How to scroll WPF ScrollViewer's content to specific location

问题

I am writing my custom WPF ItemsControl to display a list of item. The items are shown embedded inside a ScrollViewer:

<Style TargetType="MyCustomItemsControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="MyCustomItemsControl">
                    <ScrollViewer x:Name="PART_MyScrollViewer" >
                           <ItemsPresenter/>
                    </ScrollViewer>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
</Style>

I want to make sure that when I move the mouse into the control, a particular item (marked as selected) will be scrolled into the mouse position. In my OnMouseEnter method I am able to find the item but I don't know what to do next. Does anyone have any idea?

protected override void OnMouseEnter(MouseEventArgs e)
{
    for (int i = 0; i < Items.Count; i++)
    {
        ContentPresenter uiElement = (ContentPresenter)ItemContainerGenerator.ContainerFromIndex(i);
        var item = uiElement.Content as MyCustomObject;
        if (item.IsSelected)
        {
            // How to scroll the uiElement to the mouse position?
            break;
        }
    }
}

回答1:

Something like the following:

var sv = (ScrollViewer)Template.FindName("PART_MyScrollViewer", this); // If you do not already have a reference to it somewhere.
var ip = (ItemsPresenter)sv.Content;
var point = item.TranslatePoint(new Point() - (Vector)e.GetPosition(sv), ip);
sv.ScrollToVerticalOffset(point.Y + (item.ActualHeight / 2));

回答2:

// How to scroll the uiElement to the mouse position?
uiElement.BringIntoView();

REF: https://msdn.microsoft.com/en-us/library/ms598110.aspx

UPDATE: (thanks to @jmbpiano) Note, it does not bring the control exactly to the current mouse cursor position. It just brings the control to a visible position, where the Operator will be able to click it with the mouse (which in 99% of cases is all someone who finds this question is likely to need).

回答3:

Use UIElement.TranslatePoint() to calculate what position you want to scroll to

Use ScrollViewer.ScrollToVerticalOffset() to do the scrolling

回答4:

Try this below code :


private void ScrollViewerFromVSTree(DependencyObject element, double pos)
{
    try
    {
        int totalElementcount = VisualTreeHelper.GetChildrenCount(element);
        for (int counter = 0; counter < totalElementcount; counter++)
        {
            DependencyObject ele = VisualTreeHelper.GetChild(element, counter);
            if (ele.GetType().Name == "ScrollViewer")
            {
                ScrollViewer scrollViewer = ele as ScrollViewer;
                if (pos > "YourAssumption") // for me it is 610
                {
                    scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + 45);
                }
                else if (pos < "YourAssumption") //for me it is 40
                {
                    scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset - 45);
                }
                break;
            }
            ScrollViewerFromVSTree(VisualTreeHelper.GetChild(element, counter), pos);
        }
    }
    catch (Exception)
    {
    }
}

来源：https://stackoverflow.com/questions/6336441/how-to-scroll-wpf-scrollviewers-content-to-specific-location

标签

wpf

mouse

position

scrollviewer