真?WPF 按钮拖动和调整大小

时间：2020-09-10 22:39:47 阅读：66 评论：0 收藏：0 [点我收藏+]

独立观察员 2020 年 8 月 29 日

手头有个 Winform 程序，是使用动态生成按钮，然后拖动、调整大小，以此来记录一些坐标数据，最后保存坐标数据的。

在数据量（按钮数量）比较小的时候是使用得挺愉快的，但是，当按钮数上去之后，比如达到四五百个按钮，那就比较痛苦了。具体来说就是，无论是移动窗口，还是拖动滚动条，或者是最小化窗口再还原，都会引起界面重绘，表现为按钮一个接一个地出现。

经过实测，与电脑的性能和 GPU 都没有关系，网上针对 Winform 这个问题的解决方案，比如开启双缓冲等，都大致尝试了，并无任何起色，反而可能更糟。所以就像网友所说，这个要么不要在同一个界面上放置太多控件；要么使用 WPF，毕竟 WPF 采用的是 DirectX 作为底层绘图引擎，而 Winform 则采用传统的 GDI 。由于业务需求，不让在界面上放置过多控件的方案不太可行，或者说暂未想到有什么变通的办法，所以决定改版为 WPF 试试。

经过几天的改造，原 Winform 版软件的一小部分功能已改版为 WPF 版，而且成果喜人，同样的按钮数量，现在无论怎样折腾，这几百个按钮就如同钉在了界面上一样，不再能看到他们载入的过程了。在这个改造的过程中，我是将 Winform 版软件中关于按钮拖动和调整大小的代码改造为 WPF 版的，听上去挺简单的，但是还是碰到了一些问题，比如 WPF 屏蔽了鼠标左键的一些事件，需要额外处理一下，还有的就是关于坐标定位的一些问题了，下面将给出一些关键代码，和大家相互交流学习一下。

首先，先上一道小菜，解决一下 WPF 按钮控件（Button）中文字自动换行的问题。

不对，还是先看看 Demo 的界面结构吧：

技术图片

其它控件和布局就不说了（最后会给出 Demo 地址），关键的是中间这个 ScrollViewer 包裹的 Canvas，我们生成的按钮都是在这个 Canvas 上的，拖动和调整大小也是。Winform 的布局是依赖于坐标的，WPF 的布局控件则基本是不使用坐标定位的，甚至都不推荐指定大小，而只有 Canvas 布局控件保留了以坐标定位的模式，正好适合我们的需求（之前 Winform 版使用的是 Panel 控件）。

可以看到里面我还注释了一个 Button ，这个就是用来演示我们的 “小菜” 问题（按钮文字自动换行）的。我们先把注释放开，并且只保留其宽和高的设置：

技术图片

可以看到当按钮宽度窄于文本内容时，文本内容并不能进行自动换行，且 Button 控件并没有相关属性进行设置。解决方法就是在按钮中添加 TextBlock 控件，然后设置其 TextWrapping 属性，当然，这里我们不直接这样写，而是使用内容模板：

<Button Width="38" Height="75" ContentTemplate="{DynamicResource DataTemplateButtonWrap}">1A005</Button>

这个模板的资源放在 App.xaml 中：

<Application.Resources>
    <DataTemplate x:Key="DataTemplateButtonWrap" DataType="Button">
        <Grid>
            <TextBlock TextWrapping="Wrap" Text="{TemplateBinding Content}"></TextBlock>
        </Grid>
    </DataTemplate>
</Application.Resources>

TextBlock 中使用了 TemplateBinding 将 Button 的 Content “绑架” 到了自己的 Text 中，哈哈。看看效果：

至于后台动态绑定资源则是使用 SetResourceReference 方法，后面代码里也有体现。

好了，小菜吃完了，开始吃主菜吧：

#region 成员

private Control _control;
private int _btnNum = 0;

#endregion

/// <summary>
/// 设置控件在Canvas容器中的位置;
/// </summary>
private void SetControlLocation(Control control, Point point)
{
    Canvas.SetLeft(control, point.X);
    Canvas.SetTop(control, point.Y);
}

/// <summary>
/// 添加按钮
/// </summary>
private void AddBtnHandler()
{
    string btnContent = GetBtnContent();

    Button btn = new Button
    {
        Name = "btn" + btnContent,
        Content = "btn" + btnContent,
        Width = 80,
        Height = 20,
    };

    _control = btn;
    AddContorlToCanvas(_control);
    SetControlLocation(_control, new Point(163, 55));
}

/// <summary>
/// 添加控件到界面;
/// </summary>
/// <param name="control"></param>
private void AddContorlToCanvas(Control control)
{
    control.MouseDown += MyMouseDown;
    control.MouseLeave += MyMouseLeave;
    //_control.MouseMove += MyMouseMove;
    control.KeyDown += MyKeyDown;

    //解决鼠标左键无法触发 MouseDown 的问题;
    control.AddHandler(Button.MouseLeftButtonDownEvent, new MouseButtonEventHandler(MyMouseDown), true);
    control.AddHandler(Button.MouseMoveEvent, new MouseEventHandler(MyMouseMove), true);

    CanvasMain.Children.Add(control);

    if (control is Button)
    {
        //模板中设置按钮文字换行(模板资源在App.xaml中);
        control.SetResourceReference(ContentTemplateProperty, "DataTemplateButtonWrap");
        _btnNum++;
    }
}

/// <summary>
/// 生成按钮内容
/// </summary>
/// <returns></returns>
private string GetBtnContent()
{
    return (_btnNum + 1).ToString().PadLeft(3, ‘0‘);
}

/// <summary>
/// 删除按钮
/// </summary>
private void DelBtnHandler()
{
    CanvasMain.Children.Remove(_control);
}

上面代码是对按钮生成、添加到界面的一些操作逻辑，每个方法都有注释，具体的大家自己看看，这里就不在赘述了。其中添加控件到界面的方法 AddContorlToCanvas 中，给控件（本文指的是按钮）添加了 MouseDown、MouseLeave、MouseMove、KeyDown 等鼠标键盘事件，然后开头说过，WPF 屏蔽了 Button 的鼠标左键的一些事件，所以需要使用 AddHandler 进行处理。

下面来看看主菜中的精华：

#region 实现窗体内的控件拖动

const int Band = 5;
const int BtnMinWidth = 10;
const int BtnMinHeight = 10;
private EnumMousePointPosition _enumMousePointPosition;
private Point _point; //记录鼠标上次位置;

#region btn按钮拖动

/// <summary>
/// 鼠标按下
/// </summary>
private void MyMouseDown(object sender, MouseEventArgs e)
{
    //选择当前的按钮
    Button button = (Button)sender;
    _control = button;
    //Point point = e.GetPosition(CanvasMain);

    //左键点击按钮后可按WSAD进行上下左右移动;
    if (e.LeftButton == MouseButtonState.Pressed)
    {
        button.KeyDown += new KeyEventHandler(MyKeyDown);
    }

    double left = Canvas.GetLeft(_control);
    double top = Canvas.GetTop(_control);

    //右键点击按钮可向选定方向生成新按钮;
    if (e.RightButton == MouseButtonState.Pressed)
    {
        Button btn = new Button
        {
            Name = "btn" + GetBtnContent(), 
            Content = GetStrEndNumAddOne(button.Content.ToString())
        };

        CheckRepeat(btn.Content.ToString());

        btn.Width = _control.Width;
        btn.Height = _control.Height;

        if (rbUpper.IsChecked == true)//上
        {
            int h = txtUpper.Text.Trim() == "" ? 0 : Convert.ToInt32(txtUpper.Text.Trim());
            SetControlLocation(btn, new Point(left, top - _control.Height - h));
        }
        if (rbLower.IsChecked == true)//下
        {
            int h = txtLower.Text.Trim() == "" ? 0 : Convert.ToInt32(txtLower.Text.Trim());
            SetControlLocation(btn, new Point(left, top + _control.Height + h));
        }
        if (rbLeft.IsChecked == true)//左
        {
            int w = txtLeft.Text.Trim() == "" ? 0 : Convert.ToInt32(txtLeft.Text.Trim());
            SetControlLocation(btn, new Point(left - _control.Width - w, top));
        }
        if (rbRight.IsChecked == true)//右
        {
            int w = txtRight.Text.Trim() == "" ? 0 : Convert.ToInt32(txtRight.Text.Trim());
            SetControlLocation(btn, new Point(left + _control.Width + w, top));
        }

        _control = btn;
        AddContorlToCanvas(_control);
    }
    
    //TODO 中键点击按钮可进行信息编辑;
}

/// <summary>
/// 检查重复内容按钮
/// </summary>
/// <param name="content"></param>
private void CheckRepeat(string content)
{
    foreach (Control c in CanvasMain.Children)
    {
        if (c is Button btn)
        {
            if (content == btn.Content.ToString())
            {
                MessageBox.Show("出现重复按钮内容：" + content, "提示");
                return;
            }
        }
    }
}

/// <summary>
/// 获取非纯数字字符串的数值加一结果;
/// </summary>
private string GetStrEndNumAddOne(string str)
{
    int numberIndex = 0; //数字部分的起始位置;
    int charIndex = 0;
    foreach (char tempchar in str.ToCharArray())
    {
        charIndex++;
        if (!char.IsNumber(tempchar))
        {
            numberIndex = charIndex;
        }
    }

    string prefix = str.Substring(0, numberIndex);
    string numberStrOrigin = str.Remove(0, numberIndex);
    string numberStrTemp = "";

    if (numberStrOrigin != "")
    {
        numberStrTemp = (Convert.ToInt32(numberStrOrigin) + 1).ToString();
    }

    string result = "";
    if (numberStrOrigin.Length <= numberStrTemp.Length)
    {
        result = prefix + numberStrTemp;
    }
    else
    {
        result = prefix + numberStrTemp.PadLeft(numberStrOrigin.Length, ‘0‘);
    }

    return result;
}

/// <summary>
/// 鼠标离开
/// </summary>
private void MyMouseLeave(object sender, EventArgs e)
{
    _enumMousePointPosition = EnumMousePointPosition.MouseSizeNone;
    _control.Cursor = Cursors.Arrow;
}

/// <summary>
/// 鼠标移动
/// </summary>
private void MyMouseMove(object sender, MouseEventArgs e)
{
    _control = (Control)sender;
    double left = Canvas.GetLeft(_control);
    double top = Canvas.GetTop(_control);
    Point point = e.GetPosition(CanvasMain);
    double height = _control.Height;
    double width = _control.Width;

    if (e.LeftButton == MouseButtonState.Pressed)
    {
        switch (_enumMousePointPosition)
        {
            case EnumMousePointPosition.MouseDrag:

                SetControlLocation(_control, new Point(left + point.X - _point.X, top + point.Y - _point.Y));

                break;

            case EnumMousePointPosition.MouseSizeBottom:

                height += point.Y - _point.Y;

                break;

            case EnumMousePointPosition.MouseSizeBottomRight:

                width += point.X - _point.X;
                height += point.Y - _point.Y;

                break;

            case EnumMousePointPosition.MouseSizeRight:

                width += point.X - _point.X;

                break;

            case EnumMousePointPosition.MouseSizeTop:

                SetControlLocation(_control, new Point(left, top + point.Y - _point.Y));
                height -= (point.Y - _point.Y);

                break;

            case EnumMousePointPosition.MouseSizeLeft:

                SetControlLocation(_control, new Point(left + point.X - _point.X, top));
                width -= (point.X - _point.X);

                break;

            case EnumMousePointPosition.MouseSizeBottomLeft:

                SetControlLocation(_control, new Point(left + point.X - _point.X, top));
                width -= (point.X - _point.X);
                height += point.Y - _point.Y;

                break;

            case EnumMousePointPosition.MouseSizeTopRight:

                SetControlLocation(_control, new Point(left, top + point.Y - _point.Y));
                width += (point.X - _point.X);
                height -= (point.Y - _point.Y);

                break;

            case EnumMousePointPosition.MouseSizeTopLeft:

                SetControlLocation(_control, new Point(left + point.X - _point.X, top + point.Y - _point.Y));
                width -= (point.X - _point.X);
                height -= (point.Y - _point.Y);

                break;

            default:

                break;
        }

        //记录光标拖动到的当前点
        _point.X = point.X;
        _point.Y = point.Y;

        if (width < BtnMinWidth) width = BtnMinWidth;
        if (height < BtnMinHeight) height = BtnMinHeight;
        _control.Width = width;
        _control.Height = height;
    }
    else
    {
        _enumMousePointPosition = GetMousePointPosition(_control, e); //‘判断光标的位置状态

        switch (_enumMousePointPosition) //‘改变光标
        {
            case EnumMousePointPosition.MouseSizeNone:
                _control.Cursor = Cursors.Arrow;       //‘箭头
                break;

            case EnumMousePointPosition.MouseDrag:
                _control.Cursor = Cursors.SizeAll;     //‘四方向
                break;

            case EnumMousePointPosition.MouseSizeBottom:
                _control.Cursor = Cursors.SizeNS;      //‘南北
                break;

            case EnumMousePointPosition.MouseSizeTop:
                _control.Cursor = Cursors.SizeNS;      //‘南北
                break;

            case EnumMousePointPosition.MouseSizeLeft:
                _control.Cursor = Cursors.SizeWE;      //‘东西
                break;

            case EnumMousePointPosition.MouseSizeRight:
                _control.Cursor = Cursors.SizeWE;      //‘东西
                break;

            case EnumMousePointPosition.MouseSizeBottomLeft:
                _control.Cursor = Cursors.SizeNESW;    //‘东北到南西
                break;

            case EnumMousePointPosition.MouseSizeBottomRight:
                _control.Cursor = Cursors.SizeNWSE;    //‘东南到西北
                break;

            case EnumMousePointPosition.MouseSizeTopLeft:
                _control.Cursor = Cursors.SizeNWSE;    //‘东南到西北
                break;

            case EnumMousePointPosition.MouseSizeTopRight:
                _control.Cursor = Cursors.SizeNESW;    //‘东北到南西
                break;

            default:
                break;
        }
    }
}

/// <summary>
/// 按键WSAD(上下左右)
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void MyKeyDown(object sender, KeyEventArgs e)
{
    double left = Canvas.GetLeft(_control);
    double top = Canvas.GetTop(_control);

    switch (e.Key)
    {
        case Key.W://上
        {
            SetControlLocation(_control, new Point(left, top-1));
            break;
        }
        case Key.S://下
        {
            SetControlLocation(_control, new Point(left, top+1));
            break;
        }
        case Key.A://左
        {
            SetControlLocation(_control, new Point(left-1, top));
            break;
        }
        case Key.D://右
        {
            SetControlLocation(_control, new Point(left+1, top));
            break;
        }
    }
}

#endregion 按钮拖动

#region 鼠标位置

/// <summary>
/// 鼠标指针位置枚举;
/// </summary>
private enum EnumMousePointPosition
{
    /// <summary>
    /// 无
    /// </summary>
    MouseSizeNone = 0,

    /// <summary>
    /// 拉伸右边框
    /// </summary>
    MouseSizeRight = 1,

    /// <summary>
    /// 拉伸左边框
    /// </summary>
    MouseSizeLeft = 2,

    /// <summary>
    /// 拉伸下边框
    /// </summary>
    MouseSizeBottom = 3,

    /// <summary>
    /// 拉伸上边框
    /// </summary>
    MouseSizeTop = 4,

    /// <summary>
    /// 拉伸左上角
    /// </summary>
    MouseSizeTopLeft = 5,

    /// <summary>
    /// 拉伸右上角
    /// </summary>
    MouseSizeTopRight = 6,

    /// <summary>
    /// 拉伸左下角
    /// </summary>
    MouseSizeBottomLeft = 7,

    /// <summary>
    /// 拉伸右下角
    /// </summary>
    MouseSizeBottomRight = 8,       

    /// <summary>
    /// 鼠标拖动
    /// </summary>
    MouseDrag = 9
}

/// <summary>
/// 获取鼠标指针位置;
/// </summary>
/// <param name="control"></param>
/// <param name="e"></param>
/// <returns></returns>
private EnumMousePointPosition GetMousePointPosition(Control control, MouseEventArgs e)
{
    Size size = control.RenderSize;
    Point point = e.GetPosition(control);

    Point pointCanvas = e.GetPosition(CanvasMain);
    _point.X = pointCanvas.X;
    _point.Y = pointCanvas.Y;

    if ((point.X >= -1 * Band) | (point.X <= size.Width) | (point.Y >= -1 * Band) | (point.Y <= size.Height))
    {
        if (point.X < Band)
        {
            if (point.Y < Band)
            {
                return EnumMousePointPosition.MouseSizeTopLeft;
            }
            else
            {
                if (point.Y > -1 * Band + size.Height)
                {
                    return EnumMousePointPosition.MouseSizeBottomLeft;
                }
                else
                {
                    return EnumMousePointPosition.MouseSizeLeft;
                }
            }
        }
        else
        {
            if (point.X > -1 * Band + size.Width)
            {
                if (point.Y < Band)
                {
                    return EnumMousePointPosition.MouseSizeTopRight;
                }
                else
                {
                    if (point.Y > -1 * Band + size.Height)
                    {
                        return EnumMousePointPosition.MouseSizeBottomRight;
                    }
                    else
                    {
                        return EnumMousePointPosition.MouseSizeRight;
                    }
                }
            }
            else
            {
                if (point.Y < Band)
                {
                    return EnumMousePointPosition.MouseSizeTop;
                }
                else
                {
                    if (point.Y > -1 * Band + size.Height)
                    {
                        return EnumMousePointPosition.MouseSizeBottom;
                    }
                    else
                    {
                        return EnumMousePointPosition.MouseDrag;
                    }
                }
            }
        }
    }
    else
    {
        return EnumMousePointPosition.MouseSizeNone;
    }
}

#endregion 鼠标位置

#endregion 实现窗体内的控件拖动