well it's needed.
I have some example of creating a gpx file https://github.com/M-Yankov/SimpleTracker/blob/7b5c20e4fbe588d60db841941261976c43848c8b/GpxCreator/Program.cs#L67 . it's from old project, but it might help of reading a gpx file.
Technical details:
The main idea is to have two logic methods one for .fit files another for .gpx files. Both should be able to parse data from to same models in project. They will implement same interface

This happens when two widgets are selected for export from Same category like speed and Pace widgets.

Maybe a solution could be a each widget to have own folder.

The main progress bar is set manually to 100%, but it's seems not correct

Just find how to make a standalone installer as any other program (Next, Next), Nullsoft installer, etc.

Each widget could have a setting page/pop-up/modal where user sets specific widgets settings like colors, sizes etc.
all widgets will receive a settings data object where they can take specific settings.

• Click one slider
• It gets highlighted
• click arrows moves the slider left/right with one second change (±1s)
• click Crtl + arrows moves the slider left/right with one minute change (±1m)
• click Crtl + Shift + arrows moves the slider left/right with one hour change (±1h)

Keep in mind the limits, to not overflow sliders

It's more useful to have images directly exported to be ready for use.
Zip archive can be used to move files somewhere else before use.

The formula will be:
approxSize = (selectedRange).TotalSeconds * fps * (sumOfSelectedExampleWidgetSizeInKb)

It should located somewhere at the bottom near export Button.

The application have 3 main loops:

1. Map data from FitMessages to Customdata regarding framerate (saved in collection over 10k objects). usually is very fast
2. Calculate widget data into images (frames)
3. Save frames into physical device (this step waits completion of 100 object results from the previous steps, blocks the thread, process and returns back to previous step)

The example below suggest a solution for non blocking thread (safe-thread) showing last two steps separated in classes using concurrent Queue. (Code samples are generated from Open AI ⚠️ )

using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

public class DataFiller
{
    private readonly ConcurrentQueue<int> _dataQueue;
    private readonly SemaphoreSlim _dataAvailable;

    public DataFiller(ConcurrentQueue<int> dataQueue, SemaphoreSlim dataAvailable)
    {
        _dataQueue = dataQueue;
        _dataAvailable = dataAvailable;
    }

    public async Task FillDataAsync(int count, CancellationToken cancellationToken)
    {
        Random random = new Random();
        for (int i = 0; i < count; i++)
        {
            await Task.Delay(100, cancellationToken); // Simulate some delay
            int value = random.Next(1, 100);
            _dataQueue.Enqueue(value);
            _dataAvailable.Release(); // Signal that new data is available
        }
    }
}

Processor:

using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

public class DataProcessor
{
    private readonly ConcurrentQueue<int> _dataQueue;
    private readonly SemaphoreSlim _dataAvailable;

    public DataProcessor(ConcurrentQueue<int> dataQueue, SemaphoreSlim dataAvailable)
    {
        _dataQueue = dataQueue;
        _dataAvailable = dataAvailable;
    }

    public async Task ProcessDataAsync(CancellationToken cancellationToken)
    {
        int sum = 0;
        while (!cancellationToken.IsCancellationRequested)
        {
            await _dataAvailable.WaitAsync(cancellationToken); // Wait for data to be available
            if (_dataQueue.TryDequeue(out int value))
            {
                sum += value; // Process the data
                Console.WriteLine($"Processed value: {value}, Current Sum: {sum}");
            }
        }
    }
}

program.cs

using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

public class DataProcessor
{
    private readonly ConcurrentQueue<int> _dataQueue;
    private readonly SemaphoreSlim _dataAvailable;

    public DataProcessor(ConcurrentQueue<int> dataQueue, SemaphoreSlim dataAvailable)
    {
        _dataQueue = dataQueue;
        _dataAvailable = dataAvailable;
    }

    public async Task ProcessDataAsync(CancellationToken cancellationToken)
    {
        int sum = 0;
        while (!cancellationToken.IsCancellationRequested)
        {
            await _dataAvailable.WaitAsync(cancellationToken); // Wait for data to be available
            if (_dataQueue.TryDequeue(out int value))
            {
                sum += value; // Process the data
                Console.WriteLine($"Processed value: {value}, Current Sum: {sum}");
            }
        }
    }
}

Steps to reproduce:

• Any .fit activity
• Select a range from the middle
• Check the "Start statistics from left marker"
• Check the distance widget
• Export

Actual

• First frame of distance widget shows the real value as it is

Expected

• First frame to show 0.00 km

Depends on #30 (needs to be integrated)
You are doing some outdoor activity by following some track. but at some point you get out of track for some reason.
The original path needs to be shows in the trace widget. Try something like overlapping, the down layer is the following track, above it is the recorded track.
If the trace widget is slowed down drastically, the image size is too large or it's too difficult, then the solution could be to export only one image and then to be handled in the video editor.

https://www.electronjs.org/

Sliders gets out of sync

steps (for left):

• move left slider (without release the the button)
• move mouse up or down in such way it lose tracking the slider
• move right slider

This happens for both sliders

possible solution:
when moving one slider, calculate position for other slider too.

For undefined reason some frames are missing: ~16 per widget
4 fps setting.

If the activity is too long and need to export the data only for a certain period (like a crash, jump, some highlight) it should be possible to provide to dates (during the session) and extract the data between them.

• additionally for all the widgets which are showing data since the beginning (distance, trace, elevation etc) there should be an option to render them like the beginning /ending is from selected date ranges (like the range in the dashed red lines)
  

C:\GitHub\TelemetryExporter\TelemetryExporter.UI\ViewModels\SelectWidgetsViewModel.cs

It was exported a partial range activity with start from left marker mode
The speed is on top

Location could be shown as well

If it's reasonable to replace the attribute with a static properties inside widgets.

In diagnostics tool the memory drops like 500MB when export starts for the second time. It seems some objects are left in memory unused (not disposed) and GC cleans the. But the fact is that the code produces too much memory constantly.
TODO:
{ScreenShot}

dotnet/maui#9592

Add SKPaint variables in a common class. To be shared. They have common settings like font, width, style etc. Or method than can construct the paint settings.

• Optionally a method that can recolor some parts of the widgets, (like Garmin main/secondary color) also colors for texts.

Azure, virtual machines test

Get activity name from fit file.