WIP: more work towards implementing pan/zoom in a pure-Reactive framework

src/GtkUtilities.jl

@@ -2,31 +2,21 @@ __precompile__()
 
 module GtkUtilities
 
-using Cairo, Gtk.ShortNames, Colors
-
-using Graphics
+using Cairo, Gtk.ShortNames, Colors, Reactive, Graphics
+import Gtk.GConstants.GdkEventMask: KEY_PRESS, SCROLL
 
 export
-    # Link
-    AbstractState,
-    State,
-    link,
-    disconnect,
-    get,
-    set!,
-    set_quietly!,
-    widget,
-    id,
-    lLabel,
-    lEntry,
-    lScale,
+    # general
+    keysignal,
+    mouseposition,
     # GUIData
     guidata,
     trigger,
     # Rubberband
     rubberband_start,
     # PanZoom
     Interval,
+    ViewROI,
     interior,
     fullview,
     panzoom,
@@ -44,6 +34,39 @@ include("panzoom.jl")
 using .PanZoom
 import .PanZoom: interior, fullview   # for extensions
 
+"""
+    signal = keysignal(widget, [setfocus=true])
+
+Create a signal for monitoring keypresses on a canvas or other
+`widget`. The signal fires every time a key is pressed. At least for
+some widgets (e.g., canvases), `setfocus` must be true or the widget
+will not process key press events.
+
+The signal value is a GdkEventKey; the `keyval` and `state` fields can
+be used to monitor the pressed key and any held modifiers,
+respectively.
+"""
+function keysignal(widget::Gtk.GtkWidget, setfocus::Bool=true)
+    add_events(widget, KEY_PRESS)
+    if setfocus
+        setproperty!(widget, :can_focus, true)
+        setproperty!(widget, :has_focus, true)
+    end
+    evt = Gtk.GdkEventKey()
+    sig = Signal(evt)
+    id = signal_connect(widget, :key_press_event) do widget, event
+        push!(sig, event)
+    end
+    return sig
+end
+
+"""
+    signal = mouseposition(canvas)
+
+Creates a Reactive signal that updates whenever the mouse pointer
+position changes within the canvas.
+"""
+
 function Base.copy!{C<:Colorant}(ctx::CairoContext, img::AbstractArray{C})
     save(ctx)
     Cairo.reset_transform(ctx)