[ge-talk] Performance Re: A layout manager

[Paul van Nugteren]

Hmm I'm not convinced, IIRC when I would resize eg. SoundPlay in BeOS R5
it would do that very smoothly certainly not in the 10th's of ms but
sure I am not. It is certainly not jumpy

On Mon, 27 Aug 2007 16:16:19 +1200, "Christof Lutteroth"
<lutteroth at cs.auckland.ac.nz> said:
> Fredrik Holmqvist wrote:
> > It would be very interesting to try it. Up until now my favourite 
> > layoutmanager (for java) has been https://designgridlayout.dev.java.net/
> 
> The LP model proposed by my colleagues and me is also based on the 
> notion of a grid, but as far as I can see (from the few examples that I 
> have read about the DesignGridLayout) it is more general and thus more 
> powerful. The order in which you add controls is irrelevant, and it is 
> possible to add controls that span not only several columns but also 
> several rows, in addition to other things such as linear constraints and 
> overlapping areas etc.
> 
> Let us consider the DesignGridLayout introductory example (a bit 
> adapted), i.e. a grid with 6 buttons arranged in 2 columns and 2 rows:
> 
> DesignGridLayout layout = new DesignGridLayout( top );
> layout.row().add( button1, button2 );
> layout.row().add( button3, button4 );
> layout.row().add( button5, button6 );
> 
> 
> In the LP model you would do it like this:
> 
> Layout l = new Layout();
> XTab x1 = new XTab();
> YTab y1 = new YTab(), y2 = new YTab();
> l.AddArea(l.Left, l.Top, x1, y1, button1);
> l.AddArea(x1, l.Top, l.Right, y1, button2);
> l.AddArea(l.Left, y1, x1, y2, button3);
> l.AddArea(x1, y1, l.Right, y2, button4);
> l.AddArea(l.Left, y2, x1, l.Bottom, button5);
> l.AddArea(x1, y2, l.Right, l.Bottom, button6);
> 
> * XTabs and YTabs correspond to vertical and horizontal grid lines.
> * l.Left, l.Top, l.Right, l.Bottom are predefined grid lines defining 
> the bounds of the total layout area.
> * each AddArea call defines the top, left, right and bottom gridline 
> that define the bounds of a layout "area" (i.e. a rectangular part, 
> usually  with a control in it)
> 
> So you could say that using DesignGridLayout is shorter for this 
> example. But LP makes the definition of the areas more explicit and 
> allows developers to set many more parameters in the AddArea method 
> (such as margins, minsize, maxsize, alignment, etc). The actual 
> dimensions of the areas are determined considering the preferred sizes 
> of the buttons using linear optimization. That is, the dimensions are 
> not just set as being all equal (or multiples of some size x) for the 
> controls in a row.
> 
> Then, you can easily restructure the areas by merging them together. 
> Say, we want to drop button6 and let button4 span vertically over two 
> cells instead:
> 
> l.AddArea(l.Left, l.Top, x1, y1, button1);
> l.AddArea(x1, l.Top, l.Right, y1, button2);
> l.AddArea(l.Left, y1, x1, y2, button3);
> l.AddArea(x1, y1, l.Right, l.Bottom, button4);
> l.AddArea(l.Left, y2, x1, l.Bottom, button5);
> 
> Such changes can also be done dynamically, by changing the Area objects 
> that are part of the layout. In one of my projects, I used the layout 
> model to implement a fully dynamic tree view on complex structured data, 
> changing synchronously with the data.
> 
> Regarding the performance, it really depends on the implementation. I 
> have used a standard open-source solver, a very slow graphics renderer 
> and have not used some algorithmical optimizations that could be used 
> (besides code optimizations). The rendering time was in the order of 
> milliseconds (about 1-50ms depending on the complexity of the layout) on 
> a 3.4Ghz Pentium4. Re-rendering (e.g. after resizing) is generally much 
> faster than the initial rendering due to incremental solving. Common 
> layout specifications can be simplified upfront (what I didn't do), 
> which makes it again faster. Other researchers have shown that also for 
> slower hardware rendering times can be made to stay in the lower 
> millisecond range, for small changes such as resizing usually below 
> 10ms. IMO this is well worth it, considering the expressiveness of 
> linear constraints. Such a layout system could also be used for other 
> applications such as print layout.
> 
> Cheers,
> Christof
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