Screen functions

Fl global screen functions declared in <FL/Fl.H>. More...

Functions
static int	Fl::h ()
	Returns the height in pixels of the main screen work area. More...
static void	Fl::keyboard_screen_scaling (int value)
	Controls the possibility to scale all windows by ctrl/+/-/0/ or cmd/+/-/0/. More...
static int	Fl::screen_count ()
	Gets the number of available screens.
static void	Fl::screen_dpi (float &h, float &v, int n=0)
	Gets the screen resolution in dots-per-inch for the given screen. More...
static int	Fl::screen_num (int x, int y)
	Gets the screen number of a screen that contains the specified screen position x, y. More...
static int	Fl::screen_num (int x, int y, int w, int h)
	Gets the screen number for the screen which intersects the most with the rectangle defined by x, y, w, h. More...
static float	Fl::screen_scale (int n)
	Current value of the GUI scaling factor for screen number n.
static void	Fl::screen_scale (int n, float factor)
	Set the value of the GUI scaling factor for screen number n. More...
static int	Fl::screen_scaling_supported ()
	See if scaling factors are supported by this platform. More...
static void	Fl::screen_work_area (int &X, int &Y, int &W, int &H, int mx, int my)
	Gets the bounding box of the work area of a screen that contains the specified screen position mx, my. More...
static void	Fl::screen_work_area (int &X, int &Y, int &W, int &H, int n)
	Gets the bounding box of the work area of the given screen. More...
static void	Fl::screen_work_area (int &X, int &Y, int &W, int &H)
	Gets the bounding box of the work area of the screen that contains the mouse pointer. More...
static void	Fl::screen_xywh (int &X, int &Y, int &W, int &H)
	Gets the bounding box of a screen that contains the mouse pointer. More...
static void	Fl::screen_xywh (int &X, int &Y, int &W, int &H, int mx, int my)
	Gets the bounding box of a screen that contains the specified screen position mx, my. More...
static void	Fl::screen_xywh (int &X, int &Y, int &W, int &H, int n)
	Gets the screen bounding rect for the given screen. More...
static void	Fl::screen_xywh (int &X, int &Y, int &W, int &H, int mx, int my, int mw, int mh)
	Gets the screen bounding rect for the screen which intersects the most with the rectangle defined by mx, my, mw, mh. More...
static int	Fl::w ()
	Returns the width in pixels of the main screen work area. More...
static int	Fl::x ()
	Returns the leftmost x coordinate of the main screen work area. More...
static int	Fl::y ()
	Returns the topmost y coordinate of the main screen work area. More...

Detailed Description

Fl global screen functions declared in <FL/Fl.H>.

FLTK supports high-DPI screens using a screen scaling factor. The scaling factor is initialized by the library to a value based on information obtained from the OS. If this initial value is not satisfactory, the FLTK_SCALING_FACTOR environment variable can be set to a value FLTK will use as initial scaling factor. The scaling factor value can be further changed at runtime by typing ctrl-/+/-/0/ (cmd-/+/-/0/ under MacOS). FLTK sends the FL_ZOOM_EVENT when the factor value is changed, to which a callback can be associated with Fl::add_handler(). By default, FLTK also displays the new scaling factor value in a yellow, transient window. This can be changed with option Fl::OPTION_SHOW_SCALING. The scaling factor value is programmatically get and set with the Fl::screen_scale() functions.

Function Documentation

h()

int Fl::h ( )

static

Returns the height in pixels of the main screen work area.

keyboard_screen_scaling()

void Fl::keyboard_screen_scaling ( int  value )

static

Controls the possibility to scale all windows by ctrl/+/-/0/ or cmd/+/-/0/.

This function should be called before fl_open_display() runs. If it is not called, the default is to handle these keys for window scaling.

Note

This function can currently only be used to switch the internal handler off, i.e. value must be 0 (zero) - all other values result in undefined behavior and are reserved for future extension.

Parameters

value

0 to stop recognition of ctrl/+/-/0/ (or cmd/+/-/0/ under macOS) keys as window scaling.

screen_dpi()

void Fl::screen_dpi ( float &  h, float &  v, int  n = 0  )

static

Gets the screen resolution in dots-per-inch for the given screen.

Parameters

[out]	h,v	horizontal and vertical resolution
[in]	n	the screen number (0 to Fl::screen_count() - 1)

See also

void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)

screen_num() [1/2]

int Fl::screen_num ( int  x, int  y  )

static

Gets the screen number of a screen that contains the specified screen position x, y.

Parameters

[in]

x,y

the absolute screen position

screen_num() [2/2]

int Fl::screen_num ( int  x, int  y, int  w, int  h  )

static

Gets the screen number for the screen which intersects the most with the rectangle defined by x, y, w, h.

Parameters

[in]

x,y,w,h

the rectangle to search for intersection with

screen_scale()

void Fl::screen_scale ( int  n, float  factor  )

static

Set the value of the GUI scaling factor for screen number n.

When this function is called before the first window is show()'n it sets the application's initial scaling factor value. Otherwise, it sets the scale factor value of all windows mapped to screen number n

screen_scaling_supported()

int Fl::screen_scaling_supported ( )

static

See if scaling factors are supported by this platform.

Returns

0 if scaling factors are not supported by this platform, 1 if a single scaling factor value is shared by all screens, 2 if each screen can have its own scaling factor value.

See also

Fl::screen_scale(int)

screen_work_area() [1/3]

void Fl::screen_work_area ( int &  X, int &  Y, int &  W, int &  H, int  mx, int  my  )

static

Gets the bounding box of the work area of a screen that contains the specified screen position mx, my.

Parameters

[out]	X,Y,W,H	the work area bounding box
[in]	mx,my	the absolute screen position

screen_work_area() [2/3]

void Fl::screen_work_area ( int &  X, int &  Y, int &  W, int &  H, int  n  )

static

Gets the bounding box of the work area of the given screen.

Parameters

[out]	X,Y,W,H	the work area bounding box
[in]	n	the screen number (0 to Fl::screen_count() - 1)

See also

void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)

screen_work_area() [3/3]

void Fl::screen_work_area ( int &  X, int &  Y, int &  W, int &  H  )

static

Gets the bounding box of the work area of the screen that contains the mouse pointer.

Parameters

[out]

X,Y,W,H

the work area bounding box

See also

void screen_work_area(int &x, int &y, int &w, int &h, int mx, int my)

screen_xywh() [1/4]

void Fl::screen_xywh ( int &  X, int &  Y, int &  W, int &  H  )

static

Gets the bounding box of a screen that contains the mouse pointer.

Parameters

[out]

X,Y,W,H

the corresponding screen bounding box

See also

void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)

screen_xywh() [2/4]

void Fl::screen_xywh ( int &  X, int &  Y, int &  W, int &  H, int  mx, int  my  )

static

Gets the bounding box of a screen that contains the specified screen position mx, my.

Parameters

[out]	X,Y,W,H	the corresponding screen bounding box
[in]	mx,my	the absolute screen position

screen_xywh() [3/4]

void Fl::screen_xywh ( int &  X, int &  Y, int &  W, int &  H, int  n  )

static

Gets the screen bounding rect for the given screen.

Under Windows, Mac OS X, and the Gnome desktop, screen #0 contains the menubar/taskbar

Parameters

[out]	X,Y,W,H	the corresponding screen bounding box
[in]	n	the screen number (0 to Fl::screen_count() - 1)

See also

void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)

screen_xywh() [4/4]

void Fl::screen_xywh ( int &  X, int &  Y, int &  W, int &  H, int  mx, int  my, int  mw, int  mh  )

static

Gets the screen bounding rect for the screen which intersects the most with the rectangle defined by mx, my, mw, mh.

Parameters

[out]	X,Y,W,H	the corresponding screen bounding box
[in]	mx,my,mw,mh	the rectangle to search for intersection with

See also

void screen_xywh(int &X, int &Y, int &W, int &H, int n)

w()

int Fl::w ( )

static

Returns the width in pixels of the main screen work area.

x()

int Fl::x ( )

static

Returns the leftmost x coordinate of the main screen work area.

y()

int Fl::y ( )

static

Returns the topmost y coordinate of the main screen work area.