Color Chooser (XForms (Forms Library) - Version 1.2 (Rev. 4) A Graphical User Interface Toolkit for X)

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### 6.4 Color Chooser

It’s also not uncommon that an application lets the user use an arbitrary color (not necessarily already in the colormap). The color chooser shows a form that allows the user to select a new color either using a HSV color wheel and a slider for the intensity or by entering HSV or RGB values directly.

To show such a form call

    int fl_show_color_chooser(const int *rgb_in, int * rgb_out);

The first argument is a pointer to an array with the 3 RGB values to use for the color to be displayed when the color chooser is shown. If it is `NULL` white is used. The second argument is another pointer to an array for the 3 RGB values of the selected color to be returned on success. On success the function returns 1 (and sets the `rgb_out` array), but if the user clicked on the "Cancel" button 0 gets returns (and the `rgb_out` array is not modified.

Please keep in mind that there’s no 1-to-1 mapping between the HSV and RGB color space, there are a lot more HSV than RGB triples and some colors don’t even have a unique representation in HSV space like, for example, all shades of grey, including white and black.