C# 图像处理（图像缩放、屏幕截取、图像合并、保存图像）

# region 图像处理功能函数

/// <summary>
/// 按指定尺寸对图像pic进行非拉伸缩放
/// </summary>
public static Bitmap shrinkTo(Image pic, Size S, Boolean cutting)
{
//创建图像
Bitmap tmp = new Bitmap(S.Width, S.Height); //按指定大小创建位图

//绘制
Graphics g = Graphics.FromImage(tmp); //从位图创建Graphics对象
g.Clear(Color.FromArgb(0, 0, 0, 0)); //清空

Boolean mode = (float)pic.Width / S.Width > (float)pic.Height / S.Height; //zoom缩放
if (cutting) mode = !mode; //裁切缩放

//计算Zoom绘制区域
if (mode)
S.Height = (int)((float)pic.Height * S.Width / pic.Width);
else
S.Width = (int)((float)pic.Width * S.Height / pic.Height);
Point P = new Point((tmp.Width - S.Width) / 2, (tmp.Height - S.Height) / 2);

g.DrawImage(pic, new Rectangle(P, S));

return tmp; //返回构建的新图像
}

[DllImport("user32.dll")]
static extern bool GetCursorInfo(out CURSORINFO pci);

private const Int32 CURSOR_SHOWING = 0x00000001;
[StructLayout(LayoutKind.Sequential)]
struct POINT
{
public Int32 x;
public Int32 y;
}

[StructLayout(LayoutKind.Sequential)]
struct CURSORINFO
{
public Int32 cbSize;
public Int32 flags;
public IntPtr hCursor;
public POINT ptScreenPos;
}

/// <summary>
/// 截取屏幕指定区域为Image，保存到路径savePath下，haveCursor是否包含鼠标
/// </summary>
public static Image getScreen(int x=0, int y=0, int width=-1, int height=-1, String savePath="", bool haveCursor = true)
{
if (width == -1) width = SystemInformation.VirtualScreen.Width;
if (height == -1) height = SystemInformation.VirtualScreen.Height;

Bitmap tmp = new Bitmap(width, height); //按指定大小创建位图
Graphics g = Graphics.FromImage(tmp); //从位图创建Graphics对象
g.CopyFromScreen(x, y, 0, 0, new Size(width, height)); //绘制

// 绘制鼠标
if (haveCursor)
{
CURSORINFO pci;
pci.cbSize = Marshal.SizeOf(typeof(CURSORINFO));
GetCursorInfo(out pci);
System.Windows.Forms.Cursor cur = new System.Windows.Forms.Cursor(pci.hCursor);
cur.Draw(g, new Rectangle(pci.ptScreenPos.x, pci.ptScreenPos.y, cur.Size.Width, cur.Size.Height));
}

if (!savePath.Equals("")) saveIcon(tmp, tmp.Size, savePath); // 保存到指定的路径下

return tmp; //返回构建的新图像
}

//在图像pic上添加logo
public static Bitmap SetLogo(Image pic, Image logo)
{
//创建图像
Bitmap tmp = new Bitmap(pic.Width, pic.Height);//按指定大小创建位图

//绘制
Graphics g = Graphics.FromImage(tmp); //从位图创建Graphics对象
g.Clear(Color.FromArgb(0, 0, 0, 0)); //清空

g.DrawImage(pic, 0, 0); //从pic的给定区域进行绘制
g.DrawImage(logo, 0, 0); //为图像添加logo

return tmp; //返回构建的新图像
}

//保存图像pic到文件fileName中，指定图像保存格式
public static void SaveToFile(Image pic, string fileName, bool replace, ImageFormat format) //ImageFormat.Jpeg
{
//若图像已存在，则删除
if (System.IO.File.Exists(fileName) && replace)
System.IO.File.Delete(fileName);

//若不存在则创建
if (!System.IO.File.Exists(fileName))
{
if (format == null) format = getFormat(fileName); //根据拓展名获取图像的对应存储类型

if (format == ImageFormat.MemoryBmp) pic.Save(fileName);
else pic.Save(fileName, format); //按给定格式保存图像
}
}

//根据文件拓展名，获取对应的存储类型
public static ImageFormat getFormat(string filePath)
{
ImageFormat format = ImageFormat.MemoryBmp;
String Ext = System.IO.Path.GetExtension(filePath).ToLower();

if (Ext.Equals(".png")) format = ImageFormat.Png;
else if (Ext.Equals(".jpg") || Ext.Equals(".jpeg")) format = ImageFormat.Jpeg;
else if (Ext.Equals(".bmp")) format = ImageFormat.Bmp;
else if (Ext.Equals(".gif")) format = ImageFormat.Gif;
else if (Ext.Equals(".ico")) format = ImageFormat.Icon;
else if (Ext.Equals(".emf")) format = ImageFormat.Emf;
else if (Ext.Equals(".exif")) format = ImageFormat.Exif;
else if (Ext.Equals(".tiff")) format = ImageFormat.Tiff;
else if (Ext.Equals(".wmf")) format = ImageFormat.Wmf;
else if (Ext.Equals(".memorybmp")) format = ImageFormat.MemoryBmp;

return format;
}

# endregion