3dsnip: center the interactive message on the plot area (racket#80, r…

…acket#49)

When the legend is placed outside the plot, the message used to be in the center of the entire 
plot image, which didn't look correct.

plot-gui-lib/plot/private/gui/lazy-snip-types.rkt

@@ -19,9 +19,11 @@
 (define-type Make-3D-Plot-Snip
   (-> (Instance Bitmap%)
       Plot-Parameters
-      (-> Boolean Real Real Positive-Integer Positive-Integer (Instance Bitmap%))
+      (-> Boolean Real Real Positive-Integer Positive-Integer
+          (Values (Instance Bitmap%) (U #f (Instance 3D-Plot-Area%))))
       Real
       Real
+      (U #f (Instance 3D-Plot-Area%))
       Positive-Integer
       Positive-Integer
       (Instance Snip%)))

plot-gui-lib/plot/private/gui/lazy-snip-untyped.rkt

@@ -20,10 +20,10 @@
 
 (define (-make-3d-plot-snip
          init-bm saved-plot-parameters
-         make-bm angle altitude width height)
+         make-bm angle altitude area width height)
   (make-3d-plot-snip
    init-bm saved-plot-parameters
-   make-bm angle altitude width height))
+   make-bm angle altitude area width height))
 
 (define (-make-snip-frame snip width height label)
   (make-snip-frame snip width height label))

plot-gui-lib/plot/private/gui/plot3d.rkt

@@ -93,7 +93,7 @@
     ;; For 3D legend can be calculated once since we don't change the bounding box
     (define legend (get-legend-entry-list renderer-list bounds-rect))
 
-    (: make-bm (-> Boolean Real Real Positive-Integer Positive-Integer (Instance Bitmap%)))
+    (: make-bm (-> Boolean Real Real Positive-Integer Positive-Integer (Values (Instance Bitmap%) (U #f (Instance 3D-Plot-Area%)))))
     (define (make-bm anim? angle altitude width height)
       (parameterize/group ([plot-parameters  saved-plot-parameters]
                            [plot-animating?  (if anim? #t (plot-animating?))]
@@ -124,11 +124,12 @@
 
         (send area end-renderers)
         (send area end-plot)
-        bm))
+        (values bm area)))
 
+    (define-values (bm area) (make-bm #f angle altitude width height))
     (make-3d-plot-snip
-     (make-bm #f angle altitude width height) saved-plot-parameters
-     make-bm angle altitude width height)))
+     bm saved-plot-parameters
+     make-bm angle altitude area width height)))
 
 ;; ===================================================================================================
 ;; Plot to a frame

plot-gui-lib/plot/private/gui/snip3d.rkt

@@ -17,20 +17,26 @@
 (define 3d-plot-snip%
   (class plot-snip%
     (init init-bm saved-plot-parameters)
-    (init-field make-bm angle altitude width height)
+    (init-field make-bm angle altitude area width height)
 
     (inherit set-bitmap get-bitmap
              get-saved-plot-parameters
-             set-message stop-message set-message-center reset-message-timeout
+             set-message stop-message reset-message-timeout
              update-thread-running? set-update
              get-left-down-here?)
 
     (super-make-object init-bm saved-plot-parameters)
 
+    (define (set-message-center)
+      (match-define (vector x-mid y-mid) (rect-center (send area get-area-bounds-rect)))
+      (send this set-message-center x-mid y-mid))
+
+    (set-message-center)
+
     (define/override (copy)
       (make-object this%
         (get-bitmap) (get-saved-plot-parameters)
-        make-bm angle altitude width height))
+        make-bm angle altitude area width height))
 
     (define mouse-x 0)
     (define mouse-y 0)
@@ -58,8 +64,10 @@
                       (make-bm animating? angle altitude width height)])))
             (λ (animating?) (draw-command animating? angle altitude width height))
             (λ (rth)
-              (define new-bm (worker-thread-try-get rth))
+              (define-values (new-bm new-area)
+                (worker-thread-try-get rth (λ () (values #f #f))))
               (cond [(is-a? new-bm bitmap%)
+                     (set! area new-area)
                      (set-bitmap new-bm)
                      (when (not (and (= last-angle angle)
                                      (= last-altitude altitude)))
@@ -126,7 +134,7 @@
       (when (not (and (= w width) (= h height)))
         (set! width w)
         (set! height h)
-        (set-message-center (* 1/2 w) (* 1/2 h))
+        (set-message-center)
         (stop-message)
         (when (not (update-thread-running?))
           (start-update-thread #t))
@@ -136,7 +144,7 @@
 
 (define (make-3d-plot-snip
          init-bm saved-plot-parameters
-         make-bm angle altitude width height)
+         make-bm angle altitude area width height)
   (make-object 3d-plot-snip%
     init-bm saved-plot-parameters
-    make-bm angle altitude width height))
+    make-bm angle altitude area width height))

plot-lib/plot/private/plot3d/plot-area.rkt

@@ -114,6 +114,7 @@
          [get-z-far-ticks (-> (Listof tick))]
          [get-bounds-rect (-> Rect)]
          [get-clip-rect (-> Rect)]
+         [get-area-bounds-rect (-> Rect)]
          [get-render-tasks  (-> render-tasks)]
          [set-render-tasks  (-> render-tasks Void)]
          [start-plot (-> Void)]
@@ -969,6 +970,9 @@
     (define area-y-min top)
     (define area-y-max (- dc-y-size bottom))
 
+    (define/public (get-area-bounds-rect)
+      (vector (ivl area-x-min area-x-max) (ivl area-y-min area-y-max)))
+
     ;; ===============================================================================================
     ;; Plot decoration