More Graphics in Java

1. More Graphics in Java A picture's worth a thousand words CS 102-02 Lecture 7-1

2. Agenda • Fonts • Lines • Rectangles • Ovals • Arcs

3. Logical Fonts • Different systems have different fonts • Java uses logical fonts • Maps logical fonts into system-specific fonts

4. Specifying Fonts • Font name • Serif, Sans Serif, Dialog, DialogInput and Monospaced Sans Serif With Serif • Font style • Bold, italic and plain • Font size • Point size (1pt = 1/72nd of an inch)

5. Font Names • Listed names are guaranteed, but there might be more • From my Win NT 4.0 machine: Dialog, SansSerif, Serif, Monospaced, Helvetica, TimesRoman, Courier, DialogInput, ZapfDingbats

6. Getting the List • Use the Toolkit • Toolkit is the link between Java and the specific system String fonts[] = Toolkit.getDefaultToolkit().getFontList();

7. Constant Styles • Font class includes constants for setting style • Font.BOLD, Font.ITALIC, Font.PLAIN • Combine them with +, as in • Font.BOLD+Font.ITALIC gives a bold, italic font

8. What Does Size Mean? • Every font has many sizes associated with it • Different sizes are the font's metrics • Font's size (in points) is a rough gauge of the overall size

9. Font Metrics From the Java Tutorial

10. How High? • getAscent(), getMaxAscent() • Number of pixels between the ascender line and the baseline • Ascender line represents the typical height of capital letters (chosen by the font's designer to represent the correct text "color") • Ascent typically provides enough room for almost all of the characters in the font, except perhaps for accents on capital letters • getMaxAscent() method accounts for these exceptionally tall characters.

11. How Low Can You Go? getDescent(), getMaxDescent() • Number of pixels between the baseline and the descender line • In most fonts, all characters fall within the descender line at their lowest point • Use the getMaxDescent() method to get a distance guaranteed to encompass all characters.

12. Font Height • getHeight() • Returns the number of pixels normally found between the baseline of one line of text and the baseline of the next line of text • Includes an allowance for leading.

13. Leading getLeading() • Returns the suggested distance (in pixels) between one line of text and the next • Leading is the distance between the descender line of one line of text and the ascender line of the next line of text.

14. Will the Real Size Please Stand Up? • Font size (returned by the Font class getSize() method) is an abstract measurement • In theory: corresponds to the ascent plus the descent • Reality: font designer decides exactly how tall a "12 point" font (for example) is • 12-point Times is often slightly shorter than 12-point Helvetica.

15. Font Measurements • Use a FontMetrics object • Call methods such as getAscent() and getDescent() from a FontMetrics object int ascent = g.getFontMetrics().getAscent(); • When text is drawn at (x,y), the specified point is used as the reference point Baseline

16. Drawing Lines • Use the drawLine() method of the Graphics class drawLine(int x1, int y1, int x2, int y2) • Specify four coordinates x1, y1 x2, y2

17. Drawing Rectangles • Two dimensions gives more options • Filled and unfilled • Fill color is the current color -- not an argument to the method • Just a rectangle drawRect( int x, // top-left int y, // coordinate int width, int height)

18. Filled & Unfilled x, y x, y height width

19. Rectangle Flavors • Outline rectangle drawRect() • Filled (in current foreground color) rectangle fillRect() • Filled (in background color) rectangle clearRect()

20. Rounded Rectangles x, y height • To draw a rounded rectangle drawRoundRect(x, y, width, height, arcWidth, arcHeight) • Rounded rectangles can also be filled fillRoundRect() arcWidth arcHeight width

21. Drawing 3-D Rectangles • Draw a 3-D highlighted outline of the specified rectangle • Edges of the rectangle are highlighted so that they appear to be beveled • Lit from the upper left corner draw3DRect(int x, int y, int width, int height, boolean raised)

22. 3-D Highlighting • Colors used for the highlighting effect are based on the current color • Resulting rectangle covers an area that is width + 1 pixels wide by height + 1 pixels tall • Filled 3D rectangles with fill3DRect()

23. Drawing Ovals • Drawing ovals is similar to drawing rectangles because you specify the bounding box for the oval • For an unfilled oval: drawOval( int x, // top-left int y, // coordinate int width, int height)

24. A Filled Oval and Its Box x, y height width

25. Drawing Arcs arcAngle + startAngle • Draws the outline of a circular or elliptical arc covering the specified rectangle (filled arcs too) startAngle

26. Arc Parameters • Resulting arc begins at startAngle and extends for arcAngle degrees, using the current color • Angles are interpreted such that 0 degrees is at the 3 o'clock position • Positive value indicates a counter-clockwise rotation while a negative value indicates a clockwise rotation

27. More Arc Parameters • Center of the arc is the center of the rectangle whose origin is (x, y) • Size is specified by the width and height arguments • Resulting arc covers an area width + 1 pixels wide by height + 1 pixels tall