101)
	convenience function to generate a ready-made hot colourmap
ColourMap	jet (int number=101)
	convenience function to generate a ready-made jet colourmap
template<class ImageType>
void	imshow (const ImageType &image, const ColourMap &cmap, const bool zero_is_transparent=false)
	Display an indexed image to the terminal, according to the colourmap supplied.
template<class ImageType>
void	imshow (const ImageType &image, double min, double max, const bool zero_is_transparent=false, const ColourMap &cmap=gray())
	Display a scalar image to the terminal, rescaled between (min, max)
Plot	plot (int width=512, int height=256)
	Convenience function to use for immediate rendering.

Variables
constexpr std::string	Home = "\033[H"
	VT100 code to set the cursor position to the top left of the screen.
constexpr std::string	Clear = "\033[2J"
	VT100 code to clear the screen.
constexpr float	lim_expand_by_factor = 0.1f

Detailed Description

The namespace within which all functionality is placed.

Typedef Documentation

ctype

using TG::ctype = unsigned char

the data type to use to store intensities:

ColourMap

using TG::ColourMap = std::vector<std::array<ctype,3>>

The data structure used to hold a colourmap.

A ColourMap is a way to associate an index with a colour. It can be represented as a simple table with 3 columns per row, to represent the red, green & blue components of each colour, one colour per row. When in use, the colour to be used is retrieved by looking up the values in the row at the specified index.

Since this is a simple structure, we use existing C++ objects to store this information, as a (dynamically-sized) vector of (fixed-sized) arrays of 3 values. For convenience, we define the shorthand name 'ColourMap' for this specific type.

Note that the sixel protocol we rely on in this implementation expects colourmap intensity values between 0 & 100.

Defining a simple colourmap can be done by list initialisation, for example:

const ColourMap my_cmap = {
               { 0, 0, 100 },     // pure red
               { 0, 100, 0 },     // pure green
               { 100, 0, 0 }      // pure blue
           };

More complex colourmaps can be generated if required, see implementation of the gray() colourmap for inspiration.

Function Documentation

gray()

ColourMap TG::gray ( int number = 101 )

inline

convenience function to generate a ready-made grayscale colourmap

hot()

ColourMap TG::hot ( int number = 101 )

inline

convenience function to generate a ready-made hot colourmap

jet()

ColourMap TG::jet ( int number = 101 )

inline

convenience function to generate a ready-made jet colourmap

imshow() [1/2]

template<class ImageType>

void TG::imshow ( const ImageType & image, const ColourMap & cmap, const bool zero_is_transparent = false )

inline

Display an indexed image to the terminal, according to the colourmap supplied.

ImageType can be any object that implements the following methods:

• int width() const
• int height() const
• integer_type operator() (int x, int y) const

Indexed images contain integer values that correspond to entries in the associated ColourMap. Different image values can have completely different colours, depending on the ColourMap used.

The ColourMap must be specified via the cmap argument. See the documentation for ColourMap for details.

imshow() [2/2]

template<class ImageType>

void TG::imshow ( const ImageType & image, double min, double max, const bool zero_is_transparent = false, const ColourMap & cmap = gray() )

inline

Display a scalar image to the terminal, rescaled between (min, max)

ImageType can be any object that implements the following methods:

• int width() const
• int height() const
• scalar_type operator() (int x, int y) const (where scalar_type can be any integer or floating-point type)

Note that as for most image formats, the x index rasters from left to right, while the y index rasters from top to bottom.

min & max specify how image values map to displayed intensities. Values <= min will render as pure black, while values >= max will render as pure white (assuming the default gray colourmap).

A different colourmap can be specified via the cmap argument. See the documentation for ColourMap for details on how to generate different colourmaps if necessary.

plot()

Plot TG::plot ( int width = 512, int height = 256 )

inline

Convenience function to use for immediate rendering.

This returns a (temporary) Plot object, which methods can be called on, and daisy-chain to achieve the desired series of commands. The Plot::show() method will implicitly be called when the temporary object is destroyed, in other words immediately after the closing semicolon.

For example:

std::vector x (10), y(10);
...
TG::plot (256,128)
  .set_ylim (-1,2)
  .add_line (x, y, 3)
  .set_grid (2, 0.5)
  .add_text ("my plot", 5, 2);

See methods in TG::Plot for details.

Variable Documentation

Home

std::string TG::Home = "\033[H"

constexpr

VT100 code to set the cursor position to the top left of the screen.

This can be used in conjuction with TG::Clear to provide running updates. Simply feed the string to std::cout to issue the instruction, for example:

std::cout << TG::Clear;
while (true) {
  std::cout << TG::Home << "Current progress:\n";
  TG::plot().add_line(...);
 
  ...
  // perform computations, etc.
  ...
}

See also

TG::Clear

Clear

std::string TG::Clear = "\033[2J"

constexpr

VT100 code to clear the screen.

See also

TG::Home

lim_expand_by_factor

float TG::lim_expand_by_factor = 0.1f

constexpr