Pmw.Color

Name

Pmw.Color - contains functions for handling colors and color schemes

Description

This module is a set of functions for manipulating colors and for modifying the color scheme of an application or a widget. Many of the functions in this module take or return colors. These values may represent colors in the following ways:

name

a standard color name, eg 'orange' or '#ffa500'

rgb

a 3-element sequence of red, green and blue intensities each between 0.0 (dark) and 1.0 (light), eg [1.0, 0.6, 0.0].

hsi

a 3-element sequence (hue, saturation, intensity). The value of hue is between 0.0 and 2pi (6.28318) giving a range of colors covering, in order, red, orange, yellow green, cyan, blue, magenta and back to red. The value of saturation is between 0.0 (grey) and 1.0 (brilliant) and the value of intensity is between 0.0 (dark) and 1.0 (bright).

As used in these functions, the brightness of a color is the perceived grey level of the color as registered by the human eye. For example, even though the colors red, blue and yellow have the same intensity (1.0), they have different brightnesses, 0.299, 0.114 and 0.886 respectively, reflecting the different way these colors appear to the eye. The brightness of a color is a value between 0.0 (dark) and 1.0 (bright).

A color scheme is a set of colors defined for each of the default color options in the Tk option database. Color schemes can be used in two ways. Firstly, using Pmw.Color.setscheme(), the Tk option database can be set to the values in the color scheme. This will not have any effect on currently existing widgets, but any new widgets created after setting the options will have these colors as their defaults. Secondly, using Pmw.Color.changecolor() the color scheme can be used to change the colors of a widget and all its child widgets.

A color scheme is specified by defining one or more color options (one of the defined options must be background). Not all options need be specified - if any options are not defined, they are calculated from the other colors. These are the options used by a color scheme, together with their values if not specified:

 background:            (must be specified)
 foreground:            black
 activeForeground:      same as foreground
 insertBackground:      same as foreground
 selectForeground:      same as foreground
 highlightColor:        same as foreground
 disabledForeground:    between fg and bg but closer to bg
 highlightBackground:   same as background
 activeBackground:      a little lighter that bg
 selectBackground:      a little darker that bg
 troughColor:           a little darker that bg
 selectColor:           yellow

There are many functions in this module. As well as Pmw.Color.setscheme() and Pmw.Color.changecolor(), some of the most useful are Pmw.Color.spectrum(), Pmw.Color.changebrightness() and Pmw.Color.getdefaultpalette().

Functions

The following functions are available.

Pmw.Color.average(rgb1, rgb2, fraction)

Return an rgb color fraction of the way "between" the colors rgb1 and rgb2, where fraction must be between 0.0 and 1.0. If fraction is close to 0.0, then the color returned will be close to rgb1. If it is close to 1.0, then the color returned will be close to rgb2. If it is near 0.5, then the color returned will be half way between the two colors.

Pmw.Color.bhi2saturation(brightness, hue, intensity)

Return the saturation of the color represented by brightness, hue and intensity.

Pmw.Color.bordercolors(root, colorName)

Return a tuple (light, dark) of color names that can be used as the light and dark border shadows on a widget where the background is colorName. This is the same method that Tk uses for shadows when drawing reliefs on widget borders. The root argument is only used to query Tk for the rgb values of colorName.

Pmw.Color.changebrightness(root, colorName, brightness)

Find the hue of the color colorName and return a color of this hue with the required brightness. If brightness is None, return the name of color with the given hue and with saturation and intensity both 1.0. The root argument is only used to query Tk for the rgb values of colorName.

Pmw.Color.changecolor(widget, background = None, **kw)

Change the color of widget and all its child widgets according to the color scheme specified by the other arguments. This is done by modifying all of the color options of existing widgets that have the default value. The color options are the lower case versions of those described in the color scheme section. Any options which are different to the previous color scheme (or the defaults, if this is the first call) are not changed.

For example to change a widget to have a red color scheme with a white foreground:

 Pmw.Color.changecolor(widget,
     background = 'red3', foreground = 'white')

The colors of widgets created after this call will not be affected.

Note that widget must be a Tk widget or toplevel. To change the color of a Pmw megawidget, use it's hull component. For example:

 widget = megawidget.component('hull')
 Pmw.Color.changecolor(widget, background = 'red3')

Pmw.Color.correct(rgb, correction)

Return the "corrected" value of rgb. This can be used to correct for dull monitors. If correction is less than 1.0, the color is dulled. If correction is greater than 1.0, the color is brightened.

Pmw.Color.getdefaultpalette(root)

Return a dictionary of the default values of the color options described in the color scheme section.

To do this, a few widgets are created as children of root, their defaults are queried, and then the widgets are destroyed. (Tk supplies no other way to get widget default values.)

Note that root must be a Tk widget or toplevel. To use a Pmw megawidget as the root, use it's hull component. For example:

 root = megawidget.component('hull')
 Pmw.Color.getdefaultpalette(root)

Pmw.Color.hsi2rgb(hue, saturation, intensity)

Return the rgb representation of the color represented by hue, saturation and intensity.

Pmw.Color.hue2name(hue, brightness = None)

Return the name of the color with the specified hue and brightness. If hue is None, return a grey of the requested brightness. Otherwise, the value of hue should be as described above. If brightness is None, return the name of color with the given hue and with saturation and intensity both 1.0.

Pmw.Color.name2rgb(root, colorName, asInt = 0)

Return colorName as an rgb value. If asInt is true, then the elements of the return sequence are in the range 0 to 65535 rather than 0.0 to 1.0. The root argument is only used to query Tk for the rgb values of colorName.

Pmw.Color.rgb2brightness(rgb)

Return the brightness of the color represented by rgb.

Pmw.Color.rgb2hsi(rgb)

Return a tuple (hue, saturation, intensity) corresponding to the color specified by the rgb sequence.

Pmw.Color.rgb2name(rgb)

Return the name of the color represented by rgb as a string of the form '#RRGGBB' suitable for use with Tk color functions.

Pmw.Color.setscheme(root, background = None, **kw)

Set the color scheme for the application by setting default colors (in the Tk option database of the root window of root) according to the color scheme specified by the other arguments. This will affect the initial colours of all widgets created after the call to this function.

For example to initialise an application to have a red color scheme with a white foreground:

 Pmw.Color.setscheme(root,
     background = 'red3', foreground = 'white')

This function does not modify the colors of already existing widgets. Use Pmw.Color.changecolor() to do this.

Note that root must be a Tk widget or toplevel. To use the Tk option database of the root window of a Pmw megawidget, use the megawidget's hull component. For example:

 root = megawidget.component('hull')
 Pmw.Color.setscheme(root, background = 'red3')

Pmw.Color.spectrum(numColors, correction = 1.0, saturation = 1.0, intensity = 1.0, extraOrange = 1, returnHues = 0)

Return a list of numColors different colors making up a spectrum. If extraOrange is false, the colors are evenly spaced by hue from one end of the spectrum (red) to the other (magenta). If extraOrange is true, the hues are not quite evenly spaced - the hues around orange are emphasised, thus preventing the spectrum from appearing to have to many cool hues.

If returnHues is false, the return values are the names of the colors represented by the hues together with saturation and intensity and corrected by correction.

If returnHues is true, the return values are hues.