Draw Line in Layout View with ArcObjects

Question

I'm trying to draw a line on layout view on ArcMap with C# and ArcObjects. I'm working on this sample. But I have some problems.

1.) This code for draw line on data view but I need to draw line on layout view(In box frame).I want to see properties of line element when I selected my line Item.

2.) When I click on this line in ArcMap, It become invisible..why is this happening?

This is Code Sample :

protected override void OnClick()
 {
 //drawing a polyline
 Point p1 = new PointClass();
 p1.X = 10; p1.Y = 10;
 IPoint p2 = new PointClass();
 p2.X = 20; p2.Y = 20;
 IPoint p3 = new PointClass();
 p3.X = 35; p3.Y = 15;
 IPoint p4 = new PointClass();
 p4.X = 40; p4.Y = 17;
 IPoint p5 = new PointClass();
 p5.X = 50; p5.Y = 19;
 IPoint p6 = new PointClass();
 p6.X = 60; p6.Y = 18;
 IPolyline polyline = new PolylineClass();
 IPointCollection pointColl = polyline as IPointCollection;
 pointColl.AddPoint(p1);
 pointColl.AddPoint(p2);
 pointColl.AddPoint(p3);
 pointColl.AddPoint(p4);
 pointColl.AddPoint(p5);
 pointColl.AddPoint(p6);
 IMxDocument mxdoc = ArcMap.Application.Document as IMxDocument;
 IActiveView activeView = mxdoc.ActiveView;
 IScreenDisplay screenDisp = activeView.ScreenDisplay;
 short screenCache = Convert.ToInt16(esriScreenCache.esriNoScreenCache);
 screenDisp.StartDrawing(screenDisp.hDC, screenCache);
 IRgbColor color = new RgbColorClass();
 color.Red = 0; color.Blue = 0; color.Green = 0;
 ISimpleLineSymbol simpleLineSymbol = new SimpleLineSymbolClass();
 simpleLineSymbol.Color = color;
 simpleLineSymbol.Width = 1;
 screenDisp.SetSymbol(simpleLineSymbol as ISymbol);
 screenDisp.DrawPolyline(polyline);
 screenDisp.FinishDrawing();
 }

Answer 1

The reason why this code is failing is that you are writing to the screen cache, which you are obtaining from the activeview and this could be the map or pagelayout; you need to be more explicit.

As soon as there is any sort of screen refresh you loose the graphic you have drawn. If you want graphics to persist you need to be storing them in the PageLayout graphics container. The following VBA code shows you how to do this using your example points.

Public Sub drawline()
 ' Create a polyline
 Dim p1 As IPoint
 Set p1 = New Point
 p1.X = 10
 p1.Y = 10
 Dim p2 As IPoint
 Set p2 = New Point
 p2.X = 20
 p2.Y = 20
 Dim p3 As IPoint
 Set p3 = New Point
 p3.X = 30
 p3.Y = 15
 Dim p4 As IPoint
 Set p4 = New Point
 p4.X = 40
 p4.Y = 15
 Dim p5 As IPoint
 Set p5 = New Point
 p5.X = 50
 p5.Y = 19
 Dim p6 As IPoint
 Set p6 = New Point
 p6.X = 60
 p6.Y = 18
 Dim pPolyline As IPolyline
 Set pPolyline = New Polyline
 Dim pPointColl As IPointCollection
 Set pPointColl = pPolyline
 pPointColl.AddPoint p1
 pPointColl.AddPoint p2
 pPointColl.AddPoint p3
 pPointColl.AddPoint p4
 pPointColl.AddPoint p5
 pPointColl.AddPoint p6
 ' Create a colour
 Dim pColour As IRgbColor
 Set pColour = New RgbColor
 With pColour
 .Red = 0
 .Blue = 0
 .Green = 0
 End With
 ' Create a line symbol
 Dim pSimpleLineSymbol As ISimpleLineSymbol
 Set pSimpleLineSymbol = New SimpleLineSymbol
 With pSimpleLineSymbol
 .Width = 1
 .Style = esriSLSSolid
 .Color = pColour
 End With
 ' Create a line element, this is the graphic that will get added to the container
 Dim pElement As IElement
 Set pElement = New LineElement
 pElement.Geometry = pPolyline
 Dim pLineElement As ILineElement
 Set pLineElement = pElement
 pLineElement.Symbol = pSimpleLineSymbol
 ' Get the MXD
 Dim pMXD As IMxDocument
 Set pMXD = ThisDocument
 ' Get a handle on the page layout
 Dim pPageLayout As IPageLayout
 Set pPageLayout = pMXD.PageLayout
 ' Get the graphics container of the PAGELAYOUT
 Dim pGraphicsContainer As IGraphicsContainer
 Set pGraphicsContainer = pPageLayout
 ' Add element and refresh
 pGraphicsContainer.AddElement pElement, 0
 Dim pActiveView As IActiveView
 Set pActiveView = pPageLayout
 pActiveView.Refresh
End Sub

Note: the coordinates are interpreted as page coordinates, not geographic so the line that gets created is much larger than your page.

Answer 2

this is c# code for your solution :

protected override void OnClick() {
 //Create a polyline 
 Point p1 = new PointClass();
 p1.X = 10; p1.Y = 10;
 IPoint p2 = new PointClass();
 p2.X = 20; p2.Y = 20;
 IPoint p3 = new PointClass();
 p3.X = 35; p3.Y = 15;
 IPoint p4 = new PointClass();
 p4.X = 40; p4.Y = 17;
 IPoint p5 = new PointClass();
 p5.X = 50; p5.Y = 19;
 IPoint p6 = new PointClass();
 p6.X = 60; p6.Y = 18;
 IPolyline polyline = new PolylineClass();
 IPointCollection pointColl = polyline as IPointCollection;
 pointColl.AddPoint(p1);
 pointColl.AddPoint(p2);
 pointColl.AddPoint(p3);
 pointColl.AddPoint(p4);
 pointColl.AddPoint(p5);
 pointColl.AddPoint(p6);
 // Create a colour 
 IRgbColor color = new RgbColorClass();
 color.Red = 0; color.Blue = 0; color.Green = 0;
 // Create a line symbol
 ISimpleLineSymbol simpleLineSymbol = new SimpleLineSymbolClass();
 simpleLineSymbol.Color = color;
 simpleLineSymbol.Width = 1;
 // Create a line element, this is the graphic that will get added to container
 IElement element = new LineElement();
 element.Geometry = polyline;
 ILineElement lineElement;
 lineElement = element as ILineElement;
 lineElement.Symbol = simpleLineSymbol;
 // Get the Mxd
 IMxDocument mxdoc = ArcMap.Application.Document as IMxDocument;
 // Get the handle on the page layout
 IPageLayout pageLayout = new PageLayout();
 pageLayout = mxdoc.PageLayout;
 // Get the graphics container of the PageLayout
 IGraphicsContainer graphicsContainer = pageLayout as IGraphicsContainer;
 // Add element an refresh
 graphicsContainer.AddElement(element, 0);
 IActiveView activeView = pageLayout as IActiveView;
 activeView.Refresh();
 }