AWT Enhancements in V1.1 - Supporting Richer GUI Development
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The AWT was modified in version 1.1 of the JDK to provide major quality improvements while introducing the beginnings of a richer infrastructure for larger-scale GUI development.
![TRACKING THE MEDIA
• Useful for synchronous media preparation
• Defined in the MediaTracker class
• Applicable to both audio and images, but only images
supported currently
tracker = new MediaTracker(this);
for (int i = 0; i < 5; i++)
tracker.addImage(anim[i], 1);
for (int i = 0; i < 5; i++)
tracker.waitForID(i);](https://image.slidesharecdn.com/awtenhancements-250311020439-b96397d6/85/AWT-Enhancements-in-V1-1-Supporting-Richer-GUI-Development-21-320.jpg)
AWT Enhancements in V1.1 - Supporting Richer GUI Development
- 1. AWT ENHANCEMENTS Arun Seetharaman March 10, 1998
- 2. OVERVIEW • AWT Enhancements • Popup menus • Scroll pane • Clipboard • The AppletContext object • Audio and Images • Inter-applet communication
- 3. DESKTOP COLORS • The new SystemColor class helps Java detect the color scheme set for the desktop • Programmers can uses these colors by accessing the final members of the class • activeCaption : Caption background color • contolText : Control’s text color • desktop : Desktop’s background color • menuText : Menu’s text color • window : Window’s background color
- 4. POPUP MENUS • Dynamically popped menus as specified position within the component • Defined the PopupMenu class of Java • Invoke the show method to popup the menu • void show(Component,int,int) • If the popup menu object is used in place of a menu item, the show() cannot be invoked
- 5. POPUP MENU - AN EXAMPLE public void mouseReleased( MouseEvent evt) { if (evt.isPopupTrigger()) { popup.show(evt.getSource(), evt.getX(), evt.getY()); } else { System.out.println("no popup"); } }
- 7. SCROLLING CONTAINERS • Container implementing automatic scrolling for a single child component • Needed in situations where the viewport is smaller than the window • Clipping the child’s contents appropriately depending on the scroll position
- 8. THE SCROLLPANE CLASS • Display policy can be set • as needed • always • never • Placement is controlled by platform-specifc properties • Implements the Adjustable interface, which can be used for fine tuning
- 9. SCROLLPANE - AN EXAMPLE ScrollPane sp = new ScrollPane(); sp.getHAdjustable().setUnitIncrement(2); sp.getVAdjustable().setUnitIncrement(2); sp.add(new ImageComponent( getToolkit().getImage(filename))); add(sp, BorderLayout.CENTER); setSize(200, 150);
- 11. DATA TRANSFER • Clipboard and Drag-drop are the two major models of data transfer • Data transfer occurs using “flavors” defined by the Transfer APIs • The flavors to be used for data transfer encapsulate the various MIME types • The java.awt.datatransfer package caters to the needs of these operations
- 12. CLIPBOARD • Clipboard is a globally shared memory • The toolkit has an instance of a clipboard, that uses the system clipboard • Class willing to write to a clipboard need to implement the ClipboardOwner interface • Data flavors need to be compatible for transfer of data using clipboard
- 13. WRITING TO A CLIPBOARD class ClipboardSource extends Frame implements ClipboardOwner { TextArea ta = new TextArea(); void setContents() { String s = ta.getSelectedText(); StringSelection contents = new StringSelection(s); getToolkit().getSystemClipboard( ).setContents(contents, this); } }
- 15. READING FROM CLIPBOARD Transferable t = getToolkit(). getSystemClipboard().getContents( this); if(t.isDataFlavorSupported( DataFlavor.stringFlavor)) { String str = t.getTransferData( DataFlavor.stringFlavor); }
- 16. DRAG AND DROP • Uses the same data transfer mechanism • Discussed later as a part of JFC
- 17. APPLET CONTEXT • Corresponds to the applet’s execution environment • In the normal execution circumstances, this object is the browser • Defined by the AppletContext interface • Use the getAppletContext() method to access the context object
- 18. USING AUDIO • Defined by the AudioClip interface • A simple abstraction for playing audio clips • Multiple clips can be played simltaneously • Created using the getAudioClip() method of the applet context • Can play the audio clip using • play() • loop()
- 19. IMAGING • Defined by the Image class • BufferedImage can be used to achieve buffering during image rendering • Use getImage() of applet context to create a Image object • Use the drawImage() method in the Graphics class to render images
- 20. ADVANCED FEATURES • Defined in the java.awt.image package • ImageProducer : a source of image data • ImageConsumer : a user of image data • ImageObserver : asynchronous notification on the image • Defines color models to be used • Defines some image filters
- 21. TRACKING THE MEDIA • Useful for synchronous media preparation • Defined in the MediaTracker class • Applicable to both audio and images, but only images supported currently tracker = new MediaTracker(this); for (int i = 0; i < 5; i++) tracker.addImage(anim[i], 1); for (int i = 0; i < 5; i++) tracker.waitForID(i);
- 22. LOADING WEB PAGES • Java applets can load other web pages • Use the showDocument() method of the applet context • Can also be used to address framesets • _self : same frame • _parent : applet’s parent frame • _top : top-level frame of applet • _new : a new top-level window • name : specified frame name
- 23. INTER-APPLET COMMUNICATION • Applets within the same applet context can communicate with each other • Obtain the object reference of the other applets using • void getApplet(String); • Enumeration getApplets(); • Communicate by invoking public methods
- 24. SCRIPTING APPLETS • Help in communicating with applets from an external entity <SCRIPT LANGUAGE=VBScript> Sub Update_onClick() Marquee.setMessage(Message.Value) End Sub </SCRIPT> <INPUT TYPE="Text" NAME="Message" VALUE=""> <INPUT TYPE="Button" NAME="Update" VALUE="Update">
- 25. REVIEW • AWT offer capabilities like context menus, clipboard support etc. • Applet contexts help in • rendering images and playing audio • loading web pages • inter-applet communication