Dataset and Overlay Properties

Dataset Properties

Cadcorp SIS Desktop understands many different datasets, e.g. AutoCAD DXF or Ordnance Survey NTF.

Note: See list of datasets for more information on their properties.

Dataset properties are set and queried using the SIS_OT_DATASET constant and the

• GetFlt/GetInt/GetStr/GetProperty and
• SetFlt/SetInt/SetStr/SetProperty methods.

The nObject& argument must be the serial number of the dataset.

To check the serial number, access it from the _nDataset& property of an overlay or from the GetDataset, GetDatasetContainer, FindExternalDataset or TopoGetNamedSeedDataset methods.

Dataset serial numbers can change during the course of a SIS session. Therefore ensure you query serial numbers immediately before use and not stored for later access.

Overlay Properties

Overlay properties are set and queried using the SIS_OT_OVERLAY constant and the GetFlt/GetInt/GetStr/GetProperty and SetFlt/SetInt/SetStr/SetProperty methods.

The nObject& argument should be the index in the list of overlays in the current window of the required overlay.

The _nOverlay& property is the total number of overlays in the current window.

Note: Overlay indices run from zero to one less than the number of overlays.

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Overlay Properties

• Attributes: _attributes$
  The user defined attributes stored with the overlay.
  
  
• Bitmap: _GBitmapAlphaTransparency&
  Valid values are: 0 - 255. The higher the value the greater the transparency.
  
  
• Brush: _brush$
  The Brush to use for items if their Brush is "By Overlay", i.e. if they have no Brush of their own, or if the overlay Brush override is set.
  
  
• Brush alpha: _brushAlpha&
  Valid values are: 0 - 255. The higher the value the greater the transparency.
  
  
• Brush alpha override: _bBrushAlphaOverride&
  
  
• Brush override: _bBrushOverride&
  Should the overlay Brush override any Item Brush?
  
  
• Colour: _colour$
  The overlay colour, a space-separated RGB triple, e.g. "0 0 255" is blue, and "255 255 255" is white. When the overlay colour override is True, items will use this colour instead of their Pen colour.
  
  
• Colour override: _bColourOverride&
  Should the overlay colour override any Item Pen colour? If this is False, then the overlay colour is ignored.
  

• Dataset: _nDataset&
  The serial number of the overlay's dataset.
  
  
• External: _bExternal&
  Is the overlay's dataset a file?
  
  
• Font: _font$
  The font to use for items if their font is "By Overlay", i.e. if they have no font of their own, or if the overlay font override is set.
  
  
• Font override: _bFontOverride&
  Should the overlay font override any item font?
  
  
• Icon: _nIcon&
  The overlay icon index.
  
  
• Maximum scale: _scalemax#
  The highest reproduction scale at which an Item on an overlay will be drawn. If you set this value to 1000, and then zoom out to 1:2000 the item will become invisible.
  
  This value is stored internally using a low precision byte. The value you enter will be rounded to the nearest valid value automatically.
  
  
• Minimum scale: _scalemin#
  The lowest reproduction scale at which an Item on an overlay will be drawn. If you set this value to 100, and then zoom out to 1:50 the item will become invisible.
  
  This value is stored internally using a low precision byte. The value you enter will be rounded to the nearest valid value automatically.
  
  
• Name: _name$
  The overlay name. If the overlay's dataset is a file, then this name is an alias.
  
  
• Non-Printable: _bNonPrintable&
  Sets the overlay to be non-printable.
  
  
• Notes: _notes$
  The overlay notes. These notes can be used to store free-form textual information about the overlay.
  
  
• Number of themes: _nTheme&
  The number of Theme objects on the overlay.
  
  
• Order By: _orderBy$
  For Cadcorp Base Dataset and Cadcorp Internal Datasets, supports drawing in user-defined order, which can be any expression.
  
  
• Order By Max Scale: _orderByScalemax#
  A pre-drawing sorting step that can be skipped at small scales, where strict ordering may be expensive in terms of memory and/or processing resource and/or unnecessary.
  
  
• Pen: _pen$
  The Pen to use for items if their Pen is "By Overlay", i.e. if they have no Pen of their own, or if the overlay Pen override is set.
  
  
• Pen alpha: _penAlpha&
  Valid values are: 0 - 255. The higher the value the greater the transparency.
  
  
• Pen alpha override: _bPenAlphaOverride&
  
  
• Pen override: _bPenOverride&
  Should the overlay Pen override any item Pen?
  
  
• Point scale override: _pointScaleOverride#
  To ensure a Symbol is displayed at the correct scale set the attribute to -1.
  
  
• Scale: _scale#
  The overlay scale, which optionally overrides the overlay's dataset scale.
  
  
• Scale override: _bScaleOverride&
  Should the overlay scale override the overlay's dataset scale?
  
  
• Symbol: _shape$
  The Symbol to use for items if their Symbol is "By Overlay", i.e. if they have no Symbol of their own, or if the overlay Symbol override is set.
  
  
• Symbol override: _bShapeOverride&
  Should the overlay Symbol override any item Symbol?
  
  
• Sprites: _bSprites&
  A boolean value that indicates whether the overlay is a sprites overlay. If the overlay contains Items that are considered to be sprites set this value to True (-1).
  See Sprites Overlay
  
  
• Status: _status&
  The overlay status. Valid values are:
  

  SIS_INVISIBLE	Items are invisible.
  SIS_VISIBLE	Items are visible.
  SIS_HITTABLE	Items are visible and can be selected.
  SIS_EDITABLE	Items are selectable and can be edited.

• The following numbers can also be used: 0=Invisible 1=Visible 2=Hittable 3=Editable
• Theme titles: _themes$
  A list of Themes on the overlay.

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