add get-gl-client-size to canvas%

GL scaling in a canvas depends on a combination of the `gl-config%`
setting and the platform, so `get-gl-client-size` takes into account
both.

gui-doc/scribblings/gui/canvas-class.scrbl

@@ -100,6 +100,20 @@ The @racket[gl-config] argument determines properties of an OpenGL
 }
 
 
+@defmethod[(get-gl-client-size) (values dimension-integer? dimension-integer?)]{
+
+Returns the canvas's drawing-area dimensions in OpenGL units for a
+@racket[canvas%] instance with the @racket['gl] style.
+
+The result is the same as @method[canvas<%> get-unscaled-client-size]
+in a canvas without the @racket['gl] style or on Windows and Unix. On
+Mac OS X, the result can be the same as @method[window<%>
+get-client-size] if the @racket[gl-config%] specification provided on
+creation does not specify high-resolution mode.
+
+@history[#:added "1.16]}
+
+
 @defmethod[(get-scroll-page [which (or/c 'horizontal 'vertical)])
            positive-dimension-integer?]{
 

gui-doc/scribblings/gui/canvas-intf.scrbl

@@ -158,7 +158,8 @@ a viewport size for OpenGL drawing in @racket[canvas%] instance with
 the @racket['gl] style. On Mac OS X, however, the viewport will match
 the scaled size unless the canvas is created with a
 @racket[gl-config%] specification that is adjusted to high-resolution
-mode via @method[gl-config% set-hires-mode].
+mode via @method[gl-config% set-hires-mode]. See also
+@xmethod[canvas% get-gl-client-size].
 
 @history[#:added "1.13"]}
 

gui-lib/info.rkt

@@ -30,4 +30,4 @@
 
 (define pkg-authors '(mflatt robby))
 
-(define version "1.15")
+(define version "1.16")

gui-lib/mred/private/mrcanvas.rkt

@@ -134,6 +134,8 @@
         (if ctx
             (send ctx call-as-current thunk)
             (fail))))
+    (define/public (get-gl-client-size)
+      (send wx get-gl-client-size))
     (define accept-tab-focus
       (entry-point
        (case-lambda

gui-lib/mred/private/wx/cocoa/canvas.rkt

@@ -884,6 +884,15 @@
        (define cw (->long (NSSize-width cs)))
        (define ch (->long (NSSize-height cs)))
        (values cw ch))
+     
+     (define/public (get-gl-client-size)
+       (if (or (not is-gl?)
+               (tell #:type _BOOL content-cocoa wantsBestResolutionOpenGLSurface))
+           (get-scaled-client-size)
+           (let ([x (box 0)]
+                 [y (box 0)])
+             (get-client-size x y)
+             (values (unbox x) (unbox y)))))
 
      (define/override (get-cursor-width-delta)
        0)

gui-lib/mred/private/wx/gtk/canvas.rkt

@@ -504,7 +504,13 @@
        (define wb (box #f))
        (define hb (box #f))
        (get-client-size wb hb)
-       (values (->screen (unbox wb)) (->screen (unbox hb))))
+       (define s (if gtk3?
+		     (gtk_widget_get_scale_factor gtk)
+		     1))
+       (values (* s (->screen (unbox wb))) (* s (->screen (unbox hb)))))
+
+     (define/public (get-gl-client-size)
+       (get-scaled-client-size))
 
      (define/override (get-client-gtk) client-gtk)
      (define/override (get-container-gtk) container-gtk)

gui-lib/mred/private/wx/win32/window.rkt

@@ -491,6 +491,9 @@
     (let ([r (GetClientRect (get-client-hwnd))])
       (values (- (RECT-right r) (RECT-left r))
               (- (RECT-bottom r) (RECT-top r)))))
+  
+  (define/public (get-gl-client-size)
+    (get-scaled-client-size))
 
   (define/public (get-size w h)
     (let ([r (GetWindowRect (get-client-hwnd))])