[C#] Winform - 加载动画效果

一、预览效果

二、创建项目

1、创建应用

2、添加自定义控件

using System;using System.Drawing;using System.Windows.Forms;using WindowsFormsApp.LoadingControlDemo.Helpers;namespace WindowsFormsApp.LoadingControlDemo.Controls{public partial class LoadingControl : Control{private Image _image;public Image Image{get { return _image; }set { _image = value; }}private float _angle = 0;public LoadingControl(){InitializeComponent();timer1.Start();}protected override void OnPaint(PaintEventArgs pe){base.OnPaint(pe);AppHelper.RotateImage(_image, pe.Graphics, _angle, Width);}private void Timer1_Tick(object sender, EventArgs e){_angle += 18;if (_angle > 360)_angle -= 360;Invalidate();}}}

重点：

1、重写“OnPaint”方法，旋转图片；

2、使用Timer，在Tick方法中改变“角度值”，并触发OnPaint。 

3、使用自定义控件

1）从工具箱中拖拽“LoadingControl”控件到MainForm窗体：

2）在MainForm.cs后台代码里面绑定Image：

using System;using System.Drawing;using System.IO;using System.Windows.Forms;namespace WindowsFormsApp.LoadingControlDemo{public partial class MainForm : Form{public MainForm(){InitializeComponent();loadingControl1.Image = Image.FromFile(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, \"loading.png\"));}}}

三、帮助文件

AppHelper.cs

using System;using System.Drawing;namespace WindowsFormsApp.LoadingControlDemo.Helpers{internal class AppHelper{public static void RotateImage(Image image, Graphics g, float angle, int radius){if (image == null)return;int edge = (int)(radius / Math.Sqrt(2));int space = (radius - edge) / 2;g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;g.TranslateTransform(edge / 2, edge / 2);g.RotateTransform(angle);g.TranslateTransform(-edge / 2, -edge / 2);g.DrawImage(image, space, space, edge - space * 2, edge - space * 2);}}}

 重点：

1、edge：表示LoadingControl控件(正方形)里面内切圆的内接正方形的边长，保证Image在旋转时不会溢出；

2、space：表示Image的边距，保证Image水平和垂直居中显示。