SWT & JFace. Подключаем SWT. "Hello, World" in SWT. Создание элементов SWT. Освобождение ресурсов в SWT

SWT & JFace

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Подключаем SWT

• org.eclipse.swt_3.5.2.v3557f.jar
• org.eclipse.swt.win32.win32.x86_3.5.2.v3557f.jar

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"Hello, World" in SWT

import org.eclipse.swt.widgets.*; import org.eclipse.swt.SWT; public class HelloWorld { public static void main(String[] args) { Display display = new Display(); Shell shell = new Shell(display); Label label = new Label(shell, SWT.CENTER); label.setText("Hello, World"); label.setBounds(shell.getClientArea()); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } }

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Создание элементов SWT

• Всегда создаётся пара объектов
  • Label label = new Label(shell, SWT.CENTER);
  • //что решает ряд проблем, например (MFC)
  • CButton button; // Construct the C++ object on the stack CString str = _T("Hi"); // Create a CString to text button.SetWindowText(str); // Set the button text-PROBLEM!
  • button.Create(…); // Creates the Windows widget
• Родительский эл. и стиль
  • Label label = new Label(shell, SWT.CENTER);

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Освобождение ресурсов в SWT

• Rule 1 : If You Created it, You Dispose It
  • Color color1 = new Color(display, 255, 0, 0);
  • ………….
  • Rule 1 says you created it, so you must dispose it when you are done using it, like this:
  • color1.dispose();
  • However, if you don't call a constructor to get a resource, you must not dispose the resource:
  • Color color2 = display.getSystemColor(SWT.COLOR_RED);
  • …………..

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• Rule 2 : Disposing the Parent Disposes the Children
  • // Create the text field
  • Text text = new Text(shell, SWT.BORDER);
  • // Create the new font
  • Font font = new Font(display, "Arial", 14, SWT.BOLD);
  • // Set the font into the text field
  • text.setFont(font);
  • ???.dispose();

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• Rule 3 : Ignoring Disposed Objects
  • org.eclipse.swt.SWTException: Widget is disposed at org.eclipse.swt.SWT.error(SWT.java:2332) at org.eclipse.swt.SWT.error(SWT.java:2262) at org.eclipse.swt.widgets.Widget.error(Widget.java:385) at org.eclipse.swt.widgets.Control.getDisplay(Control.java:735) at org.eclipse.swt.widgets.Widget.isValidThread(Widget.java:593) at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:315) at org.eclipse.swt.widgets.Text.getText(Text.java:705) at Broken.main(Version.java:24)

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Display object

• void asyncExec(Runnable runnable)
  • Gives non-user-interface threads the ability to invoke the protected functions of the SWT widget classes. The user-interface thread performs the code (invokes the run() method) of the runnable at its next "reasonable opportunity." This function returns immediately.
• void syncExec(Runnable runnable)
  • Like asyncExec(), but this function returns after the run method of the Runnable object returns.
• void update()
  • Causes all pending paint requests to be processed.
• static Display findDisplay (Thread thread)
  • Given a user-interface thread, this function returns the associated Display object. If the given thread isn't a user-interface thread, this method returns null.

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Shell object

• BORDER - Adds a border.
• CLOSE - Adds a close button.
• MIN - Adds a minimize button.
• MAX - Adds a maximize button.
• NO_TRIM - Creates a Shell that has no border and can't be moved, closed, resized, minimized, or maximized. Not very useful, except perhaps for splash screens.
• RESIZE - Adds a resizable border.
• TITLE - Adds a title bar.
• DIALOG_TRIM = TITLE | CLOSE | BORDER.
• SHELL_TRIM = CLOSE | TITLE | MIN | MAX | RESIZE.
• APPLICATION_MODAL - Creates a Shell that's modal to the application.
• PRIMARY_MODAL - Creates a primary modal Shell.
• SYSTEM_MODAL - Creates a Shell that's modal system-wide.
• MODELESS - Creates a modeless Shell.

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Менеджеры расположения

• FillLayout - This layout arranges components horizontally on a row or vertically on a column (BoxLayout)
• RowLayout - Similar to FillLayout but more flexible, allowing multiple rows, fill, wrapping, and custom spacing (FlowLayout)
• GridLayout - Lays components on a grid; offers many options for fine-grained control (GridBagLayout)
• FormLayout - Relative layout that uses attachments to a container edge or a sibling widget's edge (Нет аналога)
• StackLayout - Stacks components, only top component is visible (CardLayout)
• null layout - You can place controls absolutely.

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Untyped Listeners

• Listener interface, contains one method:
  • void handleEvent(Event event)
• Add an untyped listener to a widget:
  • void addListener(int eventType, Listener l)
• button.addListener(SWT.Selection, new Listener() { public void handleEvent(Event e) {
• switch (e.type) {
• case SWT.Selection:
• System.out.println(“pressed");
• break;
• } } };

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Typed Listeners

• ControlListener - Listens for move and resize events
• DisposeListener - Listens for dispose events
• FocusListener - Listens for focus gained and lost events
• HelpListener - Listens for help requests
• KeyListener - Listens for key presses and releases
• MenuListener - Listens for menu events
• ModifyListener - Listens for text modifications
• MouseListener - Listens for mouse button presses
• MouseMoveListener - Listens for mouse movements
• MouseTrackListener - Listens for when the mouse enters
• PaintListener - Listens for paint events
• SelectionListener - Listens for selection events (for example, button clicks)
• ShellListener - Listens for shell events
• TraverseListener - Listens for traverse events
• TreeListener - Listens for tree events
• VerifyListener - Listens for, and potentially intercepts, text modifications

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• JFace:
  • Provides Viewer classes that handle the tedious tasks of populating, sorting, filtering, and updating widgets
  • Provides Actions to allow users to define their own behavior and to assign that behavior to specific components, e.g. menu items, tool items, push buttons, etc.
  • Provides registries that hold Images and Fonts
  • Defines standard dialogs and wizards, and defines a framework for building complex interactions with the user

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• Window: The org.eclipse.jface.window package provides window creation and management facilities. Of particular interest is the ApplicationWindow class, which provides a higher-level application window and encapsulates the SWT event loop.
• Viewers: The org.eclipse.jface.viewers package provides a framework of viewers such as TreeViewer and TableViewer, which are model-driven components that make use of SWT widgets and adapt content of a model to the widget.
• Dialogs: The org.eclipse.jface.dialogs package provides several commonly used dialog boxes.
• Actions: The org.eclipse.jface.actions package provides a UI action framework that's similar