通过按钮单击 C# 在 Pan 和 Crop 之间切换

Question

我正在使用 WinForms。在我的表单中，我有一个能够平移和裁剪的图片框。我的程序的问题是我无法通过单击按钮在裁剪和平移之间切换。我怎样才能做到这一点？我在下面提供了我的代码。

    //------CROP::::::::::::::
    int cropX;
    int cropY;
    int cropWidth;

    int cropHeight;
    public Pen cropPen;
    //------PAN::::::::::::::::
    private Point _pt;
    private Point _pt2;
    bool _isPanning = false;
    Point startPt;
    //-----Button on/off:::::::
    private bool crop_btn_OFF = false;
    private bool pan_btn_OFF = false;

    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        _isPanning = true;
        startPt = e.Location;

        if (e.Button == System.Windows.Forms.MouseButtons.Left )
            {
                Cursor = Cursors.Cross;
                cropX = e.X;
                cropY = e.Y;

                cropPen = new Pen(Color.FromArgb(153, 180, 209), 3);

                cropPen.DashStyle = DashStyle.DashDotDot;
            }
            pictureBox1.Refresh();

    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            //X and Y are the position of the crop
            pictureBox1.Refresh();
            cropWidth = e.X - cropX;
            cropHeight = e.Y - cropY;
            pictureBox1.CreateGraphics().DrawRectangle(cropPen, cropX, cropY, cropWidth, cropHeight);
        }

        //if (_isPanning) Un-comment this to Pan the image
        //{    
        //    Cursor = Cursors.SizeAll;
        //    Control c = (Control)sender;
        //    c.Left = (c.Left + e.X) - startPt.X;
        //    c.Top = (c.Top + e.Y) - startPt.Y;
        //    c.BringToFront();
        //}
    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        _isPanning = false;
        Cursor = Cursors.Default;
    }

    private void btn_Crop_Click(object sender, EventArgs e)
    {

        crop_btn_OFF = true;
        pan_btn_OFF = false;


        if (cropWidth < 1)
        {
            return;
        }
        Rectangle rect = new Rectangle(cropX, cropY, cropWidth, cropHeight);
        //First we define a rectangle with the help of already calculated points
        Bitmap OriginalImage = new Bitmap(pictureBox1.Image, pictureBox1.Width, pictureBox1.Height);
        //Original image
        Bitmap _img = new Bitmap(cropWidth, cropHeight);
        // for cropinf image
        Graphics g = Graphics.FromImage(_img);
        // create graphics
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
        g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
        //set image attributes
        g.DrawImage(OriginalImage, 0, 0, rect, GraphicsUnit.Pixel);

        pictureBox1.Image = _img;
        pictureBox1.Width = _img.Width;
        pictureBox1.Height = _img.Height;
    }

    private void btn_Pan_Click(object sender, EventArgs e)
    {
        crop_btn_OFF = false;
        pan_btn_OFF = true;
    }

Answer 1

如果我明白你想做什么，那么你需要名为 pictureBox1_MouseDown 的方法和名为 pictureBox1_MouseMove 的方法来了解用户是处于平移模式还是裁剪模式.您通过定义名为 _isPanning 的变量开始了这个想法，但您需要在我提到的方法中使用此数据。

希望我的回答能让您朝着正确的方向前进。我不愿给出更具体的答案，因为解决问题的方法不止一种。

Answer 2

一个好主意是使用枚举。例如，定义一个 State 枚举：

 public enum State
        {
            Pan,
            Crop
        }

并包含一个字段

private State currentState;

当您单击“平移”或“裁剪”按钮时，将 currentState 设置为：

public void btnCrop_Click()
        {
            currentState = State.Crop;
        }

 public void btnPan_Click()
        {
            currentState = State.Pan;
        }

并且在您的方法中，使用 currentState 字段指定它们应该做什么

public void Foo()
{
    if (currentState == State.Pan)
    {
        // Do Pan work
    }
    else if (currentState == State.Crop)
    {
        // Do Crop Work
    }
}

Answer 3

仔细考虑单击按钮或拖动图像时希望发生的情况。目前，您的裁剪按钮会尝试做两件事：设置模式和应用裁剪。

尝试更好地分离模式。您的按钮单击处理程序应仅按照@Leigh 的建议切换模式，鼠标处理程序应根据模式平移或裁剪。

我没有测试你的方法的内容，所以它们可能需要一些调试。为了使这更容易，请在命名变量时尝试遵循某种约定：例如私有字段以下划线开头，方法和属性以大写字母开头，方法中的变量以小写字母开头。我还在您的评论后添加了一些空格，因为尚不清楚它们是应用于之前的行还是之后的行。

private enum State
{
    Pan,
    Crop
}
private State _currentState;

public void btnCrop_Click()
{
    _currentState = State.Crop;
}

public void btnPan_Click()
{
    _currentState = State.Pan;
}

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    if (_currentState == State.Crop)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Left )
        {
            Cursor = Cursors.Cross;
            _cropX = e.X;
            _cropY = e.Y;

            _cropPen = new Pen(Color.FromArgb(153, 180, 209), 3);

            _cropPen.DashStyle = DashStyle.DashDotDot;
            pictureBox1.Refresh();
        }
    }
    else // state = pan
    {            
        _isPanning = true;
        _startPt = e.Location;
    }
}

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (_currentState == State.Crop)
    {
        Cursor = Cursors.Cross;
        if (e.Button == System.Windows.Forms.MouseButtons.Left)
        {
            //X and Y are the position of the crop
            pictureBox1.Refresh();
            _cropWidth = e.X - _cropX;
            _cropHeight = e.Y - _cropY;
            pictureBox1.CreateGraphics().DrawRectangle(_cropPen, _cropX, _cropY, _cropWidth, _cropHeight);
        }
    }
    else // state = pan
        if (_isPanning)
        {    
            Cursor = Cursors.SizeAll;
            Control c = (Control)sender;
            c.Left = (c.Left + e.X) - _startPt.X;
            c.Top = (c.Top + e.Y) - _startPt.Y;
            c.BringToFront();
        }
    }
}

private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
    Cursor = Cursors.Default;
    if (_currentState == State.Crop)
    {            
        if (cropWidth < 1)
        {
            return;
        }

        Rectangle rect = new Rectangle(_cropX, _cropY, _cropWidth, _cropHeight);
        //First we define a rectangle with the help of already calculated points

        Bitmap originalImage = new Bitmap(pictureBox1.Image, pictureBox1.Width, pictureBox1.Height);
        //Original image

        Bitmap img = new Bitmap(_cropWidth, _cropHeight);
        // for cropinf image

        Graphics g = Graphics.FromImage(img);
        // create graphics

        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
        g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
        //set image attributes

        g.DrawImage(originalImage, 0, 0, rect, GraphicsUnit.Pixel);

        pictureBox1.Image = img;
        pictureBox1.Width = img.Width;
        pictureBox1.Height = img.Height;
    }
    else // state = pan
    {
        // nothing to do here but leaving it for symmetry with the other methods
    }        
}

为了使功能对用户来说更明显，您可以将按钮替换为单选按钮，或者弄清楚如何使按钮与当前状态相对应remain pushed in。

通过按钮单击 C# 在 Pan 和 Crop 之间切换

Switch between Pan and Crop by button click C#

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