ReoGrid Forum

Frank

Member

Registered: 2017-05-08

Posts: 1

Modified WindowsFormsHost for using Winform version of ReoGrid

I am working on a WPF project that need table controls which behaves like excel, with all of its keyboard navigation. Fortunately I found here... However the WPF version is not as robust as I like. I eventually fall back to the Winform version, which is quite useable.

I get some modified WindowsFormsHost code from internet, then modify it further to handle scaling issues when in a ScrollViewer. I would like post its code here, in case anyone interested.

    public class WindowsFormsHostEx : WindowsFormsHost
    {
        private PresentationSource _presentationSource;
        private double scalingFactor = 1;

        public WindowsFormsHostEx()
        {
            PresentationSource.AddSourceChangedHandler(this, SourceChangedEventHandler);
        }

        protected override void OnWindowPositionChanged(Rect rcBoundingBox)
        {
            rcBoundingBox = new Rect(rcBoundingBox.X / scalingFactor,
                                     rcBoundingBox.Y / scalingFactor,
                                     rcBoundingBox.Width / scalingFactor,
                                     rcBoundingBox.Height / scalingFactor);
            base.OnWindowPositionChanged(rcBoundingBox);

            if (ParentScrollViewer == null)
                return;

            GeneralTransform tr = RootVisual.TransformToDescendant(ParentScrollViewer);
            var scrollRect = new Rect(new System.Windows.Size(ParentScrollViewer.ViewportWidth, ParentScrollViewer.ViewportHeight));

            var t = tr.TransformBounds(rcBoundingBox);

            var intersect = Rect.Intersect(scrollRect, tr.TransformBounds(rcBoundingBox));
            if (!intersect.IsEmpty)
            {
                tr = ParentScrollViewer.TransformToDescendant(this);
                intersect = tr.TransformBounds(intersect);
            }
            else
                intersect = new Rect();

            int x1 = (int)(Math.Round(intersect.Left) * scalingFactor);
            int y1 = (int)(Math.Round(intersect.Top) * scalingFactor);
            int x2 = (int)(Math.Round(intersect.Right) * scalingFactor);
            int y2 = (int)(Math.Round(intersect.Bottom) * scalingFactor);

            SetRegion(x1, y1, x2, y2);
        }

        public void Release()
        {
            Dispose(true);
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);

            if (disposing)
                PresentationSource.RemoveSourceChangedHandler(this, SourceChangedEventHandler);
        }

        private void SourceChangedEventHandler(Object sender, SourceChangedEventArgs e)
        {
            ParentScrollViewer = FindParentScrollViewer();
        }

        private ScrollViewer FindParentScrollViewer()
        {
            DependencyObject vParent = this;
            ScrollViewer parentScroll = null;
            while (vParent != null)
            {
                parentScroll = vParent as ScrollViewer;
                if (parentScroll != null)
                    break;

                vParent = LogicalTreeHelper.GetParent(vParent);
            }
            return parentScroll;
        }

        private void SetRegion(int x1, int y1, int x2, int y2)
        {
            SetWindowRgn(Handle, CreateRectRgn(x1, y1, x2, y2), true);
        }

        private Visual RootVisual
        {
            get
            {
                if (_presentationSource == null)
                {
                    var source = PresentationSource.FromVisual(this);
                    scalingFactor = source.CompositionTarget.TransformToDevice.M11;
                    _presentationSource = source;
                }

                return _presentationSource.RootVisual;
            }
        }

        private ScrollViewer ParentScrollViewer { get; set; }

        [DllImport("User32.dll", SetLastError = true)]
        static extern int SetWindowRgn(IntPtr hWnd, IntPtr hRgn, bool bRedraw);

        [DllImport("gdi32.dll")]
        static extern IntPtr CreateRectRgn(int nLeftRect, int nTopRect, int nRightRect, int nBottomRect);
    }

Just make sure invoking Release() method when the table is not needed. WinForm has to be manually disposed when hosted in a WPF app. Otherwise you will see that the 'User Object' keep increasing till it hits 10000. :-)

Jingwood

Moderator

From: jing at reogrid.net

Registered: 2014-06-03

Posts: 615

Re: Modified WindowsFormsHost for using Winform version of ReoGrid

Nice! thanks!