Tutorial :Is there a way to get graphic text to scale in ArcMap?



Question:

I'm using this code to create text in ArcMap. But I can't seem to get it to scale like annotation text when you zoom in.

Does anyone know how to do this?

//'First setup a color.  We'll use RGB red                      IRgbColor pRGBcolor = new RgbColor();                  pRGBcolor.Blue = 0;                  pRGBcolor.Red = 255;                  pRGBcolor.Green = 0;                    //'Next, cocreate a new TextElement                      ITextElement pTextElement = new TextElementClass();                    //'Query Interface (QI) to an IElement pointer and set                      //'the geometry that was passed in                      IElement pElement = pTextElement as IElement;                  pElement.Geometry = Point;                    //'Next, setup a font                  stdole.IFontDisp pFontDisp = new stdole.StdFont() as stdole.IFontDisp;                  pFontDisp.Name = "Arial";                  pFontDisp.Bold = true;                    //'Next, setup a TextSymbol that the TextElement will draw with                      ITextSymbol pTextSymbol = new ESRI.ArcGIS.Display.TextSymbolClass();                  pTextSymbol.Font = pFontDisp;                  pTextSymbol.Color = pRGBcolor;                  pTextSymbol.Size = Size;                  pTextSymbol.HorizontalAlignment = esriTextHorizontalAlignment.esriTHACenter;                  pTextSymbol.VerticalAlignment = esriTextVerticalAlignment.esriTVACenter;                  pTextSymbol.Angle = Angle;                  pTextSymbol.Text = Text;                    //'set the size of the text symbol here, rather than on the font                          //'Next, Give the TextSymbol and text string to the TextElement                      pTextElement.Symbol = pTextSymbol;                  pTextElement.Text = pTextSymbol.Text;                  pTextElement.ScaleText = true;                    ESRI.ArcGIS.Carto.IElementProperties3 aoElementPro = pTextElement as ESRI.ArcGIS.Carto.IElementProperties3;                  aoElementPro.ReferenceScale = cGISHelpers.MapDomain.Map.MapScale;  


Solution:1

We can very well add text which changes it size according to the scale. for this, we need to use the IElementProperties3.ReferenceScale Property.

I do not have C# code, but am attaching some sample VBA code that you can modify.

'--------------------------------  Sub ChangeTextElemRefScale()      Dim pDoc As IMxDocument      Dim pContainer As IGraphicsContainer      Dim pElement As IElement      Dim pTextElement As ITextElement      Dim pActiveView As IActiveView        Set pDoc = ThisDocument      Set pActiveView = pDoc.ActiveView      Set pContainer = pActiveView        'Loop through the graphics container      pContainer.Reset      Set pElement = pContainer.Next      While not pElement Is Nothing          'Get the specific text element          If TypeOf pElement Is ITextElement Then             Set pTextElement = pElement             If pTextElement.Text = "oregon" Then  'change this to your text element's text                  Dim pElemProp As IElementProperties3                  Set pElemProp = pTextElement                  pElemProp.ReferenceScale = 15000000              End If          End If          Set pElement = pContainer.Next      Wend        pDoc.ActiveView.PartialRefresh esriViewGraphics, Nothing, Nothing  End Sub  '--------------------------------  


Solution:2

To my knowledge, you can't get a TextSymbol to scale along with the map. That's because the TextElement isn't changeable based upon the map's extent but, instead, uses the font size to determine how large it's going to appear on the screen.

The best way that I can think of to do it while still using a TextSymbol is to change the point size (and, if the extent is large enough, hide/show the element) as the extent changes. I don't know of a "text control that pays attention to the extent," which is what you would really need.

Alternately, couldn't you just use an annotation layer or label the layer where you want the text size to change?


Solution:3

The ITextElement has got a property ITextElement.ScaleText. Set this to true and the text size will adapt automatically.


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