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Dataset and Overlay Properties

Dataset Properties

SIS understands many different datasets, e.g. AutoCAD DXF or Ordnance Survey NTF, and each of these datasets has its own properties. See the list of datasets for further details of these 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. The serial number can be obtained from the _nDataset& property of an overlay, or from the GetDataset, GetDatasetContainer, FindExternalDataset or TopoGetNamedSeedDataset methods. The serial number should be queried immediately before use and not stored for later use, because dataset serial numbers may change during the course of a SIS session.

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.

Attributes
Bitmap
Brush
Brush alpha
Brush alpha override
Brush override
Colour
Colour override
Dataset
External
Font
Font override
Icon
Maximum scale
Minimum scale
Name
Non-Printable
Notes
Number of themes
Order By
Order By Max Scale
Pen
Pen alpha
Pen alpha override
Pen override
Point scale override
Scale
Scale override
Symbol
Symbol override
Sprites
Status
Theme titles

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.
Theme titles: _themes$
A list of Themes on the overlay.

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`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.