Bug 87774

Description Florian Priester 2005-03-11 10:31:14 EST

(Moved from bug 58569)

SWT-win32, v3124

Between 3.0M7 and 3.0M8 in Q1/Q2 2004, major internal changes were made
to the StyledText class and its underlying line-wrapping and text layout
mechanisms. As a result of those changes, the size (and presence) of the
caret no longer seems to be taken into account when handling issues
concerning the preferred size of the StyledText and the layout of its
contents. More specifically, this means that:

1.) If the caret offset is after the last character of a logical line
    and there is enough room for the actual text but not for the caret,
    the caret will be clipped (that is, the caret disappears, the user
    does not see it anymore). See screenshots 1a (for the SWT.WRAP case)
    and 1b (for the SWT.H_SCROLL case).
2.) If the caret offset is at the end of a visual line and is preceded by
    one or more whitespace characters, the caret will be clipped if
    there is enough room for the non-whitespace text but not for the
    whitespace text and the caret. See screenshot 2 (SWT.WRAP only).

The request here is that this bug be fixed in a way that ensures that
the caret will be visible at all times. The old version of the StyledText
widget solved this by wrapping the text as soon as needed (or updating
the scroll bar in the SWT.H_SCROLL case). Note that all of this should
also work for caret widths greater than 1 pixel.

---

import org.eclipse.swt.*;
import org.eclipse.swt.custom.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class StyledTextCaretTest {
  public static void main(String[] args) {
    Display display = new Display();
    
    Shell shell = new Shell(display);
    
    GridLayout layout = new GridLayout();
    layout.marginWidth  = 10;
    layout.marginHeight = 10;
    shell.setLayout(layout);
    
    Font font = new Font(display, "Tahoma", 14, SWT.NORMAL);
      
    StyledText text = new StyledText(shell, SWT.MULTI | SWT.WRAP);
    text.setFont(font);
    text.setText("The quick brown fox jumps over the lazy dog.");
    text.setLayoutData(new GridData(GridData.FILL_BOTH));
    
    // case #1
    text.setCaretOffset(text.getText().length());
    // case #2
    //text.setCaretOffset(26);
    
    shell.setSize(500, 200);
    shell.open();
    
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    
    font.dispose();
    display.dispose();
  }
}