Develop Reference

How to get contents to show up inside a ScrolledComposite

I am creating a legend view and inside the shell is supposed to have a rectangle followed by a label describing the color. I was able to get the view to work using just a normal composite but the legend continues beyond the screen and no way of see it without making the window larger. I am trying to use a scrolledComposite view for my shell but when I execute the program, nothing appears.
public void createPartControl(Composite parent)
{
display = parent.getDisplay();
parent.setLayout(new FillLayout());
sc = new ScrolledComposite(parent, SWT.V_SCROLL | SWT.H_SCROLL);
LegendView.composite = new Composite(sc, SWT.NONE);
RowLayout layout = new RowLayout();
layout.wrap = true;
layout.spacing = 5;
composite.setLayout(layout);
}
public static void addRectangle(String legendMessage)
{
final String propId = legendMessage;
final String[] s = propId.split(",");
if (display != null)
{
display.syncExec(new Runnable()
{
#Override
public void run()
{
// Creating the color using the RBG values
final Color color =
new Color(display, Integer.parseInt(s[0]), Integer.parseInt(s[1]), Integer.parseInt(s[2]));
// Creating a canvas for which the rectangle can be drawn on
Canvas canvas = new Canvas(composite, SWT.NONE);
// Maybe set the bounds of the canvas
canvas.addPaintListener(new PaintListener()
{
public void paintControl(PaintEvent e)
{
e.gc.drawRectangle(1, 1, 50, 60);
e.gc.setBackground(color);
e.gc.fillRectangle(2, 2, 49, 59);
}
});
// Disposing the color after it has been used
canvas.addDisposeListener(new DisposeListener()
{
public void widgetDisposed(DisposeEvent e)
{
color.dispose();
}
});
// Creating a label and setting the font
Label label = new Label(composite, SWT.NULL);
Font boldFont = new Font( label.getDisplay(), new FontData( "Arial", 12, SWT.BOLD ) );
label.setFont( boldFont );
label.setText(s[3]);
composite.redraw();
composite.layout(true);
sc.setContent(composite);
}
});
}
}
I am calling add rectangle in a different class. I am fairly new at using SWT and after looking at examples and reading the docs for scrolled Composite, this is what I interpreted it as. Any help would be very appreciated.

You haven't told the ScrolledComposite how to manage the size. You must either call setSize or setMinSize. For this you probably want:
sc.setExpandHorizontal(true);
sc.setExpandVertical(true);
sc.setMinSize(composite.computeSize(SWT.DEFAULT, SWT.DEFAULT));

Enter Key Listener for Date is not working in linux flavours

Here is my full coding.I have Two class firstone MyDateTime and Second one is Employee.
i have included currently working coding of mine.For the EmployeePart class,AbstractEditorPart is our own parent class Which is extended
public class MyDateTime extends DateTime{
public DateTime(Composite parent, int style)
{
super(parent, style);
}
public Date getValue()
{
Date date = new Date(getYear(), getMonth(), getDay());
return date;
}
}
public Class EmployeePart extends AbstractEditorPart(
private MyDateTime currentDate;
public void createBody(Composite parent){
currentDate=Util.createDateChooserCombo(parent, toolkit, "Date:", 2);
}
public void save(Employee input){
return null;
}
}
}

Turns out to be a little more complicated than I first thought.
One solution is to define a TabList for the Composite that contains your Widgets.
This way you can first define in which order you want them to be traversed.
Then add a Listener to each of the Widgets you want to traverse. This Listener will determine the next item in the TabList and force the focus on this item when either Tab or Enter is pressed.
Here is some example code:
public static void main(String[] args)
{
Display display = Display.getDefault();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
final Composite content = new Composite(shell, SWT.NONE);
content.setLayout(new FillLayout());
Text first = new Text(content, SWT.BORDER);
Text second = new Text(content, SWT.BORDER);
content.setTabList(new Control[] {first, second});
Listener enterListener = new Listener()
{
#Override
public void handleEvent(Event event)
{
/* Is it a traverse via Tab or Enter? */
if(event.keyCode == SWT.CR || event.keyCode == SWT.TRAVERSE_RETURN || event.keyCode == SWT.TRAVERSE_TAB_NEXT)
{
/* Get source of event */
Widget source = event.widget;
/* Get traverse order of content composite */
Control[] tabList = content.getTabList();
/* Try to find current position in the tab list */
for(int i = 0; i < tabList.length; i++)
{
if(source.equals(tabList[i]))
{
/* Get the next item in the tab list */
Control nextControl = tabList[(i + 1) % tabList.length];
/* And force the focus on this item */
nextControl.setFocus();
nextControl.forceFocus();
return;
}
}
}
}
};
first.addListener(SWT.KeyUp, enterListener);
second.addListener(SWT.KeyUp, enterListener);
shell.pack();
shell.open();
while (!shell.isDisposed())
{
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}

Java SWT - listen if new children are added to the Composite?

I have a Composite.
In SWT the children are added, by children, no by parents:
Composite parent = new Composite(shell, SWT.none);
Composite child = new Composite(parent, SWT.none);
That means, that inside of the parent I do not know, in which way and when the children are added to their parents.
QUESTION:
Inside of the parent I need to know, when new children are added to the parent.
Is there any way to register an onChildAddListener or any add() method to override?

The only way to add custom MyComposite and create custom ChildEvent as well as ChildEventListener interface. MyComposite is capable of registering listeners of ChildEvent and fire this event when a child Composite is created.
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.TypedEvent;
import org.eclipse.swt.internal.SWTEventListener;
import org.eclipse.swt.widgets.*;
/*
* This example demonstrates the minimum amount of code required
* to open an SWT Shell and process the events.
*/
public class HelloWorld1 {
public static void main (String [] args) {
Display display = new Display ();
Shell shell = new HelloWorld1 ().open (display);
while (!shell.isDisposed ()) {
if (!display.readAndDispatch ()) display.sleep ();
}
display.dispose ();
}
public Shell open (Display display) {
Shell shell = new Shell (display);
MyComposite parent = new MyComposite(shell, SWT.NONE);
parent.addChildEventListener(new ChildEventListener() {
#Override
public void add(ChildEvent e) {
System.out.println("Child added.");
}
});
MyComposite child = new MyComposite(parent, SWT.NONE);
// shell.open ();
return shell;
}
}
class MyComposite extends Composite {
ChildEventListener[] childEventListeners = new ChildEventListener[0];
public MyComposite(Composite parent, int style) {
super(parent, style);
if (parent instanceof MyComposite){
((MyComposite)parent).fireChildEvent(new ChildEvent(this));
}
}
public void addChildEventListener (ChildEventListener listener) {
checkWidget();
if (listener == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
ChildEventListener[] newChildEventListeners = new ChildEventListener[childEventListeners.length + 1];
System.arraycopy(childEventListeners, 0, newChildEventListeners, 0, childEventListeners.length);
childEventListeners = newChildEventListeners;
childEventListeners[childEventListeners.length - 1] = listener;
}
public void removeChildEventListener (ChildEventListener listener) {
if (childEventListeners.length == 0) return;
int index = -1;
for (int i = 0; i < childEventListeners.length; i++) {
if (listener == childEventListeners[i]){
index = i;
break;
}
}
if (index == -1) return;
if (childEventListeners.length == 1) {
childEventListeners = new ChildEventListener[0];
return;
}
ChildEventListener[] newChildEventListeners = new ChildEventListener[childEventListeners.length - 1];
System.arraycopy (childEventListeners, 0, newChildEventListeners, 0, index);
System.arraycopy (childEventListeners, index + 1, newChildEventListeners, index, childEventListeners.length - index - 1);
childEventListeners = newChildEventListeners;
}
public void fireChildEvent(ChildEvent event){
for (int i = 0; i < childEventListeners.length; i++) {
childEventListeners[i].add (event);
}
}
}
interface ChildEventListener extends SWTEventListener {
public void add(ChildEvent e);
}
class ChildEvent extends TypedEvent {
public ChildEvent(Widget widget) {
super(widget);
// TODO Auto-generated constructor stub
}
}

The purpose for which I wanted to know about child addition - is for layoing out the children
(adding LayoutData e.g. GridData) when the child is added to a child, which is layed out with a particular Layout (e.g. GridLayout).
Since it is not possible to layout children on addition - check their layout on every widget resize:
/*
* To make the forms fill the group - laying out the children is necessary.
* Unfortunately it is not possible to listen for children addition, in order to layout the children addition automatically.
* This means that the user will have to remember to layout the children, which is a nogo.
*
* Solution:
* istead of adding right layout on child addition - check if there are new children every time the widget is resized.
* if a widget without layoutData is found (new child not layed out) - add a layout
*/
this.addControlListener(new ControlAdapter() {
#Override
public void controlResized(ControlEvent e) {
layoutChildren();
}
});
}
private void layoutChildren(){
for(Control child:getChildren()){
if(child.getLayoutData() == null){
child.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));
}
}
}
public void addToGroup(Composite child){
child.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));
}

Drop File on SWT Label with Image (DND)

Problem description:
The user should be able to drag an Image-File from his computer to a RCP Application. The drop-target is a SWT-Label which is generated through the Eclipse FormToolkit. (Eclipse Forms)
With the following code, the user is able to drag Image-Files as well as Images from a Browser and drop them on the label (works well).
The problem occurs, when the label shows a image:
lblImage.setImage()
In my example, I set the image of the label, after the user dropped a file. As a consequence, subsequent drags are no longer registered.
(dragEnter method is no longer invoked)
/** create label **/
Label lblImage = fFormToolkit.createLabel(fForm.getBody(), "");
GridData gd = new GridData();
gd.widthHint = 200;
gd.heightHint = 200;
lblImage.setLayoutData(gd);
/** drag drop support **/
int ops = DND.DROP_COPY | DND.DROP_LINK | DND.DROP_DEFAULT;
final FileTransfer fTransfer = FileTransfer.getInstance();
final ImageTransfer iTransfer = ImageTransfer.getInstance();
Transfer[] transfers = new Transfer[] { fTransfer, iTransfer };
DropTarget target = new DropTarget(fLblArtWork, ops);
target.setTransfer(transfers);
target.addDropListener(new DropTargetAdapter() {
#Override
public void drop(DropTargetEvent event) {
if (event.data instanceof String[]) {
String[] filenames = (String[]) event.data;
if (filenames.length > 0){
Image i = new Image(Display.getCurrent(), filepath);
lblImage.setImage(i);
}
} else if (event.data instanceof ImageData) {
Image i = new Image(Display.getCurrent(), data);
lblImage.setImage(i);
}
}
public void dragEnter(DropTargetEvent event) {
System.out.println("drag enter");
event.detail = DND.DROP_COPY;
}
});
Question: How do I register dragEnter Events on a SWT Label that shows an Image?
Thanks

In your example there were some problems that caused this not to compile for me. After I fixed the issues I was able to drag png files onto the component and each successive drop changed the image correctly.
Here are the changes:
Original
DropTarget target = new DropTarget(fLblArtWork, ops);
became:
DropTarget target = new DropTarget(lblImage, ops);
Original
Image i = new Image(Display.getCurrent(), filepath);
became:
Image i = new Image(Display.getCurrent(), filenames[0]);
Original
Image i = new Image(Display.getCurrent(), data);
became
Image i = new Image(Display.getCurrent(), (ImageData) event.data);
I also create my label the following way:
final Label lblImage = new Label(shell, SWT.NONE);
but that shouldn't make a difference.

I used SashForm here to set an background image from the local system. AS per your requirement I have done the text and label also but I didn't set. You can set it by the labelobject.setImage(image);
final SashForm sashForm = new SashForm(composite, SWT.BORDER);
sashForm.setBounds(136, 10, 413, 237);
final Label lblHello = new Label(composite, SWT.NONE);
DragSource dragSource = new DragSource(lblHello, DND.DROP_NONE);
ImageTransfer imgTrans=ImageTransfer.getInstance();
FileTransfer fileTrans=FileTransfer.getInstance();
Transfer[] transfer=new Transfer[] { fileTrans,imgTrans,TextTransfer.getInstance() };
DropTarget dropTarget = new DropTarget(sashForm, DND.DROP_NONE);
dropTarget.setTransfer(transfer);
dragSource.setTransfer(transfer);
lblHello.setBounds(27, 219, 55, 15);
lblHello.setText("Hello");
dragSource.addDragListener(new DragSourceAdapter() {
#Override
public void dragStart(DragSourceEvent event) {
event.doit=true;
}
});
//Drop Event
dropTarget.addDropListener(new DropTargetAdapter() {
#Override
public void drop(DropTargetEvent event) {
System.out.println(event.detail);
//String path = System.getProperty("C:\\Users\\Public\\Pictures\\Sample Pictures\\Desert.jpg");
Image image=new Image(display, "C:\\Users\\Public\\Pictures\\Sample Pictures\\Desert.jpg");
sashForm.setBackgroundImage(image);
}
});

Easy Way : Drop File on SWT Label with Image (DND)
The drop event occurs when the user releases the mouse over the Drop target.
final CLabel lblNewLabel = new CLabel(parent, SWT.BORDER);
lblNewLabel.setBounds(10, 43, 326, 241);
lblNewLabel.setText("Drop Target");
// Allow data to be copied or moved to the drop target
DropTarget dropTarget = new DropTarget(lblNewLabel, DND.DROP_MOVE| DND.DROP_COPY | DND.DROP_DEFAULT);
// Receive data in Text or File format
final TextTransfer textTransfer = TextTransfer.getInstance();
final FileTransfer fileTransfer = FileTransfer.getInstance();
Transfer[] types = new Transfer[] {fileTransfer, textTransfer};
dropTarget.setTransfer(types);
// DropTargetEvent
dropTarget.addDropListener(new DropTargetAdapter() {
#Override
public void drop(DropTargetEvent event) {
if (textTransfer.isSupportedType(event.currentDataType)) {
String text = (String)event.data;
lblNewLabel.setText(text);
}
if (fileTransfer.isSupportedType(event.currentDataType)){
//clear Label Text
lblNewLabel.setText("");
//list out selected file
String[] files = (String[])event.data;
for (int i = 0; i < files.length; i++) {
String[] split = files[i].split("\\.");
String ext = split[split.length - 1];
// Set Images format "jpg" and "png"
if(ext.equalsIgnoreCase("jpg") || ext.equalsIgnoreCase("png"))
{
lblNewLabel.setImage(SWTResourceManager.getImage(files[i]));
}
else
{
lblNewLabel.setText(files[i]);
}
}//end for loop
}
}//End drop()
});//End addDropListener

SWT composite - redraw problem

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)
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 ?

In the changeText() function, the
testCell.redraw();
line should be replaced by
testCell.layout();
Or, if you want to resize it correctly you should use
shell.layout();.

I would say add a selectionListener on the label.
.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(final SelectionEvent e) {
//Change text by Label.setText();
}
}