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C H A P T E R 1 3
Drawing and Graphics
Using the Drawing Interface
13-13
If the style frame includes a
clipping
slot, the drawing of all shapes affected by
this style frame is clipped according to the value of the
clipping
slot. If the
value of the
clipping
slot is
nil
or if the
clipping
slot is not supplied, the
clipping behavior of the destination view is used.
If the
clipping
slot contains a region shape, that region is used as the clipping
boundary for drawing operations affected by this style frame. If the
clipping
slot
contains an array of shapes or regions, the system passes the contents of the
clipping
slot to the
MakeRegion
function to automatically create a new
clipping region from the contents of this slot.
Note
Although putting an array of shapes in the
clipping
slot may
seem convenient, it significantly increases the time required to
process the style frame. For best performance from the view
system, do not use this shortcut in style frames that are used
repeatedly.
Transforming a Shape
13
The
transform
slot changes the size or location of a shape without altering the
shape itself. It accepts an array specifying an x, y coordinate pair or a pair of
rectangles. The x, y coordinate arguments relocate a shape by specifying an offset
from the origin of the destination view's coordinate plane. The rectangle arguments
specify a mapping of the source and destination views that alters both the size and
location (offset) of the source view when it is drawn in the destination view.
The rectangle arguments work the same way as the parameters to the
ScaleShape
function (although transforms won't accept
nil
for the boundaries
of the source rectangle): the size of the shape is changed proportionately according
to the dimensions of the destination rectangle, and the coordinates of the
destination rectangle can also be used to draw the shape in a new location.
The following code fragments demonstrate the use of offset coordinates and
mapping rectangles as the value of the
transform
slot:
transform: [30,50],// offset shapes by 30 h and 50 v
or
transform:
[SetBounds(0,0,100,100),SetBounds(25,25,75,75)],
// half width and height, centered in relation to
// the original object(not the view) assuming that
// the first rect actually specified correct bounds
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