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));

Frame inside custom view

I have implemented a custom view in my Eclipse plugin project, where I want to display different graphs, which are selected by the user. I have no problem with creating a custom view, using org.eclipse.swt.graphics.GC and drawing the required parts but I would like to implement the following:
Inside the custom view I want to have some fixed area on the bounds of the view, where I can display the coordinate system (x- and y-axis with the corresponding labeling), which is fixed. Between these bounds I would like to display the graph, which is changing dynamically, depending on user selection.
So what I need is a custom view, that is built like the following:
Inside the grey area on the left and on the bottom I want to have the coordinate system axes (shown red) and inside the white area I want to draw the graph.
How do I create such an area inside my view? It should just be a filed, without any translations or scales, just a independend area, like a view inside a view...
#Override
public void init(IViewSite site) throws PartInitException {
super.init(site);
}
#Override
public void createPartControl(Composite parent) {
canvas = new Canvas(parent, SWT.NONE);
canvas.addPaintListener(new PaintListener() {
public void paintControl(PaintEvent e) {
drawCoordinateSystem(e);
drawGraph(e);
});
public void drawCoordinateSystem(PaintEvent e) {
// 1. create area inside view
// 2. draw coordinate system
}
public void drawGraph() {
// 3. draw graph
}
I know how to solve point 2 and 3. But I don't know, how to create such an area inside my view.
I would appreciate any help!

I would suggest that you add multiple controls and handle drawing for different cases in a different way.
For example, instead of having just one monolithic Canvas that draws everything from graph to coordinates, to helpful labels. Add a bunch of label controls on top for showing coordinates, add a parent, or labels for coordinate systems etc.
Your createPartControl should look something like below:
Composite topBar = new Composite(parent, SWT.None);
topBar.setLayout(new GridLayout(3, false));
Label title = new Label(topBar, SWT.NONE);
title.setLayoutData(new GridData(GridData.FILL, GridData.CENTER, true, false));
Label x = new Label(topBar, SWT.NONE);
Label y = new Label(topBar, SWT.NONE);
Composite graphArea = new Composite(parent, SWT.NONE);
graphArea.setLayout(new GridLayout(2, false));
Canvas xAxis = new Canvas(graphArea, SWT.NONE);
GridData gd = new GridData(GridData.CENTER, GridData.FILL, false, true);
gd.widthHint = 10;
xAxis.setLayoutData(gd);
xAxis.addPaintListener(new PaintListener() {
#Override
public void paintControl(PaintEvent e) {
drawXAxis();
}
});
Canvas graph = new Canvas(graphArea, SWT.NONE);
graph.addPaintListener(new PaintListener() {
public void paintControl(PaintEvent e) {
drawGraph(e);
}
});
Label emptySpace = new Label(graphArea, SWT.NONE);
Canvas yAxis = new Canvas(graphArea, SWT.NONE);
GridData gd = new GridData(GridData.FILL, GridData.CENTER, true, false);
gd.heightHint = 10;
xAxis.setLayoutData(gd);
yAxis.addPaintListener(new PaintListener() {
#Override
public void paintControl(PaintEvent e) {
drawYAxis();
}
});

You should draw everything in Your paintListener, if Your graph changes just redraw area of graph for example:
Rectangle rect = getGraphBoundries(); //you must implement this method
canvas.redraw(rect.x, rect.y, rect.width, rect.height, true);
this will redraw graph area. To avoid unnecessary computing of axes area in in paintListener paintEvent's gc has area that need to be redrawn called clipping. You can write condition like this:
public void paintControl(PaintEvent e) {
...
if(drawGraph(e.gc.getClipping().intersects(getGraphBoundries())) {
drawGraph(e);
}
...
}

How to always show vertical scroll bar in SWT table?

Is it possible to always show the vertical scroll bar in a SWT table even if the table is empty? By always showing a (possible disabled) vertical scroll bar one can avoid that the last column get partially hidden when the columns use ColumnWeightData for layouting.
I tried to initialize the table with SWT.V_SCROLL or to use table.getVerticalBar().setVisible(true) - both without success.
There is a method setAlwaysShowScrollBars in ScrollableComposite. What I am looking for is a similar method in Table.
UPDATE: I suppose that the scroll bars which are visible when the table contains enough data are not those scroll bars which Table inherits from Scrollable. I have debugged ScrollBar.setVisible(boolean) and it seems not be called on table layout updates. Is this observation correct?
UPDATE 2: Here is a snippet for a table construction. It would be great to have the vertical scrollbar visible even if the table is empty and to have the column headers visible even if the table data are scrolled down. Note: The snippet has left out some details as the label provider and some other controls arranged at the same parent composite.
protected void createMasterPart(final IManagedForm managedForm, Composite parentComposite)
{
FormToolkit toolkit = managedForm.getToolkit();
Composite contentComposite = toolkit.createComposite(parentComposite, SWT.NONE);
contentComposite.setLayoutData(new GridData(SWT.LEFT, SWT.TOP, false, false, 1, 1));
toolkit.paintBordersFor(contentComposite);
contentComposite.setLayout(new GridLayout(2, false));
GridData gd;
Composite tableComposite = new Composite(contentComposite, SWT.NONE);
TableColumnLayout tableColumnLayout = new TableColumnLayout();
tableComposite.setLayout(tableColumnLayout);
gd = new GridData(SWT.FILL, SWT.FILL, true, false, 1, 3);
tableComposite.setLayoutData(gd);
speakerTableViewer = new TableViewer(tableComposite, SWT.BORDER | SWT.FULL_SELECTION);
speakerTableViewer.setContentProvider(ArrayContentProvider.getInstance());
Table speakerTable = speakerTableViewer.getTable();
speakerTable.setHeaderVisible(true);
speakerTable.setLinesVisible(true);
toolkit.paintBordersFor(speakerTable);
TableViewerColumn tableViewerAudiosampleColumn = new TableViewerColumn(speakerTableViewer, SWT.NONE);
TableColumn audiosampleColumn = tableViewerAudiosampleColumn.getColumn();
tableColumnLayout.setColumnData(audiosampleColumn, new ColumnWeightData(60, true));
audiosampleColumn.setText("Sample");
TableViewerColumn tableViewerSpeakerColumn = new TableViewerColumn(speakerTableViewer, SWT.NONE);
TableColumn speakerColumn = tableViewerSpeakerColumn.getColumn();
tableColumnLayout.setColumnData(speakerColumn, new ColumnWeightData(60, true));
speakerColumn.setText("Speaker");
TableViewerColumn tableViewerRemarkColumn = new TableViewerColumn(speakerTableViewer, SWT.NONE);
TableColumn remarkColumn = tableViewerRemarkColumn.getColumn();
tableColumnLayout.setColumnData(remarkColumn, new ColumnWeightData(120, true));
remarkColumn.setText("Remark");
}

It's not possible to force the Table to always show scroll bars, the OS decides when to show them.
Alternatives
Right, I came up with a solution very similar to my answer to this question:
Is it possible to get the vertical/horizontal scroll bar visible when the SWT List is in disabled state?
The idea is to use a ScrolledComposite (as the other answer already suggested) to take care of the scrolling. The Table itself won't scroll. However, this won't make any difference, because the user won't be able to tell the difference.
ScrolledComposite has a method called setAlwaysShowScrollBars(boolean) with which you can force it to always show the scroll bars, even if they aren't required.
Here is some sample code, that will illustrate what I just talked about:
public static void main(String[] args)
{
final Display display = new Display();
final Shell shell = new Shell(display);
shell.setLayout(new GridLayout());
final ScrolledComposite composite = new ScrolledComposite(shell, SWT.V_SCROLL);
composite.setLayout(new GridLayout());
composite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
final Table table = new Table(composite, SWT.NO_SCROLL | SWT.FULL_SELECTION);
table.setHeaderVisible(true);
composite.setContent(table);
composite.setExpandHorizontal(true);
composite.setExpandVertical(true);
composite.setAlwaysShowScrollBars(true);
composite.setMinSize(table.computeSize(SWT.DEFAULT, SWT.DEFAULT));
Button fillTable = new Button(shell, SWT.PUSH);
fillTable.setText("Fill table");
fillTable.setLayoutData(new GridData(SWT.FILL, SWT.END, true, false));
fillTable.addListener(SWT.Selection, new Listener()
{
#Override
public void handleEvent(Event arg0)
{
if (table.getColumnCount() < 1)
{
for (int col = 0; col < 4; col++)
{
TableColumn column = new TableColumn(table, SWT.NONE);
column.setText("Column " + col);
}
}
for (int row = 0; row < 20; row++)
{
TableItem item = new TableItem(table, SWT.NONE);
for (int col = 0; col < table.getColumnCount(); col++)
{
item.setText(col, "Item " + row + " " + col);
}
}
for (int col = 0; col < table.getColumnCount(); col++)
{
table.getColumn(col).pack();
}
composite.setMinSize(table.computeSize(SWT.DEFAULT, SWT.DEFAULT));
}
});
Button clearTable = new Button(shell, SWT.PUSH);
clearTable.setText("Clear table");
clearTable.setLayoutData(new GridData(SWT.FILL, SWT.END, true, false));
clearTable.addListener(SWT.Selection, new Listener()
{
#Override
public void handleEvent(Event arg0)
{
table.removeAll();
composite.setMinSize(table.computeSize(SWT.DEFAULT, SWT.DEFAULT));
}
});
shell.pack();
shell.setSize(400, 300);
shell.open();
while (!shell.isDisposed())
{
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
Looks like this:
As you can see, the scroll bar is always visible.
UPDATE
As pointed out in the comment, this approach will not keep the Table headers visible when you scroll down. If you could post a small working code example that illustrates your problem, we might come up with an alternative (unrelated to forcing the scroll bars).
UPDATE2
Here is some code that should do what you want, the trick is to trigger a resize event on the parent of the TableViewer, the horizontal scrollbar that is shown isn't really necessary and it disappears after you resize the window:
public static void main(String[] args)
{
final Display display = new Display();
final Shell shell = new Shell(display);
shell.setText("StackOverflow");
shell.setLayout(new GridLayout());
createMasterPart(shell);
shell.pack();
shell.setSize(400, 300);
shell.open();
shell.layout(true, true);
while (!shell.isDisposed())
{
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
private static void createMasterPart(Composite parentComposite)
{
Composite composite = new Composite(parentComposite, SWT.NONE);
composite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
composite.setLayout(new GridLayout(1, false));
Composite tableComposite = new Composite(composite, SWT.NONE);
TableColumnLayout tableColumnLayout = new TableColumnLayout();
tableComposite.setLayout(tableColumnLayout);
tableComposite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
TableViewer tableViewer = new TableViewer(tableComposite, SWT.BORDER | SWT.FULL_SELECTION);
tableViewer.setContentProvider(ArrayContentProvider.getInstance());
Table table = tableViewer.getTable();
table.setHeaderVisible(true);
table.setLinesVisible(true);
TableViewerColumn firstTableViewerColumn = new TableViewerColumn(tableViewer, SWT.NONE);
TableColumn firstTableColumn = firstTableViewerColumn.getColumn();
firstTableColumn.setText("Sample");
firstTableViewerColumn.setLabelProvider(new ColumnLabelProvider()
{
#Override
public String getText(Object element)
{
Dummy p = (Dummy) element;
return p.first;
}
});
TableViewerColumn secondTableViewerColumn = new TableViewerColumn(tableViewer, SWT.NONE);
TableColumn secondTableColumn = secondTableViewerColumn.getColumn();
secondTableColumn.setText("Speaker");
secondTableViewerColumn.setLabelProvider(new ColumnLabelProvider()
{
#Override
public String getText(Object element)
{
Dummy p = (Dummy) element;
return p.second;
}
});
TableViewerColumn thirdTableViewerColumn = new TableViewerColumn(tableViewer, SWT.NONE);
TableColumn thirdTableColumn = thirdTableViewerColumn.getColumn();
thirdTableColumn.setText("Remark");
thirdTableViewerColumn.setLabelProvider(new ColumnLabelProvider()
{
#Override
public String getText(Object element)
{
Dummy p = (Dummy) element;
return p.third;
}
});
List<Dummy> elements = new ArrayList<>();
for(int i = 0; i < 20; i++)
{
elements.add(new Dummy("firstfirstfirst " + i, "secondsecondsecond " + i, "thirdthirdthirdthirdthirdthird " + i));
}
tableViewer.setInput(elements);
tableColumnLayout.setColumnData(firstTableColumn, new ColumnWeightData(1, true));
tableColumnLayout.setColumnData(secondTableColumn, new ColumnWeightData(1, true));
tableColumnLayout.setColumnData(thirdTableColumn, new ColumnWeightData(2, true));
}
private static class Dummy
{
public String first;
public String second;
public String third;
public Dummy(String first, String second, String third)
{
this.first = first;
this.second = second;
this.third = third;
}
}

I have created a solution that I think is better than put your table inside a ScrolledComposite.
My solution: fill my table with empty items until my scroll bar is visible.
Example:
// Flag that knows if the empty item was added or not
boolean addedEmptyItem = false;
// Get the table client area
Rectangle rect = table.getClientArea ();
// Get the item height
int itemHeight = table.getItemHeight ();
// Get the header height
int headerHeight = table.getHeaderHeight ();
// Calculate how many items can be visible without scrolling
int visibleCount = (rect.height - headerHeight + itemHeight - 1) / itemHeight;
while ( visibleCount > table.getItemCount() ) {
// Add an empty item
new TableItem( table, SWT.NONE );
// Set the flag
addedEmptyItem = true;
}
// Vertical bar é disabled if an empty item was added
table.getVerticalBar().setEnabled( !addedEmptyItem );
I hope this solution helps someone.
Thanks.

I don't think you can do this but you can try call ScrolledComposite.setAlwaysShowScrollbars() to true, but you will see both of the enabled scrollbars all the time.

Properly resize GridLayout in a PartView

I have an Image in a grid that scales when the PartView is resized. If the BarsView starts smaller than 64 high (the size of the canvas), the bottom portion of the image gets cut off below the initial size. If it starts larger than what it is resized to, the minivitals does not shrink as it should. How can I the layout, when resized, to look like it does when I open the program at that size?
Screenshot of when the program is opened at normal size:
Shrunk after opening at normal size (notice the concentration bar is pushed off the bottom of the screen):
Opened at smaller size:
Opened at smaller size then expanded:
Restarting between resizing has the desired effect, except for the needing to restart part.
public class BarsView extends ViewPart {
private PageBook book;
public void createPartControl(Composite parent) {
book = new PageBook(parent, SWT.NONE);
book.setLayout(new FillLayout());
Composite page = new BarsPageView(book, view);
book.showPage(page);
}
private class BarsPageView extends Composite {
public BarsPageView(Composite parent, GameView view) {
super(parent, SWT.NONE);
this.setLayout(new GridLayout(3, false));
// This is a wrapper around a StyledText
entry = new StormFrontEntry(this, view);
GridData entryData = new GridData(SWT.FILL, SWT.BEGINNING, true, false);
entryData.heightHint = 22;
entry.getWidget().setLayoutData(entryData); // getWidget() returns the StyledText
// This is a Composite containing a Canvas
status = new StormFrontStatus(this, view);
status.setLayoutData(new GridData(SWT.CENTER, SWT.BEGINNING, false, false));
// This is defined below
GridData compassData = new GridData(SWT.CENTER, SWT.CENTER, false, false, 1, 2);
compassData.heightHint = 64;
compass = new WarlockCompass(this, SWT.NONE, theme, compassData);
compass.setLayoutData(compassData);
minivitals = new StormFrontDialogControl(this, SWT.NONE);
GridData mvData = new GridData(SWT.FILL, SWT.FILL, true, true, 2, 1);
minivitals.setLayoutData(mvData);
}
}
public class WarlockCompass extends Canvas {
public WarlockCompass (final Composite parent, int style, CompassTheme theme, GridData layoutData) {
super(parent, style);
addPaintListener(new PaintListener() {
public void paintControl(PaintEvent e) {
drawCompass(e.gc);
}
});
parent.addListener(SWT.Resize, new Listener() {
#Override
public void handleEvent(Event event) {
// I cut out the calculations for this
layoutData.heightHint = height;
WarlockCompass.this.setSize(width, height);
}
});
}
private void drawCompass (GC gc) {
// Cut out the calculations to scale the image to fix the canvas
gc.drawImage(scaledImage, 0, 0);
}
}

// This is defined below
GridData compassData = new GridData(SWT.CENTER, SWT.CENTER, false, false, 1, 2);
compassData.heightHint = 64;
compass = new WarlockCompass(this, SWT.NONE, theme, compassData);
compass.setLayoutData(compassData);
Should have been:
// This is defined below
GridData compassData = new GridData(SWT.CENTER, SWT.CENTER, false, true, 1, 2);
compassData.heightHint = 64;
compass = new WarlockCompass(this, SWT.NONE, theme, compassData);
compass.setLayoutData(compassData);
Changing that flag makes it resize properly.

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();
}
}