Question

我想实现一个“手工工具”，用户可以使用鼠标滚动/移动某些东西。此功能可从各种程序中获知，例如Gimp。如果用户按下鼠标左键，则应激活该工具。如果现在移动鼠标，则还应将基础对象 - 比例移动到鼠标移动。因此，如果用户按下鼠标并通过例如移动它来移动鼠标。 10px，底层对象也应移动10px。我认为它应该适用于我下面的代码，但它无法正常工作。基础ScrolledComposite的移动太快了。

以下代码已准备就绪，因此您可以直接使用它。

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseMoveListener;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class HandTool {

  public static boolean moveGraphActive = false;
  public static Point moveStartPos = new Point(0, 0);
  public static ScrolledComposite sc;

  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    sc = new ScrolledComposite(shell, SWT.V_SCROLL);

    Text text = new Text(sc, SWT.MULTI | SWT.READ_ONLY);
    String multiLineText = "";
    for (int i = 0; i < 30; i++) {
      multiLineText += "Hello World SWT " + i + System.lineSeparator();
    }
    text.setText(multiLineText);
    text.setEnabled(false);
    text.pack();
    sc.setContent(text);

    sc.addMouseListener(new MouseAdapter() {
      @Override
      public void mouseDown(final MouseEvent e) {
        moveGraphActive = e.button == 1;
        if (moveGraphActive) {
          moveStartPos.x = e.x;
          moveStartPos.y = e.y;
        }
      }

      @Override
      public void mouseUp(final MouseEvent e) {
        moveGraphActive = false;
      }
    });

    sc.addMouseMoveListener(new MouseMoveListener() {
      @Override
      public void mouseMove(final MouseEvent e) {
        if (moveGraphActive) {
          // FIXME the movement of the canvas should be proportional
          // to the mouse
          // movement
          final int newX = sc.getOrigin().x + moveStartPos.x - e.x;
          final int newY = sc.getOrigin().y + moveStartPos.y - e.y;
          sc.setOrigin(newX, newY);
        }
      }
    });

    shell.setSize(500, 150);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}

Answer 1

你几乎做对了，只有一个小错误。

final int newX = sc.getOrigin().x + moveStartPos.x - e.x;
final int newY = sc.getOrigin().y + moveStartPos.y - e.y;

应该是

final int newX = startOrigin.x + moveStartPos.x - e.x;
final int newY = startOrigin.y + moveStartPos.y - e.y;

其中startOrigin是您开始拖动时ScrolledComposite的来源。我已经更新了你的代码：

private static boolean           moveGraphActive = false;
private static Point             moveStartPos    = new Point(0, 0);
private static ScrolledComposite sc;
private static Point             startOrigin;

public static void main(String[] args)
{
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    sc = new ScrolledComposite(shell, SWT.V_SCROLL);

    Text text = new Text(sc, SWT.MULTI | SWT.READ_ONLY);
    String multiLineText = "";
    for (int i = 0; i < 30; i++)
    {
        multiLineText += "Hello World SWT " + i + System.lineSeparator();
    }
    text.setText(multiLineText);
    text.setEnabled(false);
    text.pack();
    sc.setContent(text);

    sc.addMouseListener(new MouseAdapter()
    {
        @Override
        public void mouseDown(final MouseEvent e)
        {
            moveGraphActive = e.button == 1;
            if (moveGraphActive)
            {
                moveStartPos.x = e.x;
                moveStartPos.y = e.y;
                startOrigin = sc.getOrigin();
            }
        }

        @Override
        public void mouseUp(final MouseEvent e)
        {
            moveGraphActive = false;
            startOrigin = null;
        }
    });

    sc.addMouseMoveListener(new MouseMoveListener()
    {
        @Override
        public void mouseMove(final MouseEvent e)
        {
            if (moveGraphActive)
            {
                // FIXED
                final int newX = startOrigin.x + moveStartPos.x - e.x;
                final int newY = startOrigin.y + moveStartPos.y - e.y;
                sc.setOrigin(newX, newY);
            }
        }
    });

    shell.setSize(500, 150);
    shell.open();
    while (!shell.isDisposed())
    {
        if (!display.readAndDispatch())
            display.sleep();
    }
    display.dispose();
}

SWT ScrolledComposite手工工具：滚动比例鼠标移动

1 个答案: