SwingLayoutStyle.java

package org.jdesktop.layout;

import java.awt.Container;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javax.swing.JComponent;

class SwingLayoutStyle extends LayoutStyle {
	private static final Method SWING_GET_LAYOUT_STYLE_METHOD;

	private static final Method SWING_GET_PREFERRED_GAP_METHOD;
	private static final Method SWING_GET_CONTAINER_GAP_METHOD;

	private static final Object RELATED_TYPE;
	private static final Object UNRELATED_TYPE;
	private static final Object INDENT_TYPE;

	static {
		Method getLayoutStyle = null;
		Method getPreferredGap = null;
		Method getContainerGap = null;
		Object relatedType = null;
		Object unrelatedType = null;
		Object indentType = null;
		try {
			Class<?> swingLayoutStyleClass;
			Class<?> swingComponentPlacementClass;

			swingLayoutStyleClass = Class.forName("javax.swing.LayoutStyle");
			swingComponentPlacementClass = Class
					.forName("javax.swing.LayoutStyle$ComponentPlacement");
			swingLayoutStyleClass = Class.forName("javax.swing.LayoutStyle");
			getLayoutStyle = swingLayoutStyleClass.getMethod("getInstance",
					null);
			getPreferredGap = swingLayoutStyleClass.getMethod(
					"getPreferredGap", new Class[] { JComponent.class,
							JComponent.class, swingComponentPlacementClass,
							int.class, Container.class });
			getContainerGap = swingLayoutStyleClass.getMethod(
					"getContainerGap", new Class[] { JComponent.class,
							int.class, Container.class });
			relatedType = swingComponentPlacementClass.getField("RELATED").get(
					null);
			unrelatedType = swingComponentPlacementClass.getField("UNRELATED")
					.get(null);
			indentType = swingComponentPlacementClass.getField("INDENT").get(
					null);
		} catch (ClassNotFoundException cnfe) {
		} catch (NoSuchMethodException nsme) {
		} catch (NoSuchFieldException nsfe) {
		} catch (IllegalAccessException iae) {
		}
		SWING_GET_LAYOUT_STYLE_METHOD = getLayoutStyle;
		SWING_GET_PREFERRED_GAP_METHOD = getPreferredGap;
		SWING_GET_CONTAINER_GAP_METHOD = getContainerGap;
		RELATED_TYPE = relatedType;
		UNRELATED_TYPE = unrelatedType;
		INDENT_TYPE = indentType;
	}

	private static final Object layoutStyleTypeToComponentPlacement(int type) {
		if (type == LayoutStyle.RELATED) {
			return RELATED_TYPE;
		} else if (type == LayoutStyle.UNRELATED) {
			return UNRELATED_TYPE;
		} else {
			assert (type == LayoutStyle.INDENT);
			return INDENT_TYPE;
		}
	}

	private static final Object getSwingLayoutStyle() {
		try {
			return SWING_GET_LAYOUT_STYLE_METHOD.invoke(null, null);
		} catch (IllegalAccessException iae) {
		} catch (InvocationTargetException ite) {
		}
		return null;
	}

	public int getPreferredGap(JComponent component1, JComponent component2,
			int type, int position, Container parent) {
		super.getPreferredGap(component1, component2, type, position, parent);
		Object componentPlacement = layoutStyleTypeToComponentPlacement(type);
		Object layoutStyle = getSwingLayoutStyle();
		try {
			return ((Integer) SWING_GET_PREFERRED_GAP_METHOD
					.invoke(layoutStyle, new Object[] { component1, component2,
							componentPlacement, new Integer(position), parent }))
					.intValue();
		} catch (IllegalAccessException iae) {
		} catch (InvocationTargetException ite) {
		}
		return 0;
	}

	public int getContainerGap(JComponent component, int position,
			Container parent) {
		super.getContainerGap(component, position, parent);
		Object layoutStyle = getSwingLayoutStyle();
		try {
			return ((Integer) SWING_GET_CONTAINER_GAP_METHOD.invoke(
					layoutStyle, new Object[] { component,
							new Integer(position), parent })).intValue();
		} catch (IllegalAccessException iae) {
		} catch (InvocationTargetException ite) {
		}
		return 0;
	}
}