RichTextBox 中的图像在调整大小后变得模糊

Question

我有一个 RichTextBox。我通过复制+粘贴插入图像。我使用装饰器来调整图像大小。 RTB 将被保存，同时为 RTB 文本使用一个 XAML 文件，为每个图像分别使用一个 PNG 文件。使用装饰器和 SAVE 调整图像大小后，图像变得模糊。对于每次保存，图像变得越来越模糊 - 即使没有进一步调整大小。请问我能做什么？

<Window x:Name="windowRTB" x:Class="RichTextBox.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Title="MainWindow" Height="450" Width="800">
<Grid>
    <DockPanel Name="mainPanel">
        <ToolBar Name="mainToolBar" Height="30" DockPanel.Dock="Top" Background="{x:Null}">
            <Button Click="SaveContent" Loaded="Button_Loaded" Content="SAVE" FontWeight="Bold"/>
        </ToolBar>
        <RichTextBox Name="rtb" IsDocumentEnabled="True" AcceptsTab="True" IsReadOnly="False" TextChanged="Rtb_TextChanged">
        </RichTextBox>
    </DockPanel>
</Grid>

public partial class MainWindow : Window
{
    const string gc_pathAppDataXAML = @"C:\Users\RB\Documents\XAML\";
    const string gc_pathAppDataPNG = @"C:\Users\RB\Documents\PNG\";
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Rtb_TextChanged(object sender, TextChangedEventArgs e)
    {
        foreach (Image img in rtb.FindChildren<Image>())
        {
            img.Loaded += delegate
            {
                img.PreviewMouseDown += new MouseButtonEventHandler(Image_PreviewMouseDown);
            };
        }
    }

    private void Image_PreviewMouseDown(object sender, MouseButtonEventArgs e)
    {
        if (rtb.IsReadOnly == false)
        {
            Image img = (Image)e.OriginalSource;

            AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(img);
            if (adornerLayer != null)
            {
                adornerLayer.Add(new ResizingAdorner(img));
            }
        }
    }

    private void SaveContent(object sender, RoutedEventArgs e)
    {
        SaveXamlPackage(gc_pathAppDataXAML + "RTB-Test" + ".xaml");
    }

    private void SaveXamlPackage(string iv_fileName)
    {
        try
        {
            //Separately saving the images
            ExtractImages();

            //Save RTB content with placeholders for the images
            TextRange range1;
            FileStream fStream1;
            range1 = new TextRange(rtb.Document.ContentStart, rtb.Document.ContentEnd);
            fStream1 = new FileStream(iv_fileName, FileMode.Create);
            range1.Save(fStream1, DataFormats.XamlPackage);
            fStream1.Close();

            //Load RichTextBox
            LoadXamlPackage(iv_fileName);
        }
        catch (Exception error)
        {
            MessageBox.Show(error.Message);
            return;
        }
    }

    private void ExtractImages() //Separately saving the images
    {
        Image Image;
        int lv_cnt = 0;

        foreach (Block block in rtb.Document.Blocks)
        {
            if (block is Paragraph)
            {
                Paragraph paragraph = (Paragraph)block;
                foreach (Inline inline in paragraph.Inlines)
                {
                    if (inline is InlineUIContainer)
                    {
                        InlineUIContainer uiContainer = (InlineUIContainer)inline;
                        if (uiContainer.Child is System.Windows.Controls.Image)
                        {
                            lv_cnt++;
                            Image = (Image)uiContainer.Child;
                            SaveToPng(Image, gc_pathAppDataPNG + "RTB-Test".ToString() + "-" + lv_cnt + ".png");

                            Image.Source = new BitmapImage(
                            new Uri("pack://application:,,,/RichTextBox;component/RTB_Platzhalter.png"));
                        }
                    }
                }
            }
            else if (block is BlockUIContainer)
            {
                BlockUIContainer container = (BlockUIContainer)block;
                if (container.Child is Image)
                {
                    lv_cnt++;
                    Image = (Image)container.Child;
                    SaveToPng(Image, gc_pathAppDataPNG + "RTB-Test".ToString() + "-" + lv_cnt + ".png");

                    Image.Source = new BitmapImage(
                    new Uri("pack://application:,,,/RichTextBox;component/RTB_Platzhalter.png"));
                }
            }
        }

        void SaveToPng(FrameworkElement visual, string fileName)
        {
            var encoder = new PngBitmapEncoder();
            SaveUsingEncoder(visual, fileName, encoder);
        }

        void SaveUsingEncoder(FrameworkElement visual, string fileName, BitmapEncoder encoder)
        {
            RenderTargetBitmap bitmap = new RenderTargetBitmap((int)visual.ActualWidth, (int)visual.ActualHeight, 96, 96, PixelFormats.Pbgra32);
            Size visualSize = new Size(visual.ActualWidth, visual.ActualHeight);
            visual.Measure(visualSize);
            visual.Arrange(new Rect(visualSize));
            bitmap.Render(visual);
            BitmapFrame frame = BitmapFrame.Create(bitmap);
            encoder.Frames.Add(frame);

            using (FileStream stream = File.Create(fileName))
            {
                encoder.Save(stream);
            }
        }
    }

    private void LoadContent()  //While creating instance of windowRTB
    {
        LoadXamlPackage(gc_pathAppDataXAML + "RTB-Test".ToString() + ".xaml");
    }

    private void LoadXamlPackage(string iv_fileName)
    {
        try
        {
            TextRange range;
            FileStream fStream;
            if (File.Exists(iv_fileName))
            {
                range = new TextRange(rtb.Document.ContentStart, rtb.Document.ContentEnd);
                fStream = new FileStream(iv_fileName, FileMode.OpenOrCreate);
                range.Load(fStream, DataFormats.XamlPackage);
                fStream.Close();
            }

            LoadImages();
        }
        catch (Exception error)
        {
            MessageBox.Show(error.Message);
            return;
        }
    }

    private void LoadImages() //Reloading of separately saved images
    {
        Image Image;
        int lv_cnt = 0;

        foreach (Block block in rtb.Document.Blocks)
        {
            if (block is Paragraph)
            {
                Paragraph paragraph = (Paragraph)block;
                foreach (Inline inline in paragraph.Inlines)
                {
                    if (inline is InlineUIContainer)
                    {
                        InlineUIContainer uiContainer = (InlineUIContainer)inline;
                        if (uiContainer.Child is System.Windows.Controls.Image)
                        {
                            lv_cnt++;
                            Image = (System.Windows.Controls.Image)uiContainer.Child;
                            Image.Source = null;
                            using (FileStream fs = new FileStream(gc_pathAppDataPNG + "RTB-Test".ToString() + "-" + lv_cnt + ".png", FileMode.Open))
                            {
                                BitmapImage imageSource = new BitmapImage();
                                imageSource.BeginInit();
                                imageSource.CacheOption = BitmapCacheOption.OnLoad;
                                imageSource.StreamSource = fs;
                                imageSource.EndInit();
                                Image.Source = imageSource;
                            }
                        }
                    }
                }
            }
            else if (block is BlockUIContainer)
            {
                BlockUIContainer container = (BlockUIContainer)block;
                if (container.Child is System.Windows.Controls.Image)
                {
                    lv_cnt++;
                    Image = (System.Windows.Controls.Image)container.Child;
                    using (FileStream fs = new FileStream(gc_pathAppDataPNG + "RTB-Test".ToString() + "-" + lv_cnt + ".png", FileMode.Open))
                    {
                        BitmapImage imageSource = new BitmapImage();
                        imageSource.BeginInit();
                        imageSource.CacheOption = BitmapCacheOption.OnLoad;
                        imageSource.StreamSource = fs;
                        imageSource.EndInit();
                        Image.Source = imageSource;
                    }
                }
            }
        }
    }


    private void Button_Loaded(object sender, RoutedEventArgs e)
    {
        LoadContent();
    }
}

public class ResizingAdorner : Adorner
{
    // Resizing adorner uses Thumbs for visual elements.   
    // The Thumbs have built-in mouse input handling. 
    Thumb topLeft, topRight, bottomLeft, bottomRight;

    // To store and manage the adorner's visual children. 
    VisualCollection visualChildren;

    // Initialize the ResizingAdorner. 
    public ResizingAdorner(UIElement adornedElement) : base(adornedElement)
    {
        visualChildren = new VisualCollection(this);

        // Call a helper method to initialize the Thumbs 
        // with a customized cursors. 
        BuildAdornerCorner(ref topLeft, Cursors.SizeNWSE);
        BuildAdornerCorner(ref topRight, Cursors.SizeNESW);
        BuildAdornerCorner(ref bottomLeft, Cursors.SizeNESW);
        BuildAdornerCorner(ref bottomRight, Cursors.SizeNWSE);

        // Add handlers for resizing. 
        bottomLeft.DragDelta += new DragDeltaEventHandler(HandleBottomLeft);
        bottomRight.DragDelta += new DragDeltaEventHandler(HandleBottomRight);
        topLeft.DragDelta += new DragDeltaEventHandler(HandleTopLeft);
        topRight.DragDelta += new DragDeltaEventHandler(HandleTopRight);
    }

    // Handler for resizing from the bottom-right. 
    void HandleBottomRight(object sender, DragDeltaEventArgs args)
    {
        FrameworkElement adornedElement = this.AdornedElement as FrameworkElement;
        Thumb hitThumb = sender as Thumb;

        if (adornedElement == null || hitThumb == null) return;
        FrameworkElement parentElement = adornedElement.Parent as FrameworkElement;

        // Ensure that the Width and Height are properly initialized after the resize. 
        EnforceSize(adornedElement);

        // Change the size by the amount the user drags the mouse, as long as it's larger  
        // than the width or height of an adorner, respectively. 
        double lv_oldWidth = adornedElement.Width;
        adornedElement.Width = Math.Max(adornedElement.Width + args.HorizontalChange, hitThumb.DesiredSize.Width);
        adornedElement.Height = adornedElement.Height * adornedElement.Width / lv_oldWidth;
    }

    // Handler for resizing from the bottom-left. 
    void HandleBottomLeft(object sender, DragDeltaEventArgs args)
    {
        FrameworkElement adornedElement = AdornedElement as FrameworkElement;
        Thumb hitThumb = sender as Thumb;

        if (adornedElement == null || hitThumb == null) return;

        // Ensure that the Width and Height are properly initialized after the resize. 
        EnforceSize(adornedElement);

        // Change the size by the amount the user drags the mouse, as long as it's larger  
        // than the width or height of an adorner, respectively. 
        double lv_oldWidth = adornedElement.Width;
        adornedElement.Width = Math.Max(adornedElement.Width - args.HorizontalChange, hitThumb.DesiredSize.Width);
        adornedElement.Height = adornedElement.Height * adornedElement.Width / lv_oldWidth;
    }

    // Handler for resizing from the top-right. 
    void HandleTopRight(object sender, DragDeltaEventArgs args)
    {
        FrameworkElement adornedElement = this.AdornedElement as FrameworkElement;
        Thumb hitThumb = sender as Thumb;

        if (adornedElement == null || hitThumb == null) return;
        FrameworkElement parentElement = adornedElement.Parent as FrameworkElement;

        // Ensure that the Width and Height are properly initialized after the resize. 
        EnforceSize(adornedElement);

        // Change the size by the amount the user drags the mouse, as long as it's larger  
        // than the width or height of an adorner, respectively. 
        double lv_oldWidth = adornedElement.Width;
        adornedElement.Width = Math.Max(adornedElement.Width + args.HorizontalChange, hitThumb.DesiredSize.Width);
        adornedElement.Height = adornedElement.Height * adornedElement.Width / lv_oldWidth;
    }

    // Handler for resizing from the top-left. 
    void HandleTopLeft(object sender, DragDeltaEventArgs args)
    {
        FrameworkElement adornedElement = AdornedElement as FrameworkElement;
        Thumb hitThumb = sender as Thumb;

        if (adornedElement == null || hitThumb == null) return;

        // Ensure that the Width and Height are properly initialized after the resize. 
        EnforceSize(adornedElement);

        // Change the size by the amount the user drags the mouse, as long as it's larger  
        // than the width or height of an adorner, respectively. 
        double lv_oldWidth = adornedElement.Width;
        adornedElement.Width = Math.Max(adornedElement.Width - args.HorizontalChange, hitThumb.DesiredSize.Width);
        adornedElement.Height = adornedElement.Height * adornedElement.Width / lv_oldWidth;
    }

    // Arrange the Adorners. 
    protected override Size ArrangeOverride(Size finalSize)
    {
        // desiredWidth and desiredHeight are the width and height of the element that's being adorned.   
        // These will be used to place the ResizingAdorner at the corners of the adorned element.   
        double desiredWidth = AdornedElement.DesiredSize.Width;
        double desiredHeight = AdornedElement.DesiredSize.Height;
        // adornerWidth & adornerHeight are used for placement as well. 
        double adornerWidth = this.DesiredSize.Width;
        double adornerHeight = this.DesiredSize.Height;

        topLeft.Arrange(new Rect(-adornerWidth / 2, -adornerHeight / 2, adornerWidth, adornerHeight));
        topRight.Arrange(new Rect(desiredWidth - adornerWidth / 2, -adornerHeight / 2, adornerWidth, adornerHeight));
        bottomLeft.Arrange(new Rect(-adornerWidth / 2, desiredHeight - adornerHeight / 2, adornerWidth, adornerHeight));
        bottomRight.Arrange(new Rect(desiredWidth - adornerWidth / 2, desiredHeight - adornerHeight / 2, adornerWidth, adornerHeight));

        // Return the final size. 
        return finalSize;
    }

    // Helper method to instantiate the corner Thumbs, set the Cursor property,  
    // set some appearance properties, and add the elements to the visual tree. 
    void BuildAdornerCorner(ref Thumb cornerThumb, Cursor customizedCursor)
    {
        if (cornerThumb != null) return;

        cornerThumb = new Thumb();

        // Set some arbitrary visual characteristics. 
        cornerThumb.Cursor = customizedCursor;
        cornerThumb.Height = cornerThumb.Width = 10;
        cornerThumb.Opacity = 0.40;
        cornerThumb.Background = new SolidColorBrush(Colors.MediumBlue);

        visualChildren.Add(cornerThumb);
    }

    // This method ensures that the Widths and Heights are initialized.  Sizing to content produces 
    // Width and Height values of Double.NaN.  Because this Adorner explicitly resizes, the Width and Height 
    // need to be set first.  It also sets the maximum size of the adorned element. 
    void EnforceSize(FrameworkElement adornedElement)
    {
        if (adornedElement.Width.Equals(Double.NaN))
            adornedElement.Width = adornedElement.DesiredSize.Width;
        if (adornedElement.Height.Equals(Double.NaN))
            adornedElement.Height = adornedElement.DesiredSize.Height;

        FrameworkElement parent = adornedElement.Parent as FrameworkElement;
        if (parent != null)
        {
            adornedElement.MaxHeight = parent.ActualHeight;
            adornedElement.MaxWidth = parent.ActualWidth;
        }
    }
    // Override the VisualChildrenCount and GetVisualChild properties to interface with  
    // the adorner's visual collection. 
    protected override int VisualChildrenCount { get { return visualChildren.Count; } }
    protected override Visual GetVisualChild(int index) { return visualChildren[index]; }
}

/// <summary>
/// Helper methods for UI-related tasks.
/// </summary>
public static class TreeHelper
{
    #region find parent
    public static T TryFindParent<T>(this DependencyObject child)
        where T : DependencyObject
    {
        //get parent item
        DependencyObject parentObject = GetParentObject(child);

        //we've reached the end of the tree
        if (parentObject == null) return null;

        //check if the parent matches the type we're looking for
        T parent = parentObject as T;
        if (parent != null)
        {
            return parent;
        }
        else
        {
            //use recursion to proceed with next level
            return TryFindParent<T>(parentObject);
        }
    }

    public static DependencyObject GetParentObject(this DependencyObject child)
    {
        if (child == null) return null;

        //handle content elements separately
        ContentElement contentElement = child as ContentElement;
        if (contentElement != null)
        {
            DependencyObject parent = ContentOperations.GetParent(contentElement);
            if (parent != null) return parent;

            FrameworkContentElement fce = contentElement as FrameworkContentElement;
            return fce != null ? fce.Parent : null;
        }

        //also try searching for parent in framework elements (such as DockPanel, etc)
        FrameworkElement frameworkElement = child as FrameworkElement;
        if (frameworkElement != null)
        {
            DependencyObject parent = frameworkElement.Parent;
            if (parent != null) return parent;
        }

        //if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
        return VisualTreeHelper.GetParent(child);
    }

    #endregion

    #region find children

    public static IEnumerable<T> FindChildren<T>(this DependencyObject source) where T : DependencyObject
    {
        if (source != null)
        {
            var childs = GetChildObjects(source);
            foreach (DependencyObject child in childs)
            {
                //analyze if children match the requested type
                if (child != null && child is T)
                {
                    yield return (T)child;
                }

                //recurse tree
                foreach (T descendant in FindChildren<T>(child))
                {
                    yield return descendant;
                }
            }
        }
    }

    public static IEnumerable<DependencyObject> GetChildObjects(this DependencyObject parent)
    {
        if (parent == null) yield break;

        if (parent is ContentElement || parent is FrameworkElement)
        {
            //use the logical tree for content / framework elements
            foreach (object obj in LogicalTreeHelper.GetChildren(parent))
            {
                var depObj = obj as DependencyObject;
                if (depObj != null) yield return (DependencyObject)obj;
            }
        }
        else
        {
            //use the visual tree per default
            int count = VisualTreeHelper.GetChildrenCount(parent);
            for (int i = 0; i < count; i++)
            {
                yield return VisualTreeHelper.GetChild(parent, i);
            }
        }
    }

    #endregion

    #region find from point

    public static T TryFindFromPoint<T>(UIElement reference, Point point)
        where T : DependencyObject
    {
        DependencyObject element = reference.InputHitTest(point) as DependencyObject;

        if (element == null) return null;
        else if (element is T) return (T)element;
        else return TryFindParent<T>(element);
    }

    #endregion
}

Answer 1

上面代码中的问题是使用视觉对象的大小而不是源图像大小（及其内容）。因此，当您更改文档中图像的大小（无论是减小还是增大大小）然后保存文档时，保存的图像总是会失去质量。

解决方案是使用原始大小和内容保存图像。

因此，进行更改以使用图像源 ( (+1)):

void SaveToPng(Image image, string fileName)
{
    var encoder = new PngBitmapEncoder();                
    SaveUsingEncoder(image, fileName, encoder);
}
   
void SaveUsingEncoder(Image image, string fileName, BitmapEncoder encoder)
{
    encoder.Frames.Add(BitmapFrame.Create((BitmapSource)image.Source));
    using (FileStream stream = new FileStream(fileName, FileMode.Create))
        encoder.Save(stream);
}

RichTextBox 中的图像在调整大小后变得模糊

Image in RichTextBox is blurry after resizing

c#

wpf

image

adorner

richtextbox