/// <summary>
/// 生成普通缩略图
/// </summary>
/// <param name="sourceFile"> 源图的路径(含文件名及扩展名) </param>
/// <param name="destFile"> 生成的缩略图所保存的路径(含文件名及扩展名)</param>
/// <param name="width"> 欲生成的缩略图的宽度(像素值) </param>
/// <param name="height"> 欲生成的缩略图的高度(像素值) </param>
private static bool GenThumbnail(string sourceFile, string destFile, int width, int height)
{
System.Drawing.Image imageFrom = null;
Bitmap bmp = null;
Graphics g = null;
try
{
imageFrom = System.Drawing.Image.FromFile(sourceFile);
// 源图宽度及高度
int imageFromWidth = imageFrom.Width;
int imageFromHeight = imageFrom.Height;
// 根据源图及欲生成的缩略图尺寸,计算缩略图的实际尺寸及其在"画布"上的位置
if (imageFromWidth > imageFromHeight)
{
height = imageFromHeight * width / imageFromWidth;
}
else
{
width = imageFromWidth * height / imageFromHeight;
}
// 创建画布
bmp = new Bitmap(width, height);
g = Graphics.FromImage(bmp);
// 用白色清空
g.Clear(Color.White);
// 指定高质量的双三次插值法。执行预筛选以确保高质量的收缩。此模式可产生质量最高的转换图像。
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
// 指定高质量、低速度呈现。
g.SmoothingMode = SmoothingMode.HighQuality;
// 在指定位置并且按指定大小绘制指定的 Image 的指定部分。
g.DrawImage(imageFrom, new Rectangle(0, 0, width, height), new Rectangle(0, 0, imageFromWidth, imageFromHeight), GraphicsUnit.Pixel);
string destPath = Path.GetDirectoryName(destFile);
if (!string.IsNullOrWhiteSpace(destPath))
{
if (!Directory.Exists(destPath))
{
Directory.CreateDirectory(destPath);
}
}
//经测试 .jpg 格式缩略图大小与质量等最优
bmp.Save(destFile, ImageFormat.Jpeg);
return(true);
}
catch (Exception ex)
{
throw new Exception("从" + sourceFile + "生成缩略图到" + destFile + "出现异常:" + ex);
}
finally
{
//显示释放资源
imageFrom.DisposeIfNotNull();
g.DisposeIfNotNull();
bmp.DisposeIfNotNull();
}
}
/// <summary>
/// 给图片添加文字水印
/// </summary>
/// <param name="srcFile">源图片存放路径</param>
/// <param name="destFile">目标图片存放路径</param>
/// <param name="fontSize">字号，可超过72号的</param>
/// <param name="throwException">出现异常时是否抛出</param>
/// <param name="text">要添加的文字</param>
public static bool AddWatermarkText(string srcFile, string destFile, int fontSize, string text)
{
if (string.IsNullOrWhiteSpace(srcFile) || string.IsNullOrWhiteSpace(destFile))
{
throw new Exception("源图或目标图片的存放路径都不能为空");
}
System.Drawing.Image img = null;
Graphics picture = null;
Font crFont = null;
StringFormat StrFormat = new StringFormat();
SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0));
SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));
try
{
img = System.Drawing.Image.FromFile(srcFile);
picture = Graphics.FromImage(img);
SizeF crSize = new SizeF();
crFont = new Font("arial", fontSize, FontStyle.Bold);
crSize = picture.MeasureString(text, crFont);
float xpos = 0;
float ypos = 0;
xpos = (img.Width - crSize.Width) / 2;
ypos = (img.Height - crSize.Height) / 2;
StrFormat.Alignment = StringAlignment.Near;
picture.DrawString(text, crFont, semiTransBrush2, xpos + 1, ypos + 1, StrFormat);
picture.DrawString(text, crFont, semiTransBrush, xpos, ypos, StrFormat);
string destPath = Path.GetDirectoryName(destFile);
if (!string.IsNullOrWhiteSpace(destPath))
{
if (!Directory.Exists(destPath))
{
Directory.CreateDirectory(destPath);
}
}
img.Save(destFile);
return(true);
}
catch (Exception ex)
{
throw new Exception("给图片添加水印时发生异常：" + ex);
}
finally
{
crFont.DisposeIfNotNull();
StrFormat.DisposeIfNotNull();
semiTransBrush2.DisposeIfNotNull();
semiTransBrush.DisposeIfNotNull();
picture.DisposeIfNotNull();
img.DisposeIfNotNull();
}
}
/// <summary>
/// 生成PNG缩略图
/// </summary>
/// <param name="sourceFile"></param>
/// <param name="destFile"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <returns></returns>
private static bool PngThumbnail(string sourceFile, string destFile, int width, int height)
{
System.Drawing.Image.GetThumbnailImageAbort myCallBack = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallBack);//提供一个回调方法，用于决定获取缩略图的方法在何时提前取消执行。
Bitmap bmp = null;
System.Drawing.Image thumbnail = null;
try
{
bmp = new Bitmap(sourceFile);
if (bmp.Width > bmp.Height)//计算等比例缩放的宽高，原图中2者中较大的值来计算
{
height = bmp.Height * width / bmp.Width;
}
else
{
width = bmp.Width * height / bmp.Height;
}
thumbnail = bmp.GetThumbnailImage(width, height, myCallBack, IntPtr.Zero);//检索图片中是否包含缩略图，如果不包含，就按比例缩放来生成一个缩略图。
string destPath = Path.GetDirectoryName(destFile);
if (!string.IsNullOrWhiteSpace(destPath))
{
if (!Directory.Exists(destPath))
{
Directory.CreateDirectory(destPath);
}
}
thumbnail.Save(destFile);//将图像保存到指定path中。
return(true);
}
catch (Exception ex)
{
throw new Exception("生成PNG缩略图时发生异常：" + ex);
}
finally
{
bmp.DisposeIfNotNull();
thumbnail.DisposeIfNotNull();
}
}
