ClemensFischer/XAML-Map-Control
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Image loading with cancellation

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ClemensFischer 2025-08-19 23:20:11 +02:00
parent 81eabef257
commit 69bba213f0
13 changed files with 103 additions and 88 deletions
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47
MapControl/Shared/MapImageLayer.cs
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@ -1,5 +1,6 @@
using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
#if WPF
using System.Windows;
@ -53,7 +54,7 @@ namespace MapControl
private readonly Progress<double> loadingProgress;
private readonly DispatcherTimer updateTimer;
private bool updateInProgress;
private CancellationTokenSource cancellationTokenSource;
public MapImageLayer()
{
@ -165,39 +166,37 @@ namespace MapControl
}
}
protected abstract Task<ImageSource> GetImageAsync(BoundingBox boundingBox, IProgress<double> progress);
protected abstract Task<ImageSource> GetImageAsync(BoundingBox boundingBox, IProgress<double> progress, CancellationToken cancellationToken);
protected async Task UpdateImageAsync()
{
if (updateInProgress)
updateTimer.Stop();
if (cancellationTokenSource != null)
{
// Update image on next tick, start timer if not running.
//
updateTimer.Run();
cancellationTokenSource.Cancel();
cancellationTokenSource = null;
}
else
if (ParentMap != null && ParentMap.ActualWidth > 0d && ParentMap.ActualHeight > 0d)
{
updateInProgress = true;
updateTimer.Stop();
var width = ParentMap.ActualWidth * RelativeImageSize;
var height = ParentMap.ActualHeight * RelativeImageSize;
var x = (ParentMap.ActualWidth - width) / 2d;
var y = (ParentMap.ActualHeight - height) / 2d;
ImageSource image = null;
BoundingBox boundingBox = null;
var boundingBox = ParentMap.ViewRectToBoundingBox(new Rect(x, y, width, height));
if (ParentMap != null && ParentMap.ActualWidth > 0d && ParentMap.ActualHeight > 0d)
cancellationTokenSource = new CancellationTokenSource();
var image = await GetImageAsync(boundingBox, loadingProgress, cancellationTokenSource.Token);
cancellationTokenSource = null;
if (image != null)
{
var width = ParentMap.ActualWidth * RelativeImageSize;
var height = ParentMap.ActualHeight * RelativeImageSize;
var x = (ParentMap.ActualWidth - width) / 2d;
var y = (ParentMap.ActualHeight - height) / 2d;
boundingBox = ParentMap.ViewRectToBoundingBox(new Rect(x, y, width, height));
image = await GetImageAsync(boundingBox, loadingProgress);
SwapImages(image, boundingBox);
}
SwapImages(image, boundingBox);
updateInProgress = false;
}
}