Motif 如何计算或检索字体像素大小？

Question

I am trying to write code in Motif to change a dialog warning box to resize size it if the box is not wide enough. The width and height is always being set by the calling classes and its not always wide enough for the message being displayed and the end of the line is truncated off. Instead of fixing everywhere to use auto sizing (ie width is 0 or not set at all) they want to figure out what the pixel width size is for a character in the dialog. They can then multiple the longest line X pixels width to get the lines length in pixels. Then we would see if the dialog declared width needs to be reset to stop the truncation. Only dialogs that are too short will be changed (dialogs too wide are not to be changed).

However; I can't find any example on how get the character width in pixels anywhere. I remember years ago I was on a project where they created some type of widget, inserted a character into it, and then did a XtGetValues to get the width and height so I think it can be done. So does anyone know how to do this?

Answer 1

That was a long time ago, but if memory serves, Xt doesn't have any specific support for fonts, it relies on plain libx11. You will need to call XQueryFont or XLoadQueryFont to get the XFontStruct describing your font, then grovel through the per_char array to find the extents of individual glyphs.