sizegrip.java

Eclipse 编程技术与实例,讲解了Eclipse编辑器的使用方法

package org.test.custom.form;

import java.util.Timer;
import java.util.TimerTask;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * 这是非本地的尺寸控制器，它就像本地Win32的尺寸控制器。 SHADOW_IN样式会在窗口的右下角画几道斜线。
 * 该控件是否可见由窗口是否最大化决定。如果窗口是最大的，不论是否使用了setVisible(true)方法，它都将被隐。
 *  
 */

public final class SizeGrip extends Canvas {
	private static final int WIDTH = 13;

	private static final int HEIGHT = 13;

	private static final long UPDATE_DELAY = 25;

	private int mouseDownOffsetX, mouseDownOffsetY, snapBackX, snapBackY;

	private boolean cancelled;

	private Cursor sizeCursor;

	private Point minSize;

	private boolean userVisible = true;

	private volatile long lastUpdate;

	private Timer timer = new Timer(true);

	private TimerTask timerTask;

	private Composite resizableParent;

	public SizeGrip(Composite parent, int style) {
		this(parent, parent.getShell(), style);
	}

	public SizeGrip(Composite parent, final Composite resizableParent, int style) {
		super(parent, style = checkStyle(style));
		this.resizableParent = resizableParent;
		setSize(WIDTH, HEIGHT);

		sizeCursor = new Cursor(getDisplay(), SWT.CURSOR_SIZENWSE);
		setCursor(sizeCursor);

		// 为控件注册各种事件侦听器
		addListener(SWT.Dispose, new Listener() {
			public void handleEvent(Event e) {
				if (sizeCursor != null) {
					sizeCursor.dispose();
					sizeCursor = null;
				}
			}
		});

		addListener(SWT.Paint, new Listener() {
			public void handleEvent(Event event) {
				Rectangle r = getClientArea();
				if (r.width == 0 || r.height == 0)
					return;

				Display disp = getDisplay();
				Color shadow = disp
						.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW);
				Color highlight = disp
						.getSystemColor(SWT.COLOR_WIDGET_HIGHLIGHT_SHADOW);

				event.gc.setLineWidth(1);

				// 根据控件创建时的样式画出不同的图形
				if ((getStyle() & SWT.FLAT) != 0) {
					event.gc.setBackground(highlight);
					event.gc.fillRectangle(r.width - 3, r.height - 3, 2, 2);
					event.gc.fillRectangle(r.width - 7, r.height - 3, 2, 2);
					event.gc.fillRectangle(r.width - 11, r.height - 3, 2, 2);
					event.gc.fillRectangle(r.width - 3, r.height - 7, 2, 2);
					event.gc.fillRectangle(r.width - 7, r.height - 7, 2, 2);
					event.gc.fillRectangle(r.width - 3, r.height - 11, 2, 2);
					event.gc.setBackground(shadow);
					event.gc.fillRectangle(r.width - 4, r.height - 4, 2, 2);
					event.gc.fillRectangle(r.width - 8, r.height - 4, 2, 2);
					event.gc.fillRectangle(r.width - 12, r.height - 4, 2, 2);
					event.gc.fillRectangle(r.width - 4, r.height - 8, 2, 2);
					event.gc.fillRectangle(r.width - 8, r.height - 8, 2, 2);
					event.gc.fillRectangle(r.width - 4, r.height - 12, 2, 2);
					event.gc.setForeground(highlight);
				} else {
					event.gc.setForeground(shadow);
					event.gc.drawLine(r.width - 3, r.height - 2, r.width - 2,
							r.height - 3);
					event.gc.drawLine(r.width - 4, r.height - 2, r.width - 2,
							r.height - 4);
					event.gc.drawLine(r.width - 7, r.height - 2, r.width - 2,
							r.height - 7);
					event.gc.drawLine(r.width - 8, r.height - 2, r.width - 2,
							r.height - 8);
					event.gc.drawLine(r.width - 11, r.height - 2, r.width - 2,
							r.height - 11);
					event.gc.drawLine(r.width - 12, r.height - 2, r.width - 2,
							r.height - 12);

					event.gc.setForeground(highlight);
					event.gc.drawLine(r.width - 5, r.height - 2, r.width - 2,
							r.height - 5);
					event.gc.drawLine(r.width - 9, r.height - 2, r.width - 2,
							r.height - 9);
					event.gc.drawLine(r.width - 13, r.height - 2, r.width - 2,
							r.height - 13);
				}

				if ((getStyle() & SWT.SHADOW_IN) != 0) {
					if (event.width > WIDTH)
						event.gc.drawLine(0, r.height - 1, r.width - 14,
								r.height - 1);
					if (event.height > HEIGHT)
						event.gc.drawLine(r.width - 1, 0, r.width - 1,
								r.height - 14);
				}
			}
		});

		addListener(SWT.MouseDown, new Listener() {
			public void handleEvent(Event event) {
				if (event.button == 1) {
					mouseDownOffsetX = event.x;
					mouseDownOffsetY = event.y;
					Point p = resizableParent.getSize();
					snapBackX = p.x;
					snapBackY = p.y;
					cancelled = false;
					//System.out.println("x="+mouseDownOffsetX+",
					// y="+mouseDownOffsetY);
				} else if (event.button == 3
						&& (event.stateMask & SWT.BUTTON1) != 0) // chord click
				{
					if (snapBackX > 0 && snapBackY > 0) {
						resizableParent.setSize(snapBackX, snapBackY);
						snapBackX = 0;
						snapBackY = 0;
						cancelled = true;
					}
				}
			}
		});

		addListener(SWT.MouseMove, new Listener() {
			public void handleEvent(final Event event) {
				if (!cancelled && (event.stateMask & SWT.BUTTON1) != 0) {
					if (timerTask != null) {
						timerTask.cancel();
						timerTask = null;
					}
					long now = System.currentTimeMillis();
					if (lastUpdate + UPDATE_DELAY < now) {
						performResize(event);
						lastUpdate = now;
					} else {
						timerTask = new TimerTask() {
							public void run() {
								final TimerTask executingTask = this;
								event.display.asyncExec(new Runnable() {
									public void run() {
										if (executingTask != timerTask)
											return;
										performResize(event);
									}
								});
							}
						};
						timer.schedule(timerTask, UPDATE_DELAY);
					}
				}
			}
		});

		addListener(SWT.MouseUp, new Listener() {
			public void handleEvent(Event event) {
				if (timerTask != null) {
					timerTask.cancel();
					timerTask = null;
				}
				if (!cancelled && (event.stateMask & SWT.BUTTON1) != 0) {
					performResize(event);
				}
			}
		});

		// 注册改变窗口大小的事件侦听器
		final Listener resizeListener = (resizableParent instanceof Shell) ? new Listener() {
			public void handleEvent(Event event) {
				updateVisibility();
			}
		}
				: null;

		if (resizeListener != null)
			resizableParent.addListener(SWT.Resize, resizeListener);

		addListener(SWT.Dispose, new Listener() {
			public void handleEvent(Event event) {
				timer.cancel();
				if (resizeListener != null)
					resizableParent.removeListener(SWT.Resize, resizeListener);
			}
		});

		updateVisibility();
	}

	private void performResize(Event event) {
		// 首先确定是否处在窗口内
		Rectangle ca;
		if (resizableParent instanceof Shell)
			ca = getDisplay().getClientArea();
		else
			ca = getDisplay().map(resizableParent.getParent(), null,
					resizableParent.getParent().getClientArea());
		Point limit = toControl(ca.x + ca.width - 1, ca.y + ca.height - 1);
		event.x = Math.min(event.x, limit.x);
		event.y = Math.min(event.y, limit.y);

		Point p = resizableParent.getSize();
		int newX = p.x + event.x - mouseDownOffsetX;
		int newY = p.y + event.y - mouseDownOffsetY;
		if (minSize != null) {
			newX = Math.max(minSize.x, newX);
			newY = Math.max(minSize.y, newY);
		}
		if (newX != p.x || newY != p.y)
			resizableParent.setSize(newX, newY);
	}

	// 根据窗口是否最大化，设置控件的可见性
	private void updateVisibility() {
		if (resizableParent instanceof Shell) {
			boolean vis = super.getVisible();
			boolean max = ((Shell) resizableParent).getMaximized();
			boolean newVis = userVisible && !max;
			if (vis != newVis)
				super.setVisible(newVis);
		} else if (userVisible != super.getVisible())
			super.setVisible(userVisible);
	}

	public Point computeSize(int wHint, int hHint, boolean changed) {
		checkWidget();
		if (wHint == SWT.DEFAULT)
			wHint = WIDTH;
		if (hHint == SWT.DEFAULT)
			hHint = HEIGHT;
		return new Point(wHint, hHint);
	}

	private static int checkStyle(int style) {
		int mask = SWT.SHADOW_IN | SWT.FLAT;
		style &= mask;
		return style;
	}

	public boolean setFocus() {
		checkWidget();
		return false;
	}

	public boolean isReparentable() {
		checkWidget();
		return false;
	}

	// 设置窗口最小允许的尺寸
	public void setMinimumShellSize(Point p) {
		checkWidget();
		this.minSize = p;
	}

	public void setMinimumShellSize(int width, int height) {
		checkWidget();
		this.minSize = new Point(width, height);
	}

	public boolean getVisible() {
		checkWidget();
		return userVisible;
	}

	public void setVisible(boolean visible) {
		checkWidget();
		userVisible = visible;
		updateVisibility();
	}
}