Image of police car -> dynamically draw police car number

Question

Let's say I have 10 police cars using the same image, and I want each one to be numbered 1 - 10, but the number 1 is dynamically drawn on top of the police car image. What is the class / interface I use for that with C# and ArcEngine 10.

Answer 1

I'd use a multilayer markersymbol with two symbol layers. The bottom symbol would be a picturemarkersymbol of a police car. On top of that would be one or more charactermarkersymbols, with the car number set via ICharactermarkersymbol.CharacterIndex.

As I've said before, you really need to get Arcview arcmap if you haven't already done so. It has interactive symbol editing that would allow you to create symbols interactively, save them to a file that your arcengine app could then load. Defining these symbols without arcview (or desktop) arcmap will be quite tedious.

Answer 2

Kirk was right. Here's the code if anyone wants it.

  IDynamicGlyph createMultiGlyph(String imagePathName, String text, int fontSize, System.Drawing.FontStyle fontstyle = System.Drawing.FontStyle.Bold, String fontType = "Arial")
    {
        IMultiLayerMarkerSymbol multiLayerMarkerSymbol = new MultiLayerMarkerSymbolClass();
        pictureMarkerSymbol = new PictureMarkerSymbolClass();
        pictureMarkerSymbol.CreateMarkerSymbolFromFile(esriIPictureType.esriIPictureBitmap, imagePathName);
        pictureMarkerSymbol.Size = 100;
        IColor whiteTransparencyColor = ESRI.ArcGIS.ADF.Connection.Local.Converter.ToRGBColor(Color.FromArgb(255, 255, 255)) as IColor;
        pictureMarkerSymbol.BitmapTransparencyColor = whiteTransparencyColor;
        multiLayerMarkerSymbol.AddLayer(pictureMarkerSymbol);

        List<int> asciiList = stringToAscii(text);

        int pixelsBetweenLetters = 2;
        int numLetters = text.Length;
        int widthOfAllSpaces = (numLetters -1) * pixelsBetweenLetters;
        int adjustmentMultiplier = 3; //TextRenderer.MeasureText is not perfect

        int width = 0; 
        for (int i = 0; i < text.Length; i++)
        {
            SizeF size = TextRenderer.MeasureText(text[i].ToString(), new Font(fontType, fontSize, fontstyle));
            width = ((width + Convert.ToInt32(size.Width)) / adjustmentMultiplier); 
        }
        int negativeXoffset = -1 * ((width + widthOfAllSpaces) / 2);
        int currentOffset = negativeXoffset; 

        for (int i = 0; i < asciiList.Count; i++)
        {
            ICharacterMarkerSymbol characterMarkerSymbol = new CharacterMarkerSymbolClass();
            Font arialFont = new Font(fontType, fontSize, fontstyle);
            characterMarkerSymbol.Font = ESRI.ArcGIS.ADF.Connection.Local.Converter.ToStdFont(arialFont);
            characterMarkerSymbol.Size = fontSize;
            characterMarkerSymbol.Color = SymbolCreator.getColor(255, 0, 0) as IColor;
            characterMarkerSymbol.XOffset = currentOffset;
            characterMarkerSymbol.CharacterIndex = asciiList[i];
            multiLayerMarkerSymbol.AddLayer(characterMarkerSymbol);

            SizeF size = TextRenderer.MeasureText(text[i].ToString(), new Font(fontType, fontSize));
            currentOffset += Convert.ToInt32(size.Width / adjustmentMultiplier) + pixelsBetweenLetters; 
        }

        IDynamicGlyph returnGlyph = dynamicGlyphFactory.CreateDynamicGlyph((ISymbol)multiLayerMarkerSymbol);
        return returnGlyph; 
    }


       public List<int> stringToAscii(String stringToConvert)
            {
                List<int> asciiList = new List<int>(); 
                for (int i = 0; i < stringToConvert.Length; i++)
                {
                    char c = stringToConvert[i];
                    byte b = (byte)c;
                    asciiList.Add(b); 
                }
                return asciiList; 
            }

Answer 3

First I would consider using standard labeling mechanisms. If this approach is insufficient, I suggest looking into custom renderers (IFeatureRenderer). You could also employ custom layers but I guess that is unnecessary in your case.

But, if your objects (cars) change position very often, you will want to work with dynamic display.