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api:dk11:delphi:gislayerpixel.tgis_layerpixel.loop_tgis_extent_double_tgis_shape_string_boolean

TGIS_LayerPixel.Loop(TGIS_Extent; Double; TGIS_Shape; String; Boolean) method

DK11 for Delphi | GisLayerPixel.TGIS_LayerPixel.Loop | Overloads | Constructors | Fields | Methods | Properties | Events

Prepare enumerator to iterate layer. Pixel will be treated as points.

Available also on: .NET | Java | ActiveX.

Syntax

// Delphi
public
  function Loop(
    const _extent : TGIS_Extent;
    const _pixelsize : Double;
    const _shape : TGIS_Shape;
    const _de9im : String;
    const _writable : Boolean
  ) : TGIS_LayerPixelEnumeratorFactory; overload; virtual;
// C++ Builder
public:
  virtual TGIS_LayerPixelEnumeratorFactory* Loop(
    TGIS_Extent* const _extent,
    const double _pixelsize,
    TGIS_Shape* const _shape,
    const UnicodeString _de9im,
    const bool _writable
  ) /* overload */;

Parameters

Name Type Description
_extent TGIS_Extent extent of items to be found; expected _extent units are in the Layer coordinate space
_pixelsize Double minimum requested size of image pixel; by providing 0, the maximum possible resolution will be used, which is also the fastest method if a layer is fully in-memory because, in such situation, a pointer to existing memory is used
_shape TGIS_Shape if not nil, then only pixels matching _de9im matrix with be found;
_de9im String DE-9IM matrix of comparison
_writable Boolean if true than layer will post back any changes in locked area; if write is not possible then TGIS_PixelItem.Writable will be set accordingly

Result

Type Description
TGIS_LayerPixelEnumeratorFactory Pixel item returned row by row, column by column.

Remarks

_pixelsize

By providing _pixelsize=0, a native layer resolution is requested. This is also the fastest method if a layer is fully in-memory because, in such situation, a pointer to existing memory is used

Example

General way to query for terrain profile:

foreach (TatukGIS.NDK.TGIS_PixelItem px in lp.Loop(0, line, false))
{
  Memo.AppendText(
    String.Format("Distance: {0}, Height:{1}\r\n", px.Distance, px.Value)
  );
}

General way to query for pixels within polygon and modifying value:

foreach (TGIS_PixelItem px in lp.Loop(polygon.Extent, 0, polygon, "T", true))
{
  px.Color = TGIS_Color.Red;
}

References

2019/09/27 01:08