Add convenience definitions to (lispkit draw).

Author: objecthub

Sources/LispKit/Primitives/DrawingLibrary.swift

@@ -101,7 +101,7 @@ public final class DrawingLibrary: NativeLibrary {
 
   /// Dependencies of the library.
   public override func dependencies() {
-    self.`import`(from: ["lispkit", "core"],    "define-syntax", "syntax-rules")
+    self.`import`(from: ["lispkit", "core"],    "define", "define-syntax", "syntax-rules")
     self.`import`(from: ["lispkit", "control"], "let")
     self.`import`(from: ["lispkit", "dynamic"], "parameterize")
     self.`import`(from: ["lispkit", "system"],  "current-directory")
@@ -200,6 +200,16 @@ public final class DrawingLibrary: NativeLibrary {
     self.define(Procedure("rect-width", rectWidth))
     self.define(Procedure("rect-height", rectHeight))
 
+    // Define constants
+    self.define("zero-point", via: "(define zero-point (point 0 0))")
+    self.define("black", via: "(define black (make-color 0 0 0))")
+    self.define("gray", via: "(define gray (make-color 0.5 0.5 0.5))")
+    self.define("white", via: "(define white (make-color 1 1 1))")
+    self.define("red", via: "(define red (make-color 1 0 0))")
+    self.define("green", via: "(define green (make-color 0 1 0))")
+    self.define("blue", via: "(define blue (make-color 0 0 1))")
+    self.define("yellow", via: "(define yellow (make-color 1 1 0))")
+    
     // Syntax definitions
     self.define("drawing", via: """
       (define-syntax drawing

Sources/LispKit/Resources/Examples/Plot.scm

@@ -42,20 +42,21 @@
       ; Move rest of drawing into the bounding box
       (transform (translate (rect-x rect) (rect-y rect))
         ; Draw the coordinate axis
-        (make-color 0.3 0.3 0.3)
+        (set-color (make-color 0.3 0.3 0.3))
         (if (and (<= xmin 0.0) (>= xmax 0.0))
           (draw (line (point (* xfac (- xmin)) 0)
                       (point (* xfac (- xmin)) (rect-height rect))) 0.3))
         (if (and (<= ymin 0.0) (>= ymax 0.0))
           (draw (line (point 0 (+ (rect-height rect) (* yfac ymin)))
                       (point (rect-width rect) (+ (rect-height rect) (* yfac ymin)))) 0.3))
         ; Draw flipped interpolation shape
-        (set-color (make-color 0 0 1))
+        (set-color blue)
         (draw graph)
         ; Draw interpolation points
-        (set-color (make-color 0 0 0))
-        (set-fill-color (make-color 0 0 0))
-        (for-each (lambda (p) (fill (flip-shape (circle p 1) (shape-bounds graph)))) ps)
+        (set-fill-color white)
+        (for-each (lambda (p)
+                    (let ((s (flip-shape (circle p 1) (shape-bounds graph))))
+                      (fill s) (draw s 0.3))) ps)
         ; Draw the label
         (draw-text label
                    (point 30 (- (rect-height rect) 12))
@@ -68,10 +69,7 @@
   (define page
     (drawing
       ; Draw a header in font "Helvetica-Bold" of size 8
-      (draw-text "Demo of library (lispkit draw)"
-                 (point 160 8)
-                 (font "Helvetica-Bold" 8)
-                 (make-color 0 0 0))
+      (draw-text "Demo of library (lispkit draw)" (point 160 8) (font "Helvetica-Bold" 8) black)
       ; Plot four graphs
       (draw-drawing (plot sin -1 6.3 50 (rect 10 30 200 100) "sin(x)"))
       (draw-drawing (plot cos -1 6.3 50 (rect 220 30 200 100) "cos(x)"))