.NET下GDI＋的一些常用应用（水印，文字，圆角处理）

在某些情况下希望处理一些图片，比如

给图片添加一般文字：
原图



程序处理成



给图片添加水印：
原图



程序处理成



还有圆角效果：
原图



程序处理成



注：
（1）以下程序针对这个应用，也许这些对你没有用，但是基本的原理都差不多
（2）以上图为测试用，应该不算侵犯肖像权吧

程序界面：



程序点击这里下载。

如果需要提高图片质量，把
image.Save(sDstFilePath, ImageFormat.Jpeg);
改成

ImageCodecInfo myImageCodecInfo;
Encoder myEncoder;
EncoderParameter myEncoderParameter;
EncoderParameters myEncoderParameters;
myImageCodecInfo = ImageCodecInfo.GetImageEncoders()[0];
myEncoder = Encoder.Quality;
myEncoderParameters = new EncoderParameters(1);
myEncoderParameter = new EncoderParameter(myEncoder, 100L); // 0-100
myEncoderParameters.Param[0] = myEncoderParameter;
image.Save(sDstFilePath, myImageCodecInfo, myEncoderParameters);
myEncoderParameter.Dispose();
myEncoderParameters.Dispose();
这是提高质量后的效果：



附一些关键代码：

public class MyGDI
{
public static void CreateWatermark(string sSrcFilePath, string sDstFilePath, string sText1, string sColor1, string sSize1, string sFont1, string sText2, string sColor2, string sSize2, string sFont2, string sBgColor, string sTransparence)
{
System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
Graphics g = Graphics.FromImage(image);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; //文字抗锯齿
g.DrawImage(image, 0, 0, image.Width, image.Height);
Font f1 = new Font(sFont1, float.Parse(sSize1));
Font f2 = new Font(sFont2, float.Parse(sSize2));
Brush brushfortext1 = new SolidBrush(ColorTranslator.FromHtml(sColor1));
Brush brushfortext2 = new SolidBrush(ColorTranslator.FromHtml(sColor2));
Brush brushforbg = new SolidBrush(Color.FromArgb(Convert.ToInt16(255 * float.Parse(sTransparence)), ColorTranslator.FromHtml(sBgColor)));
g.RotateTransform(-20);
Rectangle rect = new Rectangle(-image.Width/2-50, image.Height - 50, image.Width * 2, 40);
g.DrawRectangle(new Pen(brushforbg), rect);
g.FillRectangle(brushforbg, rect);
Rectangle rectfortext1 = new Rectangle(-image.Width/2 + image.Width / 5, image.Height - 45, image.Width * 2, 60);
for (int i = 0; i < 10; i++)
g.DrawString(sText1, f1, brushfortext1, rectfortext1);
Rectangle rectfortext2 = new Rectangle(-image.Width / 2 + image.Width / 5, image.Height -25, image.Width * 2, 60);
for (int i = 0; i < 10; i++)
g.DrawString(sText2, f2, brushfortext2, rectfortext2);
image.Save(sDstFilePath, ImageFormat.Jpeg);
image.Dispose();

}

public static void CreateRoundedCorner(string sSrcFilePath, string sDstFilePath, string sCornerLocation)
{
System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
Graphics g = Graphics.FromImage(image);
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);
GraphicsPath rectPath = CreateRoundRectanglePath(rect, image.Width / 10, sCornerLocation); //构建圆角外部路径
Brush b = new SolidBrush(Color.White);//圆角背景白色
g.DrawPath(new Pen(b), rectPath);
g.FillPath(b, rectPath);
g.Dispose();
image.Save(sDstFilePath, ImageFormat.Jpeg);
image.Dispose();
}

public static void CreatePlainText(string sSrcFilePath, string sDstFilePath,string sText, string sColor, string sSize, string sFont)
{
System.Drawing.Image image = System.Drawing.Image.FromFile(sSrcFilePath);
Graphics g = Graphics.FromImage(image);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
g.DrawImage(image, 0, 0, image.Width, image.Height);
g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias; //文字抗锯齿
Font f = new Font(sFont,float.Parse(sSize));
Brush b = new SolidBrush(ColorTranslator.FromHtml(sColor));
Rectangle rect = new Rectangle(10, 5, image.Width, image.Height); //适当空开一段距离
for (int i = 0; i < 30; i++) //加强亮度
g.DrawString(sText, f, b, rect);
image.Save(sDstFilePath, ImageFormat.Jpeg);
image.Dispose();
}

private static GraphicsPath CreateRoundRectanglePath(Rectangle rect, int radius, string sPosition)
{
GraphicsPath rectPath = new GraphicsPath();
switch (sPosition)
{
case "TopLeft":
{
rectPath.AddArc(rect.Left, rect.Top, radius * 2, radius * 2, 180, 90);
rectPath.AddLine(rect.Left, rect.Top, rect.Left, rect.Top + radius);
break;
}

case "TopRight":
{
rectPath.AddArc(rect.Right - radius * 2, rect.Top, radius * 2, radius * 2, 270, 90);
rectPath.AddLine(rect.Right, rect.Top, rect.Right - radius, rect.Top);
break;
}

case "BottomLeft":
{
rectPath.AddArc(rect.Left, rect.Bottom - radius * 2, radius * 2, radius * 2, 90, 90);
rectPath.AddLine(rect.Left, rect.Bottom - radius, rect.Left, rect.Bottom);
break;
}

case "BottomRight":
{
rectPath.AddArc(rect.Right - radius * 2, rect.Bottom - radius * 2, radius * 2, radius * 2, 0, 90);
rectPath.AddLine(rect.Right - radius, rect.Bottom, rect.Right, rect.Bottom);
break;
}
}
return rectPath;
}
}