[Laszlo-dev] For Review: Change 20071103-bargull-0 Summary: Add maxlength-support for multiline inputtexts (DHTML)

[André Bargull]

Change 20071103-bargull-0 by bargull at dell--p4--2-53 on 2007-11-03 18:09:41
in /home/Admin/src/svn/openlaszlo/trunk
for http://svn.openlaszlo.org/openlaszlo/trunk

Summary: Add maxlength-support for multiline inputtexts (DHTML)

New Features:

Bugs Fixed:
LPP-4747 - "Edittext maxlength does not work"

Technical Reviewer: max
QA Reviewer: promanik
Doc Reviewer: (pending)

Documentation:

Release Notes:

Details:
The HTML-<textarea> object does not support maxlength natively, so we 
need to implement a js-solution in DHTML.
I've used the "onkeyup"-event to check the current text-length and if 
the length exceeds its limit and I simply re-assigning the value 
property of the <textarea> object. This approach does not give the best 
visual experience, because the maxlength-test does happen after the new 
input is already visible for the user. Alternatives to "onkeyup" are: 
"onkeydown" and "onkeypress".
contra "onkeydown": we cannot determine which character the user enters, 
because we just have access to the "keyCode", which represents the 
pressed key on the keyboard (think about different keyboard-layouts, OS, 
etc.)
contra "onkeypress": (sometimes,) we can determine which character the 
user enters. "sometimes" means, it's browsers-dependent. For example, IE 
and FF do give us this char-information (through "keyCode" resp. 
"charCode"), but no chance in Opera (I did test not Safari). Opera's 
handling is somehow "interesting": if you press a "alphanumeric"-key, 
you get the char-code through "keyCode", but if you press a 
"function"-key, you get the key-code through "keyCode" ("charCode" is 
not supported in Opera). So it's almost the same problem as for 
"onkeydown", because we cannot easily determine which character was 
entered by the user.
I am open for any suggestions for this changeset (i.e.: implement 
"onkeypress"-handling for IE/FF/?, and "onkeyup" for Opera/?). It'd be 
good to know how Safari handles this issue, because Safari is an A-list 
browser whereas Opera is just B-list.


Tests:

Files:
M WEB-INF/lps/lfc/kernel/dhtml/LzSprite.js
M WEB-INF/lps/lfc/kernel/dhtml/LzInputTextSprite.js

Changeset: 
http://svn.openlaszlo.org/openlaszlo/patches/20071103-bargull-0.tar