利用GDI+可以很方便的制作带水印效果的图片，网上介绍这方面的文章也很多，但鲜有Delphi的，本文参照网上文章http://www.codeproject.com/KB/GDI-plus/watermark.aspx介绍的方法，用Delphi 2007制作水印效果图片，原代码如下：

unit Main;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, Gdiplus, StdCtrls;

type

TMainForm = class(TForm)

Button1: TButton;

procedure FormPaint(Sender: TObject);

procedure FormCreate(Sender: TObject);

procedure FormDestroy(Sender: TObject);

procedure Button1Click(Sender: TObject);

private

{ Private declarations }

Phot TGpImage;

PhWidth: Integer;

PhHeight: Integer;

Watermark: TGpImage;

WmWidth: Integer;

WmHeight: Integer;

Bmp: TGpBitmap;

public

{ Public declarations }

end;

var

MainForm: TMainForm;

implementation

uses GdipTypes;

{$R *.dfm}

procedure TMainForm.Button1Click(Sender: TObject);

var

Clsid: TGUID;

Parameters: TEncoderParameters;

Quality: Integer;

begin

// 设置图像品质编码参数

Parameters.Count := 1;

Parameters.Parameter[0].Guid := EncoderQuality;

Parameters.Parameter[0].ValueType := EncoderParameterValueTypeLong;

Parameters.Parameter[0].NumberOfValues := 1;

// 设置参数的值：品质等级，最高为100，图像文件大小与品质成正比

Quality := 100;

Parameters.Parameter[0].Value := @Quality;

if GetEncoderClsid('image/jpeg', Clsid) then

Bmp.Save('WatermarkPhoto.jpg', Clsid, @Parameters);

end;

procedure TMainForm.FormCreate(Sender: TObject);

const

ColorMatrix: TColorMatrix =

(

(1.0, 0.0, 0.0, 0.0, 0.0),

(0.0, 1.0, 0.0, 0.0, 0.0),

(0.0, 0.0, 1.0, 0.0, 0.0),

(0.0, 0.0, 0.0, 0.3, 0.0),

(0.0, 0.0, 0.0, 0.0, 1.0)

);

WorkingDirectory = '....Media';

copyright = 'Copyright © 2008 - Maozefa';

var

gp: TGpGraphics;

imageAttr: TGpImageAttributes;

strFormat: TGpStringFormat;

font: TGpFont;

x, y: Single;

begin

// 读取原始图片

Photo := TGpImage.Create(WorkingDirectory + '100_0349.jpg');

PhWidth := Photo.Width;

PhHeight := Photo.Height;

// 读取水印图片

Watermark := TGpImage.Create(WorkingDirectory + 'Watermark.bmp');

WmWidth := Watermark.Width;

WmHeight := Watermark.Height;

// 建立一个新的位图，分辨率为72

Bmp := TGpBitmap.Create(PhWidth, PhHeight, pf32bppArgb);

Bmp.SetResolution(72, 72);

// 建立新位图的画布，并设置图像显示质量和文本显示质量

gp := TGpGraphics.Create(Bmp);

gp.SmoothingMode := smAntiAlias;

gp.TextRenderingHint := thAntiAlias;

// 在画布上画原始图片

gp.DrawImage(Photo, GpRect(0, 0, PhWidth, PhHeight),

0, 0, PhWidth, PhHeight, utPixel);

// 建立图像显示辅助类

imageAttr := TGpImageAttributes.Create;

// 设置透明颜色为水印图片四角的底色，水印图显示为圆角图片

imageAttr.SetColorKey($ff00ff00, $ff00ff00, ctBitmap);

// 设置水印图片不透明度为0.3

imageAttr.SetColorMatrix(ColorMatrix, cfDefault, ctBitmap);

// 在画布左上角画水印图

gp.DrawImage(Watermark, GpRect({PhWidth - WmWidth - }10, 10, WmWidth, WmHeight),

0, 0, WmWidth, WmHeight, utPixel, imageAttr);

// 设置文本字体和显示格式

font := TGpFont.Create('arial', 16, [fsBold]);

strFormat := TGpStringFormat.Create;

strFormat.Alignment := saCenter;

// 在画布下方居中显示阴影文本

x := PhWidth / 2;

y := PhHeight - 26;

gp.DrawString(copyright, font, Brushs[$99000000], x + 1, y + 1, strFormat);

gp.DrawString(copyright, font, Brushs[$99ffffff], x, y, strFormat);

font.Free;

strFormat.Free;

imageAttr.Free;

gp.Free;

end;

procedure TMainForm.FormDestroy(Sender: TObject);

begin

Photo.Free;

Watermark.Free;

Bmp.Free;

end;

procedure TMainForm.FormPaint(Sender: TObject);

var

g: TGpGraphics;

begin

g := TGpGraphics.Create(Canvas.Handle);

// 显示原始图片

g.DrawImage(Photo, 0, 0, PhWidth, PhHeight);

// 显示水印原始图片

g.TranslateTransform(0, PhHeight + 5);

g.DrawImage(Watermark, 0, 0, WmWidth, WmHeight);

// 显示带水印和文本的图像

g.TranslateTransform(PhWidth, -(PhHeight + 5));

g.DrawImage(Bmp, 0, 0, PhWidth, PhHeight);

g.Free;

end;

end.