winform滚动条自定义

Question

Sorry about the translator. I want to customize the scroll bar with winform.

What I want is the ability to drag the control out of the bar and return to the original value without changing the value when the mouse is raised.

I've tried scrollbar.mouseLeave , but it's not immediate and the value has to be outside the client's range so it doesn't change. It must be completed with winform. I appreciate your help.

If you scroll out of range of that scrollbar and mouse-up, you want to return to the original value. The existing value is the value before scrolling.

Answer 1

The default behavior when you drag the thumb and the mouse leaves the client area of the scrollbar is resetting the Value property to it's before-dragging-the-thumb-value. You don't need to write any additional code if this is what you want.

However, you can handle the Scroll event to override the default behavior to keep the last thumb position or the Minimum / Maximum values when the mouse pointer leaves the client area of the control:

private void testScrollBar_Scroll(object sender, ScrollEventArgs e)
{
    if (!testScrollBar.ClientRectangle.Contains(testScrollBar.PointToClient(MousePosition))
        && e.NewValue != e.OldValue)
    {
        e.NewValue = e.OldValue;
        testScrollBar.Invalidate();
    }
}

On the other hand, if you want to reset the value to the before-dragging-the-thumb-value only when you release the mouse button:

private void testScrollBar_Scroll(object sender, ScrollEventArgs e)
{
    if (e.Type == ScrollEventType.ThumbTrack &&
        !testScrollBar.ClientRectangle.Contains(testScrollBar.PointToClient(MousePosition)))
    {
        e.NewValue = e.OldValue;
        testScrollBar.Invalidate();
    }
}

The demo illustrates the three behaviors.