A colour wheel for N_GUI: one point in a disc, dragged. More...

#include "nilorea/n_gui.h"

Include dependency graph for n_gui_colorwheel.h:

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Typedefs
typedef void(*	N_GUI_COLORWHEEL_CHANGE) (int widget_id, int dragging, void *user_data)
	Called when the point moves.
typedef ALLEGRO_COLOR(*	N_GUI_COLORWHEEL_COLOUR) (float u, float v, void *user_data)
	The colour the disc shows for a point.

Functions
int	n_gui_colorwheel_get (N_GUI_CTX ctx, int widget_id, float u, float *v)
	Read the point.
ALLEGRO_COLOR	n_gui_colorwheel_hue (float u, float v, void *user_data)
	The default disc colour: HSV, hue by angle with red to the right and going counter clockwise, saturation by distance from the centre, value one.
int	n_gui_colorwheel_new (N_GUI_CTX ctx, int window_id, float x, float y, float w, float h, N_GUI_COLORWHEEL_CHANGE on_change, void user_data)
	Add a colour wheel, its point in the centre.
int	n_gui_colorwheel_set (N_GUI_CTX *ctx, int widget_id, float u, float v)
	Set the point.
void	n_gui_colorwheel_set_colour (N_GUI_CTX ctx, int widget_id, N_GUI_COLORWHEEL_COLOUR colour, void user_data)
	Paint the disc with the caller's colours.

Detailed Description

A colour wheel for N_GUI: one point in a disc, dragged.

A disc whose point, u across and v up, both -1 to 1 and never outside the unit circle, is set by pressing and dragging with the left button; a right press or a double click puts it back in the centre, the double click timed as the context times it (n_gui_set_double_click_time()). What the point means is the caller's: a hue and a strength, a shift on two colour axes, a direction. So is what the disc shows: n_gui_colorwheel_set_colour() paints each place of it with the caller's colour for that point, so the wheel shows what choosing it does. By default the disc is an HSV hue circle, saturated at the rim and grey in the centre.

The widget is a custom one (n_gui_add_custom() with n_gui_custom_set_mouse()), so it lives in any window and its state is freed with it. on_change is called on every change, with dragging set while the button is held.

Author: Castagnier Mickael

Version: 1.0

Date: 28/09/2026

Definition in file n_gui_colorwheel.h.

Typedefs

Functions

Detailed Description