Re: [AD] Window Resizing

[Peter Wang <tjaden@xxxxxxxxxx>]

On 2005-10-04, Dustin Dettmer <dustin@xxxxxxxxxx> wrote:
> What are the plans for implementing this?  Is there
> already some API decided upon?

We won't do anything about that in 4.2.

> How would this function sound?
> int install_resizer(int (*proc)(int w, int h));
> 
> proc would be passed the new w / h and could pass
> non-zero to approve the change or 0 to deny the
> change.  If the change was approved, the screen bitmap
> would be reallocated to the correct size and the
> SCREEN_* would be fixed to evaluate to the correct
> values.

This kind of proposal has come up before and it's not enough.  `proc' is
presumably called from an auxiliary thread, in which case the screen can
be resized at any time[1].  You need a function for the main thread to
acknowledge the resize, and delay any resizing operation until that
function has been called.  Otherwise this piece of code is wrong:

	blit(bmp, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H);

The screen could be resized between the time you get the SCREEN_W/H
values and the time that blit() is called.


For the new_api_branch, AL_DISPLAYs are event sources.  When the user
tries to resize a window, the AL_DISPLAY will generate a "resize
request" event, which is entered into an event queue.  When the program
receives the event it can acknowledge the resize request, at which time
the resize will actually take place.  That's my idea, at least.

Peter

[1] Unless you allow `proc' to block until it is ready for the resize to
occur, but that is even trickier.