How to plot scale on the canvas

I want to plot scale on the canvas. I try to use the scale map of the left axis.
When I turn on the YLeft Axis or XBottom Axis, It works good.
But When I turn off the YLeft Axis It works in a wrong way. It shows just a part of the plot .why??? Hope for help!!
I tried many times , I find out the problem is the laylout stuff, but I don't know how to solve it .
When I turn on 1 axis, the layout works fine, if I turn off the axis, It works wrong.
Just pay attention on the left green part!
I put he plot in a QVBoxLayout to layout it.
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Quote:

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Originally Posted by baoxuefei771

I want to plot scale on the canvas.

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There is a plot item for this: http://qwt.sourceforge.net/class_qwt...cale_item.html

Quote:

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Originally Posted by baoxuefei771

I try to use the scale map of the left axis.

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With "scaleItem->setYAxis( QwtPlot::yLeft )" the scale gets synchronized with the coordinate system of the left scale, what is the coordinate system of the plot - even if this axis is in a hidden state.

Uwe

PS: unfortunately none of the examples is using this item

Thank you for your reply!:)
Thank you so much!!