pie.html
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<TITLE>Drawing a Pie Chart
(Java Developers Almanac Example)
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<h3>
e594.
Drawing a Pie Chart</h3>
This example implements a method for drawing a pie chart.
<pre>
// Class to hold a value for a slice
public class PieValue {
double value;
Color color;
public PieValue(double value, Color color) {
this.value = value;
this.color = color;
}
}
// slices is an array of values that represent the size of each slice.
public void drawPie(Graphics2D g, Rectangle area, PieValue[] slices) {
// Get total value of all slices
double total = 0.0D;
for (int i=0; i<slices.length; i++) {
total += slices[i].value;
}
// Draw each pie slice
double curValue = 0.0D;
int startAngle = 0;
for (int i=0; i<slices.length; i++) {
// Compute the start and stop angles
startAngle = (int)(curValue * 360 / total);
int arcAngle = (int)(slices[i].value * 360 / total);
// Ensure that rounding errors do not leave a gap between the first and last slice
if (i == slices.length-1) {
arcAngle = 360 - startAngle;
}
// Set the color and draw a filled arc
g.setColor(slices[i].color);
g.fillArc(area.x, area.y, area.width, area.height, startAngle, arcAngle);
curValue += slices[i].value;
}
}
</pre>
Here's some code that uses the <code>drawPie()</code> method:
<pre>
class MyComponent extends JComponent {
PieValue[] slices = new PieValue[4];
MyComponent() {
slices[0] = new PieValue(25, Color.red);
slices[1] = new PieValue(33, Color.green);
slices[2] = new PieValue(20, Color.pink);
slices[3] = new PieValue(15, Color.blue);
}
// This method is called whenever the contents needs to be painted
public void paint(Graphics g) {
// Draw the pie
drawPie((Graphics2D)g, getBounds(), slices);
}
}
</pre>
<pre>
// Show the component in a frame
JFrame frame = new JFrame();
frame.getContentPane().add(new MyComponent());
frame.setSize(300, 200);
frame.setVisible(true);
</pre>
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Related Examples
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e590. <a class="eglink" href="DrawBasic.html?l=rel">
Drawing Basic Shapes
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e591. <a class="eglink" href="FillBasic.html?l=rel">
Filling Basic Shapes
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e592. <a class="eglink" href="StrokeShape.html?l=rel">
Creating a Shape from a Stroked Shape
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e593. <a class="eglink" href="StrokeFill.html?l=rel">
Stroking or Filling a Shape
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See also:
<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Colors">
Colors
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Components">
Components
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Containers">
Containers
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Cursors">
Cursors
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Drawing">
Drawing
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Events">
Events
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Focus">
Focus
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Frames">
Frames
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#GridBagLayout">
GridBagLayout
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Images">
Images
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Simulating%20Events">
Simulating Events
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#Text">
Text
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<a class="eglink" href="/egs/java.awt/pkg.html?l=rel#The%20Screen">
The Screen
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