Question

I am calling com.google.gwt.user.client.ui.TextArea.setText(myText) to set the content. After that I call setCursorPosition(myText.length()) to get the cursor to the end. This works well.

When myText has more lines then the text area can display at once, it shows a scroll bar. But it does not scroll to the cursor position. Even worse – it scrolls to the top.

How can I scroll the GWT TextArea to the cursor position? I realy need the cursor position, not the bottom of the TextArea. A JSNI workaround would be ok too.

Answer 1

I had a scenario where the textarea will already have something and when a new command is submitted it will add the data to it and scroll to the start of the newly added data. this is what I did

    // Hold the previous height to set the scroll.
    final int prevHeight = document.get().getElementById(textareadid).getScrollHeight();
    // Hold the prev position if output area already has some data.
    final int prevPos = this.textArea.getValue() != null ?  
    this.textArea.getValue().length() : 0;

after processing and setting the new data

        int posCount = 0;
        if (previousResponse != null && !previousResponse.isEmpty())
        {
            final String dataStr = "new data from process";
            // add 15 lines for the cursor position
            posCount = getRelativeCount(dataStr);
        }
        this.textArea.getElement().setScrollTop(prevHeight);
        this.textArea.setCursorPos(prevPos + posCount);

 private int getRelativeCount(final String str)
{
    int charCount = 0;

    if (str != null)
    {

        int NUM_ROWS = 15;

        if (getUserAgent().contains("msie"))
        {
            NUM_ROWS = 16;
        }

        final String[] splitArr = str.split("\n"); // split on the new line
                                                   // char

        for (int index = 0; index < splitArr.length && index < NUM_ROWS; index++)
        {
            charCount += splitArr[index].length();
        }
    }
    return charCount;
}