Hi there,

for some CustomDrawing operations I need to know the exact visible Start and End DateTime of an item being drawn in the resourceview. In case the item is drawn completely these DateTimes should exactly match the Start and End time of the item given in args.Item. But I can't achieve this...

My test was as follows: I created an Item starting at 09:12:05. In the ItemDrawing event I called GetExactDateAt(args.Bounds.X, 10) assuming this should be the same as the start time (as long as the item is completely visible on the chart). But the result was 09:07:05. Then I thought, maybe it's an issue regarding the coordinate system of GDI+ but it isn't.

var s1 = _ganttChart.GetExactDateAt(args.Bounds.X - 1, 10);
var s2 = _ganttChart.GetExactDateAt(args.Bounds.X + 1, 10);
 

s1 is 09:04:51 for the item
s2 is 09:10:45 for the item

I thought at least one of the calls to GetExactDateAt() should return a value equal or greater than 09:12:05 (the items start time).

Is this a bug or am I using the wrong method? For precise painting on the time line I need a way to precisely map between the drawn coordinates and the time values. Thanks in advance for any help on this topic.

Best regards
Achim

Meppy,

theoretically GetExactDateAt(), when accepting pixel coordinates, at least should return a TimeSpan because one pixel represents a range of time. Otherwise it should be well defined, which point in this TimeSpan the method returns, for example the starting point or the end point. Then, if I call the method with args.Bounds.X, it should return a value that lies within the range of one pixel. So I would be able to match the result of the method and evaluate if the a given DateTime lies within this range (or let it call the "scale" one pixel shows; can be expressed in Pixel/TimeUnit, e.g. px/hour).

BTW I have the following settings:

var tlBottom = calendarControl.ResourceViewSettings.BottomTimelineSettings;
var tlMiddle = calendarControl.ResourceViewSettings.MiddleTimelineSettings;
var tlTop = calendarControl.ResourceViewSettings.TopTimelineSettings;

tlBottom.Format = "HH";
tlBottom.Unit = TimeUnit.Hour;
tlBottom.UnitCount = 1;

tlMiddle.Format = "dd.MM.";
tlMiddle.Unit = TimeUnit.Day;
tlMiddle.UnitCount = 1;

tlTop.Format = "MMMM yy";
tlTop.Unit = TimeUnit.Month;
tlTop.UnitCount = 1;

calendarControl.ResourceViewSettings.ScrollStep = new TimeSpan(0,30,0);
calendarControl.ResourceViewSettings.SnapUnit = TimeUnit.Minute;
calendarControl.ResourceViewSettings.SnapUnitCount = 10;
 

Thanks for your help
Achim

Hi Meppy,

thank you for your help. I understand your advice - it's exactly the behavior I'm expecting

I'll try the new build and report here.

Best regards
Achim