Getting Range coordinates only for Ranges on the screen

Question

I am currently using the following method to find the coordinates of a Range within a document:

private Rectangle GetRangeCoordinates(Window w, Range r)
{
    int left = 0;
    int top = 0;
    int width = 0;
    int height = 0;

    w.GetPoint(out left, out top, out width, out height, r);

    return new Rectangle(left, top, width, height);
}

This works really well unless the Range is off the screen by a fairly large margin (quite a few pages), in which case I get the following exception:

System.Runtime.InteropServices.COMException (0x800A1066): Command failed at Microsoft.Office.Interop.Word.Window.GetPoint(Int32& ScreenPixelsLeft, Int32& ScreenPixelsTop, Int32& ScreenPixelsWidth, Int32& ScreenPixelsHeight, Object obj) at [ProjectName].[TaskpaneName].GetRangeCoordinates(Window w, Range r) in [...somePath...][TaskpaneName].cs:line 66

Is there a way to figure out if a Range is on screen or not, so that I can only call this method when it is?

Answer 1

This is how I did this.

I created a few extension methods for Application and Range:

public static class ApplicationExensions
{
    // more (rather than less)
    // does not do headers and footers
    public static Range GetCurrentlyVisibleRange(this Application application)
    {
        try
        {
            Window activeWindow = application.ActiveWindow;
            var left = application.PointsToPixels(activeWindow.Left);
            var top = application.PointsToPixels(activeWindow.Top);
            var width = application.PointsToPixels(activeWindow.Width);
            var height = application.PointsToPixels(activeWindow.Height);
            var usableWidth = application.PointsToPixels(activeWindow.UsableWidth);
            var usableHeight = application.PointsToPixels(activeWindow.UsableHeight);

            var startRangeX = left;// + (width - usableWidth);
            var startRangeY = top;// + (height - usableHeight);

            var endRangeX = startRangeX + width;//usableWidth;
            var endRangeY = startRangeY + height;//usableHeight;

            Range start = (Range) activeWindow.RangeFromPoint((int) startRangeX, (int) startRangeY);
            Range end = (Range) activeWindow.RangeFromPoint((int) endRangeX, (int) endRangeY);

            Range r = application.ActiveDocument.Range(start.Start, end.Start);

            return r;
        }
        catch (COMException)
        {
            return null;
        }
    }
}

public static class RangeExtensions
{
    public static bool Intersects(this Range a, Range b)
    {
        return a.Start <= b.End && b.Start <= a.End;
    }

    public static Rectangle? GetCoordinates(this Range range)
    {
        try
        {
            Application application = range.Application;
            Window window = application.ActiveWindow;

            int left = 0;
            int top = 0;
            int width = 0;
            int height = 0;

            window.GetPoint(out left, out top, out width, out height, range);

            return new Rectangle(left, top, width, height);
        }
        catch (COMException e)
        {
            return null;
        }
    }
}

And then I used them like this:

Range currentlyVisibleRange = application.GetCurrentlyVisibleRange();

if (currentlyVisibleRange.Intersects(rng)){
    var coords = rng.GetCoordinates();
}