Style Attributes (IM: XG)

Inside Macintosh: QuickDraw GX Graphics /

Chapter 3 - Geometric Styles / Geometric Styles Reference

Style Attributes
Each style object has a set of style attributes, which are a group of flags that modify the behavior of the style object. In particular, these flags allow you to specify how QuickDraw GX places the pen with respect to a shape's geometry and whether the shape should be constrained to a grid. These constants are defined in the gxStyleAttributes enumeration:
enum gxStyleAttributes {
   gxCenterFrameStyle   = 0,
   gxSourceGridStyle    = 0x0001,
   gxDeviceGridStyle    = 0x0002,
   gxInsideFrameStyle   = 0x0004,
   gxOutsideFrameStyle  = 0x0008,
   gxAutoInsetStyle     = 0x0010
};
typedef long gxStyleAttribute;
Constant descriptions

gxCenterFrameStyle
Indicates that QuickDraw GX should center the geometric pen along the shape's contours.
gxSourceGridStyle
Constrains the geometric points of the shape in geometry space. When drawing a shape whose style object has this flag set, QuickDraw GX moves each geometric point of the shape's geometry to the closest integral position before applying the shape's style and transform. (Note that the original geometric points are unchanged; this operation occurs only as the shape is being drawn.) See "Grids" beginning on page 3-20 for more information.
gxDeviceGridStyle
Constrains the geometric points of the shape in device space. When drawing a shape whose style object has this flag set, QuickDraw GX moves the shape's geometric points, after applying the shape's style and transform, to the closest integral position (that is, pixel position) in the device space. (Note that the original geometric points are unchanged; this operation occurs only as the shape is being drawn.) See "Grids" beginning on page 3-20 for more information.
gxInsideFrameStyle
Indicates that QuickDraw GX should position the pen along the inside of the shape's contours. By default, QuickDraw GX uses the direction of a contour to determine which side is the inside; the right side of a contour is considered the inside.
gxOutsideFrameStyle
Indicates that QuickDraw GX should place the pen along the outside of the shape's contours. By default, QuickDraw GX uses the direction of a contour to determine which side is the inside; the left side of a contour is considered the outside.
gxAutoInsetStyle

Alters the default definition of the inside and outside of a contour. When this flag is not set, QuickDraw GX assumes the right side of a contour is the inside and the left side of a contour is the outside (which provides the correct behavior for TrueType fonts). When the gxAutoInsetStyle flag is set, QuickDraw GX finds the true inside of each contour, regardless of the contour direction.
Setting both the gxInsideFrameStyle and gxOutsideFrameStyle style attributes results in the inconsistent_parameters error.
See "Grids" on page 3-20 and "Constraining Shape Geometries to Grids" beginning on page 3-40 for details about how QuickDraw GX constrains shapes to a grid. See "The Geometric Pen" on page 3-15 and "Manipulating Pen Width and Placement" on page 3-51 for examples of pen placement.