Mastering Perl/Tk

Screen Information

The following methods all return information based on the screen (which can be a virtual desktop or a normal desktop) and the colors of the desktop.

Screen Name

Each screen you use has a name associated with it. To get the name, use the screenmethod:

$name = $widget->screen;

The name returned will be formatted as " displayName.screenIndex ". For more details refer to Chapter 11.

Screen Height and Width

The screen height and width is really just the resolution of the screen. Sometimes you might need information to determine how large a window can fit on a user’s display. To get the height and width of the screen in pixels, use the screenheight and screenwidthmethods:

$height = $widget->screenheight;
$width = $widget->screenwidth;

If your display dimensions are 1024x768, then screenheight returns 768 and screenwidth returns 1024. If you prefer to get the size of the screen in millimeters, use screenmmheight and screenmmwidth:

$heightmm = $widget->screenmmheight;
$widthmm = $widget->screenmmwidth;

The same resolution, 1024x768, returns 203 millimeters as the height and 270 millimeters as the width.

Cell Count

The number of cells in the default colormap is retrieved by using screencells:

$count = $widget->screencells;

Screen Depth

To determine the number of bits per pixel your screen has, use the screendepthmethod:

$depth = $widget->screendepth;

Color Type

The type of color is defined by one of the following classes: "directcolor", "grayscale", "pseudocolor" ...