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One Tutorial For All

Szymon Witamborski edited this page · 24 revisions

In this tutorial I'll cover Swing and SWT at once. First reason for this is I'm lazy and don't want to write two identical tutorials. Second would be demonstrating the hype: "Wow, you can use GUI FTW! with Swing and SWT!"

Please, read Overview now. Probably code in this tutorial explains itself but in case in doubt, refer to the overview.

Project

First, we need to init a project with Leiningen.

Swing SWT
d:/Tymczas $ lein new swingftw
Created new project in: d:\Tymczas\swingftw
d:/Tymczas $ cd swingftw/
d:/Tymczas/swingftw $
d:/Tymczas $ lein new swtftw
Created new project in: d:\Tymczas\swtftw
d:/Tymczas $ cd swtftw/
d:/Tymczas/swtftw $

Dependencies

Then, we need to edit project.clj files. We'll set dependencies and set :main class (to be able to easily run it from command line). Look on Clojars for the newest version of GUI FTW!.

Swing SWT
For Swing we add just GUI FTW!. In SWT we need to add GUI FTW! and SWT in version specific to your OS/architecture. Use Clojars again to find the one for you.
```clj (defproject swingftw "1.0.0-SNAPSHOT" :description "FIXME: write description" :main swingftw.core :dependencies [[org.clojure/clojure "1.2.0"] [guiftw "0.2.0-SNAPSHOT"]]) ``` ```clj (defproject swtftw "1.0.0-SNAPSHOT" :description "FIXME: write description" :main swtftw.core :dependencies [[org.clojure/clojure "1.2.0"] [guiftw "0.2.0-SNAPSHOT"] [org.eclipse/swt-win32-win32-x86_64 "3.5.2"]]) ```

Then, run lein deps and wait until Leiningen downloads all libraries.

Writing Code

Our program won't be complicated: we'll create a small window with one button and hook into one event.

Importing

We need to import every class that we want to use without naming the package each time. GUI FTW! could have automatic lookup but doesn't because GUI FTW! can support any custom widgets from any custom namespace.

Swing SWT
Open src/swingftw/core.clj. We need to import JFrame (window), JButton and JOptionPane (to show message dialog) classes from javax.swing. We need also ActionListener to hook into button action. On GUI FTW! part, we need to :use (or :refer) guiftw.swing and guiftw.styles. Open src/swtftw/core.clj. We need Shell, Button, MessageBox and FillLayout classes. We also need SelectionListener interface to hook into widgetSelected event. Also, every SWT app need SWT class. On GUI FTW! part, we need to :use (or :refer) guiftw.swt and guiftw.styles.
```clj (ns swingftw.core (:gen-class) (:use (guiftw swing styles)) (:import (javax.swing JOptionPane JFrame JButton) (java.awt.event ActionListener))) ``` ```clj (ns swtftw.core (:gen-class) (:use (guiftw swt styles)) (:import (org.eclipse.swt SWT) (org.eclipse.swt.widgets Shell Button MessageBox) (org.eclipse.swt.events SelectionListener) (org.eclipse.swt.layout FillLayout))) ```

Notice also the (:gen-class) line. Thanks to that Clojure compiler will create a class named just like the namespace.

GUI Structure

Here we define structure of our GUI. In this example we have just one button inside one window. The resulting window function will be used to create GUI at runtime. To keep code maximally clean objects will get only ids and no properties.

Swing SWT
```clj (def window (swing [JFrame [*id :main-window] [JButton [*id :super-button]]])) ``` ```clj (def window (swt [Shell [*id :main-window] [Button [*id :super-button]]])) ```

Event handler

We want to handle button action (either mouse clicking or pressing Enter key). We'll display simple info about event and use this function to get that info:

(defn get-info [obj]
  (reduce str
    (for [[k v] (bean obj)]
      (str k " " (->> v str (take 50) (reduce str)) "\n"))))

Notice that we shorten each value to 50 characters max.

Handlers:

Swing SWT
```clj (defn show-info [gui event] (JOptionPane/showMessageDialog (:root @gui) (get-info event) "Event Info" JOptionPane/INFORMATION_MESSAGE)) ``` ```clj (defn show-info [gui event] (doto (MessageBox. (:root @gui) (bit-or SWT/ICON_INFORMATION SWT/OK)) (.setText "Event Info") (.setMessage (get-info event)) .open)) ```

Style Sheets

Now it's time to define how our window will look like.

Swing SWT
```clj (def look (stylesheet [:main-window] [:title "Swing FTW!" :size ^unroll (300 200) :default-close-operation JFrame/EXIT_ON_CLOSE :visible true] [:super-button] [:text "Make something happen!"])) ``` ```clj (def look (stylesheet [:main-window] [:text "SWT FTW!" :size ^unroll (300 200) :layout (FillLayout.)] [:super-button] [:*cons [SWT/PUSH] :text "Make something happen!"))) ```

And how will our button behave. Look and actions are here put separetly just because it's probably not good idea to mix them for the sake of code elegance.

Swing SWT
```clj (def actions (stylesheet [:super-button] [:action++performed show-info])) ``` ```clj (def actions (stylesheet [:super-button] [:selection+widget-selected show-info])) ```

Main Function

Thanks to :gen-class, we can create -main fn for entry point to our program (in generated class, -main function is implementation of static void main(String[] args)). Most simple applications just start one window and exit when user close that window and that's how this example will behave.

The essential part is to create a window by invoking generated window function with style sheets as parameters.

Swing SWT
Swing implementation is really straightforward: we just create the window. :default-close-operation property of the window will cause program to exit when window is closed. We'll also set Nimbus LAF, just because the default is ugly. In SWT, it's necessary to handle the event loop by hand. GUI FTW! have a function for that: swt-loop. It takes optional shell argument to stop the loop when the shell is closed. We also need to manually invoke the open method on window.
```clj (defn -main [& args] (set-laf "Nimbus") (window look actions)) ``` ```clj (defn -main [& args] (let [gui (window look actions) shell (:root @gui)] (.open shell) (swt-loop shell))) ```

Running

To run the example just type lein run in command line. You can also do lein uberjar and start the uberjar (file with standalone suffix) like any other Java application (either double-clicking or by java -jar <file>.jar).

Full code here:

Swing SWT
project.clj
src/swingftw/core.clj
project.clj
src/swtftw/core.clj

You can also clone this wiki repo and navigate to sources dir.

git clone https://santamon@github.com/santamon/GUIFTW.wiki.git
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