[jsword-devel] More changes coming

[DM Smith]

I was working on the "reuse of tabs" issue in bugs.txt.
1) The program would close a BibleViewPane, even when it was empty. The 
net end-user effect was that the tab was renamed from Untitled 1 to 
Untitled 2.
2) In MDI view it was possible to use the "X" close button on the window 
to close the BibleViewPane. But changing back to TDI mode would have the 
BibleViewPane still there. The problem was that Desktop.java maintained 
a cache of views and the close on the InternalJFrame did not change that 
list.
3) When a user clicked on a daily reading, without having done anything 
else, the passage was open in a second tab, leaving the other one 
"Untitled 1". It should have use the empty one.
4) When a user clicked on a daily reading, it always opened another tab, 
even when it was already in a tab. It should have found that it was 
already there and brought it to the front.

As a general design issue, there was tight coupling between the code 
that managed the view layout and the manipulation of BibleViewPanes.

Here are the changes I made in fixing these 4 problems.
I first split Desktop.java into two parts. The one part builds the 
screen and holds the relationship between the BibleViewPanes, and the 
reference pane. The other manages the layout and creation of views.

I made it generic, having no knowledge of BibleViewPane, and it can be 
used for any application that could use a MDI of windows that all hold 
the same thing.

I decoupled it from the rest of the code by using events to communicate 
changes and by introducing a few interfaces that represent the key 
contract that this new code needs to care about.

Specifically, I created a ViewManager which could switch between a TDI 
and a MDI layout. The current layout needs to be able to request and add 
a new view. To remove an existing view. To make views available to the 
rest of the program. It turns out that the relationship between a tab or 
internal window and a view is that the tab/window needs to get its title 
from the view. For this I created an interface Titleable.getTitle(). 
When removing a view, the current layout cannot remove the last one, but 
has to clear it instead. (The old code would remove the last one, note 
that there no longer is one and then create a new one.) This required an 
interface Clearable w/ clear and isClear. To create a new view, the 
ViewManager needs to be able to createView(). I created an interface 
ViewGenerator for this. When the ViewManager is created, it is passed a 
ViewGenerator.

To solve the problem of closing an InternalJFrame, I had removeView fire 
a ViewEvent for viewRemoved(). Listeners could then respond 
appropriately. Initially, I did not have this and the program looked 
like it behaved correctly, but I found that I had a memory leak in that 
these removed BibleViewPanes were being held in listener lists.

I moved all this generic code from BibleDesktop to common.swing.desktop.