c# - 可调整大小的控制用户的 WPF Adorner

Question

我为 TextBlock 元素创建了一个简单的装饰器，允许用户更改其大小。您可以更改 block 的四个角的大小，即一次更改两个大小(左上拇指、右上拇指、左下拇指、右下拇指)。一切正常，您可以在第一个 gif 上看到它:

另外，我想添加按住 Shift 键按比例调整大小的功能。你可以在第二个 gif 中看到这个结果:

如您所见，左上拇指和右下拇指可让您正确更改尺寸。但是，其他两个拇指元素不起作用，我不明白是怎么做到的。

XAML:

<Window x:Class="BagControlResize.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">
    <Canvas x:Name="canvas">
        <TextBlock x:Name="testBlock" Canvas.Left="250" Canvas.Top="120" Width="300" Height="200" Background="Green"/>
    </Canvas>
</Window>

创建装饰器:

using System.Windows;
using System.Windows.Documents;

namespace BagControlResize
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            Loaded += (sender, e) =>
            {
                var adorner = AdornerLayer.GetAdornerLayer(canvas);
                adorner.Add(new TextBlockAdorner(testBlock));
            };
        }

    }
}

装饰品:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace BagControlResize
{
    public class TextBlockAdorner : Adorner
    {
        private double angle = 0.0;
        private Point transformOrigin = new Point(0, 0);
        private TextBlock childElement;
        private VisualCollection visualChilderns;
        private Thumb leftTop, rightTop, leftBottom, rightBottom;

        public TextBlockAdorner(UIElement element) : base(element)
        {
            visualChilderns = new VisualCollection(this);
            childElement = element as TextBlock;
            CreateThumbPart(ref leftTop);
            leftTop.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    double _max = hor > vert ? hor : vert;
                    hor = _max;
                    vert = _max;
                }
                ResizeX(hor);
                ResizeY(vert);
                e.Handled = true;
            };
            CreateThumbPart(ref rightTop);
            rightTop.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    // THIS: NO WORKED
                    double _max = Math.Abs(hor) > Math.Abs(vert) ? Math.Abs(hor) : Math.Abs(vert);
                    if (hor >= 0 && vert <= 0)
                    {
                        hor = _max;
                        vert = -_max;
                    }
                    else
                    {
                        hor = -_max;
                        vert = _max;
                    }
                }
                ResizeWidth(hor);
                ResizeY(vert);
                e.Handled = true;
            };
            CreateThumbPart(ref leftBottom);
            leftBottom.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    // THIS: NO WORKED
                    double _max = Math.Abs(hor) > Math.Abs(vert) ? Math.Abs(hor) : Math.Abs(vert);
                    if (hor <= 0 && vert >= 0)
                    {
                        hor = -_max;
                        vert = _max;
                    }
                    else
                    {
                        hor = _max;
                        vert = -_max;
                    }
                }
                ResizeX(hor);
                ResizeHeight(vert);
                e.Handled = true;
            };
            CreateThumbPart(ref rightBottom);
            rightBottom.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    double _max = hor > vert ? hor : vert;
                    hor = _max;
                    vert = _max;
                }
                ResizeWidth(hor);
                ResizeHeight(vert);
                e.Handled = true;
            };
        }
        private void ResizeWidth(double e)
        {
            double deltaHorizontal = Math.Min(-e, childElement.ActualWidth - childElement.MinWidth);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) - transformOrigin.X * deltaHorizontal * Math.Sin(angle));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + (deltaHorizontal * transformOrigin.X * (1 - Math.Cos(angle))));
            childElement.Width -= deltaHorizontal;
        }
        private void ResizeX(double e)
        {
            double deltaHorizontal = Math.Min(e, childElement.ActualWidth - childElement.MinWidth);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + deltaHorizontal * Math.Sin(angle) - transformOrigin.X * deltaHorizontal * Math.Sin(angle));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + deltaHorizontal * Math.Cos(angle) + (transformOrigin.X * deltaHorizontal * (1 - Math.Cos(angle))));
            childElement.Width -= deltaHorizontal;
        }
        private void ResizeHeight(double e)
        {
            double deltaVertical = Math.Min(-e, childElement.ActualHeight - childElement.MinHeight);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + (transformOrigin.Y * deltaVertical * (1 - Math.Cos(-angle))));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) - deltaVertical * transformOrigin.Y * Math.Sin(-angle));
            childElement.Height -= deltaVertical;
        }
        private void ResizeY(double e)
        {
            double deltaVertical = Math.Min(e, childElement.ActualHeight - childElement.MinHeight);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + deltaVertical * Math.Cos(-angle) + (transformOrigin.Y * deltaVertical * (1 - Math.Cos(-angle))));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + deltaVertical * Math.Sin(-angle) - (transformOrigin.Y * deltaVertical * Math.Sin(-angle)));
            childElement.Height -= deltaVertical;
        }
        public void CreateThumbPart(ref Thumb cornerThumb)
        {
            cornerThumb = new Thumb { Width = 25, Height = 25, Background= Brushes.Black };
            visualChilderns.Add(cornerThumb);
        }
        public void EnforceSize(FrameworkElement element)
        {
            if (element.Width.Equals(Double.NaN))
                element.Width = element.DesiredSize.Width;
            if (element.Height.Equals(Double.NaN))
                element.Height = element.DesiredSize.Height;
            FrameworkElement parent = element.Parent as FrameworkElement;
            if (parent != null)
            {
                element.MaxHeight = parent.ActualHeight;
                element.MaxWidth = parent.ActualWidth;
            }
        }
        protected override Size ArrangeOverride(Size finalSize)
        {
            base.ArrangeOverride(finalSize);
            double desireWidth = AdornedElement.DesiredSize.Width;
            double desireHeight = AdornedElement.DesiredSize.Height;
            double adornerWidth = this.DesiredSize.Width;
            double adornerHeight = this.DesiredSize.Height;
            leftTop.Arrange(new Rect(-adornerWidth / 2 - 15, -adornerHeight / 2 - 15, adornerWidth, adornerHeight));
            rightTop.Arrange(new Rect(desireWidth - adornerWidth / 2 + 15, -adornerHeight / 2 - 15, adornerWidth, adornerHeight));
            leftBottom.Arrange(new Rect(-adornerWidth / 2 - 15, desireHeight - adornerHeight / 2 + 15, adornerWidth, adornerHeight));
            rightBottom.Arrange(new Rect(desireWidth - adornerWidth / 2 + 15, desireHeight - adornerHeight / 2 + 15, adornerWidth, adornerHeight));
            return finalSize;
        }
        protected override int VisualChildrenCount => visualChilderns.Count;
        protected override Visual GetVisualChild(int index) => visualChilderns[index];
        protected override void OnRender(DrawingContext drawingContext) => base.OnRender(drawingContext);
    }
}

我至少展示了一个自给自足的示例，以便您可以准确地了解我在做什么。代码很容易编译。我在代码中标记了两个卡住的地方。

谢谢

更新 1:

Answer 1

@Frenchy 的解决方案有帮助，但代码仍然存在问题。尝试按住 Shift 键并单击左上角或左下角，然后立即直接向上拖动，或者以恒定速度非常缓慢地向左拖动右上角。

问题是由于在每次调用 DragDelta 时根据最大移动的方向计算比例拖动方向引起的。代码很容易改变方向并变得困惑，或者甚至不知道它应该以哪种方式正确运行。

解决此问题的一种方法是在比例拖动开始时确定拖动方向，并继续进行直到结束。这似乎效果更好，并解决了上述问题。代码如下。

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace BagControlResize
{
    public class TextBlockAdorner : Adorner
    {
        private double angle = 0.0;
        private Point transformOrigin = new Point(0, 0);
        private TextBlock childElement;
        private VisualCollection visualChilderns;
        public Thumb leftTop, rightTop, leftBottom, rightBottom;
        private bool dragStarted = false;
        private bool isHorizontalDrag = false;

        public TextBlockAdorner(UIElement element) : base(element)
        {
            visualChilderns = new VisualCollection(this);
            childElement = element as TextBlock;
            CreateThumbPart(ref leftTop);
            leftTop.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    if (dragStarted) isHorizontalDrag = Math.Abs(hor) > Math.Abs(vert);
                    if (isHorizontalDrag) vert = hor; else hor = vert;
                }
                ResizeX(hor);
                ResizeY(vert);
                dragStarted = false;
                e.Handled = true;
            };
            CreateThumbPart(ref rightTop);
            rightTop.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                System.Diagnostics.Debug.WriteLine(hor + "," + vert + "," + (Math.Abs(hor) > Math.Abs(vert)) + "," + childElement.Height + "," + childElement.Width + "," + dragStarted + "," + isHorizontalDrag);
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    if (dragStarted) isHorizontalDrag = Math.Abs(hor) > Math.Abs(vert);
                    if (isHorizontalDrag) vert = -hor; else hor = -vert;
                }
                ResizeWidth(hor);
                ResizeY(vert);
                dragStarted = false;
                e.Handled = true;
            };
            CreateThumbPart(ref leftBottom);
            leftBottom.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                System.Diagnostics.Debug.WriteLine(hor + "," + vert + "," + (Math.Abs(hor) > Math.Abs(vert)) + "," + childElement.Height + "," + childElement.Width + "," + dragStarted + "," + isHorizontalDrag);
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    if (dragStarted) isHorizontalDrag = Math.Abs(hor) > Math.Abs(vert);
                    if (isHorizontalDrag) vert = -hor; else hor = -vert;
                }
                ResizeX(hor);
                ResizeHeight(vert);
                dragStarted = false;
                e.Handled = true;
            };
            CreateThumbPart(ref rightBottom);
            rightBottom.DragDelta += (sender, e) =>
            {
                double hor = e.HorizontalChange;
                double vert = e.VerticalChange;
                if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
                {
                    if (dragStarted) isHorizontalDrag = Math.Abs(hor) > Math.Abs(vert);
                    if (isHorizontalDrag) vert = hor; else hor = vert;
                }
                ResizeWidth(hor);
                ResizeHeight(vert);
                dragStarted = false;
                e.Handled = true;
            };
        }
        public void CreateThumbPart(ref Thumb cornerThumb)
        {
            cornerThumb = new Thumb { Width = 25, Height = 25, Background = Brushes.Black };
            cornerThumb.DragStarted += (object sender, DragStartedEventArgs e) => dragStarted = true;
            visualChilderns.Add(cornerThumb);
        }

        private void ResizeWidth(double e)
        {
            double deltaHorizontal = Math.Min(-e, childElement.ActualWidth - childElement.MinWidth);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) - transformOrigin.X * deltaHorizontal * Math.Sin(angle));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + (deltaHorizontal * transformOrigin.X * (1 - Math.Cos(angle))));
            childElement.Width -= deltaHorizontal;
        }
        private void ResizeX(double e)
        {
            double deltaHorizontal = Math.Min(e, childElement.ActualWidth - childElement.MinWidth);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + deltaHorizontal * Math.Sin(angle) - transformOrigin.X * deltaHorizontal * Math.Sin(angle));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + deltaHorizontal * Math.Cos(angle) + (transformOrigin.X * deltaHorizontal * (1 - Math.Cos(angle))));
            childElement.Width -= deltaHorizontal;
        }
        private void ResizeHeight(double e)
        {
            double deltaVertical = Math.Min(-e, childElement.ActualHeight - childElement.MinHeight);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + (transformOrigin.Y * deltaVertical * (1 - Math.Cos(-angle))));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) - deltaVertical * transformOrigin.Y * Math.Sin(-angle));
            childElement.Height -= deltaVertical;
        }
        private void ResizeY(double e)
        {
            double deltaVertical = Math.Min(e, childElement.ActualHeight - childElement.MinHeight);
            Canvas.SetTop(childElement, Canvas.GetTop(childElement) + deltaVertical * Math.Cos(-angle) + (transformOrigin.Y * deltaVertical * (1 - Math.Cos(-angle))));
            Canvas.SetLeft(childElement, Canvas.GetLeft(childElement) + deltaVertical * Math.Sin(-angle) - (transformOrigin.Y * deltaVertical * Math.Sin(-angle)));
            childElement.Height -= deltaVertical;
        }
        //public void EnforceSize(FrameworkElement element)
        //{
        //    if (element.Width.Equals(Double.NaN))
        //        element.Width = element.DesiredSize.Width;
        //    if (element.Height.Equals(Double.NaN))
        //        element.Height = element.DesiredSize.Height;
        //    FrameworkElement parent = element.Parent as FrameworkElement;
        //    if (parent != null)
        //    {
        //        element.MaxHeight = parent.ActualHeight;
        //        element.MaxWidth = parent.ActualWidth;
        //    }
        //}
        protected override Size ArrangeOverride(Size finalSize)
        {
            base.ArrangeOverride(finalSize);
            double desireWidth = AdornedElement.DesiredSize.Width;
            double desireHeight = AdornedElement.DesiredSize.Height;
            double adornerWidth = this.DesiredSize.Width;
            double adornerHeight = this.DesiredSize.Height;
            leftTop.Arrange(new Rect(-adornerWidth / 2 - 15, -adornerHeight / 2 - 15, adornerWidth, adornerHeight));
            rightTop.Arrange(new Rect(desireWidth - adornerWidth / 2 + 15, -adornerHeight / 2 - 15, adornerWidth, adornerHeight));
            leftBottom.Arrange(new Rect(-adornerWidth / 2 - 15, desireHeight - adornerHeight / 2 + 15, adornerWidth, adornerHeight));
            rightBottom.Arrange(new Rect(desireWidth - adornerWidth / 2 + 15, desireHeight - adornerHeight / 2 + 15, adornerWidth, adornerHeight));
            return finalSize;
        }
        protected override int VisualChildrenCount => visualChilderns.Count;
        protected override Visual GetVisualChild(int index) => visualChilderns[index];
        //protected override void OnRender(DrawingContext drawingContext) => base.OnRender(drawingContext);
    }
}