如何制作上传图片的水印

水印的制作功能分为两大部分：

第一是水印库的管理：包括水印库列表，水印的新建，水印的编辑和水印的删除和激活管理。

第二是上传文件添加水印图片的过程。

首先我们来了解一下水印库的管理功能。

1.设计水印数据库表

增加表：  Watermark

字段列表：

 

WatermarkID： PK ,int, not null

OriginalFile:   nvarchar(100), not null   －－>  该值保存用户上传的图片的原始名称。 

FileName:   nvarchar(100), not null   －－> 以本条记录的ID做为该图片的文件名进而重新命名该文件。

WatermarkFile:   nvarchar(100), not null   －－>  水印图片名字。以guid值命名。

Ｗidth： int, not null

Height:   int, not null

Location: int, not null    －－>  1 － 左上角；  2  － 右上角；  3 － 中间； 4 － 左下角； 5 － 右下角

Spin：int, not null:   存储图片翻转的角度。

Transparency： int, not null: 存储图片的透明度。

CreateDate: datetime, not null

ModifiedDate: datetime, not null

ModifiedByID: int , not null

Active: bit, not null

 

存储过程：

WatermarkList,  WatermarkSelectByWatermarkID, WatermarkInsert, WatermarkUpdate, WatermarkDelete

 

2.新建和编辑水印设置

 

以上功能全部用javascript脚本语言来实现，图片旋转和透明度采用了jquery插件来控制。

 

3.水印库的管理

该部分主要分为水印的激活和删除功能。

 

最后一部分就是上传图片水印的处理。

  Dim ImgSourcePhoto As Image = Image.FromFile(SaveToLocation & NewFileName)
                        Dim WaterFilePath As String = IO.Path.Combine(SWRequestCache.CMSSettings.RootFolderPath, Schoolwires.CMS.WatermarkGallery.WatermarkGallery.AssetPath & WatermarkID & "/" & WatermarkFile)
                        Dim imgWatermark As Image = Image.FromFile(WaterFilePath)

                        If ImgSourcePhoto.Width > imgWatermark.Width AndAlso ImgSourcePhoto.Height > imgWatermark.Height Then
                            Dim phWidth As Integer = ImgSourcePhoto.Width
                            Dim phHeight As Integer = ImgSourcePhoto.Height
                            Dim bmPhoto As Bitmap = New Bitmap(phWidth, phHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb)
                            bmPhoto.SetResolution(ImgSourcePhoto.HorizontalResolution, ImgSourcePhoto.VerticalResolution)
                            Dim grPhoto As Graphics = Graphics.FromImage(bmPhoto)
                            Dim locationArr As ArrayList = GetLocation(Location, ImgSourcePhoto, imgWatermark)
                            grPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High
                            grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality
                            grPhoto.Clear(Color.Transparent)
                            grPhoto.DrawImage(ImgSourcePhoto, New Rectangle(0, 0, phWidth, phHeight), 0, 0, phWidth, phHeight, GraphicsUnit.Pixel)

                            Dim bmWatermark As Bitmap = New Bitmap(bmPhoto)
                            bmWatermark.SetResolution(ImgSourcePhoto.HorizontalResolution, ImgSourcePhoto.VerticalResolution)
                            Dim grWatermark As Graphics = Graphics.FromImage(bmWatermark)
                            Dim imageAttributes As ImageAttributes = New ImageAttributes
                            Dim colorMap As ColorMap = New ColorMap
                            colorMap.OldColor = Color.FromArgb(255, 0, 255, 0)
                            colorMap.NewColor = Color.FromArgb(0, 0, 0, 0)
                            Dim remapTable() As ColorMap = {colorMap}
                            imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap)

                            Dim colorMatrixElements()() As Single = {New Single() {1.0F, 0.0F, 0.0F, 0.0F, 0.0F}, New Single() {0.0F, 1.0F, 0.0F, 0.0F, 0.0F}, New Single() {0.0F, 0.0F, 1.0F, 0.0F, 0.0F}, New Single() {0.0F, 0.0F, 0.0F, 0.5F, 0.0F}, New Single() {0.0F, 0.0F, 0.0F, 0.0F, 1.0F}}
                            Dim wmColorMatrix As ColorMatrix = New ColorMatrix(colorMatrixElements)
                            imageAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap)
                            Dim arrLocation As ArrayList = GetLocation(Location, ImgSourcePhoto, imgWatermark)
                            grWatermark.DrawImage(imgWatermark, New Rectangle(CInt(arrLocation(0)), CInt(arrLocation(1)), wmWidth, wmHeight), 0, 0, wmWidth, wmHeight, GraphicsUnit.Pixel, imageAttributes)

                            ImgSourcePhoto.Dispose()
                            ImgSourcePhoto = bmWatermark
                            grPhoto.Dispose()
                            grWatermark.Dispose()
                            ImgSourcePhoto.Save(SaveToLocation & NewFileName)
                            ImgSourcePhoto.Dispose()
                            bmWatermark = Nothing
                        Else
                            ImgSourcePhoto.Dispose()
                        End If

这样，水印就贴上去了，中间下面就是水印了。