corejava第10版

corejava第10版/v1ch12/circleLayout/CircleLayout.java

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+package circleLayout;
+
+import java.awt.*;
+
+/**
+ * A layout manager that lays out components along a circle.
+ */
+public class CircleLayout implements LayoutManager
+{
+   private int minWidth = 0;
+   private int minHeight = 0;
+   private int preferredWidth = 0;
+   private int preferredHeight = 0;
+   private boolean sizesSet = false;
+   private int maxComponentWidth = 0;
+   private int maxComponentHeight = 0;
+
+   public void addLayoutComponent(String name, Component comp)
+   {
+   }
+
+   public void removeLayoutComponent(Component comp)
+   {
+   }
+
+   public void setSizes(Container parent)
+   {
+      if (sizesSet) return;
+      int n = parent.getComponentCount();
+
+      preferredWidth = 0;
+      preferredHeight = 0;
+      minWidth = 0;
+      minHeight = 0;
+      maxComponentWidth = 0;
+      maxComponentHeight = 0;
+
+      // compute the maximum component widths and heights
+      // and set the preferred size to the sum of the component sizes.
+      for (int i = 0; i < n; i++)
+      {
+         Component c = parent.getComponent(i);
+         if (c.isVisible())
+         {
+            Dimension d = c.getPreferredSize();
+            maxComponentWidth = Math.max(maxComponentWidth, d.width);
+            maxComponentHeight = Math.max(maxComponentHeight, d.height);
+            preferredWidth += d.width;
+            preferredHeight += d.height;
+         }
+      }
+      minWidth = preferredWidth / 2;
+      minHeight = preferredHeight / 2;
+      sizesSet = true;
+   }
+
+   public Dimension preferredLayoutSize(Container parent)
+   {
+      setSizes(parent);
+      Insets insets = parent.getInsets();
+      int width = preferredWidth + insets.left + insets.right;
+      int height = preferredHeight + insets.top + insets.bottom;
+      return new Dimension(width, height);
+   }
+
+   public Dimension minimumLayoutSize(Container parent)
+   {
+      setSizes(parent);
+      Insets insets = parent.getInsets();
+      int width = minWidth + insets.left + insets.right;
+      int height = minHeight + insets.top + insets.bottom;
+      return new Dimension(width, height);
+   }
+
+   public void layoutContainer(Container parent)
+   {
+      setSizes(parent);
+
+      // compute center of the circle
+
+      Insets insets = parent.getInsets();
+      int containerWidth = parent.getSize().width - insets.left - insets.right;
+      int containerHeight = parent.getSize().height - insets.top - insets.bottom;
+
+      int xcenter = insets.left + containerWidth / 2;
+      int ycenter = insets.top + containerHeight / 2;
+
+      // compute radius of the circle
+
+      int xradius = (containerWidth - maxComponentWidth) / 2;
+      int yradius = (containerHeight - maxComponentHeight) / 2;
+      int radius = Math.min(xradius, yradius);
+
+      // lay out components along the circle
+
+      int n = parent.getComponentCount();
+      for (int i = 0; i < n; i++)
+      {
+         Component c = parent.getComponent(i);
+         if (c.isVisible())
+         {
+            double angle = 2 * Math.PI * i / n;
+
+            // center point of component
+            int x = xcenter + (int) (Math.cos(angle) * radius);
+            int y = ycenter + (int) (Math.sin(angle) * radius);
+
+            // move component so that its center is (x, y)
+            // and its size is its preferred size
+            Dimension d = c.getPreferredSize();
+            c.setBounds(x - d.width / 2, y - d.height / 2, d.width, d.height);
+         }
+      }
+   }
+}