Need sounding board for GUI library

[Boyd]

On Sunday, 15 December 2013 at 12:59:27 UTC, MrSmith wrote:
> Hi Boyd.
>
> Have you uploaded your code somewhere so anyone can take a look 
> at it?
I Have not yet uploaded it, though I would like to. Where would 
be a good place to put it?

> Let me ask you some questions.
> 1. How have you done event propagation? Sinking and boobling or 
> something else? Can you cancel event propagation?
The event propagation method I use is event capturing. First the 
event goes to the outer most widget which determines whether to 
send it to child widgets.

> 2. How do you create platform dependent windows. Using WinAPI, 
> SFML, GLFW(+), SDL(+), GLUT?
Platform dependent widgets are not supported at this time. I may 
add native widgets in the future, but right now it seems more 
trouble than it's worth.

> 3. How are you rendering widgets? Using OpenGL(+), DirectX, 
> SDL, SFML, GDI? If it is OpenGL than what version of it?
I currently use GDI. It should not be that hard to change this, 
though.

> 4. How your widgets are rendered? Do you have separate 
> GuiRenderer which knows how to render basic GUI elements(+) or 
> all widgets are directly calling OpenGL code?
I have created a Canvas class that does all the drawing. This 
ensures platform independences.

You can also use graphic objects to do the drawing instead; the 
TImageGraphic object draws an image, TTextGraphic draws text, 
etc..

> 5. Do you have any styling of your widgets, external config, 
> CSS etc? If any how it is done? Can you set any image or color, 
> gradient to any widget?
I have plans for stylable widgets, but I don't have a concrete 
design for this yet. I have some ideas though, and I intend for 
it to be immensely flexible. Basically a stylable widget would be 
a widget without a style at all. The widget would only define a 
list of placeholder blocks that the theme would need to fill.

For example: The TButtonWidget could define the placeholders 
Normal, Hover, Down, DownHover. The theme would then determine 
the exact content of these placeholders. Gradients, images, text, 
borders, layout, you name it.

> 6. How is your resource management implemented? Do you have any 
> dedicated texture, font manager?
No I don't, although the theme system will do some resource 
management. Would you consider this as an important feature 
outside of themes?

> 7. Do you have animation support (plans to do it)?
No concrete plans, but eventually I do want to support it.

> 8. How is your widget events and properties implemented? 
> Signals, variants, reactive programming etc?
At first simply changing properties will have to do. I do intend 
to support something similar to signals.

> 8. Do you have model and view separation? Controllers, 
> presenters?
I'm not sure what you mean. A GUI library by its very nature is 
pure view.

> 9. How is your layouts implemented? Do you have layout 
> interface? What methods it has? When they are called?
There are to ways to do layout. You can inherit from a layout 
component, in which case you would need to implement a few 
functions. For example the gridlayout requires the implementation 
of the following functions:

/// iterates through the rows of the grid
void ForeachRow(TCanvas canvas, void delegate(TGridLayoutRow) 
exec);
/// iterates through the columns of the grid
void ForeachColumn(TCanvas canvas, void delegate(TGridLayoutRow) 
exec);
/// returns the content of the specified grid cell
TGraphic GetCell(int x, int y);

The other method is to create a TGridWidget using the constructor:

this(TGridLayoutRow[] columns, TGridLayoutRow[] rows, 
TGraphic[][] cells)

> 10. Can you access property by its name like 
> widget.getProperty("width");
No. In what situation would you consider using this?

Also Widgets don't have any positional information in them, or 
style information. This is one of main issues I have with the 
existing GUI libraries.

> 11. Do you know that in D is common to use camelCase for method 
> names?
As I said earlier I built this library to cater to my every whim, 
so I probably need to change my coding style slightly.

> 12. What other gui's are you looking at while making your own?
There are many gui libraries that have influenced my design, but 
I don't plan to immitate any of them. Most influence come from 
the old Borland delphi design, which is still used in many of the 
current ones among which is QT, WxWidgets, other ideas are from 
ExtJs and html/css. It is a fairly unique design though, which is 
why I worry about whether it will be usable by other programmers.



Thanks for the questions, I look forward to hear what you think 
of my answers. Feel free to criticise.

Cheers,
Boyd