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Line and Curve Attributes

  • Artykuł

A device context (DC) contains attributes that affect line and curve output. The line and curve attributes include the current position, brush style, brush color, pen style, pen color, transformation, and so on.

The default current position for any DC is located at the point (0,0) in logical (or world) space. You can set these coordinates to a new position by calling the MoveToEx function and passing a new set of coordinates.

Note

There are two sets of line- and curve-drawing functions. The first set retains the current position in a DC, and the second set alters the position. You can identify the functions that alter the current position by examining the function name. If the function name ends with the preposition "To", the function sets the current position to the ending point of the last line drawn (LineTo, ArcTo, PolylineTo, or PolyBezierTo). If the function name does not end with this preposition, it leaves the current position intact (Arc, Polyline, or PolyBezier).

 

The default brush is a solid white brush. An application can create a new brush by calling the CreateBrushIndirect function. After creating a brush, the application can select it into its DC by calling the SelectObject function. Windows provides a complete set of functions to create, select, and alter the brush in an application's DC. For more information about these functions and about brushes in general, see Brushes.

The default pen is a cosmetic, solid black pen that is one pixel wide. An application can create a pen by using the ExtCreatePen function. After creating a pen, your application can select it into its DC by calling the SelectObject function. Windows provides a complete set of functions to create, select, and alter the pen in an application's DC. For more information about these functions and about pens in general, see Pens.

The default transformation is the unity transformation (specified by the identity matrix). An application can specify a new transformation by calling the SetWorldTransform function. Windows provides a complete set of functions to transform lines and curves by altering their width, location, and general appearance. For more information about these functions, see Coordinate Spaces and Transformations.