通过鼠标拖动滚动 [英] Scroll by dragging with mouse

问题描述

我正在尝试制作一个可滚动面板，但没有滚动条，并通过垂直拖动鼠标来滚动......这是迄今为止有人帮助我做的事情......:

I am trying to make a scrollable panel but without the scrollbar and to scroll by dragging with mouse vertically... here is what somebody helped me to do so far.. :

 private void panel1_MouseEnter(object sender, EventArgs e)
    {
        panel1.AutoScroll = false;
    }

    private int ValidateChange(int change)
    {
        var padding = -1;
        if (change < 0)
        {
            var max = (from Control control in Controls select control.Top + control.Height + padding).Concat(new[] { int.MinValue }).Max();

            if (max < Height + Math.Abs(change))
            {
                return Height - max;
            }
        }
        else
        {
            var min = (from Control control in Controls select control.Top).Concat(new[] { int.MaxValue }).Min();

            if (min > padding - Math.Abs(change))
            {
                return padding - min;
            }
        }
        return change;
    }

    private void HandleDelta(int delta)
    {
        var change = ValidateChange(delta);

        foreach (Control control in Controls)
        {
            control.Top += change;
        }

    }

    private void panel1_MouseWheel(object sender, MouseEventArgs e)
    {
        HandleDelta(e.Delta);
        base.OnMouseWheel(e);
    }

    private Point _mouseLastPosition;

    private void panel1_MouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            _mouseLastPosition = e.Location;
        }
        base.OnMouseDown(e);
    }

    public void panel1_MouseMove(object sender, MouseEventArgs e)
    {            
            if ((MouseButtons & MouseButtons.Left) != 0)
            {
                var delta = e.Y - _mouseLastPosition.Y;
                HandleDelta(delta);
                _mouseLastPosition = e.Location;
            }
            base.OnMouseMove(e);

    }

但是速度太快了..鼠标拖动看起来有点奇怪我不知道为什么，当我尝试使用鼠标滚轮时，它会出错并给我这个错误: System.Core.dll 中发生了一个未处理的异常类型System.StackOverflowException"line var max = (from Control control in Controls select control.Top + control.Height + padding).Concat(new[] { int.MinValue }).Max();

but it goes just too fast.. the dragging by mouse looks a little bit weird i dont know why and when I try to use mouse wheel it bugs and gives me this error: An unhandled exception of type 'System.StackOverflowException' occurred in System.Core.dll at this line var max = (from Control control in Controls select control.Top + control.Height + padding).Concat(new[] { int.MinValue }).Max();

推荐答案

这对我有用.它在所有控件上保持 10 像素的填充.尝试一下，然后根据您的需要进行修改.

This works for me. It keeps a padding of 10 pixels on all controls. Try it out and just modify it to your needs.

如果缺少您需要的东西，请告诉我.

Let me know if something is missing that you needed.

public class ScrollablePanel : Panel {
    private Point _mouseLastPosition;

    protected override void OnMouseDown(MouseEventArgs e) {
        if (e.Button == MouseButtons.Left) {
            _mouseLastPosition = e.Location;
        }
        base.OnMouseDown(e);
    }

    private int ValidateChange(int change) {
        var padding = -1;
        if (change < 0) {
            var max = (from Control control in Controls select control.Top + control.Height + padding).Concat(new[] { int.MinValue }).Max();

            if (max < Height + Math.Abs(change)) {
                return Height - max;
            }
        }
        else {
            var min = (from Control control in Controls select control.Top).Concat(new[] { int.MaxValue }).Min();

            if (min > padding - Math.Abs(change)) {
                return padding - min;
            }
        }
        return change;
    }

    private void HandleDelta(int delta) {
        var change = ValidateChange(delta);

        foreach (Control control in Controls) {
            control.Top += change;
        }

    }

    protected override void OnMouseMove(MouseEventArgs e) {
        if((MouseButtons & MouseButtons.Left) != 0) { 
            var delta = e.Y - _mouseLastPosition.Y;
            HandleDelta(delta);
            _mouseLastPosition = e.Location;
        }
        base.OnMouseMove(e);
    }

    protected override void OnMouseWheel(MouseEventArgs e) {
        HandleDelta(e.Delta);
        base.OnMouseWheel(e);
    }
}

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