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.

static void	Fl::keyboard_screen_scaling (int value)
	Controls the possibility to scale all windows by ctrl/+/-/0/ or cmd/+/-/0/.

static int	Fl::screen_count ()
	Gets the total count 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.

static int	Fl::screen_num (int x, int y)
	Gets the screen number of a screen that contains the specified screen position `x`, `y`.

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`.

static float	Fl::screen_scale (int n)
	Current value of the GUI scaling factor for screen number `n` (n ∈ [0 , Fl::screen_count()-1])

static void	Fl::screen_scale (int n, float factor)
	Sets the value of the GUI scaling factor for screen number `n` (n ∈ [0 , Fl::screen_count()-1]).

static int	Fl::screen_scaling_supported ()
	See if scaling factors are supported by this platform.

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.

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`.

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.

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.

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`.

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`.

static void	Fl::screen_xywh (int &X, int &Y, int &W, int &H, int n)
	Gets the screen bounding rect for the given screen.

static int	Fl::w ()
	Returns the width in pixels of the main screen work area.

static int	Fl::x ()
	Returns the leftmost x coordinate of the main screen work area.

static int	Fl::y ()
	Returns the topmost y coordinate of the main screen work area.

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 multiply to the OS-given value. The 2 variants of functions Fl::screen_scale() allow to programmatically get and set scaling factor values. 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 displays the new scaling factor value in a yellow, transient window. This can be changed with option Fl::OPTION_SHOW_SCALING.

Function Documentation

◆ 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_count()

int Fl::screen_count ( )

static

Gets the total count of available screens.

Note: Screen numbers range from 0 to Fl::screen_count()-1 in the FLTK API.

◆ 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

Returns: a screen number ∈ [0 , Fl::screen_count()-1]

Attention: When the running system contains screens with different scaling factor values, this API may become ambiguous because a given value pair (x, y) may belong to distinct screens. In that situation, other APIs should be preferred, e.g., Fl_Window::screen_num() and Fl::screen_scale(int).

◆ 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

Returns: a screen number ∈ [0 , Fl::screen_count()-1]

◆ screen_scale()

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

static

Sets the value of the GUI scaling factor for screen number n (n ∈ [0 , Fl::screen_count()-1]).

Also sets the scale factor value of all windows mapped to screen number n, if any.

◆ 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
	)

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_work_area() [2/3]

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() [3/3]

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)

Note: Like all quantities accessible via public APIs of FLTK, values of X,Y,W,H are given in FLTK units, that is, in drawing units divided by the scaling factor of screen n.

◆ 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	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)

◆ screen_xywh() [4/4]

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 X11 + 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)

Note: Like all quantities accessible via public APIs of FLTK, values of X,Y,W,H are given in FLTK units, that is, in drawing units divided by the scaling factor of screen n.

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

Functions

Detailed Description

Function Documentation

◆ keyboard_screen_scaling()

◆ screen_count()

◆ screen_dpi()

◆ screen_num() [1/2]

◆ screen_num() [2/2]

◆ screen_scale()

◆ screen_scaling_supported()

◆ screen_work_area() [1/3]

◆ screen_work_area() [2/3]

◆ screen_work_area() [3/3]

◆ screen_xywh() [1/4]

◆ screen_xywh() [2/4]

◆ screen_xywh() [3/4]

◆ screen_xywh() [4/4]