Optimising Pivot Control windows phone 8

Question

case 1:

I have a Pivot Control with 3 Pivot Items, and each pivot item will be filled with data(from server) once it gets focus for the first time.

Now, It makes lot of delay when I navigate back from some other page to this Pivot Page. How to optimise it and reduce the delay? Even I cannot show a ProgressBar while Navigating back to this page.

Case 2:

I have a ListView with more items, say 150, On selection of an item I need a show detailed description of the selectedItem, and it should be swipeable so that the user can see the next records in the same description page.

Right now, i am using Pivot Page and Binding the Items to the ItemsSource Property, and it creates even lot more delay (of 10 seconds) while navigating to the Pivot Page and Navigating from the Pivot Page.

How to get rid of that delay?

Help me. Thanks.

You can cache the data in case 1+2 and have a refresh button on the ApplicationBar to download new data. Or you can just download a few entries at a time (maybe update your webservice) then only down some more when they're at the end of the container. There are numerous examples on SO and MSDN on how to do what I mention. — Chubosaurus Software
Thanks. It is already implemented like that only, Downloading only 50 records at a time and only at the end of the scroll the next items 50 will be downloaded. what is the thing that is causing the delay while navigating ? too many items ?. For that, you mean, save all the data in a file while navigating and restore from the file while coming back? Will it not be a costlier process ? — Pradeep AJ- Msft MVP

Ku6opr Ku6opr · Accepted Answer · 2014-09-20T07:14:43

Use LongListSelector (WP8) or ListView (WP8.1) as items holder on first page. It has UI virtualization, so no matter how much items will be on a page, only items on screen will be rendered. It must solve your case 1 delay. If doesn't - the problem is in page 2 destroying.

You details screen approach is completely wrong. Pivot is create for other purposes and its not recommended to hold more than 5 items inside.

So you need:

Create page for displaying one item and bind DataContext to LayoutRoot
Add ManipulationCompleted event handler to LayoutRoot and check if swipe has place
Update DataContext to prev or next item. This will update data displayed on the screen
When this will work, create animations to smooth transition of current page to left and right:
- when user move finger on a phone - move page left and right to the same offset
- when user leave finger - call animation to complete swipe
- when animation completed (page out of the screen), update DataContext and call animation to bring new item from other side of the screen

This will replicate Pivot behavior but with no memory consumption for unvisible items

UPD:

Step 4 implementation:

private void LayoutRoot_ManipulationDelta(object sender, System.Windows.Input.ManipulationDeltaEventArgs e)
{
    (LayoutRoot.RenderTransform as CompositeTransform).TranslateX += e.DeltaManipulation.Translation.X;
}

private void LayoutRoot_ManipulationCompleted(object sender, System.Windows.Input.ManipulationCompletedEventArgs e)
{
    if (e.TotalManipulation.Translation.X + e.FinalVelocities.LinearVelocity.X < -100)
    {
        if (current < Count - 1)
        {
            //slide to next item
            current++;
        }
        else
        {
            //no next item - slide back
        }
    }
    else if (e.TotalManipulation.Translation.X + e.FinalVelocities.LinearVelocity.X > 100)
    {
        if (current > 0)
        {
            // slide to prev item

            current--;
        }
        else
        {
            // no prev item - slide back
        }
    }
    else
    {
        // no swipe - slide back
    }
}

Optimising Pivot Control windows phone 8

1 Answers