(精华)2020年8月12日 C#基础知识点 图片相关操作
/// <summary>
/// 图片类
/// </summary>
public class ImageHelper
{<!-- -->
private static string ImagePath = ConfigurationManager.AppSettings["ImagePath"];
private static string VerifyPath = ConfigurationManager.AppSettings["ImagePath"];
//绘图的原理很简单:Bitmap就像一张画布,Graphics如同画图的手,把Pen或Brush等绘图对象画在Bitmap这张画布上
/// <summary>
/// 画验证码
/// </summary>
public static void Drawing()
{<!-- -->
Bitmap bitmapobj = new Bitmap(100, 100);
//在Bitmap上创建一个新的Graphics对象
Graphics g = Graphics.FromImage(bitmapobj);
//创建绘画对象,如Pen,Brush等
Pen redPen = new Pen(Color.Red, 8);
g.Clear(Color.White);
//绘制图形
g.DrawLine(redPen, 50, 20, 500, 20);
g.DrawEllipse(Pens.Black, new Rectangle(0, 0, 200, 100));//画椭圆
g.DrawArc(Pens.Black, new Rectangle(0, 0, 100, 100), 60, 180);//画弧线
g.DrawLine(Pens.Black, 10, 10, 100, 100);//画直线
g.DrawRectangle(Pens.Black, new Rectangle(0, 0, 100, 200));//画矩形
g.DrawString("我爱北京*", new Font("微软雅黑", 12), new SolidBrush(Color.Red), new PointF(10, 10));//画字符串
//g.DrawImage(
if (!Directory.Exists(ImagePath))
Directory.CreateDirectory(ImagePath);
bitmapobj.Save(ImagePath + "pic1.jpg", ImageFormat.Jpeg);
//释放所有对象
bitmapobj.Dispose();
g.Dispose();
}
public static void VerificationCode()
{<!-- -->
Bitmap bitmapobj = new Bitmap(300, 300);
//在Bitmap上创建一个新的Graphics对象
Graphics g = Graphics.FromImage(bitmapobj);
g.DrawRectangle(Pens.Black, new Rectangle(0, 0, 150, 50));//画矩形
g.FillRectangle(Brushes.White, new Rectangle(1, 1, 149, 49));
g.DrawArc(Pens.Blue, new Rectangle(10, 10, 140, 10), 150, 90);//干扰线
string[] arrStr = new string[] {<!-- --> "我", "们", "孝", "行", "白", "到", "国", "中", "来", "真" };
Random r = new Random();
int i;
for (int j = 0; j < 4; j++)
{<!-- -->
i = r.Next(10);
g.DrawString(arrStr[i], new Font("微软雅黑", 15), Brushes.Red, new PointF(j * 30, 10));
}
bitmapobj.Save(Path.Combine(VerifyPath, "Verif.jpg"), ImageFormat.Jpeg);
bitmapobj.Dispose();
g.Dispose();
}
/// <summary>
/// 按比例缩放,图片不会变形,会优先满足原图和最大长宽比例最高的一项
/// </summary>
/// <param name="oldPath"></param>
/// <param name="newPath"></param>
/// <param name="maxWidth"></param>
/// <param name="maxHeight"></param>
public static void CompressPercent(string oldPath, string newPath, int maxWidth, int maxHeight)
{<!-- -->
Image _sourceImg = Image.FromFile(oldPath);
double _newW = (double)maxWidth;
double _newH = (double)maxHeight;
double percentWidth = (double)_sourceImg.Width > maxWidth ? (double)maxWidth : (double)_sourceImg.Width;
if ((double)_sourceImg.Height * (double)percentWidth / (double)_sourceImg.Width > (double)maxHeight)
{<!-- -->
_newH = (double)maxHeight;
_newW = (double)maxHeight / (double)_sourceImg.Height * (double)_sourceImg.Width;
}
else
{<!-- -->
_newW = percentWidth;
_newH = (percentWidth / (double)_sourceImg.Width) * (double)_sourceImg.Height;
}
Image bitmap = new Bitmap((int)_newW, (int)_newH);
Graphics g = Graphics.FromImage(bitmap);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
g.DrawImage(_sourceImg, new Rectangle(0, 0, (int)_newW, (int)_newH), new Rectangle(0, 0, _sourceImg.Width, _sourceImg.Height), GraphicsUnit.Pixel);
_sourceImg.Dispose();
g.Dispose();
bitmap.Save(newPath, System.Drawing.Imaging.ImageFormat.Jpeg);
bitmap.Dispose();
}
/// <summary>
/// 按照指定大小对图片进行缩放,可能会图片变形
/// </summary>
/// <param name="oldPath"></param>
/// <param name="newPath"></param>
/// <param name="newWidth"></param>
/// <param name="newHeight"></param>
public static void ImageChangeBySize(string oldPath, string newPath, int newWidth, int newHeight)
{<!-- -->
Image sourceImg = Image.FromFile(oldPath);
System.Drawing.Image bitmap = new System.Drawing.Bitmap(newWidth, newHeight);
Graphics g = Graphics.FromImage(bitmap);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
g.DrawImage(sourceImg, new Rectangle(0, 0, newWidth, newHeight), new Rectangle(0, 0, sourceImg.Width, sourceImg.Height), GraphicsUnit.Pixel);
sourceImg.Dispose();
g.Dispose();
bitmap.Save(newPath, System.Drawing.Imaging.ImageFormat.Jpeg);
bitmap.Dispose();
}
//添加水印
//二维码 QRCode 二维码其实对应的是一个Url
}