[Development] Comparing two reals in Qt code

[Dominik Holland]

Hi,

it took some time to get the code simple, but here is is a little 
example code:

import QtQuick 1.0

Rectangle {
     id: root
     width: 360
     height: 360

     Item {
         id: item

         width: 50
         height: 50

         Rectangle {
             id: rect

             anchors.top: parent.top
             anchors.left: parent.left
             anchors.right: parent.right
             anchors.bottom: parent.bottom

             color: "blue"

             onWidthChanged: print("widthChanged " + width)
             onHeightChanged: print("heightChanged " + height)
         }
     }


     SequentialAnimation {
         id: animation
         loops: 200
         NumberAnimation {
             target: item;
             property: 'x';
             to: 0;
             duration: 1000;
             easing.type: Easing.OutCubic
         }
         NumberAnimation {
             target: item;
             property: 'x';
             to: 300;
             duration: 1000;
             easing.type: Easing.OutCubic
         }
     }


     MouseArea {
         anchors.fill: parent

         onClicked: {
             print("clicked")
             animation.restart()
         }
     }
}


The important thing here are the anchors of rect. If you set this to 
anchors.fill: parent it works as expected.

Best Regards
  Dominik


On 12/03/2012 08:55 AM, Samuel Rødal wrote:
> On 11/29/2012 03:01 PM, Dominik Holland wrote:
>> Hi all,
>>
>> last month i had some performance problems on a QML animation running on
>> low end hardware (imx233).
>> I debugged that problem and it was caused because of rounding errors
>> during the comparison of two reals.
> What kind of QML code leads to these rounding issues? Would be useful to
> have some examples to go from, before deciding at what level it should
> be fixed.
>
> --
> Samuel
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