如何用鼠標移動矩形

Question

我想在屏幕上移動一個矩形。 這是我當時所做的代碼：

internal class GraphicContainer : Control
{
    //---------------------METHODS---------------------
    public GraphicContainer(Control control, string text, int left, int top)
        : base(control, text, left, top, 400, 200)

    protected override void OnPaint(PaintEventArgs pe)
    {
        // Call the OnPaint method of the base class.
        base.OnPaint(pe);

        // Declare and instantiate a new pen.
        Pen pen = new Pen(Color.Fuchsia, 15);
        SolidBrush myBrush= new System.Drawing.SolidBrush(Color.HotPink);
        // Draw an aqua rectangle in the rectangle represented by the control.
        //pe.Graphics.DrawRectangle(pen, new Rectangle(this.Location,this.Size));
        Rectangle blublublu = new Rectangle(this.Location, this.Size - new Size(25, 25));
        pe.Graphics.DrawRectangle(pen,blublublu);
        pe.Graphics.FillRectangle(myBrush,blublublu);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {        
    }

    protected override void OnClick(EventArgs e)
    {
    }
}

我進行了很多搜索，沒有找到應該在“ OnMouseMove”和“ OnClick”中編寫什么代碼才能移動鼠標。

Answer 1

瑞安·雷諾茲！

使blublublu成為一個領域。 您將必須使用MouseMove ， MouseUp ， MouseDown ：

    Rectangle blublublu = new Rectangle(...); // possibly init in constructor

    protected override void OnMouseDown(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            Capture = true;
            _x = e.X; // remember coords
            _y = e.Y;
        }
        base.OnMouseDown(e);
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        Capture = false;
        base.OnMouseUp(e);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            blublublu.X += _x - e.X; // not tested, maybe use Rectangle.Offset or create a new Rectangle
            blublublu.Y += _y - e.Y;
            Invalidate();
        }
    }

當鼠標按下時，您將捕獲它（即使鼠標在控件之外，也可以接收mousemove事件）並記住坐標。 在鼠標移動期間，您可以通過差值（保存的鼠標位置減去電流）更改blublublu的當前坐標，然后調用Invalidate 。

Answer 2

您可以使Location變量並使鼠標移動時的控件無效。 此外，只有在按下鼠標左鍵時才會發生這種情況

請注意，我不會覆蓋OnMouseMove ，而是通過添加另一個處理程序來訂閱事件。

Point mouseLocation;

public GraphicContainer(Control control, string text, int left, int top)
    : base(control, text, left, top, 400, 200) {
    //prevents flickering
    this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer, true);

    //subscribes to mousemove
    this.MouseMove += (obj,e) => {
        //only when left mousebutton is pressed
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            //update the location
            mouseLocation = e.Location;
            //invalidate the control
            this.Invalidate();
        }
    };
}

protected override void OnPaint(PaintEventArgs pe)
{
    // Call the OnPaint method of the base class.
    base.OnPaint(pe);

    // Declare and instantiate a new pen.
    Pen pen = new Pen(Color.Fuchsia, 15);
    SolidBrush myBrush = new System.Drawing.SolidBrush(Color.HotPink);
    // Draw an aqua rectangle in the rectangle represented by the control.
    Rectangle blublublu = new Rectangle(mouseLocation, this.Size - new Size(25, 25));
        pe.Graphics.DrawRectangle(pen, blublublu);
    pe.Graphics.FillRectangle(myBrush, blublublu);
}

protected override void OnMouseMove(MouseEventArgs e)
{
    //nothing here
}

請注意，我在構造函數中添加了this.SetStyle(...) ，因為這將防止在移動矩形時出現閃爍。 我this.Location OnPaint方法mouseLocation更改為mouseLocation 。