Apple IIgs #92
Twisted Tales of TextEdit

Revised by Dave Lyons (December 1991)
Written by C.K. Haun <TR> and Dave Lyons (September 1990)

This Technical Note discusses some undocumented features and some bugs in the TextEdit tool set through System Software 5.0.4.

Changes since November 1990: Noted that a non-control TENew creates a Text Edit record for the current port.


TENew

TextEdit records you create with TENew are always tied to the current port at the time of the TENew call, whether or not the fNotControl bit is set. (For TextEdit controls, NewControl2 is the preferred call.)

TEInsert

Using the TEInsert call on an invisible TextEdit record causes the screen to scroll, exactly as if the TextEdit record were visible.

If you use LETextBox2 style text as input for a TEInsert call, any style change information contained at the end of the LETextBox2 text is ignored. To ensure that the style change is not ignored, append an additional character at the end of the block, then delete (with TESetSelect and TEDelete) the extra character after the TEInsert call.

TEGetText

The documentation for TEGetText says that a dataFormat value of $4 returns the text as "Formatted for input to LineEdit LETextBox2". This is not a reliable return method -- this call may or may not succeed. Greater chance for success occurs with less than 4,000 characters in the TextEdit record.

TEGetText also supports getting just the text of the current selection range. Adding $0020 (onlyGetSelection) to the number passed in bufferDescriptor returns the text of the current selection. This technique does not work with data format LETextBox2, but does work with all other formats. Also, there is no corresponding bit for the associated style record, so you cannot get the style for just the current selection this way, if you request style information you get a styleRef for the entire TextEdit record.

TEClick

Using TEClick or TestControl on an inactive record currently causes that record to activate.

TERuler

Pixel tabbing values must all be greater than zero or TextEdit loops infinitely on a tab.

TEGetRuler & TESetRuler

TERuler, for the default ruler or any ruler that uses a tabType value of $1 returns a ruler four bytes longer than described in the documentation. The extra four bytes are all $FF, and they are the terminator characters for tabType $2 rulers. Expand your buffers by four bytes to prevent overwriting any data. TextEdit also expects the additional information on a TESetRuler call, so you should pad your ruler with four $FF bytes if you are using a type $1 ruler.

TESetText

Passing a zero-length class one input string (a word length string with the word set to zero) to TESetText causes TextEdit to crash.

TEPaintText

TEPaintText currently prints colored text in only four colors.

It's Not Dirty, It's Text

There has been some confusion about determining if a TextEdit record has been changed. The documentation has been a little vague, and the process itself has mislead some people. Here is The Truth: there is a TextEdit dirty flag, and you can use it and rely on it to tell you when a TextEdit record has changed.

The TextEdit dirty flag is bit 6 (fRecordDirty in the E16.TextEdit interface file) of the ctlFlag byte. This has caused some confusion because the ctlFlag byte is at offset $12 in the control definition template, and it is at offset $10 in the TextEdit or Control record. Just remember that it is not in the same place in the record as it is in the template.

If it is set, then the TextEdit or Control record has been changed since the last time the dirty bit was cleared. The dirty bit is clear initially when you create the TextEdit or Control record. Anytime after that, if the user enters text into the TextEdit record, TextEdit sets the dirty flag. It is up to your application to clear the dirty flag; TextEdit has no way of knowing when you've saved or cleared data.

Further Reference


This and all of the other Apple II Technical Notes have been converted to HTML by Aaron Heiss as a public service to the Apple II community, with permission by Apple Computer, Inc. Any and all trademarks, registered and otherwise, are properties of their owners.