将图像从一个PictureBox拖放到另一个PictureBox，并检查目标PictureBox是否正确

Question

我是编程新手。我在Visual Studio2019 WindowsForm中为一年级的孩子制作了一个应用程序，其中一个级别是将图片从PictureBox拖动到一个空的PictureBox中，该PictureBox有一个简单定义的标签。

所以如果我有两个PictureBox，假设有一只狗和一只鸡，还有两个空PictureBox (一个带有“骨骼”标签，另一个带有“谷物”标签)。我想将狗的图片拖到PictureBox中，标签为“骨骼”，鸡在标签为“谷粒”的图片中，如果正确，我会显示文本“伟大的工作”，如果不正确，我会显示文本“再试一次”。

我可以拖动图片，但我找不到一种方法来检查是否正确。有人能帮我吗？

到目前为止，我的代码如下：

    private void NivelulDoi_Load(object sender, EventArgs e)
        {
            customPictureBox1.AllowDrop = true;
            customPictureBox2.AllowDrop = true;
            customPictureBox3.AllowDrop = true;
        }

        private void customPictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                customPictureBox1.DoDragDrop(customPictureBox1.Image, DragDropEffects.Copy);
            }
        }

        private void customPictureBox1_DragDrop(object sender, DragEventArgs e)
        {
            var data = e.Data.GetData(DataFormats.FileDrop);
            if (data != null)
            {
                var fileNames = data as string[];
                if (fileNames.Length > 0)
                {
                    customPictureBox1.Image = Image.FromFile(fileNames[0]);
                }
            }
        }

        private void customPictureBox1_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Copy;
        }

        private void customPictureBox2_DragEnter(object sender, DragEventArgs e)
        {
            Dragging(e);
        }

        private void customPictureBox2_DragDrop(object sender, DragEventArgs e)
        {
            customPictureBox2.Image = (Bitmap)e.Data.GetData(DataFormats.Bitmap, true);
            
            // figure out how to check if correct 
            /*if (customPictureBox2.Image == (Bitmap)e.Data.GetData(DataFormats.Bitmap, true))
            {
                label1.Text = "ai reusit";
            }
            else
            {
                label1.Text = "mai incearca";
            }*/   
        }

        private void customPictureBox3_DragEnter(object sender, DragEventArgs e)
        {
            Dragging(e);
        }

        private void customPictureBox3_DragDrop(object sender, DragEventArgs e)
        {
            customPictureBox3.Image = (Bitmap)e.Data.GetData(DataFormats.Bitmap, true);
        }

        private void customPictureBox4_DragEnter(object sender, DragEventArgs e)
        {
            Dragging(e);
        }

        private void customPictureBox4_DragDrop(object sender, DragEventArgs e)
        {
            customPictureBox4.Image = (Bitmap)e.Data.GetData(DataFormats.Bitmap, true);
        }

        private static void Dragging(DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.Bitmap) && (e.AllowedEffect & DragDropEffects.Copy) != 0)
            {
                e.Effect = DragDropEffects.Copy;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }
    }
}

谢谢。

Answer 1

一种简单的方法是定义一个变量来保存"picturebox drag“的名称，并定义一个字典来保存"drag-drop”对。

这是演示。

string pictureBoxFrom = "";
Dictionary<string, string> picDict = new Dictionary<string, string>();
public Form1()
{
    InitializeComponent();
    pictureBox2.AllowDrop = true;
    pictureBox4.AllowDrop = true;
    pictureBox1.MouseDown += pictureBox_MouseDown;
    pictureBox3.MouseDown += pictureBox_MouseDown;
    pictureBox2.DragEnter += pictureBox_DragEnter;
    pictureBox2.DragDrop += pictureBox_DragDrop;
    pictureBox4.DragEnter += pictureBox_DragEnter;
    pictureBox4.DragDrop += pictureBox_DragDrop;

    picDict.Add("pictureBox1", "pictureBox2"); // drag 1 to 2
    picDict.Add("pictureBox3", "pictureBox4"); // drag 3 to 4
}

private void pictureBox_MouseDown(object sender, MouseEventArgs e)
{
    pictureBoxFrom = (sender as PictureBox).Name;
    var img = (sender as PictureBox).Image;
    if (img == null) return;
    if (DoDragDrop(img, DragDropEffects.Move) == DragDropEffects.Move)
    {
        //(sender as PictureBox).Image = null;
    }
}

private void pictureBox_DragEnter(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent(DataFormats.Bitmap))
        e.Effect = DragDropEffects.Move;
}

private void pictureBox_DragDrop(object sender, DragEventArgs e)
{
    if (picDict.ContainsKey(pictureBoxFrom) && picDict[pictureBoxFrom].Equals((sender as PictureBox).Name))
    {
        var bmp = (Bitmap)e.Data.GetData(DataFormats.Bitmap);
        (sender as PictureBox).Image = bmp;
        MessageBox.Show("great job");
    }
    else
    {
        MessageBox.Show("try again");
    }
}