Question

I have the following SWT layout:

• TabItem
  • SashForm
    • Composite (GridLayout)
      • Label (Fill W, Grab H)
      • ScrolledComposite (Fill W/H, Grab H/V)
        • Composite (RowLayout)
    • Composite (GridLayout)
      • Label (Fill W, Grab H)
      • ScrolledComosite (Fill W/H, Grab H/V)
        • Composite (RowLayout)

The general idea is that there are two identical panes side-by-side with adjustable widths via the sash, and inside each panel is a label at the top, and a scrolled composite on the bottom. The scrolled composite will have many (1 – 50) 100×100 composites contained within the wrapped composite.

The problem is that when contained within a sash form, the scrolled composites will not scroll when the internal composite grows due to a large number of children. I do not experience this problem when I abandon the SashForm and use a regular Composite, like so:

• TabItem
  • Composite (GridLayout)
    • Label
    • ScrolledComposite
      • Composite
    • Label
    • ScrolledComposite
      • Composite

In this way, there is no extra composite container, and everything is in a grid layout. The only problem is that I can’t adjust the width of the panes via a common interface (sash).

---

I have tried forcing layout using layout(), and setting the minimum size using setMinSize(). I tried swapping RowLayout with a FlowLayout (swing2swt). I am assuming this is a type of layout problem, but I do not have enough SWT experience to sort it out. The layout is perfect except for the scrolling problem.

Source Example

All of the code was auto-generated by WindowBuilder Pro, and can be replicated by building the composite tree I specified. Here is a fragment I am using to populate the wrapped composite:

public void populate(Composite composite, List<Photo> items) {
   composite.setRedraw(false);
   for (Photo photo : photos) {
     PhotoComposite composite = new PhotoComposite(composite, photo, SWT.NONE);
     composite.setSize(100, 100);
   }
   composite.setRedraw(true);
   composite.layout(true);
}

Photo is a simple POJO, and PhotoComposite is a custom composite that takes a Photo as a parameter in the constructor in addition to the traditional Composite and style bits. This code appears to work fine according to my experiments.

Answer 1

It turns out the problem was a misunderstanding of setMinSize(int, int). The following changes to the populate method shown above solved the problem for me:

public void populate(ScrolledComposite scroll, Composite composite, List<Photo> items) {
   composite.setRedraw(false);
   for (Photo photo : photos) {
     PhotoComposite composite = new PhotoComposite(composite, photo, SWT.NONE);
     composite.setSize(100, 100);
   }
   composite.setRedraw(true);
   composite.layout(true);

   scroll.setMinSize(composite.computeSize(scroll.getSize().x, SWT.DEFAULT));
}