| Re: Lack of KeyMods parameter in the ::MouseUp function call -> Feature request [message #92531 is a reply to message #92530] |
Tue, 05 January 2016 13:20   |
Helder Marchetto
Messages: 520
Registered: November 2011
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Senior Member |
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On Tuesday, January 5, 2016 at 9:16:07 PM UTC, Chris Torrence wrote:
> On Wednesday, December 30, 2015 at 4:25:08 PM UTC-7, Helder wrote:
>> Hi,
>> I'm intensively using the FG event handler class. In doing so, I've come to a problem where I would like the ::MouseUp function to include information about the current keyMods. Currently, the functions ::MouseDown, ::MouseMotion and ::MouseWheel have it...
>>
>> Let me explain why I think this is useful.
>> I have a polygon on an image. I would like to add a point to the polygon. To distinguish from the translation case, I use the "alt" key to identify modifications (or alt-erations) to the polygon. Therefore, pressing the alt-key and the left mouse button results in an added point. Since I'm not always good with my hand, I would like to be able to:
>>
>> 1) press down alt-key
>> 2) press down left mouse button (a point is added)
>> 3) move mouse (and see the added point moving with the mouse)
>> 4) release the left mouse button
>> 5) release the alt-key
>>
>> Besides being useful, it is also "cool".
>>
>> However, if I would like to "cancel" the add point operation if the alt-key is released *before* the release of the left mouse button. In other words, the following sequence should delete the point after step 4):
>>
>> 1) press down alt-key
>> 2) press down left mouse button (a point is added)
>> 3) move mouse (and see the added point moving with the mouse)
>> 4) release the alt-key (the previously added point is deleted)
>> 5) release the left mouse button
>>
>> Since I cannot detect if alt is pressed when releasing the button, I cannot do this.
>>
>> Can this please be added? I don't think that it is that much of an effort...
>>
>> Cheers,
>> Helder
>
> Hi Helder,
>
> It probably isn't too hard to add, but the problem is backwards compatibility. If we just add another argument then it will break existing event handlers. We can't add a keyword for the same reason. There might be a way to check the number of accepted arguments and make the appropriate call, but then the documentation becomes ugly.
>
> So, I'll add it to the list of possible enhancements, but I wouldn't count on it making the cut.
>
> But keep making suggestions!
>
> -Chris
Hi Chris,
thanks for the answer. Just out of curiosity, what would be the problem of using a keyword? I thought that that would be the way to go to avoid backwards compatibility?
Cheers,
Helder
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