Volume 6A: Motif Programming Manual

Output of pixmaps flagup letters wingdogs xlogo64 calculator tie_fighter

To optimize the use of space by the RowColumn widget, the number of rows and columns is set to the square root of

the number of images. For example, if there are nine pixmaps to load, there should be a 3x3 grid of images. Since the

number of files to be loaded corresponds to the number of arguments in argv, argc is passed to int_sqrt() to

get the integer square root of its value. This value tells us the number of columns to specify for the XmNnumColumns

resource of the RowColumn.

The bitmap files are read using XmGetPixmap(), which is a function that creates a pixmap from the specified file.

This file must be in X11 bitmap format. Since the function needs foreground and background colors for the pixmap,

we use the colors of the RowColumn. If the specified file cannot be found or if it does not contain a bitmap, the

function returns the constant XmUNSPECIFIED_PIXMAP. XmUNSPECIFIED_PIXMAP is not 0 or NULL. Many

people have a tendency to test for these values upon return of functions that return opaque objects. The literal value is

2. If this error condition is returned, the program skips the file and goes on to the next one. For more detailed

information on XmGetPixmap() and other supporting functions, see Section #spixmaps in Chapter 3, Overview of

the Motif Toolkit.

12.1.4 Label Sensitivity

A Label can be made inactive ...