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TLazCanvas.DoPolygonFill procedure

Member of TLazCanvasprotectedIn unit LazCanvas

Implements a polygon fill algorithm not present in fcl-image prior to FPC version 3.2.3.

Declaration

pascal
procedure DoPolygonFill(const points: Array of TPoint); override

Arguments

points

Array with the TPoint records representing the polygon vertices.

Description

Implements a polygon fill algorithm not present in fcl-image. Part of the algorithm is explained here.

DoPolygonFill is defined when using FPC versions prior to 3.2.3. In FPC 3.2.3, the method already exists in the TFPPixelCanvas ancestor and is not needed in TLazCanvas.

Modified in LCL versions after 2.2.4 to call DrawPixel instead of SetColor when drawing pixels between points on the polygon. This allows the DrawingMode (opacity, alphablending, custom) to be applied to the pixels. Adds support for the non-zero winding rule in the fill operation.

See also

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.