[scribus-dev] Question about culling area

[Craig Bradney]

On 8/12/11 6:47 AM, Elvis Stansvik wrote:
> 2011/8/11 Elvis Stansvik <elvstone at gmail.com>:
>> Hi Andreas,
>>
>> 2011/8/11 Andreas Vox <andreas.vox at googlemail.com>:
>>> Hi Elvis!
>>>
>>> I introduced the culling area in order to skip objects when drawing just a
>>> rectangle part of the canvas.
>>> Culling area = null means no limitation.
>>>
>>> The culling area is not a clipping area, that's what PoLine is for. Can't
>>> you use the PoLine of the cell's
>>> textframe for your purposes?
>> Yes, I realize that I've confused myself a bit.
>>
>> My confusion comes from thinking that I could somehow paint parts of
>> the table (cells) in DrawObj_Item(...). This is obviously not possible
>> as the item needs to repaint itself entirely if requested to do so by
>> the canvas. Right?
>>
>> The problem I'm facing now is that on each key press, I'm now doing:
>>
>> m_table->activeCell().textFrame()->handleModeEditKey(event, repeat);
>> m_table->update();
>>
>> This will trigger a re-paint of the entire canvas, and the resulting
>> lag when typing is quite noticable compared to typing in a regular
>> text frame.
>>
>> I shouldn't have to call m_table->update() right? That will trigger a
>> lot of things that aren't necessary after a just a key press.
>>
>> Just something like
>>
>> m_canvas->update(m_canvas->canvasToLocal(m_table->getBoundingRect()));
>>
>> should be enough? But for some reason that isn't working; sometimes
>> the table DrawObj_Item is called and sometimes it's not :/
>>
>> Need to do more debugging here.
> So, after some investigation, the only way I've found reliably works
> to get my table repainted, without resulting in a repaint of the
> entire canvas, is:
>
> bool repeat;
> m_table->activeCell().textFrame()->handleModeEditKey(event, repeat);
> m_canvas->m_viewMode.forceRedraw = true;
> m_canvas->update(m_canvas->canvasToLocal(m_table->getBoundingRect()));
>
> This however implies making my CanvasMode_EditTable a friend of Canvas
> (to be able to set the forceRedraw). It feels like a hack, but the
> same thing is done e.g. by the CanvasMode_Normal when selecting items.
> It seems most of the canvas modes have been made friends of Canvas,
> for this or other purposes.
>
> Without the forceRedraw, the paintEvent of the Canvas will return
> without painting anything, I guess because of some internal buffering
> (I even tried with a call to m_canvas->update() without any rectangle
> parameter).
>
> Is there any cleaner solution?
>
> Otherwise I will go with this approach for now, since I need to get on
> with other things.
>
> When it comes to the optimization of not having to repaint the entire
> table on a keystroke, I'll leave that for now. Possibly in the future
> the table painter could keep a QCache of QImages of cell contents or
> something like that. But it would need measurements to see if it makes
> a difference.
>

If only a start, why not make the forceRedraw protected anyway and add a helper to set it?
That's how it should be anyway.

But as you say, not much time left.. optimisation can be done later.

Craig