More%20Graphics%20in%20Java

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More Graphics in Java
A picture's worth a thousand words

• CS 102-02
• Lecture 7-1

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Agenda

• Fonts
• Lines
• Rectangles
• Ovals
• Arcs

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Logical Fonts

• Different systems have different fonts
• Java uses logical fonts
• Maps logical fonts into system-specific fonts

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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)

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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

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Getting the List

• Use the Toolkit
• Toolkit is the link between Java and the specific
  system
• String fonts Toolkit.getDefaultToolkit().getFo
  ntList()

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Constant Styles

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

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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

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Font Metrics
From the Java Tutorial
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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.

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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.

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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.

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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.

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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.

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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
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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
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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)

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Filled Unfilled
x, y
x, y
height
width
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Rectangle Flavors

• Outline rectangle
• drawRect()
• Filled (in current foreground color) rectangle
• fillRect()
• Filled (in background color) rectangle
• clearRect()

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Rounded Rectangles
x, y
height
arcWidth
arcHeight
width

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

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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)

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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()

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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)

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A Filled Oval and Its Box
x, y
height
width
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Drawing Arcs
arcAngle startAngle
startAngle

• Draws the outline of a circular or elliptical arc
  covering the specified rectangle (filled arcs too)

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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

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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