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Graphics and Java2D

Graphics and Java2D Joe Komar Overview Graphics contexts and graphics objects Color control Font control Drawing lines, rectangles, ovals, arcs, polygons, and polylines Java2D API Java2D Shapes Graphics Coordinate System 0,0 is the upper left corner

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Graphics and Java2D

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  1. Graphics and Java2D Joe Komar Komar Associates

  2. Overview • Graphics contexts and graphics objects • Color control • Font control • Drawing lines, rectangles, ovals, arcs, polygons, and polylines • Java2D API • Java2D Shapes Komar Associates

  3. Graphics Coordinate System • 0,0 is the upper left corner • Each coordinate point represents one pixel • All coordinate values are positive x 0,0 X y x,y Y Komar Associates

  4. Coordinates Applet import java.awt.*; import java.applet.*; public class Coordinates extends Applet { public void paint (Graphics page){ setSize (300,200); page.drawRect (0, 0, 299, 199); page.drawLine (50, 50, 250, 100); page.drawString ("<50, 50>", 25, 45); page.drawString ("<250, 100>", 225, 115); }// method paint }// class Coordinates Komar Associates

  5. Output of Coordinates Applet Komar Associates

  6. Graphics • Graphics “context” enables drawing on the screen • Graphics object manages a graphics context • Graphics is an abstract class implemented on each platform • Component class is primary superclass for Applet and JApplet Komar Associates

  7. paint method of Component • Accepts a Graphics object • Must be overridden • When Applet runs, calls init, start, then paint methods • repaint method called by programmer, which calls the Component’s update then paint method Komar Associates

  8. Colors • Color class is part of java.awt • Colors are defined by a mixture of Red, Blue, and Green • RGB • defined by three numbers ranging from (0,0,0) for black to (255,255,255) for white • over 16 million colors available • many systems cannot distinguish among so many colors • Predefined colors (final static Color objects) • e.g., Color.blue, Color.green, Color.cyan Komar Associates

  9. Defining Colors • Color (int red, int green, int blue) • Integer values between 0 and 255 • Color (float red, float green, float blue) • Decimal values between 0.0 and 1.0 • Color (int rgb) • bits 0-7 represent blue, 8-15 represent green, 16-23 represent red Komar Associates

  10. Defining Colors • Color brown = new Color (107, 69, 38); • brown.getBlue() returns 38 (getRed and getGreen) • brown.brighter() • returns a bit brighter Color • brown.darker() • returns a bit darker Color Komar Associates

  11. Nature Applet import java.awt.*; import java.applet.*; public class Nature extends Applet { public void paint (Graphics page) { setBackground (Color.darkGray); page.setColor (Color.red); page.drawRect (10, 15, 125, 85); page.setColor (Color.green); page.drawString ("Nature's first green", 25,45); page.setColor (Color.yellow); page.drawString ("is gold", 50, 75); }// method paint }// class Nature Komar Associates

  12. Nature Applet Results Komar Associates

  13. ShowColors Example // Fig. 11.5: ShowColors.java // Demonstrating Colors import java.awt.*; import javax.swing.*; import java.awt.event.*; public class ShowColors extends JFrame { public ShowColors() { super( "Using colors" ); setSize( 400, 130 ); show(); } Komar Associates

  14. ShowColors Example public void paint( Graphics g ) { // set new drawing color using integers g.setColor( new Color( 255, 0, 0 ) ); g.fillRect( 25, 25, 100, 20 ); g.drawString( "Current RGB: " + g.getColor(), 130, 40 ); // set new drawing color using floats g.setColor( new Color( 0.0f, 1.0f, 0.0f ) ); g.fillRect( 25, 50, 100, 20 ); g.drawString( "Current RGB: " + g.getColor(), 130, 65 ); // set new drawing color using static Color objects g.setColor( Color.blue ); g.fillRect( 25, 75, 100, 20 ); g.drawString( "Current RGB: " + g.getColor(), 130, 90 ); Komar Associates

  15. ShowColors Example // display individual RGB values Color c = Color.magenta; g.setColor( c ); g.fillRect( 25, 100, 100, 20 ); g.drawString( "RGB values: " + c.getRed() + ", " + c.getGreen() + ", " + c.getBlue(), 130, 115 ); } Komar Associates

  16. ShowColors Example public static void main( String args[] ) { ShowColors app = new ShowColors(); app.addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent e ) { System.exit( 0 ); } } ); } } Komar Associates

  17. ShowColors Example Komar Associates

  18. JColorChooser Dialog Box • static method showDialog of class JColorChooser presents dialog • Can choose by color swatch; hue, saturation and brightness (HSB); or by red, green, blue (RGB) • Returns the Color object chosen • See example run... Komar Associates

  19. Fonts • Uses currently supported fonts on the system • Constructor takes String font-name, int style, int size • Styles - Font.PLAIN, Font.BOLD, Font.ITALIC • Size is number of points (1/72nd of an inch) Komar Associates

  20. Fonts Example // Fig. 11.9: Fonts.java // Using fonts import java.awt.*; import javax.swing.*; import java.awt.event.*; public class Fonts extends JFrame { public Fonts() { super( "Using fonts" ); setSize( 420, 125 ); show(); } Komar Associates

  21. Fonts Example public void paint( Graphics g ) { // set current font to Serif (Times), bold, 12pt // and draw a string g.setFont( new Font( "Serif", Font.BOLD, 12 ) ); g.drawString( "Serif 12 point bold.", 20, 50 ); // set current font to Monospaced (Courier), // italic, 24pt and draw a string g.setFont( new Font( "Monospaced", Font.ITALIC, 24 ) ); g.drawString( "Monospaced 24 point italic.", 20, 70 ); // set current font to SansSerif (Helvetica), // plain, 14pt and draw a string g.setFont( new Font( "SansSerif", Font.PLAIN, 14 ) ); g.drawString( "SansSerif 14 point plain.", 20, 90 ); Komar Associates

  22. Fonts Example // set current font to Serif (times), bold/italic, // 18pt and draw a string g.setColor( Color.red ); g.setFont( new Font( "Serif", Font.BOLD + Font.ITALIC, 18 ) ); g.drawString( g.getFont().getName() + " " + g.getFont().getSize() + " point bold italic.", 20, 110 ); } Komar Associates

  23. Fonts Example public static void main( String args[] ) { Fonts app = new Fonts(); app.addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent e ) { System.exit( 0 ); } } ); } } Komar Associates

  24. Fonts Example Komar Associates

  25. Font Metrics • Height -- total size • Ascent -- basic character size • Leading -- above character • Descent -- below character • Methods to get these as well as getFontMetrics to return a FontMetrics object Komar Associates

  26. Drawing Shapes • Lines, ovals, rectangles, arcs, polygons, and polylines • circle is a specific kind of oval • square is a specific kind of rectangle • polygons include any many-sided shapes • polylines are lines connected end-to-end • Most shapes can be drawn filled or unfilled • e.g. drawOval versus fillOval Komar Associates

  27. Ovals • drawOval (int x, int y, int width, int height) • fillOval (int x, int y, int width, int height) width height Komar Associates

  28. Ovals as Spinning Disk import java.awt.*; import java.applet.*; public class Rotating_Disk extends Applet { public void paint (Graphics page) { int width = 0, height = 40; int x = 100, y = 100, warp = 1; page.setXORMode (getBackground()); for (int change = 1; change < 1000; change++) { width += warp * 2; x -= warp; if (width == 0 || width == 40) warp *= -1; page.fillOval (x, y, width, height); for (int pause = 1; pause <= 500000; pause++); page.fillOval (x, y, width, height); }// for loop }// method paint }// class Rotating_Disk Komar Associates

  29. Spinning Disk In Action Rotating Disk Applet Komar Associates

  30. Rectangles • drawRect (int x, int y, int width, int height) • fillRect (int x, int y, int width, int height) • clearRect (int x, int y, int width, int height) • drawRoundRect (int x, int y, int width, int height, int arc_width, int arc_height) • fillRoundRect (int x, int y, int width, int height, int arc_width, int arc_height) • draw3DRect (int x, int y, int width, int height, boolean raised) • draw3DRect (int x, int y, int width, int height, boolean raised) Komar Associates

  31. Rounded and 3D Rectangles import java.awt.*; import java.applet.*; public class Rectangles extends Applet { public void paint (Graphics page) { page.drawRoundRect (10,10,50,50,25,25); page.setColor (Color.red); page.fillRoundRect (90,10,40,40,10,30); page.setColor (Color.blue); page.fillRoundRect (150,30,50,20,15,15); page.setColor (Color.orange); page.fill3DRect (10,70,50,50,true); page.draw3DRect (70,70,50,50,false); }// method paint }// class Rectangles Komar Associates

  32. Rectangle Results Komar Associates

  33. Arc Angle Start Angle height Width Arcs • drawArc (int x, int y, int width, int height, int start_angle, int arc_angle) • fillArc (int x, int y, int width, int height, int start_angle, int arc_angle) Komar Associates

  34. Arcs Applet import java.awt.*; import java.applet.*; public class Arcs extends Applet { public void paint (Graphics page) { page.drawArc (10,10,50,50,45,225); page.drawArc (70,10,30,70,-180,180); page.setColor (Color.red); page.fillArc (130,10,60,60,-180,-90); page.setColor (Color.blue); page.fillArc (190,10,50,50,45,270); page.setColor (Color.green); page.fillArc (250,10,80,40,-225,180); }// method paint }// Class Arcs Komar Associates

  35. Arcs Applet Results Komar Associates

  36. Polygons • Polygon class can be used to define a polygon • addPoint method adds points to the polygon • Graphics class contains methods to draw a polygon • drawPolygon(int[ ] xpoints, int[ ] ypoints, int numpoints) • drawPolygon(Polygon poly) • fillPolygon(int[ ] xpoints, int[ ] ypoints, int numpoints) • fillPolygon(Polygon poly) • Polygons are always closed shapes -- if the last point specified does not close the shape, it is automatically closed Komar Associates

  37. Polygons Applet import java.awt.*; import java.applet.*; public class Polygons extends Applet { private int[] xset1 = {110,110,115,120,150,135}; private int[] yset1 = {10,40,30,50,15,7}; private int[] xset2 = {195,170,170,195,220,220}; private int[] yset2 = {10,20,40,50,40,20}; private int[] xset3 = {110,150,110,150,110}; private int[] yset3 = {70,70,110,110,70}; private Polygon poly = new Polygon(); Komar Associates

  38. Polygons Applet public void paint (Graphics page) { page.drawPolygon (xset1, yset1, 6); page.drawPolygon (xset2, yset2, 6); page.setColor (Color.red); page.fillPolygon (xset3, yset3, 5); poly.addPoint (170, 70); poly.addPoint (170, 90); poly.addPoint (190, 110); poly.addPoint (220, 90); page.setColor (Color.blue); page.fillPolygon (poly); }// method paint }// class Polygons Komar Associates

  39. Polygons Applet Results Komar Associates

  40. Polylines • drawPolyline (int[ ] xpoints, int[ ] ypoints, int numpoints) • Similar to polygon except a polyline is not a closed shape Komar Associates

  41. Java2D API • Additional drawing capabilities beyond first java.awt release • Use Graphics2D objects • Graphics2D is a subclass of Graphics • Downcast Graphics object to Graphics2D object • Graphics2D g2 = (Graphics2D) g; • Use setPaint, draw, fill methods of Graphics2D Komar Associates

  42. Graphics2D Example // Fig. 11.22: Shapes.java // Demonstrating some Java2D shapes import javax.swing.*; import java.awt.event.*; import java.awt.*; import java.awt.geom.*; import java.awt.image.*; public class Shapes extends JFrame { public Shapes() { super( "Drawing 2D shapes" ); setSize( 425, 160 ); show(); } Komar Associates

  43. Graphics2D Example public void paint( Graphics g ) { // create 2D by casting g to Graphics2D Graphics2D g2d = ( Graphics2D ) g; // draw 2D ellipse filled with a blue-yellow gradient g2d.setPaint( new GradientPaint( 5, 30, // x1, y1 Color.blue, // initial Color 35, 100, // x2, y2 Color.yellow, // end Color true ) ); // cyclic g2d.fill( new Ellipse2D.Double( 5, 30, 65, 100 ) ); Komar Associates

  44. Graphics2D Example // draw 2D rectangle in red g2d.setPaint( Color.red ); g2d.setStroke( new BasicStroke( 10.0f ) ); g2d.draw( new Rectangle2D.Double( 80, 30, 65, 100 ) ); Komar Associates

  45. Graphics2D Example // draw 2D rounded rectangle with a buffered background BufferedImage buffImage = new BufferedImage( 10, 10, BufferedImage.TYPE_INT_RGB ); Graphics2D gg = buffImage.createGraphics(); gg.setColor( Color.yellow ); // draw in yellow gg.fillRect( 0, 0, 10, 10 ); // draw a filled rectangle gg.setColor( Color.black ); // draw in black gg.drawRect( 1, 1, 6, 6 ); // draw a rectangle gg.setColor( Color.blue ); // draw in blue gg.fillRect( 1, 1, 3, 3 ); // draw a filled rectangle gg.setColor( Color.red ); // draw in red gg.fillRect( 4, 4, 3, 3 ); // draw a filled rectangle Komar Associates

  46. Graphics2D Example // paint buffImage onto the JFrame g2d.setPaint( new TexturePaint( buffImage, new Rectangle( 10, 10 ) ) ); g2d.fill( new RoundRectangle2D.Double( 155, 30, 75, 100, 50, 50 ) ); Komar Associates

  47. Graphics2D Example // draw 2D pie-shaped arc in white g2d.setPaint( Color.white ); g2d.setStroke( new BasicStroke( 6.0f ) ); g2d.draw( new Arc2D.Double( 240, 30, 75, 100, 0, 270, Arc2D.PIE ) ); Komar Associates

  48. Graphics2D Example // draw 2D lines in green and yellow g2d.setPaint( Color.green ); g2d.draw( new Line2D.Double( 395, 30, 320, 150 ) ); float dashes[] = { 10 }; g2d.setPaint( Color.yellow ); g2d.setStroke( new BasicStroke( 4, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND, 10, dashes, 0 ) ); g2d.draw( new Line2D.Double( 320, 30, 395, 150 ) ); } Komar Associates

  49. Graphics2D Example public static void main( String args[] ) { Shapes app = new Shapes(); app.addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent e ) { System.exit( 0 ); } } ); } } Komar Associates

  50. Graphics2D Example Komar Associates

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