This article demonstrates how to convert between screen size (in pixels) and TimeSpan value representing the PixelLength of RadGanttView.
The PixelLength property works with TimeSpan values, like 1 hour, 30 minutes and so on. In some cases it is more useful to be able to set the PixelLength based on screen size in order to be able to fill a specific area in the application. In those cases you can manually test and see what TimeSpan is appropriate by hardcoding values or you can use the approach that is discussed in this article to set it to exact pixel number.
The PixelLength property of the RadGanttView control is responsible for setting the horizontal size of the TimeRuler. In order to set it to a value that matches actual screen size you can use the following formula.
PixelLength = (Ticks of the VisibleRange) / (desired pixels)
double pixelsWidth = 760;
var maxTicks = this.GanttView.VisibleRange.End.Subtract(this.GanttView.VisibleRange.Start).Ticks / pixelsWidth;
this.GanttView.PixelLength = TimeSpan.FromTicks(maxTicks);
The inverse conversion of PixelLength to pixels could be implemented with the following formula:
Pixels = (Ticks of the VisibleRange) / (desired PixelLength.Ticks)
var maxTicks = this.GanttView.PixelLength.Ticks;
var pixels = this.GanttView.VisibleRange.End.Subtract(this.GanttView.VisibleRange.Start).Ticks / maxTicks;
Find a runnable project showing the previous methods in the WPF Samples GitHub repository.