resizeAnimation | Playing with Qt widget animation & graphics effect | Animation library

I am struggling for hours with some problem I encountered while creating a simple animation in my app.

I have a LinearLayout with elements inside that is hidden behind an Image View and which should be shown (by animating on layouts width) on the click event. If I delete elements from inside the LinearLayout everything performs well, but because the children of the layout are pushing its width (which means that even if layouts width is set to 0 it is still pushed to width +/- 100dp by the elements inside) I have problems with hiding the layout.

However it is not the case when animation is performed - when I am animating layout to go to width 0 it properly crops the children. But as soon as animation is done - the layout is pushed by the children. I had an idea to make layout crop its children by default, but I have tried multiple solutions and none of them worked. Then I thought that maybe I will just hide elements (visibility gone) after animation is done. And it "kinda" solved the problem - but I am still having a problem with first occurrence of "showing" animation.

What I am doing is - at the start I am setting layouts width to 0 and hiding it along with its children (setting their to visibility gone). Then on "showing" animation I am making layout and its children visible in onAnimationStart method and then the animation increases layouts width from 0 to 156dp. "Hiding" animation is reverted - I am decreasing layouts width to 0 and onAnimationEnd I am hiding the layout and its content. The problem is that for some reason the first time showing animation is invoked and I am making the layout and views visible in onAnimationStart, there is a gap between this code and the moment which animation actually starts, which makes views visible for a split second before the animation starts.

This is how it looks: hidden, shown. And here is the xml code for it: