Java applet handouts

Java applet handouts

• 1.
  Java Applet Handouts 1. To create an applet from BlueJ, simply click new class then the applet radio button. • Note that the classes automatically imported are: • import java.awt.*; • import javax.swing.*; 2. All applets generated will extend the JApplet class thus having to implement the ff methods: • public void init() { } • public void start() { } • public void stop() { } • public void paint(Graphics g) { } • public void destroy(){ } Methods will run in sequence displayed. To customize the look of the applet, call Graphics methods in the paint method. abstract void copyArea(int x, int y, int width, int height, int dx, int dy) Copies an area of the component by a distance specified by dx and dy. void draw3DRect(int x, int y, int width, int height, boolean raised) Draws a 3-D highlighted outline of the specified rectangle. abstract void drawArc(int x, int y, int width, int height, int startAngle, int arcAngle) Draws the outline of a circular or elliptical arc covering the specified rectangle. void drawBytes(byte[] data, int offset, int length, int x, int y) Draws the text given by the specified byte array, using this graphics context's current font and color. void drawChars(char[] data, int offset, int length, int x, int y) Draws the text given by the specified character array, using this graphics context's current font and color. abstract boolean drawImage(Image img, int x, int y, Color bgcolor, ImageObserver observer) Draws as much of the specified image as is currently available. abstract boolean drawImage(Image img, int x, int y, ImageObserver observer) Draws as much of the specified image as is currently available. abstract boolean drawImage(Image img, int x, int y, int width, int height, Color bgcolor, ImageObserver observer) Draws as much of the specified image as has already been scaled to fit inside the specified rectangle. abstract boolean drawImage(Image img, int x, int y, int width, int height, ImageObserver observer) Draws as much of the specified image as has already been scaled to fit inside the specified rectangle. abstract boolean drawImage(Image img, int dx1, int dy1, int dx2, int dy2, int sx1, int sy1, int sx2, int sy2, Color bgcolor, ImageObserver observer) Draws as much of the specified area of the specified image as is currently available, scaling it on the fly to fit inside the specified area of the destination drawable surface. abstract boolean drawImage(Image img, int dx1, int dy1, int dx2, int dy2, int sx1, int sy1, int sx2, int sy2, ImageObserver observer) Draws as much of the specified area of the specified image as is currently available, scaling it on the fly to fit inside the specified area of the destination drawable surface. abstract void drawLine(int x1, int y1, int x2, int y2) Draws a line, using the current color, between the points (x1, y1) and (x2, y2) in this graphics context's coordinate system.
• 2.
  abstract void drawOval(intx, int y, int width, int height) Draws the outline of an oval. abstract void drawPolygon(int[] xPoints, int[] yPoints, int nPoints) Draws a closed polygon defined by arrays of x and y coordinates. void drawPolygon(Polygon p) Draws the outline of a polygon defined by the specified Polygon object. abstract void drawPolyline(int[] xPoints, int[] yPoints, int nPoints) Draws a sequence of connected lines defined by arrays of x and y coordinates. void drawRect(int x, int y, int width, int height) Draws the outline of the specified rectangle. abstract void drawRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight) Draws an outlined round-cornered rectangle using this graphics context's current color. abstract void drawString(AttributedCharacterIterator iterator, int x, int y) Draws the text given by the specified iterator, using this graphics context's current color. abstract void drawString(String str, int x, int y) Draws the text given by the specified string, using this graphics context's current font and color. void fill3DRect(int x, int y, int width, int height, boolean raised) Paints a 3-D highlighted rectangle filled with the current color. abstract void fillArc(int x, int y, int width, int height, int startAngle, int arcAngle) Fills a circular or elliptical arc covering the specified rectangle. abstract void fillOval(int x, int y, int width, int height) Fills an oval bounded by the specified rectangle with the current color. abstract void fillPolygon(int[] xPoints, int[] yPoints, int nPoints) Fills a closed polygon defined by arrays of x and y coordinates. void fillPolygon(Polygon p) Fills the polygon defined by the specified Polygon object with the graphics context's current color. abstract void fillRect(int x, int y, int width, int height) Fills the specified rectangle. abstract void fillRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight) Fills the specified rounded corner rectangle with the current color. abstract Color getColor() Gets this graphics context's current color. abstract Font getFont() Gets the current font. abstract void setColor(Color c) Sets this graphics context's current color to the specified color. abstract void setFont(Font font) Sets this graphics context's font to the specified font.
• 3.
  How to addMouse Events 1. Import necessary classes: a. import java.applet.*; b. import java.awt.*; c. import java.awt.event.*; d. import javax.swing.*; 2. Add interfaces a. MouseListener b. MouseMotionListener 3. Implements necessary methods • public void mouseEntered( MouseEvent e ) { // called when the pointer enters the applet's rectangular area } • public void mouseExited( MouseEvent e ) { // called when the pointer leaves the applet's rectangular area } • public void mouseClicked( MouseEvent e ) { // called after a press and release of a mouse button // with no motion in between // (If the user presses, drags, and then releases, there will be // no click event generated.) } • public void mousePressed( MouseEvent e ) { // called after a button is pressed down } • public void mouseReleased( MouseEvent e ) { // called after a button is released } • public void mouseMoved( MouseEvent e ) { // called during motion when no buttons are down } • public void mouseDragged( MouseEvent e ) { // called during motion with buttons down } 4. Add the interface in the init function a. addMouseListener( this ); b. addMouseMotionListener( this ); 5. Additional MouseEvent Methods a. Int getClickCount() Return the number of mouse clicks associated with this event. b. Int getX() Returns the horizontal x position of the event relative to the source component. c. Int getY() Returns the vertical y position of the event relative to the source component.