RichSuggestBox.Helpers.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Linq;
using Windows.Foundation;
using Windows.Graphics.Display;
using Windows.UI.Text;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace Microsoft.Toolkit.Uwp.UI.Controls
{
    /// <summary>
    /// The RichSuggestBox control extends <see cref="RichEditBox"/> control that suggests and embeds custom data in a rich document.
    /// </summary>
    public partial class RichSuggestBox
    {
        private static bool IsElementOnScreen(FrameworkElement element, double offsetX = 0, double offsetY = 0)
        {
            // DisplayInformation only works in UWP. No alternative to get DisplayInformation.ScreenHeightInRawPixels
            // Tracking issues:
            // https://github.com/microsoft/WindowsAppSDK/issues/114
            // https://github.com/microsoft/microsoft-ui-xaml/issues/4228
            // TODO: Remove when DisplayInformation.ScreenHeightInRawPixels alternative is available
            return true;

#pragma warning disable CS0162 // Unreachable code detected
            if (Window.Current == null)
            {
                return !ControlHelpers.IsXamlRootAvailable || element.XamlRoot.IsHostVisible;
            }

            var toWindow = element.TransformToVisual(null);
            var windowBounds = Window.Current.Bounds;
            var elementBounds = new Rect(offsetX, offsetY, element.ActualWidth, element.ActualHeight);
            elementBounds = toWindow.TransformBounds(elementBounds);
            elementBounds.X += windowBounds.X;
            elementBounds.Y += windowBounds.Y;
            var displayInfo = DisplayInformation.GetForCurrentView();
            var scaleFactor = displayInfo.RawPixelsPerViewPixel;
            var displayHeight = displayInfo.ScreenHeightInRawPixels;
            return elementBounds.Top * scaleFactor >= 0 && elementBounds.Bottom * scaleFactor <= displayHeight;
#pragma warning restore CS0162 // Unreachable code detected
        }

        private static bool IsElementInsideWindow(FrameworkElement element, double offsetX = 0, double offsetY = 0)
        {
            var toWindow = element.TransformToVisual(null);
            var windowBounds = ControlHelpers.IsXamlRootAvailable
                ? element.XamlRoot.Size.ToRect()
                : ApplicationView.GetForCurrentView().VisibleBounds;
            windowBounds = new Rect(0, 0, windowBounds.Width, windowBounds.Height);
            var elementBounds = new Rect(offsetX, offsetY, element.ActualWidth, element.ActualHeight);
            elementBounds = toWindow.TransformBounds(elementBounds);
            elementBounds.Intersect(windowBounds);
            return elementBounds.Height >= element.ActualHeight;
        }

        private static string EnforcePrefixesRequirements(string value)
        {
            return string.IsNullOrEmpty(value) ? string.Empty : string.Concat(value.Where(char.IsPunctuation));
        }

        /// <summary>
        /// Pad range with Zero-Width-Spaces.
        /// </summary>
        /// <param name="range">Range to pad.</param>
        /// <param name="format">Character format to apply to the padding.</param>
        private static void PadRange(ITextRange range, ITextCharacterFormat format)
        {
            var startPosition = range.StartPosition;
            var endPosition = range.EndPosition + 1;
            var clone = range.GetClone();
            clone.Collapse(true);
            clone.SetText(TextSetOptions.Unhide, "\u200B");
            clone.CharacterFormat.SetClone(format);
            clone.SetRange(endPosition, endPosition);
            clone.SetText(TextSetOptions.Unhide, "\u200B");
            clone.CharacterFormat.SetClone(format);
            range.SetRange(startPosition, endPosition + 1);
        }

        private static void ForEachLinkInDocument(ITextDocument document, Action<ITextRange> action)
        {
            var range = document.GetRange(0, 0);
            range.SetIndex(TextRangeUnit.Character, -1, false);

            // Handle link at the very end of the document where GetIndex fails to detect
            range.Expand(TextRangeUnit.Link);
            if (!string.IsNullOrEmpty(range.Link))
            {
                action?.Invoke(range);
            }

            var nextIndex = range.GetIndex(TextRangeUnit.Link);
            while (nextIndex != 0 && nextIndex != 1)
            {
                range.Move(TextRangeUnit.Link, -1);

                var linkRange = range.GetClone();
                linkRange.Expand(TextRangeUnit.Link);

                // Adjacent links have the same index. Manually check each link with Collapse and Expand.
                var previousStart = linkRange.StartPosition;
                var hasAdjacentToken = true;
                while (hasAdjacentToken)
                {
                    action?.Invoke(linkRange);

                    linkRange.Collapse(false);
                    linkRange.Expand(TextRangeUnit.Link);
                    hasAdjacentToken = !string.IsNullOrEmpty(linkRange.Link) && linkRange.StartPosition != previousStart;
                    previousStart = linkRange.StartPosition;
                }

                nextIndex = range.GetIndex(TextRangeUnit.Link);
            }
        }
    }
}