[Qgis-developer] Memory Layers - some proposals

[Leyan]

On 09/25/2014 05:10 PM, Matthias Kuhn wrote:
> Aren't there two different possibilities in which such layers can be
> used:
>
>  * As a scratch layer for the user, which he may want to save in the end
>  * As a means for plugins to show information to the user
>
> In the first scenario, the user may actually want to save the
> information because he realized in the process of drawing it, that
> it's valuable to him (if he would have known from the beginning, he
> could have started with a permanent layer type). In this case it would
> be nice to make the user aware of the risk of loosing data and offer
> him a simple way to save it (to an OGR supported format).
>
> In the second scenario, the information may be completely reproducible
> by the plugin or the information drawn by the user intercepted by the
> plugin and redirected to suitable places. In such a scenario a "Do you
> want to permanently save?" dialog would not be appropriate. And
> therefore there should be a possibility to disable it.

I think such a warning is necessary but can be limited to layers visible 
to the end user. A layer automatically made by a plugin or another 
feature would normally not be visible in the legend tree, no ?

For example, I am working on a renderer that would create a memory layer 
alongside the original layer for more advanced rendering, but hidden to 
the end user. It does not really have to be saved with the project as it 
can be regenerated, but I sure would not want a dialog popping up to ask 
whether to save a layer that the user does not know exist.

Leyan