[Konsole-devel] [PATCH] Get rid of excessive repaints when resizing a konsole part

[Andreas Kling]

...and a few minutes later, I found bug #54230. Submitting the patch to
that bug now.

Andreas Kling wrote:
> Greetings, gentle folks.
>
> When resizing a konsole part, there is a lot of flickering, especially
> noticeable with text in the terminal. This is because the TEWidget is
> cleared with the background color before each repaint.
>
> I hacked up a patch to make it use the WNoAutoErase QWidget flag and
> just draw the necessary parts once, and I've been running it for a while
> without problems.
>
> So the time has come for you guys to take a look. Please see the
> included diff against konsole (3.5 branch) in SVN.
>
> Best regards,
> Andreas Kling
>   
> ------------------------------------------------------------------------
>
> Index: TEWidget.cpp
> ===================================================================
> --- TEWidget.cpp	(revision 556756)
> +++ TEWidget.cpp	(working copy)
> @@ -316,7 +316,7 @@ void TEWidget::setFont(const QFont &)
>  /* ------------------------------------------------------------------------- */
>  
>  TEWidget::TEWidget(QWidget *parent, const char *name)
> -:QFrame(parent,name)
> +:QFrame(parent,name,WNoAutoErase)
>  ,font_h(1)
>  ,font_w(1)
>  ,font_a(1)
> @@ -982,6 +982,48 @@ void TEWidget::paintEvent( QPaintEvent* 
>    paintContents(paint, rect, pm != 0);
>  
>    drawFrame( &paint );
> +
> +  // Since we're using WNoAutoErase, we have to make sure that
> +  // every single pixel is painted by the paint event.
> +  // To do this, we must figure out which pixels are left in the
> +  // area between the terminal image and the frame border.
> +
> +  // Calculate the contents rect excluding scroll bar.
> +  QRect innerRect = contentsRect();
> +  if( scrollLoc != SCRNONE )
> +    innerRect.setWidth( innerRect.width() - scrollbar->width() );
> +
> +  innerRect.setWidth( innerRect.width() + 3 );
> +  innerRect.setHeight( innerRect.height() );
> +
> +  // Calculate the emulation rect (area needed for actual terminal contents)
> +  QRect emurect( contentsRect().topLeft(), QSize( columns * font_w + 2 * rimX, lines * font_h + 2 * rimY ));
> +
> +  // Now erase() the remaining pixels on all sides of the emulation
> +
> +  // Top
> +  QRect er( innerRect );
> +  er.setBottom( emurect.top() );
> +  erase( er );
> +
> +  // Bottom
> +  er.setBottom( innerRect.bottom() );
> +  er.setTop( emurect.bottom() );
> +  erase( er );
> +
> +  // Left
> +  er.setTop( emurect.top() );
> +  er.setBottom( emurect.bottom() - 1 );
> +  er.setRight( emurect.left() );
> +  erase( er );
> +
> +  // Right
> +  er.setRight( innerRect.right() );
> +  er.setTop( emurect.top() );
> +  er.setBottom( emurect.bottom() - 1 );
> +  er.setLeft( emurect.right() );
> +  erase( er );
> +
>    paint.end();
>    setUpdatesEnabled(true);
>  }
>   
> ------------------------------------------------------------------------
>
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