Layout help

Development
1

Hi, I have a layout like this:

	BRect frame(100, 100, 300, 400);
	sizeTestWin = new win(frame);

	BStringView* label = new BStringView("label1", "This is a test");
	BView* viu = new BView("vu", B_WILL_DRAW | B_FRAME_EVENTS);
	
	BScrollBar* scroll = new BScrollBar("scroll", viu, 0, 0, B_VERTICAL);
	BBox* top = new BBox("box");
	
	BGroupLayout* top_box = BLayoutBuilder::Group<>(top, B_VERTICAL)
		.Add(label)
		.SetInsets(B_USE_SMALL_INSETS, B_USE_SMALL_INSETS,
			B_USE_SMALL_INSETS, B_USE_SMALL_INSETS);
	
	BGroupLayout* group = BLayoutBuilder::Group<>(sizeTestWin, B_VERTICAL, 0)
		.Add(top_box)
		.AddGroup(B_HORIZONTAL, 0)
			.Add(viu)
			.Add(scroll)
		.End();

	BStringView* label2 = new BStringView("label2", "This is text");
	BStringView* label3 = new BStringView("label3", "This is more text");
	BStringView* label4 = new BStringView("label4", "This is the most text");

	BGroupLayout* view_group = BLayoutBuilder::Group<>(viu, B_VERTICAL, 20)
		.Add(label2)
		.Add(label3)
		.Add(label4)
		.AddGlue();

0size

It works fine as long as the window is larger than the inner view contents:

2size

but then when I make the window shorter, the scrollbar seems “locked” to the height of the “viu” BView. I understand that I have it targeting the view, but when the parent window is resized to shorter than the inner view, it cuts off the scroll bar instead of adjusting the scroll bar to the contents.

1size

i thought the scroll bar ought to resize/reproportion based on the parent size, as a scroll bar does. How can I make it control/scroll the inner “viu” but never get cut off by the parent window? Even if I try to adjust the scroll bar range and proportion it still gets cut off by the window.

2

The simplest way to do this is to use a BScrollView containing viu.

The ScrollView will handle most of the specifics of the layouting for you: it will provide a “barrier” between the side constraints of what’s inside it, and the side constraints outside of it.

This allows the scroll view to be smaller than its contents, and position its scrollbars at the right place at the bottom and right edges.

If you can’t use BScrollView, you have to handle this manually, this means you have to customize “viu” by setting custom size constraints on it (SetExplicitMinSize, SetExplicitMaxSize, etc) so that the size constraints of its inside layout are not used to set its minimum size. Otherwise the view will never be resized smaller than its contents.

2 Likes
3

Thank you, I will give it a try. I hadn’t thought of SetExplicit[Min|Max]Size for this but it makes sense.