C#•4mo ago

WFP InkCanvas hit test

Hi! I found a problem that my inkcanvas sometime is not being hit by VisualTreeHelper.Hittest on specific point.

1 Reply

Everything works fine when InkCanvas is added to the page like this

Container.Children.Add(new InkCanvas());
Grid pageControl = new()
{                   
  HorizontalAlignment = HorizontalAlignment.Center,
  VerticalAlignment = VerticalAlignment.Top,                   
  Background = new ImageBrush(page.PageImage)
  {                       
    Stretch = Stretch.Uniform,
   },
  Width = page.PageImage.Width,
  Height = page.PageImage.Height - 1,
  Margin = i == pages.Count - 1 ? new(0) : new(0, 0, 0, 10)
  };
Container.Children.Add(pageControl);

Container.Children.Add(new InkCanvas());
Grid pageControl = new()
{                   
  HorizontalAlignment = HorizontalAlignment.Center,
  VerticalAlignment = VerticalAlignment.Top,                   
  Background = new ImageBrush(page.PageImage)
  {                       
    Stretch = Stretch.Uniform,
   },
  Width = page.PageImage.Width,
  Height = page.PageImage.Height - 1,
  Margin = i == pages.Count - 1 ? new(0) : new(0, 0, 0, 10)
  };
Container.Children.Add(pageControl);

But when we add ink canvas like this, its not working properly

Grid pageControl = new()
{                   
  HorizontalAlignment = HorizontalAlignment.Center,
  VerticalAlignment = VerticalAlignment.Top,                   
  Background = new ImageBrush(page.PageImage)
  {                       
    Stretch = Stretch.Uniform,
   },
  Width = page.PageImage.Width,
  Height = page.PageImage.Height - 1,
  Margin = i == pages.Count - 1 ? new(0) : new(0, 0, 0, 10)
};
pageControl.Children.Add(new InkCanvas());
Container.Children.Add(pageControl);

Grid pageControl = new()
{                   
  HorizontalAlignment = HorizontalAlignment.Center,
  VerticalAlignment = VerticalAlignment.Top,                   
  Background = new ImageBrush(page.PageImage)
  {                       
    Stretch = Stretch.Uniform,
   },
  Width = page.PageImage.Width,
  Height = page.PageImage.Height - 1,
  Margin = i == pages.Count - 1 ? new(0) : new(0, 0, 0, 10)
};
pageControl.Children.Add(new InkCanvas());
Container.Children.Add(pageControl);

Page is looking like this

<ScrollViewer x:Name="ContainerScrollViewer" CanContentScroll="False" VerticalScrollBarVisibility="Auto>
  <StackPanel x:Name="Container" HorizontalAlignment="Stretch" VerticalAliggnment="Stretch" />
</ScrollViewer>

<ScrollViewer x:Name="ContainerScrollViewer" CanContentScroll="False" VerticalScrollBarVisibility="Auto>
  <StackPanel x:Name="Container" HorizontalAlignment="Stretch" VerticalAliggnment="Stretch" />
</ScrollViewer>

Every 4 hittest or inputthittest misses inkcanvas And it's the same problem for routed events, that they don't reach inkcanvas every 4 raise And every hittest and raiseevents hits scrollviewer I have observed that It's happening only with inkcanvas that size was changed dynamically in code

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WFP InkCanvas hit test