racket/draw: fix outline adjustment in `draw-rectangle' and others

collects/racket/draw/private/dc.rkt

@@ -312,6 +312,15 @@
               (set! x-align-delta (/ (bitwise-and 1 (max 1 (inexact->exact (floor (* effective-scale-x w))))) 2.0))
               (set! y-align-delta (/ (bitwise-and 1 (max 1 (inexact->exact (floor (* effective-scale-y w))))) 2.0))))))
 
+    (define/private (sub1w w)
+      (if (aligned? smoothing)
+          (max 0.0 (- w (/ effective-scale-x)))
+          w))
+    (define/private (sub1h h)
+      (if (aligned? smoothing)
+          (max 0.0 (- h (/ effective-scale-y)))
+          h))
+
     (def/public (set-font [font% f])
       (set! font f))
 
@@ -994,15 +1003,15 @@
       (with-cr 
        (check-ok who)
        cr
-       (let ([draw-one (lambda (align-x align-y brush? pen? d)
+       (let ([draw-one (lambda (align-x align-y brush? pen? sub1w sub1h)
                          (let* ([orig-x x]
                                 [orig-y y]
                                 [x (align-x x)]
                                 [y (align-y y)]
                                 [width (- (align-x (+ orig-x width)) x)]
-                                [width (if (width . >= . d) (- width d) width)]
+                                [width (sub1w width)]
                                 [height (- (align-y (+ orig-y height)) y)]
-                                [height (if (height . >= . d) (- height d) height)]
+                                [height (sub1h height)]
                                 [radius-x (/ width 2)]
                                 [radius-y (/ height 2)]
                                 [center-x (+ x radius-x)]
@@ -1024,9 +1033,10 @@
                              (cairo_restore cr)
                              (draw cr brush? pen?))))])
          (when (brush-draws?)
-           (draw-one (lambda (x) x) (lambda (y) y) #t #f 0.0))
+           (draw-one (lambda (x) x) (lambda (y) y) #t #f (lambda (x) x) (lambda (x) x)))
          (when (pen-draws?)
-           (draw-one (lambda (x) (align-x x)) (lambda (y) (align-y y)) #f #t 1.0)))))
+           (draw-one (lambda (x) (align-x x)) (lambda (y) (align-y y)) #f #t 
+                     (lambda (x) (sub1w x)) (lambda (x) (sub1h x)))))))
 
     (def/public (draw-arc [real? x] [real? y] [nonnegative-real? width] [nonnegative-real? height]
                           [real? start-radians] [real? end-radians])
@@ -1100,8 +1110,8 @@
          (cairo_new_path cr)
          (cairo_rectangle cr x y width height)
          (draw cr #t #f)
-         (let ([w2 (- (align-x (+ x (sub1 width))) ax)]
+         (let ([w2 (- (align-x (+ x (sub1w width))) ax)]
-               [h2 (- (align-y (+ y (sub1 height))) ay)])
+               [h2 (- (align-y (+ y (sub1h height))) ay)])
            (when (and (positive? w2)
                       (positive? h2))
              (cairo_new_path cr)
@@ -1125,7 +1135,7 @@
            (rounded-rect x y width height (lambda (x) x) (lambda (y) y))
            (draw cr #t #f))
          (when (pen-draws?)
-           (rounded-rect x y (sub1 width) (sub1 height)
+           (rounded-rect x y (sub1w width) (sub1h height)
                          (lambda (x) (align-x x)) (lambda (y) (align-y y)))
            (draw cr #f #t)))))
 

collects/scribblings/draw/dc-intf.scrbl

@@ -66,14 +66,16 @@ Draws a counter-clockwise circular arc, a part of the ellipse
 The current pen is used for the arc. If the current brush is not
  transparent, it is used to fill the wedge bounded by the arc plus
  lines (not drawn) extending to the center of the inscribed ellipse.
+ If both the pen and brush are non-transparent, the wedge is filled
+ with the brush before the arc is drawn with the pen. 
+
+The wedge and arc meet so that no space is left between them, but the
+ precise overlap between the wedge and arc is platform- and
+ size-specific.  Typically, the regions drawn by the brush and pen
+ overlap.  In unsmoothed or aligned mode, the path for the outline is
+ adjusted by shrinking the bounding ellipse width and height by one
+ drawing unit after scaling.
 
-If both the pen and brush are non-transparent, the wedge is filled
- with the brush before the arc is drawn with the pen. The wedge and
- arc meet so that no space is left between them, but the precise
- overlap between the wedge and arc is platform- and size-specific.
- Typically, the regions drawn by the brush and pen overlap.  More
- generally, the pen is centered over the outline of the arc, rounding
- toward the center in unsmoothed mode.
 
 @|DrawSizeNote|
 
@@ -179,15 +181,16 @@ See @method[dc<%> draw-bitmap] for information about @racket[dest-x],
 
 Draws an ellipse contained in a rectangle with the given top-left
  corner and size. The current pen is used for the outline, and the
- current brush is used for filling the shape.
+ current brush is used for filling the shape. If both the pen and
+ brush are non-transparent, the ellipse is filled with the brush
+ before the outline is drawn with the pen.
 
-If both the pen and brush are non-transparent, the ellipse is filled
+Brush filling and pen outline meet so that no space is left between
- with the brush before the outline is drawn with the pen. The filling
+ them, but the precise overlap between the filling and outline is
- and outline meet so that no space is left between them, but the
+ platform- and size-specific.  Thus, the regions drawn by the brush
- precise overlap between the filling and outline is platform- and
+ and pen may partially overlap. In unsmoothed or aligned mode, the
- size-specific.  Typically, the regions drawn by the brush and pen
+ path for the outline is adjusted by shrinking the ellipse width and
- overlap.  More generally, the pen is centered over the outline of the
+ height by one drawing unit after scaling.
- ellipse, rounding toward the center in unsmoothed mode.
 
 @|DrawSizeNote|
 
@@ -324,17 +327,15 @@ See also @method[dc<%> set-smoothing] for information on the
 
 Draws a rectangle with the given top-left corner and size.  The
  current pen is used for the outline and the current brush for filling
- the shape.
+ the shape. If both the pen and brush are non-transparent, the
+ rectangle is filled with the brush before the outline is drawn with
+ the pen.
 
-If both the pen and brush are non-transparent, the rectangle is filled
+In unsmoothed or aligned mode, when the pen is size 0 or 1, the
- with the brush before the outline is drawn with the pen. In
+ filling precisely overlaps the entire outline. More generally, in
- unsmoothed mode, when the pen is size 0 or 1, the filling precisely
+ unsmoothed or aligned mode, the path for the outline is adjusted by
- overlaps the entire outline. As a result, if a rectangle is drawn
+ shrinking the rectangle width and height by one drawing unit after
- with a size-0 or size-1 @racket['xor] @racket[pen%] and an
+ scaling.
- @racket['xor] @racket[brush%], the outline is xored twice (first by
- the brush, then by the pen), leaving it unchanged. More generally,
- the pen is centered over the outline of the rectangle, rounding
- toward the center in unsmoothed mode.
 
 See also @method[dc<%> set-smoothing] for information on the
 @racket['aligned] smoothing mode.
@@ -354,7 +355,8 @@ See also @method[dc<%> set-smoothing] for information on the
 Draws a rectangle with the given top-left corner, and with the given
  size. The corners are quarter-circles using the given radius.  The
  current pen is used for the outline and the current brush for filling
- the shape.
+ the shape. If both the pen and brush are non-transparent, the rectangle is filled
+ with the brush before the outline is drawn with the pen.
 
 If @racket[radius] is positive, the value is used as the radius of the
  rounded corner. If @racket[radius] is negative, the absolute value is
@@ -364,14 +366,12 @@ If @racket[radius] is positive, the value is used as the radius of the
 If @racket[radius] is less than @racket[-0.5] or more than half of
  @racket[width] or @racket[height], @|MismatchExn|.
 
-If both the pen and brush are non-transparent, the rectangle is filled
+Brush filling and pen outline meet so that no space is left between
- with the brush before the outline is drawn with the pen. The filling
+ them, but the precise overlap between the filling and outline is
- and outline meet so that no space is left between them, but the
+ platform- and size-specific.  Thus, the regions drawn by the brush
- precise overlap between the filling and outline is platform- and
+ and pen may partially overlap. In unsmoothed or aligned mode, the
- size-specific.  Thus, the regions drawn by the brush and pen may
+ path for the outline is adjusted by shrinking the rectangle width and
- partially overlap. More generally, the pen is centered over the
+ height by one drawing unit after scaling.
- outline of the rounded rectangle, rounding toward the center in
- unsmoothed mode.
 
 See also @method[dc<%> set-smoothing] for information on the
 @racket['aligned] smoothing mode.