效果图如下
绘制控件代码
using System.Drawing;
using System.Linq;
using System.Reflection;
using System.Windows.Forms;
namespace WindowsFormsApp2
{
public partial class MyPicControl : UserControl
{
public MyPicControl()
{
InitializeComponent();
this.Controls.Add(myPictureBox);
myPictureBox.MouseDown += new MouseEventHandler(pictureBox1_MouseDown);
myPictureBox.MouseUp += new MouseEventHandler(pictureBox1_MouseUp);
myPictureBox.MouseMove += new MouseEventHandler(pictureBox1_MouseMove);
myPictureBox.MouseWheel += new MouseEventHandler(pictureBox1_MouseWheel);
this.DragDrop += new DragEventHandler(MyPictureBox_DragDrop);
this.DragEnter += new DragEventHandler(MyPictureBox_DragEnter);
this.AllowDrop = true;//是否接收用数据拖放数据到控件上
}
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// 清理所有正在使用的资源。
/// </summary>
/// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region 组件设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要修改
/// 使用代码编辑器修改此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.SuspendLayout();
//
// MyPicControl
//
this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 15F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.Name = "MyPicControl";
this.Size = new System.Drawing.Size(754, 609);
this.ResumeLayout(false);
}
#endregion
public Bitmap GetBitmap
{
get { return myBmp; }
set
{
myBmp = value;
if (myBmp != null)
{
myPictureBox.SizeMode = PictureBoxSizeMode.Zoom; //设置picturebox为缩放模式
myPictureBox.Image = myBmp;
myPictureBox.Width = myBmp.Width;
myPictureBox.Height = myBmp.Height;
}
}
}
#region 图片展示功能
PictureBox myPictureBox = new PictureBox();
Bitmap myBmp;
Point mouseDownPoint = new Point(); //记录拖拽过程鼠标位置
bool isMove = false; //判断鼠标在picturebox上移动时，是否处于拖拽过程(鼠标左键是否按下)
int zoomStep = 20; //缩放步长
//鼠标按下功能
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
mouseDownPoint.X = Cursor.Position.X;
mouseDownPoint.Y = Cursor.Position.Y;
isMove = true;
myPictureBox.Focus();
}
}
//鼠标松开功能
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
isMove = false;
}
}
//鼠标移动功能
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (myBmp == null)
{
return;
}
myPictureBox.Focus();
if (isMove)
{
int x, y;
int moveX, moveY;
moveX = Cursor.Position.X - mouseDownPoint.X;
moveY = Cursor.Position.Y - mouseDownPoint.Y;
x = myPictureBox.Location.X + moveX;
y = myPictureBox.Location.Y + moveY;
myPictureBox.Location = new Point(x, y);
mouseDownPoint.X = Cursor.Position.X;
mouseDownPoint.Y = Cursor.Position.Y;
}
}
//鼠标滚轮滚动功能
private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
{
int x = e.Location.X;
int y = e.Location.Y;
int ow = myPictureBox.Width;
int oh = myPictureBox.Height;
int VX, VY;
if (e.Delta > 0)
{
myPictureBox.Width += zoomStep;
myPictureBox.Height += zoomStep;
PropertyInfo pInfo = myPictureBox.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
BindingFlags.NonPublic);
Rectangle rect = (Rectangle)pInfo.GetValue(myPictureBox, null);
myPictureBox.Width = rect.Width;
myPictureBox.Height = rect.Height;
}
if (e.Delta < 0)
{
if (myPictureBox.Width < myBmp.Width / 10)
return;
myPictureBox.Width -= zoomStep;
myPictureBox.Height -= zoomStep;
PropertyInfo pInfo = myPictureBox.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
BindingFlags.NonPublic);
Rectangle rect = (Rectangle)pInfo.GetValue(myPictureBox, null);
myPictureBox.Width = rect.Width;
myPictureBox.Height = rect.Height;
}
VX = (int)((double)x * (ow - myPictureBox.Width) / ow);
VY = (int)((double)y * (oh - myPictureBox.Height) / oh);
myPictureBox.Location = new Point(myPictureBox.Location.X + VX, myPictureBox.Location.Y + VY);
}
#endregion
private void MyPictureBox_DragDrop(object sender, DragEventArgs e)
{
string path = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(0).ToString();
string extension = System.IO.Path.GetExtension(path);
string[] extensions = new string[] { ".PNG", ".JPG" };
if (extensions.Contains(extension.ToUpper()))
{
myBmp = new Bitmap(path);
myPictureBox.SizeMode = PictureBoxSizeMode.Zoom; //设置picturebox为缩放模式
myPictureBox.Image = myBmp;
myPictureBox.Width = myBmp.Width;
myPictureBox.Height = myBmp.Height;
}
else
{
MessageBox.Show($"不支持{extension}格式文件");
}
}
private void MyPictureBox_DragEnter(object sender, DragEventArgs e)
{
//只允许文件拖放
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effect = DragDropEffects.Copy;
}
else
{
e.Effect = DragDropEffects.None;
}
}
}
}显示调用方法代码
/// <summary>
/// 控件的点击事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button1_Click(object sender, EventArgs e)
{
OpenFileDialog dlg = new OpenFileDialog();
dlg.Filter = "全部(*.*)|*.*";
if (dlg.ShowDialog() == DialogResult.OK)
{
Bitmap myBmp = new Bitmap(dlg.FileName);
myPicControl1.GetBitmap = myBmp;//myPicControl1 这个为自制控件 已在主窗体添加
}
}