Open autocompletion popup under RSyntaxTextArea when typing any key

Question

Currently I use in my project RSyntaxTextArea with Autocomplete. I can type a text and Ctrl+Space to open the autocomplete box. But I would like it to open by itself when I type the first letters of a variable like in Visual Studio Code.

I can't manage to set up this behavior despite my attempts

Answer 1

This should do the trick:

CompletionProvider provider = createCompletionProvider();
AutoCompletion ac = new AutoCompletion(provider);
ac.setAutoActivationEnabled(true); // Enable automatic popup
ac.setAutoActivationDelay(500); 

But in my case with lots of custom code, I had to programmatically simulate the keypress event of the autocomplete activation key (in my case, CTRL+SPACE):

        codeEditor.getDocument().addDocumentListener(new DocumentListener() {
            private void checkForDot(DocumentEvent e) {
                int offset = e.getOffset();
                try {
                    if (getCodeArea().getText(offset, 1).equals(".")) {
                        SwingUtilities.invokeLater(()->{
                            codeEditor.dispatchEvent(new KeyEvent(codeEditor, KeyEvent.KEY_PRESSED, System.currentTimeMillis(), KeyEvent.CTRL_DOWN_MASK, KeyEvent.VK_SPACE, KeyEvent.CHAR_UNDEFINED));
                        });
                    }
                } catch (BadLocationException ble) {
                    //ignore
                }
            }

            @Override
            public void insertUpdate(DocumentEvent e) {
                checkForDot(e);
            }

            @Override
            public void removeUpdate(DocumentEvent e) {
                // Do nothing
            }

            @Override
            public void changedUpdate(DocumentEvent e) {
                // Do nothing
            }
        });

With this, when the '.' character is inserted into the document, the autocomplete popup will appear as if you pressed CTRL+SPACE. You can probably adapt this idea if needed to build your solution.