tvplanit: Print GanttView in multiple pages.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8513 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/tvplanit/source/vpganttview.pas

@@ -918,10 +918,13 @@ end;
   the number of day columns in the view. }
 function TVpGanttView.GetNumDays: Integer;
 begin
-  if (FRealStartDate <> NO_DATE) then
-    Result := trunc(FRealEndDate) - trunc(FRealStartDate) + 1
-  else
   Result := 0;
+  if (FRealStartDate <> NO_DATE) then
+  begin
+    Result := trunc(FRealEndDate) - trunc(FRealStartDate) + 1;
+    if Result < 0 then
+      Result := 0;
+  end;
 end;
 
 { Determines the number of events (= rows) to be displayed in the GanttView. }

components/tvplanit/source/vpprtfmt.pas

@@ -286,6 +286,7 @@ type
 
       FDayInc: Integer;
       FDayIncUnits: TVpDayUnits;
+      FDefaultDayInc: Integer;
       FVisible: Boolean;
 
     protected
@@ -302,6 +303,8 @@ type
       destructor Destroy; override;
 
       property Collection: TVpPrintFormat read FCollection write FCollection;
+      // Replacement value used for calculating start date on next page when DayInc is 0
+      property DefaultDayInc: Integer read FDefaultDayInc write FDefaultDayInc;
 
     published
       property DayInc: Integer read FDayInc write SetDayInc;
@@ -316,7 +319,6 @@ type
   TVpPrintFormat = class(TCollection)
     private
       FOwner: TPersistent;
-
     protected
       function GetItem(Index: Integer): TVpPrintFormatItem;
       function GetOwner: TPersistent; override;
@@ -326,10 +328,8 @@ type
       {$ENDIF}
       procedure SetItem(Index: Integer; Value: TVpPrintFormatItem);
       procedure Update(Item: TCollectionItem); override;
-
     public
       constructor Create(AOwner: TPersistent);
-
       property Items[Index: Integer]: TVpPrintFormatItem read GetItem write SetItem;
   end;
 
@@ -1056,6 +1056,7 @@ begin
   FDescription := '';
   FDayInc := 0;
   FDayIncUnits := duDay;
+  FDefaultDayInc := 1;
   FVisible := True;
 end;
 {=====}
@@ -1555,6 +1556,7 @@ var
   Scale: Extended;
   StartLine: Integer;
   EndLine: Integer;
+  oldGanttStartDate, oldGanttEndDate: TDateTime;
 
   procedure GetMeasurements;
   begin
@@ -1698,18 +1700,21 @@ var
 
         itGanttView:
           begin
+            oldGanttStartDate := TVpGanttView(RenderControl).StartDate;
+            TVpGanttView(RenderControl).StartDate := GetDate(Element);
             RenderControl.RenderToCanvas(
               ACanvas,
               Rect(StartX, StartY, StopX, StopY),
               Element.Rotation,
               Scale,
-              GetDate(Element),
+              TVpGanttView(RenderControl).StartDate,
               0,        // to be completed...
               0,
               Granularity,
               true
             );
-            Element.DayOffset := TvpGanttView(RenderControl).VisibleCols;
+            FPrintFormats.Items[CurFormat].DefaultDayInc := TVpGanttview(Rendercontrol).VisibleCols;
+            TVpGanttView(RenderControl).StartDate := oldGanttStartDate;
           end;
 
         else
@@ -1854,6 +1859,8 @@ var
     end;
   end;
 
+  { Advances the date to the next page. The number of days per page is given by
+    the values of DayInc and DayIncUnits of the print format. }
   function GetNextDate(ADate: TDateTime): TDateTime;
   begin
     Result := ADate;
@@ -1865,7 +1872,7 @@ var
         duYear  : Result := IncYear(Result, PrintFormats.Items[CurFormat].DayInc);
       end;
     end else
-      Result := Result + 1;
+      Result := Result + PrintFormats.Items[CurFormat].DefaultDayInc;
   end;
 
 var
@@ -2039,7 +2046,7 @@ var
         duYear  : Result := IncYear(Result, PrintFormats.Items[CurFormat].DayInc);
       end;
     end else
-      Result := Result + 1;
+      Result := Result + PrintFormats.Items[CurFormat].DefaultDayInc;
   end;
 
 var