Qt-interest Archive, March 2008
Finding start and end visible blocks in QTextEditor
Message 1 in thread
Hi group,
I am trying to boost our text editor highlighter 's performance by just
highlight the visible part of the text (it's currently really slow for
big files ). I spent much time on Qt docs but could not find a way to
check if a text block is visible or not.
Thanks,
--
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Message 2 in thread
Tamara Nguyen wrote:
>
> Hi group,
> I am trying to boost our text editor highlighter 's performance by just
> highlight the visible part of the text (it's currently really slow for
> big files ). I spent much time on Qt docs but could not find a way to
> check if a text block is visible or not.
> Thanks,
>
Without knowing the details of your data structures available:
If you are painting the highlight by using QPainter's fillRect(), you
could trim off highlighted rectangles outside of the paint event by
testing that the QPaintEvent's rectangle intersects the highlight rectangle.
--
[ signature omitted ]
Message 3 in thread
Sorry, I did not give much background info. I am using
QSyntaxHighlighter and implemented highlightBlock() virtual function.
The way QSyntaxHighligher works is that it calls hilightBlock() on the
block that has changes. When the document is already loaded, it works
perfectly (it only reformat the changed block. However, during the
loading process, it has to reformat the whole document which could be
huge. I am trying to find out which part of the document is visible
(for a particular QTextEdit) and only reformat that part.
Tamara Nguyen
PDF Solutions, Inc.
(408) 283 5655
Rob Douglas wrote:
> Tamara Nguyen wrote:
>>
>> Hi group,
>> I am trying to boost our text editor highlighter 's performance by
>> just highlight the visible part of the text (it's currently really
>> slow for big files ). I spent much time on Qt docs but could not
>> find a way to check if a text block is visible or not.
>> Thanks,
>>
>
> Without knowing the details of your data structures available:
>
> If you are painting the highlight by using QPainter's fillRect(), you
> could trim off highlighted rectangles outside of the paint event by
> testing that the QPaintEvent's rectangle intersects the highlight
> rectangle.
>
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> "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
>
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Message 4 in thread
Tamara Nguyen wrote:
>
>
> Sorry, I did not give much background info. I am using
> QSyntaxHighlighter and implemented highlightBlock() virtual function.
> The way QSyntaxHighligher works is that it calls hilightBlock() on the
> block that has changes. When the document is already loaded, it works
> perfectly (it only reformat the changed block. However, during the
> loading process, it has to reformat the whole document which could be
> huge. I am trying to find out which part of the document is visible
> (for a particular QTextEdit) and only reformat that part.
>
>
>
> Tamara Nguyen
> PDF Solutions, Inc.
> (408) 283 5655
>
>
> Rob Douglas wrote:
>> Tamara Nguyen wrote:
>>>
>>> Hi group,
>>> I am trying to boost our text editor highlighter 's performance by
>>> just highlight the visible part of the text (it's currently really
>>> slow for big files ). I spent much time on Qt docs but could not
>>> find a way to check if a text block is visible or not.
>>> Thanks,
>>>
>>
>> Without knowing the details of your data structures available:
>>
>> If you are painting the highlight by using QPainter's fillRect(), you
>> could trim off highlighted rectangles outside of the paint event by
>> testing that the QPaintEvent's rectangle intersects the highlight
>> rectangle.
>>
>> --
>> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
>> "unsubscribe" in the subject or the body.
>> List archive and information: http://lists.trolltech.com/qt-interest/
>>
>>
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with
> "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
Though I have not tried this, you may find some use from the QTextCursor
returned from
QTextCursor QTextEdit::cursorForPosition ( const QPoint & pos ) const
I see from the docs that QTextCursor will give you a QTextBlock. You may
be able to use that to determine from screen coordinates, whether or not
a different block is on the screen.
But here I would kick off to someone whose used QSyntaxHighlighter more.
Best Regards!
-Rob
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