写一个窗体应用程序代码，按下按钮选择本地png图片导入并显示出来，图片透明部分可以看到后面的控件

以下是一个简单的窗体应用程序代码，可以实现按下按钮选择本地png图片导入并显示出来，图片透明部分可以看到后面的控件：

using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private PictureBox pictureBox1;
        private Button button1;
        private OpenFileDialog openFileDialog1;

        public Form1()
        {
            InitializeComponent();
        }

        private void InitializeComponent()
        {
            this.pictureBox1 = new System.Windows.Forms.PictureBox();
            this.button1 = new System.Windows.Forms.Button();
            this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
            ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
            this.SuspendLayout();
            // 
            // pictureBox1
            // 
            this.pictureBox1.Location = new System.Drawing.Point(12, 12);
            this.pictureBox1.Name = "pictureBox1";
            this.pictureBox1.Size = new System.Drawing.Size(300, 300);
            this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;
            this.pictureBox1.TabIndex = 0;
            this.pictureBox1.TabStop = false;
            // 
            // button1
            // 
            this.button1.Location = new System.Drawing.Point(12, 318);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(75, 23);
            this.button1.TabIndex = 1;
            this.button1.Text = "选择图片";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // openFileDialog1
            // 
            this.openFileDialog1.FileName = "openFileDialog1";
            this.openFileDialog1.Filter = "PNG文件|*.png";
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(324, 353);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.pictureBox1);
            this.Name = "Form1";
            this.Text = "窗体应用程序";
            ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                Image image = Image.FromFile(openFileDialog1.FileName);
                Bitmap bitmap = new Bitmap(image);
                bitmap.MakeTransparent(Color.White);
                pictureBox1.Image = bitmap;
            }
        }
    }
}

这个程序中，我们使用了一个PictureBox控件来显示图片，使用一个Button控件来选择图片。当用户点击选择图片按钮时，我们弹出一个OpenFileDialog对话框，让用户选择一个PNG格式的图片文件。然后，我们将这个图片文件加载到一个Image对象中，再将它转换成一个Bitmap对象，并将它的白色部分设为透明。最后，我们将这个Bitmap对象赋给PictureBox控件的Image属性，从而显示出这个图片。