[KPhotoAlbum] Speeding up annotation

[Robert Krawitz]

On Sun,  5 Jan 2020 22:33:56 -0500 (EST), Robert Krawitz wrote:
> On Sun, 05 Jan 2020 23:01:13 +0100, Johannes Zarl-Zierl wrote:
>> Am Sonntag, 5. Jänner 2020, 20:23:50 CET schrieb Robert Krawitz:
>>> I found one easy fix in the selection code after the annotations are
>>> changed.  It's still very slow and may be worse than linear, but at
>>> least one real problem is cleaned up.
>>
>> Thank you for your work!
>
> AnnotationDialog::Dialog::selectionForMultiSelect() is definitely a
> hot spot.  But I'm going to ned to call it a night, I'm afraid...

Yes, this one really is nasty.  This is the inner loop, over all
images:

    for (DB::ImageInfoList::ConstIterator imageIt = images.begin(); imageIt != images.end(); ++imageIt) {
        const StringSet itemsOnThisImage = (*imageIt)->itemsOfCategory(category);
        itemsNotSelectedOnAllImages += (allItems - itemsOnThisImage);
        itemsOnSomeImages += itemsOnThisImage;
    }

This is doing two probably expensive set operations on each image,
both in and out of the annotation dialog.  We can surely do this a lot
more quickly...
-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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