Java SWT复合-重绘问题
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SWT composite - redraw problem
提问by Amit
I have a composite element, that initially has a Label. Now I call dispose on the it (the label) and create another label in the same container (composite elm), but I don't see the new text. It brings me to question how do I enable redraw on the composite, so that the new label (or any other component I might create) will render in place of the old one. Here is the code I have (separated into a unit test for redraw a composite)
我有一个复合元素，它最初有一个标签。现在我在它（标签）上调用 dispose 并在同一个容器（复合榆树）中创建另一个标签，但我没有看到新文本。它让我质疑如何在复合上启用重绘，以便新标签（或我可能创建的任何其他组件）将代替旧标签呈现。这是我的代码（分离为重绘复合的单元测试）
private Label createLabel( Composite parent) {
Label label = new Label(parent, SWT.NONE);
label.setAlignment(SWT.CENTER);
label.setLayoutData( new GridData( SWT.CENTER, SWT.CENTER, true, true) );
return label;
}
private void changeText() {
assert testCell != null : "Please initialize test cell";
testCell.getChildren()[0].dispose();
Label l = createLabel(testCell);
l.setText("New TexT");
testCell.redraw();
}
private void draw() {
Display display = new Display();
shell = new Shell(display);
shell.setLayout(new GridLayout(2,false));
testCell = new Composite(shell,SWT.BORDER);
testCell.setLayout(new GridLayout());
Label l = createLabel(testCell);
l.setText("Old Text");
Composite btnCell = new Composite(shell,SWT.NONE);
btnCell.setLayout(new GridLayout());
Button b = new Button(btnCell, SWT.PUSH);
b.setText("Change");
b.addListener(SWT.MouseDown, new Listener() {
public void handleEvent(Event e) {
changeText();
}
});
As you can see, I am calling redraw on the composite after I add a new element. Also, I have verified that after the call to dispose, testCell.getChildren().length returns 0, as expected, and when I create a new label, I get the same expression to return 1, verifying that the new element is indeed getting added to its parent composite container Am I missing something here ?
如您所见，我在添加新元素后对复合调用重绘。另外，我已经验证在调用 dispose 之后，testCell.getChildren().length 返回 0，正如预期的那样，并且当我创建一个新标签时，我得到相同的表达式以返回 1，验证新元素确实得到添加到其父复合容器中 我在这里遗漏了什么吗？
采纳答案by Csaba_H
In the changeText()function, the
在changeText()函数中，
testCell.redraw();
testCell.redraw();
line should be replaced by
行应替换为
testCell.layout();
testCell.layout();
Or, if you want to resize it correctly you should use
或者，如果你想正确调整它的大小，你应该使用
shell.layout();.
shell.layout();.
回答by anonymous
I would say add a selectionListener on the label.
我会说在标签上添加一个 selectionListener 。
.addSelectionListener(new SelectionAdapter() {
@Override
public void widgetSelected(final SelectionEvent e) {
//Change text by Label.setText();
}
}
