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Thread: Reversing the arrows in a QSpinBox

  1. #1
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    Default Reversing the arrows in a QSpinBox

    How can I "flip" the arrows in a QSpinBox so that when you push down, the number increases and when you push up, the number decreases?

    I want to use the spinbox to set depth-value so my users found it more intuitive that down would be an increase of depth.

    I have subclassed the QSpinBox (actually a QDoubleSpinBox) and overridden the wheelEvent so that one is taken care of.

    I could look for mousepress and see if the mouse is inside the up or down arrow, maybe, but when the value is 0 (minValue), the down-arrow is gray, so just overriding the values here would not be any good. I want the up-arrow to be gray when value is at minValue.

    I've tried googling for this and the closest I've come is to completely redefine the QStyle painting routine. I found this also in "C++ GUI programming with Qt 4". This seemed overly complex and I don't want to redefine the style if this means that I would set the spinBox style to something that may be unlike the native look in different OS'es.

    Is there any painting routine I could relatively easily override where I just reposition the arrows? Or any other place I should look?

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    Default Re: Reversing the arrows in a QSpinBox

    Reimplement QAbstractSpinBox::stepBy() :
    Qt Code:
    1. void MySpinbox::stepBy(int step) {
    2. QSpinBox::stepBy(-step);
    3. }
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  3. #3
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    Default Re: Reversing the arrows in a QSpinBox

    Thanks, but it did not work for the extreme values. When the value is 0.0, the step-function is prevented. I will look more into this. Also the problem with the gray arrow was still there

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    Default Re: Reversing the arrows in a QSpinBox

    Let's try something else then. Reimplement valueFromText and textFromValue to work on negative numbers and set your maximum as 0 and your minimum as -something. Then other things should work properly.

    Qt Code:
    1. double MySpinbox::valueFromText(const QString &text) const { return -QDoubleSpinBox::valueFromText(text); }
    2. QString MySpinbox::textFromValue(double value) const { return QDoubleSpinBox::textFromValue(-value); }
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  5. The following user says thank you to wysota for this useful post:

    zarkzervo (2nd March 2011)

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    Default Re: Reversing the arrows in a QSpinBox

    This seems to fix it for the textFromValue-part, but it looks like the validator prevents the input of positive numbers when I have a range of [-45.0, 0.0]

    I will look into that. I'm much closer to this working now than a few hours ago. Thanks!

  7. #6
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    Default Re: Reversing the arrows in a QSpinBox

    You can reimplement validate() for that.
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  8. #7
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    Default Re: Reversing the arrows in a QSpinBox

    I also subclassed QDoubleSpinBox to override the scrolling function.

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