Hello,
I've posted an example of a simple model-view-controller GUI skeleton
in Clojure here:
http://lifeofaprogrammergeek.blogspot.com/2009/05/model-view-controller-gui-in-clojure.html
The GUI has a text box and a panel which draws what you type. It's not
much, but I learned a lot doing it, and thought perhaps others could
benefit from seeing it.
The add-watch function is so cool!
There's probably lots of room for improvement, I would appreciate any
recommendations. I've started looking at neman.cells, but don't really
understand it yet. Might using cells simplify this code?
Best,
Curran
Here's the code:
;A test program exploring how to structure GUI code in Clojure
;The GUI draws whatever you type in the text field nicely in the panel
below.
;license: Public domain
(import '(javax.swing JFrame JLabel JTextField JButton JPanel)
'(java.awt.event ActionListener)
'(java.awt GridBagLayout GridBagConstraints Color Font
RenderingHints))
(defn make-model [] (ref "Hello MVC!"))
(defn make-graphics-panel [model]
(let [panel
(proxy [JPanel] []
(JPanel [] (println "in constructor"))
(paint [g]
(doto g
;clear the background
(.setColor (. Color black))
(.fillRect 0 0 (.getWidth this) (.getHeight this))
;draw the text
(.setRenderingHint (. RenderingHints KEY_ANTIALIASING)
(. RenderingHints VALUE_ANTIALIAS_ON))
(.setFont (Font. "Serif" (. Font PLAIN) 40))
(.setColor (. Color white))
(.drawString @model 20 40))))]
;repaint when the model changes
(add-watch model "repaint" (fn [k r o n] (.repaint panel)))
panel))
(defn make-text-field [model]
(doto (JTextField.)
(.setText @model)
(.addActionListener
(proxy [ActionListener] []
(actionPerformed [e]
(let [new-text (.getActionCommand e)]
(dosync (ref-set model new-text))))))))
(defn make-gui-panel [model]
(defn make-text-field-constraints []
(let [c (GridBagConstraints.)]
(set! (.fill c) (. GridBagConstraints HORIZONTAL))
(set! (.weightx c) 1)
c))
(defn make-panel-constraints []
(let [c (GridBagConstraints.)]
(set! (.gridy c) 1)
(set! (.weighty c) 1)
(set! (.fill c) (. GridBagConstraints BOTH))
c))
(let [gridbag (GridBagLayout.)
text-field (make-text-field model)
panel (make-graphics-panel model)]
;set up the gridbag constraints
(doto gridbag
(.setConstraints text-field (make-text-field-constraints))
(.setConstraints panel (make-panel-constraints)))
;add the components to the panel and return it
(doto (JPanel.)
(.setLayout gridbag)
(.add text-field)
(.add panel))))
(defn show-in-frame [panel width height frame-title]
(doto (JFrame. frame-title)
(.add panel)
(.setSize width height)
(.setVisible true)))
(show-in-frame (make-gui-panel (make-model)) 300 110 "GUI Test")
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