使用鼠标 WPF C# 负调整 UIElement 的大小

问题描述

如何对画布中的 UIElement 进行负调整？让我感到困难的是可调整大小的元素和画布都可以旋转，因此调整大小必须考虑到这一点。我发现这篇很棒的文章展示了如何调整旋转元素的大小，但它不允许负调整大小。我无法绕过它。

WPF Diagram Designer: Part 1

当我说负调整大小时，我的意思是例如用户可以从右下角开始向上拖动，一旦他通过元素的顶部边缘，元素仍然应该调整大小（现在增加其大小），并且顶部位置也应该随着光标向上移动。

目前我不需要元素的镜像效果，只需调整大小即可。

我在下面发布了上面链接的精彩文章中调整拇指大小的代码。

public class ResizeThumb : Thumb
{
    private double angle;
    private Point transformOrigin;
    private ContentControl designerItem;
        
    public ResizeThumb()
    {
        DragStarted += new DragStartedEventHandler(this.ResizeThumb_DragStarted);
        DragDelta += new DragDeltaEventHandler(this.ResizeThumb_DragDelta);
    }

    private void ResizeThumb_DragStarted(object sender,DragStartedEventArgs e)
    {
        this.designerItem = DataContext as ContentControl;

        if (this.designerItem != null)
        {
            this.transformOrigin = this.designerItem.RenderTransformOrigin;
            RotateTransform rotateTransform = this.designerItem.RenderTransform as RotateTransform;

            if (rotateTransform != null)
            {
                this.angle = rotateTransform.Angle * Math.PI / 180.0;
            }
            else
            {
                this.angle = 0;
            }
        }
    }

    private void ResizeThumb_DragDelta(object sender,DragDeltaEventArgs e)
    {
        if (this.designerItem != null)
        {
            double deltaVertical,deltaHorizontal;

            switch (VerticalAlignment)
            {
                case System.Windows.VerticalAlignment.Bottom:

                    deltaVertical = Math.Min(-e.VerticalChange,this.designerItem.ActualHeight - this.designerItem.MinHeight);
                    Canvas.SetTop(this.designerItem,Canvas.GetTop(this.designerItem) + (this.transformOrigin.Y * deltaVertical * (1 - Math.Cos(-this.angle))));
                    Canvas.SetLeft(this.designerItem,Canvas.GetLeft(this.designerItem) - deltaVertical * this.transformOrigin.Y * Math.Sin(-this.angle));
                    this.designerItem.Height -= deltaVertical;
                    break;
                case System.Windows.VerticalAlignment.Top:
                    deltaVertical = Math.Min(e.VerticalChange,Canvas.GetTop(this.designerItem) + deltaVertical * Math.Cos(-this.angle) + (this.transformOrigin.Y * deltaVertical * (1 - Math.Cos(-this.angle))));
                    Canvas.SetLeft(this.designerItem,Canvas.GetLeft(this.designerItem) + deltaVertical * Math.Sin(-this.angle) - (this.transformOrigin.Y * deltaVertical * Math.Sin(-this.angle)));
                    this.designerItem.Height -= deltaVertical;
                    break;
                default:
                    break;
            }

            switch (HorizontalAlignment)
            {
                case System.Windows.HorizontalAlignment.Left:
                    deltaHorizontal = Math.Min(e.HorizontalChange,this.designerItem.ActualWidth - this.designerItem.MinWidth);
                    Canvas.SetTop(this.designerItem,Canvas.GetTop(this.designerItem) + deltaHorizontal * Math.Sin(this.angle) - this.transformOrigin.X * deltaHorizontal * Math.Sin(this.angle));
                    Canvas.SetLeft(this.designerItem,Canvas.GetLeft(this.designerItem) + deltaHorizontal * Math.Cos(this.angle) + (this.transformOrigin.X * deltaHorizontal * (1 - Math.Cos(this.angle))));
                    this.designerItem.Width -= deltaHorizontal;
                    break;
                case System.Windows.HorizontalAlignment.Right:
                    deltaHorizontal = Math.Min(-e.HorizontalChange,Canvas.GetTop(this.designerItem) - this.transformOrigin.X * deltaHorizontal * Math.Sin(this.angle));
                    Canvas.SetLeft(this.designerItem,Canvas.GetLeft(this.designerItem) + (deltaHorizontal * this.transformOrigin.X * (1 - Math.Cos(this.angle))));
                    this.designerItem.Width -= deltaHorizontal;
                    break;
                default:
                    break;
            }
        }

        e.Handled = true;
    }
}

解决方法

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