AG_HSVPAL(3)

NAME
AG_HSVPal - agar HSV color picker

SYNOPSIS

    #include <agar/core.h>
    #include <agar/gui.h>

DESCRIPTION
The AG_HSVPal widget is a HSV (Hue, Saturation, Value) color editor which allows the user to edit a color's hue, saturation, value and alpha components. The widget can bind directly to different color representations:

•   A native Agar AG_Color(3).
•   Single-precision Hue, Saturation, Value and Alpha.
•   8- or 16-bit integer RGBA components.
•   Floating-point RGBA components.
•   A 32- or 64-bit packed pixel (with corresponding AG_PixelFormat(3)).

INHERITANCE HIERARCHY
AG_Object(3) -> AG_Widget(3) -> AG_HSVPal.

INITIALIZATION
AG_HSVPal * AG_HSVPalNew(AG_Widget *parent, Uint flags)

The AG_HSVPalNew() function allocates, initializes, and attaches a new AG_HSVPal widget. Acceptable flags include:

AG_HSVPAL_SHOW_RGB
    Show the RGB value in text form.

AG_HSVPAL_SHOW_HSV
    Show the HSV value in text form.

AG_HSVPAL_NOALPHA
    (Read-only) Transparency control is disabled. Set (or cleared) when pixel-format is bound to a pixel format with (or without) alpha.

AG_HSVPAL_FORCE_NOALPHA
    Disable the transparency control.

AG_HSVPAL_NOPREVIEW
    Disable the color preview band.

AG_HSVPAL_HFILL
    Expand horizontally in parent container.

AG_HSVPAL_VFILL
    Expand vertically in parent container.

AG_HSVPAL_EXPAND
    Shorthand for AG_HSVPAL_HFILL | AG_HSVPAL_VFILL.

UPDATING VALUES
void AG_HSVPalUpdateHue(AG_HSVPal *pal, int x, int y)

void AG_HSVPalUpdateSV(AG_HSVPal *pal, int x, int y)

AG_HSVPalUpdateHue() sets the hue to that closest to cursor coordinates x, y and triggers a refresh. AG_HSVPalUpdateSV() sets the saturation and value to that at cursor coordinates x, y and triggers a refresh.

BINDINGS
The AG_HSVPal widget provides the following bindings:

AG_Color *agcolor
    A native AG_Color(3) structure.
float *hue
    Hue (0..1).
float *saturation
    Saturation (0..1).
float *value
    Value (0..1).
float *alpha
    Single-precision component value (0..1).
AG_PixelFormat **pixel-format
    Pointer to AG_PixelFormat(3) describing the packed-pixel format of pixel and pixel64. Note that pixel-format should be set first. If the format has an alpha component, AG_HSVPAL_NOALPHA will be set accordingly (use AG_HSVPAL_FORCE_NOALPHA to disable).
Uint32 *pixel
    32-bit packed pixel value.
Uint64 *pixel64
    64-bit packed pixel value. Available in AG_LARGE build.
void *RGBv
    A three-element array containing the RGB components. Acceptable binding types include FLOAT and DOUBLE, INT and UINT8. For floating point types, the values are scaled to 0.0-1.0. For integral types, the values are scaled to 0-255.
void *RGBAv
    Same as above, except that the array has 4 elements where the last element is the alpha component.

EVENTS
The AG_HSVPal widget generates the following events:

h-changed(void)
    The hue has changed.
sv-changed(void)
    The saturation or the value has changed.

BUGS
Conversion between integer RGB and HSV triplets incurs loss of precision. In cases where it is desirable to maintain the same hue throughout changes in saturation, the color should be stored in HSV format.

SEE ALSO
AG_Intro(3), AG_Widget(3), AG_Window(3)

EasyRGB: https://www.easyrgb.com/
HSV Color Space: https://en.wikipedia.org/wiki/HSV_color_space
RGB Color Model: https://en.wikipedia.org/wiki/RGB_color_model

HISTORY
The AG_HSVPal widget first appeared in Agar 1.0. The pixel64 binding, AG_HSVPalUpdateHue() and AG_HSVPalUpdateSV() appeared in Agar 1.6.0.