Re: [AD] Mouse cusor documentation

[Chris <kcat@xxxxxxxxxx>]

Evert Glebbeek wrote:
> Because gfx_capabilities is only updated after show_mouse() has been 
> called. You don't know if you have a hardware cursor or not until after 
> show_mouse() has been called. It's always been this way.

I think he means if you call show_mouse previously, then enable the 
hardware cursor. Do you need to call show_mouse after setting the 
hardware cursor if you called it before hand?

> Also, note that you can't check for the precense of relevant entries in teh 
> vtable to set gfx_capabilities once and for all: in Windows, you will only 
> be able to get a hardware cursor for cursors upto 32x32 pixels, not above. 
> So setting it always is unreliable.

But the vtable function to set a custom hardware cursor should be able 
to indicate failure via a return value. Doesn't it already do this?

> No, we don't. Allegro uses a software cursor automatically if it can't let 
> the OS draw the cursor. No need to disable the hardware cursor for that.

I think he means disable temporarilly, until it's shown on the screen again.

> I'm not sure... I think this could be considered an API breakage. Anyway, 
> with the new system and custom cursors, the code needs to be somewhat 
> rethought anyway.

True.. and I'm not really against having some API breakage as long as it 
follows these rules: 1) the break can only happen after the programmer 
explicitly calls a function that alters behavior (and the called 
function is documented to change the behavior of the other functions). 
And 2) the altered behavior is disabled by default.

Now, since enable_hardware_mouse is a new function, everything's pretty 
much fair game when it's called.. behavior changes to existing functions 
included. This includes show_mouse. /However/, the changes should be 
kept reasonable if not minimal, and I personally don't quite see the 
reason to change show_mouse. If the OS/hardware can't handle the cursor 
Allegro tries to set, it falls back to software until the proper 
conditions are met and it can use the OS/hardware again. This should 
include not only bitmap size/color restrictions, but also target bitmaps.

So, IMO when enable_hardware_mouse is called, it should use the 
hardware/OS only when the target is "screen" (not the physical screen, 
since page flipping/scrolling can change what's in view and where, but 
the pointer to the screen bitmap), and the OS/hardware can accept the 
pointer bitmap.

- Kitty Cat