A colour picker dialog for N_GUI, and a swatch to show a colour. More...

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <allegro5/allegro_primitives.h>
#include "nilorea/n_common.h"
#include "nilorea/n_log.h"
#include "nilorea/n_gui_color.h"

Include dependency graph for n_gui_color.c:

Data Structures
struct	N_GUI_COLOR_PICKER
	a colour picker: the ids of its widgets and the colour being edited More...

Macros
#define	N_GUI_COLOR_BTN_W 90.0f
	width of the Close button at scale 1
#define	N_GUI_COLOR_CHECK 6.0f
	side of one checkerboard square behind a swatch, in pixels.
#define	N_GUI_COLOR_LABEL 18.0f
	height of a label at scale 1
#define	N_GUI_COLOR_PAD 10.0f
	padding at scale 1
#define	N_GUI_COLOR_ROW 24.0f
	height of a slider or button row at scale 1
#define	N_GUI_COLOR_SWATCH 48.0f
	height of the large swatch at scale 1
#define	N_GUI_COLOR_W 300.0f
	window width at scale 1: wide enough that a slider moved by one step in 255 moves by at least a pixel

Functions
static float	_n_gui_color_clamp (float v)
	helper: clamp a channel to 0..1
static void	_n_gui_color_draw_swatch (N_GUI_WIDGET widget, float x, float y, ALLEGRO_FONT font, void *user_data)
	custom draw callback of the large swatch
static void	_n_gui_color_on_close_button (int widget_id, void *user_data)
	button callback: Close
static void	_n_gui_color_on_close_window (int window_id, void *user_data)
	title bar close: the same as the Close button, so the callback is forgotten either way
static void	_n_gui_color_on_slider (int widget_id, double value, void *user_data)
	slider callback: one channel moved
static void	_n_gui_color_set_label (N_GUI_COLOR_PICKER *picker, int channel)
	helper: write one channel's label, its name and its value out of 255
void	n_gui_color_picker_close (N_GUI_COLOR_PICKER *picker)
	Close the picker.
void	n_gui_color_picker_free (N_GUI_COLOR_PICKER **picker)
	Close the picker's window and free the handle.
int	n_gui_color_picker_get (const N_GUI_COLOR_PICKER *picker, float rgba[4])
	The colour the picker holds now.
int	n_gui_color_picker_is_open (const N_GUI_COLOR_PICKER *picker)
	Whether the picker is open.
N_GUI_COLOR_PICKER *	n_gui_color_picker_new (N_GUI_CTX ctx, const char title, float scale)
	Build a colour picker window in `ctx`, closed.
void	n_gui_color_picker_open (N_GUI_COLOR_PICKER picker, const char what, const float rgba[4], N_GUI_COLOR_FN on_change, void *user_data)
	Open the picker on a colour, centred on the display.
int	n_gui_color_picker_slider (const N_GUI_COLOR_PICKER *picker, int channel)
	The slider for one channel, for a caller or a test that drives it.
int	n_gui_color_picker_window (const N_GUI_COLOR_PICKER *picker)
	The picker's window id, for a caller that walks its windows or sets their flags.
void	n_gui_color_to_hex (const float rgba[4], char *out, size_t len)
	Write a colour as #RRGGBBAA, each channel clamped to 0..1 and rounded to the nearest of 255 steps.
void	n_gui_draw_color_swatch (float x, float y, float w, float h, const float rgba[4])
	Draw a colour as a swatch, over a checkerboard so its alpha shows, with a thin dark border.
ALLEGRO_MOUSE_CURSOR *	n_gui_eyedropper_cursor (float scale)
	Make a pipette mouse cursor, for a tool that picks a colour from an image.

Variables
static const char *const	_n_gui_color_channels [4] = {"Red", "Green", "Blue", "Alpha"}
	the four channels, in the order of the sliders

Detailed Description

A colour picker dialog for N_GUI, and a swatch to show a colour.

Author: Castagnier Mickael

Version: 1.0

Date: 24/09/2026

Definition in file n_gui_color.c.

Data Structure Documentation

◆ N_GUI_COLOR_PICKER

struct N_GUI_COLOR_PICKER

a colour picker: the ids of its widgets and the colour being edited

a colour picker dialog.

Opaque: make it with n_gui_color_picker_new(), release it with n_gui_color_picker_free().

Examples: ex_gui_color_picker.c.

Definition at line 61 of file n_gui_color.c.

Collaboration diagram for N_GUI_COLOR_PICKER:

Data Fields
int	btn_close	the Close button
N_GUI_CTX *	ctx	the context the widgets live in
int	lbl[4]	name and value over each slider
int	lbl_what	what the colour is for
N_GUI_COLOR_FN	on_change	whom to tell
float	rgba[4]	the colour being edited
int	sl[4]	one slider per channel, 0 to 255
int	swatch	the large swatch
int	syncing	non-zero while the sliders are set from code, so their callbacks are not taken for the user's
void *	user_data	handed back to on_change
int	window	the window