5.3.6
36.3 Pict Utilities
This library is unstable;
compatibility will not be maintained.
See Unstable: May Change Without Warning for more information.
| (require unstable/gui/pict) |
The functions and macros exported by this module are also exported by unstable/gui/slideshow.
36.3.1 Pict Colors
Example: | ||
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procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
procedure
pict : pict?
These functions apply appropriate colors to picture p.
Example: | ||
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These functions produce ligher or darker versions of a color.
Example: | |||||
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value
This contract recognizes color strings, color% instances, and RGB color
lists.
36.3.2 Pict Manipulation
Extends pict’s bounding box to a minimum width and/or
height, placing the original picture in the middle of the space.
Example: | ||
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procedure
pict : pict? width : real? height : real? mode : (or/c 'preserve 'inset 'distort) = 'preserve
Scales pict so that its width and height are at most
width and height, respectively. If mode is
'preserve, the width and height are scaled by the same factor
so pict’s aspect ratio is preserved; the result’s bounding
box may be smaller than width by height. If
mode is 'inset, the aspect ratio is preserved as
with 'preserve, but the resulting pict is centered in a
bounding box of exactly width by height. If
mode is 'distort, the width and height are scaled
separately.
Examples: | ||||||
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36.3.2.1 Conditional Manipulations
These pict transformers all take boolean arguments that determine whether to transform the pict or leave it unchanged. These transformations can be useful for staged slides, as the resulting pict always has the same size and shape, and its contents always appear at the same position, but changing the boolean argument between slides can control when the transformation occurs.
These functions conditionally show or hide an image, essentially choosing
between pict and (ghost pict). The only difference between
the two is the default behavior and the opposite meaning of the show?
and hide? booleans. Both functions are provided for mnemonic purposes.
Displays a strikethrough image by putting a line through the middle of
pict if strike? is true; produces pict unchanged
otherwise.
Example: | ||
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Shades pict to show with ratio of its normal opacity; if
ratio is 1 or shade? is #f, shows
pict unchanged.
Example: | ||
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36.3.2.2 Conditional Combinations
These pict control flow operators decide which pict of several to use. All branches are evaluated; the resulting pict is a combination of the pict chosen by normal conditional flow with ghost applied to all the other picts. The result is a picture large enough to accommodate each alternative, but showing only the chosen one. This is useful for staged slides, as the pict chosen may change with each slide but its size and position will not.
syntax
(pict-if maybe-combine test-expr then-expr else-expr)
maybe-combine =
| #:combine combine-expr
Chooses either then-expr or else-expr based on
test-expr, similarly to if. Combines the chosen, visible
image with the other, invisible image using combine-expr, defaulting to
pict-combine.
Example: | |||||||||
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syntax
(pict-cond maybe-combine [test-expr pict-expr] ...)
maybe-combine =
| #:combine combine-expr
Chooses a pict-expr based on the first successful test-expr,
similarly to cond. Combines the chosen, visible image with the other,
invisible images using combine-expr, defaulting to
pict-combine.
Example: | |||||||||||
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syntax
(pict-case test-expr maybe-combine [literals pict-expr] ...)
maybe-combine =
| #:combine combine-expr
Chooses a pict-expr based on test-expr and each list of
literals, similarly to case. Combines the chosen, visible
image with the other, invisible images using combine-expr, defaulting
to pict-combine.
Example: | |||||||||||
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syntax
(pict-match test-expr maybe-combine [pattern pict-expr] ...)
maybe-combine =
| #:combine combine-expr
Chooses a pict-expr based on test-expr and each
pattern, similarly to match. Combines the chosen, visible
image with the other, invisible images using combine-expr, defaulting
to pict-combine.
syntax
This syntax parameter determines the default pict combining form used by the
above macros. It defaults to lbl-superimpose.
syntax
(with-pict-combine combine-id body ...)
Sets pict-combine to refer to combine-id within each of the
body terms, which are spliced into the containing context.
Example: | ||||||||||||
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36.3.3 Shapes with Borders
The subsequent bindings were added by Vincent St-Amour.
procedure
(ellipse/border w h [ #:color color #:border-color border-color #:border-width border-width]) → pict? w : real? h : real? color : color/c = "white" border-color : color/c = "black" border-width : real? = 2
procedure
(circle/border diameter [ #:color color #:border-color border-color #:border-width border-width]) → pict? diameter : real? color : color/c = "white" border-color : color/c = "black" border-width : real? = 2
procedure
(rectangle/border w h [ #:color color #:border-color border-color #:border-width border-width]) → pict? w : real? h : real? color : color/c = "white" border-color : color/c = "black" border-width : real? = 2
procedure
(rounded-rectangle/border w h [ #:color color #:border-color border-color #:border-width border-width #:corner-radius corner-radius #:angle angle]) → pict? w : real? h : real? color : color/c = "white" border-color : color/c = "black" border-width : real? = 2 corner-radius : real? = -0.25 angle : real? = 0
These functions create shapes with border of the given color and width.
Examples: | ||||
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36.3.4 Lines with Labels
The subsequent bindings were added by Scott Owens.
procedure
(pin-label-line label pict src-pict src-coord-fn dest-pict dest-coord-fn [ #:start-angle start-angle #:end-angle end-angle #:start-pull start-pull #:end-pull end-pull #:line-width line-width #:color color #:under? under? #:x-adjust x-adjust #:y-adjust y-adjust]) → pict? label : pict? pict : pict? src-pict : pict-path? src-coord-fn : (-> pict-path? (values real? real?)) dest-pict : pict-path? dest-coord-fn : (-> pict-path? (values real? real?)) start-angle : (or/c real? #f) = #f end-angle : (or/c real? #f) = #f start-pull : real? = 1/4 end-pull : real? = 1/4 line-width : (or/c real? #f) = #f color : (or/c #f string? (is-a?/c color%)) = #f under? : any/c = #f x-adjust : real? = 0 y-adjust : real? = 0
procedure
(pin-arrow-label-line label arrow-size pict src-pict src-coord-fn dest-pict dest-coord-fn [ #:start-angle start-angle #:end-angle end-angle #:start-pull start-pull #:end-pull end-pull #:line-width line-width #:color color #:under? under? #:hide-arrowhead? hide-arrowhead? #:x-adjust x-adjust #:y-adjust y-adjust]) → pict? label : pict? arrow-size : real? pict : pict? src-pict : pict-path? src-coord-fn : (-> pict-path? (values real? real?)) dest-pict : pict-path? dest-coord-fn : (-> pict-path? (values real? real?)) start-angle : (or/c real? #f) = #f end-angle : (or/c real? #f) = #f start-pull : real? = 1/4 end-pull : real? = 1/4 line-width : (or/c real? #f) = #f color : (or/c #f string? (is-a?/c color%)) = #f under? : any/c = #f hide-arrowhead? : any/c = #f x-adjust : real? = 0 y-adjust : real? = 0
procedure
(pin-arrows-label-line label arrow-size pict src-pict src-coord-fn dest-pict dest-coord-fn [ #:start-angle start-angle #:end-angle end-angle #:start-pull start-pull #:end-pull end-pull #:line-width line-width #:color color #:under? under? #:hide-arrowhead? hide-arrowhead? #:x-adjust x-adjust #:y-adjust y-adjust]) → pict? label : pict? arrow-size : real? pict : pict? src-pict : pict-path? src-coord-fn : (-> pict-path? (values real? real?)) dest-pict : pict-path? dest-coord-fn : (-> pict-path? (values real? real?)) start-angle : (or/c real? #f) = #f end-angle : (or/c real? #f) = #f start-pull : real? = 1/4 end-pull : real? = 1/4 line-width : (or/c real? #f) = #f color : (or/c #f string? (is-a?/c color%)) = #f under? : any/c = #f hide-arrowhead? : any/c = #f x-adjust : real? = 0 y-adjust : real? = 0
These functions behave like pin-line, pin-arrow-line
and pin-arrows-line with the addition of a label attached to
the line.
Example: | ||||||||||
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36.3.5 Blur
The subsequent bindings were added by Ryan Culpepper.
procedure
p : pict? h-radius : (and/c real? (not/c negative?)) v-radius : (and/c real? (not/c negative?)) = h-radius
Blurs p using an iterated box blur that approximates a
gaussian blur. The h-radius and v-radius arguments
control the strength of the horizontal and vertical components of the
blur, respectively. They are given in terms of pict units, which may
not directly correspond to screen pixels.
The blur function takes work proportional to
(* (pict-width p) (pict-height p))
Examples: | ||||||||
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The resulting pict has the same bounding box as p, so when
picts are automatically clipped (as in Scribble documents),
the pict should be inset by the blur radius.
procedure
(shadow p radius [ dx dy #:color color #:shadow-color shadow-color]) → pict? p : pict? radius : (and/c real? (not/c negative?)) dx : real? = 0 dy : real? = dx color : (or/c #f string? (is-a?/c color%)) = #f shadow-color : (or/c #f string? (is-a?/c color%)) = #f
Creates a shadow effect by superimposing p over a
blurred version of p. The shadow is offset from p by
(dx, dy) units.
If color is not #f, the foreground part is (colorize p color); otherwise it is just p. If shadow-color is not #f, the shadow part is produced by blurring (colorize p shadow-color); otherwise it is produced by blurring p.
The resulting pict has the same bounding box as p.
Examples: | |||||||||
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procedure
(blur-bitmap! bitmap h-radius [v-radius]) → void?
bitmap : (is-a?/c bitmap%) h-radius : (and/c real? (not/c negative?)) v-radius : (and/c real? (not/c negative?)) = h-radius
Blurs bitmap using blur radii h-radius and
v-radius.
36.3.5.1 Tagged Picts
Returns a pict like p that carries a symbolic tag. The tag
can be used with find-tag to locate the pict.
procedure
(find-tag p find) → (or/c pict-path? #f)
p : pict? find : tag-path?
Locates a sub-pict of p. Returns a pict-path that can be used
with functions like lt-find, etc.
Example: | ||||||||
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procedure
(find-tag* p find) → (listof pict-path?)
p : pict? find : tag-path?
Like find-tag, but returns all pict-paths corresponding to
the given tag-path.
Example: | |||||||||||||
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Returns #t if x is a symbol or a non-empty list of
symbols, #f otherwise.
36.3.6 Shadow Frames
procedure
(shadow-frame pict ... [ #:sep separation #:margin margin #:background-color bg-color #:frame-color frame-color #:frame-line-width frame-line-width #:shadow-side-length shadow-side-length #:shadow-top-y-offset shadow-top-y-offset #:shadow-bottom-y-offset shadow-bottom-y-offset #:shadow-descent shadow-descent #:shadow-alpha-factor shadow-alpha-factor #:blur blur-radius]) → pict? pict : pict? separation : real? = 5 margin : real? = 20 bg-color : (or/c string? (is-a?/c color%)) = "white" frame-color : (or/c string? (is-a?/c color%)) = "gray" frame-line-width : (or/c real? #f) = 0 shadow-side-length : real? = 4 shadow-top-y-offset : real? = 10 shadow-bottom-y-offset : real? = 4 shadow-descent : (and/c real? (not/c negative?)) = 40 shadow-alpha-factor : real? = 3/4 blur-radius : (and/c real? (not/c negative?)) = 20
Surrounds the picts with a rectangular frame that casts a
symmetric “curled paper” shadow.
The picts are vertically appended with separation space between them. They are placed on a rectangular background of solid bg-color with margin space on all sides. A frame of frame-color and frame-line-width is added around the rectangle. The rectangle casts a shadow that extends shadow-side-length to the left and right, starts shadow-top-y-offset below the top of the rectangle and extends to shadow-bottom-y-offset below the bottom of the rectangle in the center and an additional shadow-descent below that on the sides. The shadow is painted using a linear gradient; shadow-alpha-factor determines its density at the center. Finally, the shadow is blurred by blur-radius; all previous measurements are pre-blur measurements.
Example: | ||
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procedure
(arch outer-width inner-width solid-height leg-height) → pict? outer-width : real? inner-width : real? solid-height : real? leg-height : real?
Creates an arch.
Example: | ||
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36.3.7 Additional combinators
The subsequent bindings were added by Asumu Takikawa.
Adds a background highlighted with color to
pict.
Examples: | ||||
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procedure
(cross-out pict [ #:width width #:style style #:color color]) → pict? pict : pict? width : real? = 1
style :
(or/c 'transparent 'solid 'xor 'hilite 'dot 'long-dash 'short-dash 'dot-dash 'xor-dot 'xor-long-dash 'xor-short-dash 'xor-dot-dash) = 'solid color : color/c = "black"
Crosses out pict with two diagonal lines drawn with
the given line width and with the line style.
The lines are colored with color.
Examples: | ||||||
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