[Digikam-devel] extragear/graphics/digikam

[Caulier Gilles]

Le Mercredi 13 Juillet 2005 22:59, Renchi Raju a écrit :
> On Wed, 13 Jul 2005, Gilles Caulier wrote:
> > SVN commit 434244 by cgilles:
> >
> > digiKam Ratio Crop tool : add an option to choise Composition Guide
> > width.
> >
> > If another one had a best soltion to make composition guide more visible.
> > Using animate guide is more complex to do. I had to try to use without
> > success QPainter::setPen(Qt::MPenStyle) to define a personal pen mask and
> > change it at QObject::timerEvent().
> >
> > Any suggestions ?
>
> using NoRasterOp with color0 will invert the color of the Pen, making it
> visible for all color backgrounds (that's what most imaging apps use for
> showing lines on top of unknown backgrounds).

Hum, you want say an XOR operation with the bits. This way working fine with 
hight contrast image, but still weird with low contrast.

>
> animation is going to be tricky, as qt doesn't allow customization of the
> penstyle. you could either use x11 directly 

Hum, it's complex to do ? I don't know X11 operations. QT4 will provide a 
penstyle customization method ?

> or use lots of 
> QPainter::drawline with computed positions (with qtimer for either)

Yes, already done for imageguidewidget. But it's not easy to do this operation 
with the composition guide in imageselectionwidget (aspect ratio crop tool), 
especially with Golden spiral. There are a lot of trigonometry computation to 
do. Its will increase the complexity of the code. Define dedicaced pens style 
look like more easy. If Qt4 provides this feature, i will waiting...

Gilles