GitHub FLTK Project   FLTK News RSS Feed  
  FLTK Apps      FLTK Library      Forums      Links     Login 
 Home  |  Articles & FAQs  |  Bugs & Features  |  Documentation  |  Download  ]

class Fl_Valuator

Class Hierarchy

Include Files

    #include <FL/Fl_Valuator.H>


The Fl_Valuator class controls a single floating-point value and provides a consistent interface to set the value, range, and step, and insures that callbacks are done the same for every object.

There are probably more of these classes in FLTK than any others:

Fl_Valuator widgets.

In the above diagram each box surrounds an actual subclass. These are further differentiated by setting the type() of the widget to the symbolic value labeling the widget. The ones labelled "0" are the default versions with a type(0). For consistency the symbol FL_VERTICAL is defined as zero.


Fl_Valuator::Fl_Valuator(int x, int y, int w, int h, const char *label = 0)

Creates a new Fl_Valuator widget using the given position, size, and label string. The default boxtype is FL_NO_BOX.

virtual Fl_Valuator::~Fl_Valuator()

Destroys the valuator.

void Fl_Valuator::bounds(double a, double b);

Sets the minimum (a) and maximum (b) values for the valuator widget.

int Fl_Valuator::changed() const

This value is true if the user has moved the slider. It is turned off by value(x) and just before doing a callback (the callback can turn it back on if desired).

double Fl_Valuator::clamp(double)

Clamps the passed value to the valuator range.

void Fl_Valuator::clear_changed()

Clears the changed() flag.

int Fl_Valuator::format(char *buffer)

Uses internal rules to format the fields numerical value into the character array pointed to by the passed parameter.

The actual format used depends on the current step value. If the step value has been set to zero then a %g format is used. If the step value is non-zero, then a %.*f format is used, where the precision is calculated to show sufficient digits for the current step value. An integer step value, such as 1 or 1.0, gives a precision of 0, so the formatted value will appear as an integer.

This method is used by the Fl_Value_... group of widgets to format the current value into a text string. The return value is the length of the formatted text. The formatted value is written into in buffer. buffer should have space for at least 128 bytes.

You may override this function to create your own text formatting.

double Fl_Valuator::increment(double,int n)

Adds n times the step value to the passed value. If step was set to zero it uses fabs(maximum() - minimum()) / 100.

double Fl_Valuator::maximum() const
void Fl_Valuator::maximum(double)

Gets or sets the maximum value for the valuator.

double Fl_Valuator::minimum() const
void Fl_Valuator::minimum(double)

Gets or sets the minimum value for the valuator.

void Fl_Valuator::precision(int digits);

Sets the step value to 1/10digits.

void Fl_Valuator::range(double min, double max);

Sets the minimum and maximum values for the valuator. When the user manipulates the widget, the value is limited to this range. This clamping is done after rounding to the step value (this makes a difference if the range is not a multiple of the step).

The minimum may be greater than the maximum. This has the effect of "reversing" the object so the larger values are in the opposite direction. This also switches which end of the filled sliders is filled.

Some widgets consider this a "soft" range. This means they will stop at the range, but if the user releases and grabs the control again and tries to move it further, it is allowed.

The range may affect the display. You must redraw() the widget after changing the range.

double Fl_Valuator::round(double)

Round the passed value to the nearest step increment. Does nothing if step is zero.

void Fl_Valuator::set_changed()

Sets the changed() flag.

double Fl_Valuator::step() const
void Fl_Valuator::step(double)
void Fl_Valuator::step(int A, int B)

Gets or sets the step value. As the user moves the mouse the value is rounded to the nearest multiple of the step value. This is done before clamping it to the range. For most widgets the default step is zero.

For precision the step is stored as the ratio of two integers, A/B. You can set these integers directly. Currently setting a floating point value sets the nearest A/1 or 1/B value possible.

double Fl_Valuator::value() const
int Fl_Valuator::value(double)

Gets or sets the current value. The new value is not clamped or otherwise changed before storing it. Use clamp() or round() to modify the value before calling value(). The widget is redrawn if the new value is different than the current one. The initial value is zero.

User Comments [ Add Comment ]

From Eivind Tagseth, 02:06 Nov 05, 2003 (score=4)

The increment method completely ignores the maximum and minimum values set.
Reply ]

From duncan.gibson, 08:59 Jan 28, 2006 (score=3)

The explanation text for format() is completely unclear. The name implies to me that you pass in a printf-type format string, but this gives a segmentation fault, because in fact it is expecting a pointer to a char array into which it can copy a formatted string.
Reply ]


Comments are owned by the poster. All other content is copyright 1998-2021 by Bill Spitzak and others. This project is hosted by The FLTK Team. Please report site problems to ''.