我正在寻找一种在应用程序中的某些复合材料上添加叠加层的方法。覆盖层将包含一个带有文本“无可用数据”的标签。需要显示底层组合，但用户无法执行任何操作。我的应用程序在一个屏幕中包含不同的复合部件，因此我需要一种仅将覆盖层放置在其中一个复合部件上的方法。有没有办法在SWT中实现这个？
一个可能的解决方案是在您想要覆盖的
ShellComposite棘手的部分是更新覆盖层
ShellComposite所以我决定尝试开设一个课程
OverlayControlControlControl您可以使用相应的方法设置
Overlay我做了一些简单的测试，看起来工作正常，但我不能保证任何事情。您可能想尝试一下。
使用它的简单示例：
public class OverlayTest {
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout(SWT.VERTICAL));
shell.setSize(250, 250);
// create the composite
Composite composite = new Composite(shell, SWT.NONE);
composite.setLayout(new FillLayout(SWT.VERTICAL));
// add stuff to the composite
for (int i = 0; i < 5; i++) {
new Text(composite, SWT.BORDER).setText("Text " + i);
}
// create the overlay over the composite
Overlay overlay = new Overlay(composite);
overlay.setText("No data available");
// create the button to show/hide the overlay
Button button = new Button(shell, SWT.PUSH);
button.setText("Show/hide overlay");
button.addSelectionListener(new SelectionAdapter() {
@Override
public void widgetSelected(SelectionEvent arg0) {
// if the overlay is showing we hide it, otherwise we show it
if (overlay.isShowing()) {
overlay.remove();
}
else {
overlay.show();
}
}
});
shell.open();
while (shell != null && !shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
}
}
还有
Overlayimport java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.ControlListener;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Scrollable;
import org.eclipse.swt.widgets.Shell;
/**
* A customizable overlay over a control.
*
* @author Loris Securo
*/
public class Overlay {
private List<Composite> parents;
private Control objectToOverlay;
private Shell overlay;
private Label label;
private ControlListener controlListener;
private DisposeListener disposeListener;
private PaintListener paintListener;
private boolean showing;
private boolean hasClientArea;
private Scrollable scrollableToOverlay;
public Overlay(Control objectToOverlay) {
Objects.requireNonNull(objectToOverlay);
this.objectToOverlay = objectToOverlay;
// if the object to overlay is an instance of Scrollable (e.g. Shell) then it has
// the getClientArea method, which is preferable over Control.getSize
if (objectToOverlay instanceof Scrollable) {
hasClientArea = true;
scrollableToOverlay = (Scrollable) objectToOverlay;
}
else {
hasClientArea = false;
scrollableToOverlay = null;
}
// save the parents of the object, so we can add/remove listeners to them
parents = new ArrayList<Composite>();
Composite parent = objectToOverlay.getParent();
while (parent != null) {
parents.add(parent);
parent = parent.getParent();
}
// listener to track position and size changes in order to modify the overlay bounds as well
controlListener = new ControlListener() {
@Override
public void controlMoved(ControlEvent e) {
reposition();
}
@Override
public void controlResized(ControlEvent e) {
reposition();
}
};
// listener to track paint changes, like when the object or its parents become not visible (for example changing tab in a TabFolder)
paintListener = new PaintListener() {
@Override
public void paintControl(PaintEvent arg0) {
reposition();
}
};
// listener to remove the overlay if the object to overlay is disposed
disposeListener = new DisposeListener() {
@Override
public void widgetDisposed(DisposeEvent e) {
remove();
}
};
// create the overlay shell
overlay = new Shell(objectToOverlay.getShell(), SWT.NO_TRIM);
// default values of the overlay
overlay.setBackground(objectToOverlay.getDisplay().getSystemColor(SWT.COLOR_GRAY));
overlay.setAlpha(200);
// so the label can inherit the background of the overlay
overlay.setBackgroundMode(SWT.INHERIT_DEFAULT);
// label to display a text
// style WRAP so if it is too long the text get wrapped
label = new Label(overlay, SWT.WRAP);
// to center the label
overlay.setLayout(new GridLayout());
label.setLayoutData(new GridData(SWT.CENTER, SWT.CENTER, true, true));
showing = false;
overlay.open();
overlay.setVisible(showing);
}
public void show() {
// if it's already visible we just exit
if (showing) {
return;
}
// set the overlay position over the object
reposition();
// show the overlay
overlay.setVisible(true);
// add listeners to the object to overlay
objectToOverlay.addControlListener(controlListener);
objectToOverlay.addDisposeListener(disposeListener);
objectToOverlay.addPaintListener(paintListener);
// add listeners also to the parents because if they change then also the visibility of our object could change
for (Composite parent : parents) {
parent.addControlListener(controlListener);
parent.addPaintListener(paintListener);
}
showing = true;
}
public void remove() {
// if it's already not visible we just exit
if (!showing) {
return;
}
// remove the listeners
if (!objectToOverlay.isDisposed()) {
objectToOverlay.removeControlListener(controlListener);
objectToOverlay.removeDisposeListener(disposeListener);
objectToOverlay.removePaintListener(paintListener);
}
// remove the parents listeners
for (Composite parent : parents) {
if (!parent.isDisposed()) {
parent.removeControlListener(controlListener);
parent.removePaintListener(paintListener);
}
}
// remove the overlay shell
if (!overlay.isDisposed()) {
overlay.setVisible(false);
}
showing = false;
}
public void setBackground(Color background) {
overlay.setBackground(background);
}
public Color getBackground() {
return overlay.getBackground();
}
public void setAlpha(int alpha) {
overlay.setAlpha(alpha);
}
public int getAlpha() {
return overlay.getAlpha();
}
public boolean isShowing() {
return showing;
}
public void setText(String text) {
label.setText(text);
// to adjust the label size accordingly
overlay.layout();
}
public String getText() {
return label.getText();
}
private void reposition() {
// if the object is not visible, we hide the overlay and exit
if (!objectToOverlay.isVisible()) {
overlay.setBounds(new Rectangle(0, 0, 0, 0));
return;
}
// if the object is visible we need to find the visible region in order to correctly place the overlay
// get the display bounds of the object to overlay
Point objectToOverlayDisplayLocation = objectToOverlay.toDisplay(0, 0);
Point objectToOverlaySize;
// if it has a client area, we prefer that instead of the size
if (hasClientArea) {
Rectangle clientArea = scrollableToOverlay.getClientArea();
objectToOverlaySize = new Point(clientArea.width, clientArea.height);
}
else {
objectToOverlaySize = objectToOverlay.getSize();
}
Rectangle objectToOverlayBounds = new Rectangle(objectToOverlayDisplayLocation.x, objectToOverlayDisplayLocation.y, objectToOverlaySize.x,
objectToOverlaySize.y);
Rectangle intersection = objectToOverlayBounds;
// intersect the bounds of the object with its parents bounds so we get only the visible bounds
for (Composite parent : parents) {
Rectangle parentClientArea = parent.getClientArea();
Point parentLocation = parent.toDisplay(parentClientArea.x, parentClientArea.y);
Rectangle parentBounds = new Rectangle(parentLocation.x, parentLocation.y, parentClientArea.width, parentClientArea.height);
intersection = intersection.intersection(parentBounds);
// if intersection has no size then it would be a waste of time to continue
if (intersection.width == 0 || intersection.height == 0) {
break;
}
}
overlay.setBounds(intersection);
}
}
在父级上将布局设置为 null
在父级上添加一个样式为 SWT.TRANSPARENT 的新 Composite，位于要绘制的复合体之前
手动将复合材料的边界设置为同一区域，如果可以更改，请使用调整大小侦听器。