On 31 Jan 2010, at 7:13PM, Dmitry Kazakov wrote:

On Sun, Jan 31, 2010 at 2:53 AM, Adrian Page <> wrote:
Dmitry Kazakov wrote:
> I thing this should be reverted according to Qt's QRect tradition, i.e.
> (5,7)->(5.0,7.0). Or change ALL the Krita's code that uses
> QRectF::toAlignedRect() or QRectF(intRect) to a new type of conversion.
> Other way we'll dig a deep grave for ourselves using two completely
> different coordinate systems throughout the code.

This is the way krita has worked for the last however many years.

Well, not everywhere. Please take a look into KisImage::documentToIntPixel(). It uses QRectF::toAlignedRect(). So it does just the opposite to what you are saying.

It gives the desired result - the smallest integer rectangle containing the QRectF. That's what we're after.

KisPrescaledProjection and KisView are fully based on Qt's style. (It was based on it even before my refactorings)

The standard in graphics is that when you convert int to floating point you
add 0.5, and you truncate when converting float to int. (5, 7) -> (5.5,
7.5) -> (5, 7).

Not sure about "truncating", as you may get some losses, when converting rects. I think rounding is much more stable. I remember i had many troubles in prescaled projection without rounding.

No, you shouldn't need to round. If you are rounding, then you will be losing pixels when whatever number you're rounding is > x.0 and < x.5. Floor() and ceil() gives the stability without ever losing pixels, that's what toAlignedRect() is doing. And floor() is the the truncating bit (for points).