How to add a simple tab in Intellij Idea plugin - intellij-idea

Question

I am creating a simple class diagram plugin for Intellij Idea. I'm struggling now with creating a simple tab in IDE. This tab I will fill up with a prepared JPanel and nothing else.
I have already done the same in NetBeans and I would like to find something with similar behavior as TopComponent in NetBeans provides, but anything working would be cool.

Answer 1

So here is the answer:
create implementation of com.intellij.openapi.fileEditor.FileEditor. This is your actual tab
create implementation of com.intellij.openapi.fileEditor.FileEditorProvider
accept() defines type of files which your editor opens
create() should returns the proper instance of your editor
register your FileEditoProvider in plugin.xml
Editor:
public class YourEditor implements FileEditor {
private VirtualFile file;
public YourEditor(VirtualFile file) {
this.file = file;
}
#Override
public #NotNull JComponent getComponent() {
JPanel tabContent = new JPanel();
tabContent.add(new JButton("foo"));
return tabContent;
}
#Override
public #Nullable JComponent getPreferredFocusedComponent() {
return null;
}
#Override
public #Nls(capitalization = Nls.Capitalization.Title)
#NotNull String getName() {
return "name";
}
#Override
public void setState(#NotNull FileEditorState fileEditorState) {
}
#Override
public boolean isModified() {
return false;
}
#Override
public boolean isValid() {
return true;
}
#Override
public void addPropertyChangeListener(#NotNull PropertyChangeListener propertyChangeListener) {
}
#Override
public void removePropertyChangeListener(#NotNull PropertyChangeListener propertyChangeListener) {
}
#Override
public #Nullable FileEditorLocation getCurrentLocation() {
return null;
}
#Override
public void dispose() {
Disposer.dispose(this);
}
#Override
public <T> #Nullable T getUserData(#NotNull Key<T> key) {
return null;
}
#Override
public <T> void putUserData(#NotNull Key<T> key, #Nullable T t) {
}
#Override
public #Nullable VirtualFile getFile() {
return this.file;
}
}
Provider:
public class YourEditorProvider implements FileEditorProvider, DumbAware {
private static String EDITOR_TYPE_ID = "DiagramView";
#Override
public boolean accept(#NotNull Project project, #NotNull VirtualFile virtualFile) {
return true; //will accept all kind of files, must be specified
}
#Override
public #NotNull
FileEditor createEditor(#NotNull Project project, #NotNull VirtualFile virtualFile) {
return new YourEditor(virtualFile);
}
#Override
public #NotNull
#NonNls
String getEditorTypeId() {
return EDITOR_TYPE_ID;
}
#Override
public #NotNull
FileEditorPolicy getPolicy() {
return FileEditorPolicy.HIDE_DEFAULT_EDITOR;
}
}
and finally put FileEditorProvider extension in pluxin.xml:
<extensions defaultExtensionNs="com.intellij">
<fileEditorProvider implementation="classDiagramPainter.DiagramViewProvider"/>
</extensions>