Best way to display many Images in GridView (QtQuickControls2, iOS)


  • Qt Champions 2016

    Because iOS native Image Picker doesn’t allow multi-select,
    I built my own GridView.

    works perfect - have access to alll the Albums and Photos.
    will publish the solution soon

    people can have many Photos on their iPhone, so in the
    future I'll try to deal with PHCachingImageManager, PHImageManager ...

    For now in my QtQuickControls2 app I’m using GridView with Images

    to get a flicker free scrolling I had to use

    • async Loader for the Component
    • async Image inside Component
    • Image source is path from iOS
      per ex. assets-library://asset/asset.JPG?id=AF3C1...9F1B2&ext=JPG
    • Image sourceSize was set to something smaller as my GridView’s cellSize

    Did some tests with cacheBuffer. GridView’s default is 320
    changed default: model.length < 40? 900 : 320
    now small albums with < 40 Photos are completely load and can scroll up / down without any reloading/refreshing

    but for larger Photo collections scrolling up/down reloads Photos

    only question I have: when opening first time and set the model of GridView,
    the very first Photo was displayed, then it took some time before the other
    visible Photos will be displayed - Qt seems to load Photos outside visible area
    first.
    Is there any way I can change it that visible Images will be loaded from top down ?

    Or do you have any other ideas HowTo make it better ?


  • Qt Champions 2018

    Can I ask how you are adding photos in the model? Is it a C++ model?


  • Qt Champions 2016

    @VRonin yes - it's a list of QObject*
    each entry describes a File:

    • Folder, File
    • Type (Image, Video, PDF, ...)
    • Path
    • Name (obsolet for iOS Photos)
    • entries (if Folder)
    • ...
      and I'm constructing the collection per ex. from
    PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    

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