CS 209 Programming in Java #13 Multimedia

Transcription

1 CS 209 Programming in Java #13 Multimedia Part of Textbook Chapter 14 Spring, 2006 Instructor: J.G. Neal 1 Topics Multimedia Displaying Images Using the MediaTracker class Images in Applets and Applications Playing Audio Clips Audio Clips in Applets Using the Timer Class for Animation Example Programs 2

2 Multimedia Media Can include images, audio, video, etc. Java program needs to: Get the media files Display/play/pause/replay/stop the media objects How to handle media in: Applets Applications 3 Image Display Relevant Classes Relevant classes for getting and displaying Images: 1. Use the Toolkit class and its methods such as getdefaulttoolkit and getimage 2. Use the Applet class and its methods such as getcodebase, getimage 3. Use the Class class and its methods such as getresouce 4. Use the Image class and its methods such as getheight and getwidth 5. Use the Graphics class and its method drawimage 6. Use the ImageIcon class and its methods such as loadimage and painticon 4

3 Methods Used to Get an Image for Display Methods in the Applet class Get base URL URL getcodebase() - Gets the base URL for folder URL getdocumentbase() - Returns an absolute URL for the document in which the applet is embedded Get the image public Image getimage(url url) public Image getimage(url url, String filename) 5 Getting Images in a Java Program Approach 1: Use JApplet methods getcodebase and getimage Example: String imagepath0 = "images/dukewave.gif"; String imagepath1 = "images/duke2.gif"; img0 = getimage(getcodebase(), imagepath0); img1 = getimage(getcodebase(), imagepath1); try { mt.addimage(img0, 0); mt.addimage(img1, 0); mt.waitforid(0); } catch (Exception ex) { System.out.println("\n" + ex.tostring()); } 6

4 Getting Images in a Java Program Approach 2: Use the URL class and method getresource from class Class Example: String imagepath0a = "../images/dukewave.gif"; String imagepath1a = "../images/duke2.gif"; Class object = this.getclass(); URL url0 = object.getresource(imagepath0a); URL url1 = object.getresource(imagepath1a); System.out.println("url0 = " + url0.tostring()); System.out.println("url1 = " + url1.tostring()); if ((url0!= null) && (url1!= null)) { img0 = getimage(url0); img1 = getimage(url1); try { mt.addimage(img0, 0); mt.addimage(img1, 0); mt.waitforid(0); } catch (Exception ex) { System.out.println("\n" + ex.tostring()); } } 7 Getting Images in a Java Program Approach 3: Use the Toolkit class Static Toolkit getdefaulttoolkit() - Gets the default AWT toolkit Image getimage(string filename) - Returns an image which gets pixel data from the specified file, whose format can be either GIF, JPEG or PNG Image getimage(url url) - Returns an image which gets pixel data from the specified URL Also has methods to: Get the screen resolution in dots-per-inch Get the screen size Get the system clipboard Among others Example: img[i] = Toolkit.getDefaultToolkit().getImage(imgFileName); 8

5 Displaying Images Using Graphics Methods Methods in the Graphics class to draw the image drawimage(image img, int x, int y, Color bgcolor, ImageObserver observer) - Draws the image in the specified location. The image s upper left corner is at (x, y) in the coordinate space of the graphics context. Transparent pixels are drawn in the bgcolor. The observer is the object on which the image is displayed. The image is cut off if it is larger than the area upon which it is drawn. drawimage(image img, int x, int y, ImageObserver observer) - Same as above, but no bgcolor. drawimage(image img, int x, int y, int width, int height, ImageObserver observer) - Draws a scaled version of the image. drawimage(image img, int x, int y, int width, int height, ImageObserver observer) - Same as above, but includes background color. 9 MediaTracker Class A utility class to track the status of media objects In the package: java.awt Use the import statement: import java.awt.mediatracker; Or use import statement: import java.awt.*; Media objects Could include images, audio clips, etc. As of j2sdk1.4.0, only images were supported (continued on next slide) 10

6 MediaTracker Class (cont.) To use a MediaTracker: Create an instance of the MediaTracker class MediaTracker(Component c) - Track for component c Call the MediaTracker addimage method for each image to be tracked addimage(image image, int id) - adds an image to the list of images being tracked by this media tracker addimage(image image, int id, int w, int h) - adds a scaled image to the list of images being tracked by this tracker Call the MediaTracker checkall method checkall() - checks to see if all images being tracked by this media tracker have finished loading; does not start loading any images checkall(boolean load) - checks to see if all images being tracked by this media tracker have finished loading; if the parameter is true, this method starts loading any images that are not yet being loaded (continued on next slide) 11 MediaTracker Class (cont.) Each image can be assigned a priority level identifier ID The ID controls the priority order in which images are fetched The ID is commonly not unique per image Images with a lower ID are loaded in preference to those with a higher ID number Call one of the wait methods to control processing void waitforall() - starts loading all tracked images; waits until all the images being tracked have finished loading void waitforid(int id) - starts loading all tracked images with specified ID (priority level); waits until all the images with the specified ID have finished loading 12

7 Example Java Program Purpose: To demonstrate Use of images in a Java program Providing adequate display area and scroll capabilities Program: Class name: ImageEx Package name: mymediaexs Project name: MyMediaExs Program code: See next pages 13 Example Program Execution 14

8 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\MyMedia\MyMediaExs\src\mymediaexs\ImageEx.java at 4/27/06 5:16 1 package 2 3 import 4 import 5 import 6 import 7 8 public class ImageEx extends JFrame { 9 // Instance variables 10 private 11 private 12 private private Image img = null 15 private MediaTracker mt = new MediaTracker( this 16 private int 17 private float 18 private float // The main method required for an application program 21 public static void main( String[] args ) { 22 JFrame frame = new ImageEx // Construct the window 23 frame.setsize(new Dimension 24 frame.setdefaultcloseoperation 25 frame.setvisible( true // Make the window visible 26 } public ImageEx() { 29 super 30 Container c = getcontentpane // Get content pane for JFrame window 31 c.setlayout( new BorderLayout // Set layout manager for window 32 CanvasPanel cpan = new CanvasPanel img = Toolkit.getDefaultToolkit().getImage 35 try { 36 mt.addimage 37 mt.waitforid 38 System.out.println 39 } catch ( Exception ex ) { 40 System.out.println( "\n" + ex.tostring 41 } 42 h = img.getheight( null 43 w = img.getwidth( null 44 cpan.setpreferredsize( new Dimension( Math.round(scaleFactorUp * w), 45 Math.round((scaleFactorUp + Page 1

9 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\MyMedia\MyMediaExs\src\mymediaexs\ImageEx.java at 4/27/06 5:16 46 cpan.setvisible( true 47 JScrollPane jscrollpane = new JScrollPane(cPan, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, 49 c.add 50 } // Class to provide a drawing surface for graphics display 53 class CanvasPanel extends JPanel { 54 // Constructor 55 public CanvasPanel() { 56 setbackground 57 } public void paintcomponent ( Graphics g ) { 60 super.paintcomponent 61 int 62 int 63 int 64 g.drawstring( "Image Width: " + w + ", Height: " + h, xpos, ypos 65 g.drawimage( img, xpos, ypos + sp, null // Draw scaled down version of image using method drawimage 68 int wdown = Math.round 69 int hdown = Math.round 70 g.drawstring( "Image scaled down by factor of: " + scalefactordown + 71 ", Width: " + wdown + ", Height: " + hdown, 73 g.drawimage( img, xpos, 5*sp + h, wdown, hdown, null // Create new scaled up version of image and draw it 76 int wup = Math.round 77 int hup = Math.round 78 g.drawstring( "Image scaled up by factor of: " + scalefactorup + 79 ", Width: " + w*scalefactorup + ", Height: " + h*scalefactorup, 81 g.drawimage( img, xpos, 8*sp + h + hdown, wup, hup, null 82 } 83 } // End canvaspanel class 84 } 85 Page 2

10 Displaying Images Using the ImageIcon Class Constructors and methods in the ImageIcon class Create an ImageIcon ImageIcon(Image img) - Creates ImageIcon from Image object ImageIcon(String filename) - Creates ImageIcon from file ImageIcon(URL url) - Creates ImageIcon from url Methods in the ImageIcon class int geticonheight() - Gets height of ImageIcon object int geticonwidth() - Gets width of ImageIcon object void loadimage(image img) - Loads image, returning when load is complete void painticon(component c, Graphics g, int x, int y) - Paints the icon 15 Create New Component to Display Image Various components can display images Using the JLabel class JLabel(Icon icon) JLabel(Icon icon, int halignment) JLabel(String text, Icon icon, int halignment) void seticon(icon icon) Using the JButton class JButton(Icon icon) JButton(String text, Icon icon) 16

11 Example Program Purpose: To demonstrate Use of an application program and Use of images in the graphical user interface Program: Class name: TextCompEx2Done Package name: widgetexs Project name: WidgetExs Questions: Can an image be replaced during runtime? If so, how? 17 Example Program 18

12 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\GuiDev\WidgetExs\src\widgetexs\TextCompEx2Done.java at 4/28/06 1 package 2 3 import 4 import 5 import 6 import 7 import 8 9 public class TextCompEx2Done extends JFrame implements ActionListener, ItemListener { 10 // Declare instance variables 11 private // Explanatory info for user 12 private 13 private //JCheckBox for setting line wrap 14 private // The JComboBox for font selection 15 private //JCheckBoxes for two font styles 16 private // The JComboBox for font size selection 17 private // Display area for text private // The color defined by user 20 private int 21 private int 22 private 23 private Font selectedfont = new Font(selectedFace, selectedstyle, 25 private String fontnames[] = { 27 private String fontsizes[] = { // The main method required for an application program 31 public static void main(string[] args) { 32 JFrame frame = new TextCompEx2Done // Construct the window 33 frame.setsize(new Dimension // Set its size 34 frame.setdefaultcloseoperation 35 frame.setvisible(true // Make the window visible 36 } public TextCompEx2Done() { 39 // Call parent constructor and set title in title bar of window 40 super 41 Container c = getcontentpane // Get reference to content pane 42 c.setlayout(new BorderLayout // Set layout for content pane JPanel jpan = new JPanel(new GridLayout // Create JComboBoxes for user selection of font and font size Page 1

13 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\GuiDev\WidgetExs\src\widgetexs\TextCompEx2Done.java at 4/28/06 47 jcboxfont = new JComboBox 48 jcboxfont.additemlistener(this 49 jpan.add jcboxsize = new JComboBox 52 jcboxsize.setmaximumrowcount 53 jcboxsize.additemlistener(this 54 jpan.add // Create JButton for user to choose text color 57 coloritem = new JButton 58 coloritem.addactionlistener(this 59 jpan.add // Create JCheckBox to enable user to line wrap on/off 62 linewrap = new JCheckBox("Line Wrap", false 63 linewrap.additemlistener(this 64 jpan.add // Create JCheckBoxes for two font styles, but not as a group 67 fstylebold = new JCheckBox("Bold", false 68 fstylebold.additemlistener(this 69 jpan.add fstyleitalic = new JCheckBox("Italic", false 72 fstyleitalic.additemlistener(this 73 jpan.add c.add // Get and display images for decorative purposes 78 URL url1 = this.getclass().getresource 79 JLabel jlabel1 = new JLabel(new ImageIcon 80 jlabel1.setborder(new EtchedBorder 81 c.add URL url2 = this.getclass().getresource 84 JLabel jlabel2 = new JLabel(new ImageIcon 85 jlabel2.setborder(new EtchedBorder 86 c.add // Create and add the JTextArea to be used for text display and editing 90 textarea = new JTextArea 91 textarea.setfont 92 textarea.setlinewrap(false 93 textarea.setborder(new TitledBorder Page 2

14 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\GuiDev\WidgetExs\src\widgetexs\TextCompEx2Done.java at 4/28/06 94 JScrollPane jspane = new JScrollPane 95 c.add 96 } public void actionperformed(actionevent e) { 99 if (e.getsource() == coloritem) { 100 Color returnedcolor = JColorChooser.showDialog(this, 102 if (returnedcolor!= null) { 104 textarea.setforeground 105 } 106 } 107 } public void itemstatechanged(itemevent e) { // If the JCheckBox for Bold style was clicked, set the applet's font 112 // style based on whether Bold was selected or deselected 113 if (e.getsource() == fstylebold) 114 if (e.getstatechange() == ItemEvent.SELECTED) 116 else 117 if (e.getstatechange() == ItemEvent.DESELECTED) // If the JCheckBox for Italic style was clicked, set the applet's font 121 // style based on whether Italic was selected or deselected 122 if (e.getsource() == fstyleitalic) 123 if (e.getstatechange() == ItemEvent.SELECTED) 125 else 126 if (e.getstatechange() == ItemEvent.DESELECTED) // If the JCheckBox for line wrap was selected or not, set 130 // the JTextArea's line wrap accordingly 131 if (e.getsource() == linewrap) 132 if (e.getstatechange() == ItemEvent.SELECTED) 133 textarea.setlinewrap(true 134 else 135 if (e.getstatechange() == ItemEvent.DESELECTED) 136 textarea.setlinewrap(false // If one of the items in the JComboBox was selected, 139 // set the fontname variable to the user's selection 140 if (e.getsource() == jcboxfont) { Page 3

15 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\GuiDev\WidgetExs\src\widgetexs\TextCompEx2Done.java at 4/28/ selectedface = fontnames[jcboxfont.getselectedindex 142 } if (e.getsource() == jcboxsize) { 145 selectedsize = Integer.parseInt(fontSizes[jcboxSize. getselectedindex 146 } textarea.setfont(new Font(selectedFace, selectedstyle, 149 } } Page 4

16 Using Audio Clips Methods in the Applet class Methods for using audio clips AudioClip getaudioclip(url url) - Returns the AudioClip object specified by the url; always returns immediately; data loaded when attempt to play is made static AudioClip newaudioclip(url url) - Returns the AudioClip object specified by the url Methods in the AudioClip interface class Methods for using audio clips void play() - Plays this audio clip starting from the beginning void loop() - Plays this audio clip in a loop starting at beginning void stop() - Stops playing this audio clip 19 Purpose: To demonstrate Example Program Use of an applet program and Use of audio and images in the graphical user interface Program: Class name: FlagAnthem Package name: mediaexs Project name: MediaExs Code is available on instructor s webpage Questions: What are some problems or shortcomings of this program? 20

17 Example Program 21 Timer Class Purpose Has a specified delay time interval, and repeatedly fires an action event once per time interval (e.g., once per second) The delay time interval is the time between action events For example, an animation object can use a Timer as the trigger for drawing its frames Setting up a Timer involves 1. Creating a Timer object, 2. Registering one or more action listeners on it, and 3. Starting the timer using the start method 22

18 Timer Class Selected constructors and methods Constructor Timer(int delay, ActionListener listener) - Creates a Timer that will notify its listeners every delay milliseconds Methods void setdelay(int delay) - Sets the Timer s delay, the number of milliseconds between successive action events void start() - Starts the Timer, causing it to start sending action events to its listeners void stop() - Stops the Timer, causing it to stop sending action events to its listeners 23 Example Program Purpose: To demonstrate Use of an application program and Use of a Timer object to implement animation Program: Class name: ApplicWTimer Package name: mymediaexs Project name: MyMediaExs Questions: How would you vary (e.g., slow down or speed up) the rate at which the images appear to move across the applet? 24

19 Example Program 25

20 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\MyMedia\MyMediaExs\src\mymediaexs\ApplicWTimer.java at 4/28/06 1 package 2 import 3 import 4 import 5 import 6 import 7 8 public class ApplicWTimer extends JFrame implements ActionListener { 9 private 10 private String fname[] = {"Assets.gif", "Contacts.gif", "Evtmgmt. 11 private 12 private int 13 private int 14 private 15 private Image img[] = new 16 private MediaTracker mt = new MediaTracker(this private int 19 private int private int 22 private int 23 private int 24 private int 25 private int 26 private Timer timer = new Timer(15, this // The main method required for an application program 29 public static void main( String[] args ) { 30 JFrame frame = new ApplicWTimer // Construct the window 31 frame.setdefaultcloseoperation 32 frame.setvisible( true // Make the window visible 33 } /** Creates a new instance of ApplicWTimer */ 36 public ApplicWTimer() { 37 super 38 Container c = getcontentpane 39 setsize( new Dimension 40 c.setlayout(new BorderLayout 41 setbackground // Create a panel to display moving banner 44 imgpan = new ImagePanel 45 imgpan.setborder(new EtchedBorder 46 imgpan.setborder(new TitledBorder("Demonstration of Timer-Based Page 1

21 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\MyMedia\MyMediaExs\src\mymediaexs\ApplicWTimer.java at 4/28/06 47 c.add timer.start 50 } public void actionperformed(actionevent e) { 53 imgpan.repaint 54 } public class ImagePanel extends JPanel { 57 int 58 // Constructor 59 public ImagePanel(int w) { 61 // Get images and assign into array 62 for (int 64 img[i] = Toolkit.getDefaultToolkit().getImage 65 try { 66 mt.addimage 67 mt.waitforid 68 } catch (Exception ex) { 69 System.out.println("\n" + ex.tostring 70 } 71 } set image width and height variables 74 imgwidth = img[0].getwidth(null 75 imgheight = img[0].getheight(null setbackground 78 setpreferredsize(new Dimension(apWidth, imgheight + ypos * 79 setvisible(true 80 } // Paint the JPanel 83 public void paintcomponent(graphics g) { 84 super.paintcomponent 85 int 86 int // Create and draw image 89 while (xpos < panelwidth) { 91 g.drawimage(img[currentimgindex], xpos, ypos, null Page 2

22 Printing C:\Documents and Settings\jgneal\My Documents\MyDev\MyJava\MyMedia\MyMediaExs\src\mymediaexs\ApplicWTimer.java at 4/28/06 93 } // Establish the horizontal start position for the next repaint of banner 96 // and the image with which to start if (startxpos > betweenspace) { 102 /* if (startimageindex < 0) */ 108 if (startimgindex >= fname.length) 110 } 111 } // End paintcomponent 112 } } 115 Page 3