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ScalePt |
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| Header: | Quickdraw.h | Carbon status: | Supported | |
Scales a height and width according to the proportions of two rectangles.
void ScalePt (
Point *pt,
const Rect *srcRect,
const Rect *dstRect
);
On input, a pointer to an initial height and width (specified in the two fields of a Point structure) to scale; on return, vertical and horizontal scaling factors derived by multiplying the height and width by ratios of the height and width of the rectangle in the srcRect parameter to the height and width of the rectangle in the dstRect parameter.
You do not pass coordinates in this parameter. Instead, you pass an initial height to scale in the v (or vertical) field of the Point structure, and you pass an initial width to scale in the h (or horizontal) field.
The ScalePt function scales these measurements by multiplying the initial height by the ratio of the height of the rectangle you specify in the dstRect parameter to the height of the rectangle you specify in the srcRect parameter, and by multiplying the initial width by the ratio of the width of the dstRect rectangle to the width of the srcRect rectangle.
A rectangle. The ratio of this rectangle’s height to the height of the rectangle in the dstRect parameter provides the vertical scaling factor, and the ratio of this rectangle’s width to the width of the rectangle in the dstRect parameter provides the horizontal scaling factor.
A rectangle compared to the rectangle in the srcRect parameter to determine vertical and horizontal scaling factors.
The ScalePt function produces horizontal and vertical scaling factors from the proportions of two rectangles. Use ScalePt, for example, to scale the dimensions of the graphics pen.
Where the width of the dstRect rectangle is twice the width of the srcRect rectangle, and its height is three times the height of srcRect, ScalePt scales the width of the graphics pen from 3 to 6 and scales its height from 2 to 6.
The minimum value ScalePt returns is (1,1).
If the points or rectangles supplied to this function are defined in a graphics port other than your current graphics port, you must convert them to the local coordinate system of your current graphics port. You can accomplish this by using the SetPort function to change to the graphics port containing the points or rectangles, using the LocalGlobal function to convert their locations to global coordinates, using SetPort to return to your starting graphics port, and then using the GlobalToLocal function to convert the locations of points or rectangles to the local coordinates of your current graphics port.
Supported in Carbon. Available in Carbon 1.0.2 and later when running Mac OS 8.1 or later.
© 2000 Apple Computer, Inc. (Last Updated 6/30/2000)