Functions That Post Errors or Warnings When Applied to Pictures
Some QuickDraw GX functions that operate on other types of shapes do nothing but post an error or a warning if you try to apply them to a picture shape.
For example, there are a number of shape-related functions and geometric operations that you cannot apply to picture shapes. Table 6-2 lists these functions, which are described in full in Chapter 2, "Geometric Shapes," and Chapter 4, "Geometric Operations."
Geometric operations that post errors or warnings when applied to pictures
| Function name | Error or warning posted |
|---|
| GXBreakShape | graphic_type_does_not_contain_points |
| GXContainsShape | shape_operator_may_not_be_a_picture |
| GXCountShapePoints | graphic_type_does_not_contain_points |
| GXDifferenceShape | shape_operator_may_not_be_a_picture |
| GXExcludeShape | shape_operator_may_not_be_a_picture |
| GXGetShapeCenter | illegal_type_for_shape |
| GXGetShapeDirection | graphic_type_does_not_have_multiple_contours |
| GXGetShapeLength | shape_does_not_have_length |
| GXGetShapePoints | graphic_type_does_not_contain_points |
| GXInsetShape | graphic_type_cannot_be_inset |
| GXIntersectShape | shape_operator_may_not_be_a_picture |
| GXInvertShape | shape_cannot_be_inverted |
| GXReverseDifferenceShape | shape_operator_may_not_be_a_picture |
| GXReverseShape | contour_out_of_range |
| GXShapeLengthToPoint | shape_does_not_have_length |
| GXSetShapePoints | graphic_type_does_not_contain_points |
| GXTouchesShape | shape_operator_may_not_be_a_picture |
| GXUnionShape | shape_operator_may_not_be_a_picture |
Most of these geometric operations do not apply to picture shapes because a picture's geometry is substantially different from the geometry of a geometric shape.
You can apply a few of the geometric operations to pictures, however. These functions are discussed in "Geometric Operations Applicable to Pictures" beginning on page 6-55.
