Add instructions on how to take screen shots

This instructs the adventurer on how to take screen shots using the
same look and feel used to take the ones that can be found at
`collects/scribblings/gui/image'.

There are also two scripts that might help automate this process.

collects/scribblings/gui/taking-screenshots/instructions

@@ -0,0 +1,38 @@
+-*- org -*-
+
+* Using GIMP
+  
+  To take screen shots of the widgets, you can follow these steps:
+
+  1. Take a widget screen shot
+  2. Open it with GIMP                                                                                                                                                                       
+  3. Cut it to 240 x 73                                                                                                                                                                      
+  4. Add a border using Filters/Decor/Add Border...
+     + Border X size :: 1
+     + Border Y size :: 1
+     + Border color :: black
+     + Delta value on color :: 25
+  5. Combine all layers
+  6. Add a drop shadow using Filters/Light and Shadow/Drop
+     Shadow...
+     + Offset X :: 8
+     + Offset Y :: 8
+     + Blur radius :: 9
+     + Color :: black
+     + Opacity :: 80
+     + Allow resizing :: #t
+  7. Save as .png
+     
+  There are two scripts in this directory that might help in this
+  process. Keep in mind though that the GIMP script is very fragile
+  and some tweaking might be necessary to make it work in different
+  setups.
+
+  + [[file:widget.rkt][widget.rkt]] :: Creates a "canvas" panel with a border, so it is
+                  easier to select the widget area using GIMP's Fuzzy
+                  Select Tool
+  + [[file:racket-widget.scm][racket-widget.scm]] :: GIMP's script which, when invoked, asks for a
+       window to take a screen shot and do the post production to the
+       image. This script should be put inside a specific directory,
+       here being `~/.gimp-2.6/scripts', and should be invoked at
+       File/Create/Racket Widget.

collects/scribblings/gui/taking-screenshots/racket-widget.scm

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+;;; -*- scheme -*-
+
+(script-fu-register "script-fu-racket-widget"
+                    "Racket Widget"
+                    "Take a screen shot of a Racket Widget"
+                    "Diogo F. S. Ramos"
+                    "copyright 2012, Diogo F. S. Ramos"
+                    "August, 2012"
+                    "")
+(script-fu-menu-register "script-fu-racket-widget" "<Image>/File/Create")
+
+(define (script-fu-racket-widget)
+  (define (crop-to-selection selection image)
+    (let ((x1 (list-ref selection 0))
+          (y1 (list-ref selection 1))
+          (x2 (list-ref selection 2))
+          (y2 (list-ref selection 3)))
+      (gimp-image-crop image
+                       (- x2 x1)
+                       (- y2 y1)
+                       x1 y1)))
+  (let ((image (car (plug-in-screenshot RUN-INTERACTIVE 0 0 0 0 0 0))))
+    (gimp-fuzzy-select (car (gimp-image-get-active-drawable image))
+                       (/ (car (gimp-image-width image)) 2)
+                       (/ (car (gimp-image-height image)) 2)
+                       15.0
+                       CHANNEL-OP-REPLACE
+                       TRUE
+                       FALSE
+                       0.0
+                       TRUE)
+    (gimp-selection-invert image)
+    (gimp-selection-shrink image 1.0)
+    (crop-to-selection (cdr (gimp-selection-bounds image)) image)
+    (script-fu-addborder image
+                         (car (gimp-image-flatten image))
+                         1.0
+                         1.0
+                         '(0 0 0)
+                         25)
+    (script-fu-drop-shadow image
+                           (car (gimp-image-flatten image))
+                           8.0
+                           8.0
+                           9.0
+                           '(0 0 0)
+                           80.0
+                           1)))

collects/scribblings/gui/taking-screenshots/widget.rkt

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+#lang racket/gui
+
+(provide showcase)
+
+(define showcase (lambda (#:hmult (hmult 1) . name)
+                   (define frame (new frame% (label (if (null? name)
+                                                        "widget"
+                                                        (car name)))))
+                   (define panel (new panel% (parent frame)))
+                   (define showcase-panel (new horizontal-panel%
+                                               (parent panel)
+                                               (alignment '(center center))
+                                               (style '(border))
+                                               (min-width 242)
+                                               (min-height (* hmult 75))
+                                               (border 20)))
+                   (send frame show #t)
+                   showcase-panel))