Crash on using bitmap font and autofollow with mapscript C#

[getiem]

I'm running into problems with my mapscript C#. I had truetype fonts, but due to some restrictions I can't use them on the system anymore, so I switched to type Bitmap. This will work, but only if I switch off autofollow.

Case: I have lines with labels. I had these labels with truetype and with autofollow --> MS_TRUE:

Working part: Mapscript:

layerclass.label.color.setRGB(0, 0, 0); layerclass.label.font = "Arial"; layerclass.label.size = 10; //layerclass.label.size = (double)MS_BITMAP_FONT_SIZES.MS_SMALL; layerclass.label.force = mapscript.MS_TRUE; layerclass.label.type = MS_FONT_TYPE.MS_TRUETYPE; //layerclass.label.type = MS_FONT_TYPE.MS_BITMAP; layerclass.label.position = (int)MS_POSITIONS_ENUM.MS_UC; layerclass.label.autoangle = mapscript.MS_TRUE; layerclass.label.autofollow = mapscript.MS_TRUE;

This works.. resulting in mapfile (via mapObj.save()) and image: LABEL

ANGLE FOLLOW ANTIALIAS TRUE FONT "Arial" MAXSIZE 256 MINSIZE 4 SIZE 10 TYPE TRUETYPE BUFFER 0 COLOR 0 0 0 FORCE TRUE MINDISTANCE -1 MINFEATURESIZE -1 OFFSET 0 0 PARTIALS TRUE POSITION UC

END

NOT WORKING PART: However, if I change this to using the BITMAP fonttype, It gives me an error: Mapscript: layerclass.label.color.setRGB(0, 0, 0); //layerclass.label.font = "Arial"; //layerclass.label.size = 10; layerclass.label.size = (double)MS_BITMAP_FONT_SIZES.MS_SMALL; layerclass.label.force = mapscript.MS_TRUE; //layerclass.label.type = MS_FONT_TYPE.MS_TRUETYPE; layerclass.label.type = MS_FONT_TYPE.MS_BITMAP; layerclass.label.position = (int)MS_POSITIONS_ENUM.MS_UC; layerclass.label.autoangle = mapscript.MS_TRUE; layerclass.label.autofollow = mapscript.MS_TRUE; Resulting mapfile: LABEL

SIZE SMALL TYPE BITMAP BUFFER 0 COLOR 0 0 0 FORCE TRUE MINDISTANCE -1 MINFEATURESIZE -1 OFFSET 0 0 PARTIALS TRUE POSITION UC

END

Resulting Error when calling mapObj.draw() :

Attempted to read or write protected memory. This is often an indication that ot her memory is corrupt. (something with P/Invoke)

Using MS4W with mapserver 5.6.1. Using VS2008.

[getiem]

Sample program.

[getiem]

To run sample program, be sure to add your own path environment to mapscript dll and to mapserver dll folder. I copied both in one folder, so I have only one reference. In normal situation you would reference two directories:

C:\ms4w\Apache\cgi-bin\ and C:\ms4w\Apache\cgi-bin\mapscript\csharp\ as environment variable in program.

[getiem]

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From Tamas:

Unfortunately the autofollow option is not supported with bitmap labels, so my best chance is to raise an exception or switch back to the non followed mode in this case to prevent from the memory corruption.

Best regards,

Tamas

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My reply

Ok, its not possible. I could not find documentation or comments on this, on website or in code.

Best options: For me: - NO use of option autofollow anymore. For Mapserver - A decent exception is always better then the standard memory error exception. - A litle remark within the documentation would be nice.

[tamas]

I reopen this ticket because of the need of a specific error message.

Could you describe in more detail why should you switch to bitmap fonts instead of truetypes?

[tamas]

Added the error message if anglemode 'FOLLOW' is specified with bitmap fonts. (r11082)