Gridview 读取数据库图片并 改变大小

本例是model使用LINQ写的，数据库SQLserver，解决了数据库累心转换的麻烦问题。同时，通过函数的调用，使得数据库图片读取之后，可以虽数据值的改变，按着比例改变图片的大小。数据库的存储是，图片上传之后，使用二进制存储。感谢abe的指导和帮助。

LINQ 的model

 

        private Binary _image;
        [Column(Storage = "_image", DbType = "varbinary")]
        public Binary image
        {
            get
            {
                return this._image;
            }
            set 
            {
                this._image = value;
            }
        }

 

DAL层数据的读取。通过产品的分类。读取相应的产品。

 

        /// <summary>
        /// Get all the products by classify
        /// </summary>
        /// <param name="classify"></param>
        /// <returns></returns>
        public List<Products> GetSomeCProducts(string classify )
        {
            var pspInfo = from u in db.Products
                          where u.classification == classify
                          orderby u.lastMTime
                          select u;
            return pspInfo.ToList<Products>();
        }

 

Gridview前台代码的设置。没什么好讲的。模板列的使用大家都很熟悉。

 

<asp:GridView ID ="productsList" runat ="server" AllowPaging = "true" AutoGenerateColumns = "false" 
SkinID = "GridView" OnRowDataBound = "List_RowDataBound" OnPageIndexChanging = "List_PageIndexChanging">
<Columns>
        <asp:ImageField DataImageUrlField="filename" 
            HeaderText="图片">
        </asp:ImageField>
        <asp:TemplateField HeaderText="图片">
            <ItemTemplate>
                <asp:Image ID="Image1"  runat="server" />
            </ItemTemplate>
                    
                </Columns>
</asp:GridView>

 

后台代码简要说明一下。由于数据库是存储的二进制，而Gridview的机制是使用ImageUrl才能读取，所以我们必须读取出来，存到一个缓存中，然后把缓存的URL给Gridview才能够显示图片。。。。CreateImage是把二进制的转换成Image格式，而下面的那个函数是，对图片自定义大小和背景颜色而后显示。因为图片大小不一定能满足你原有的比例，裁剪之后不一定合适，最后有背景颜色进行填充最好。。最后一个函数是Gridview的分页。

 private void InitProductsList()
        {
            string prodInfo = string.Empty;
            //分类的名称。和数据库里面的classify对应。
            prodInfo = "psp";
            BLOProducts blp = new BLOProducts();
            productsList.DataSource = blp.GetProInfo(prodInfo);
            productsList.DataBind();
        }
        /// <summary>
        /// DataBound
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void List_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                string prodInfo = string.Empty;
                if (e.Row.RowIndex < 0)
                    return;
                
                string strPersonName = (string)DataBinder.Eval(e.Row.DataItem, "filename");
                
                System.Web.UI.WebControls.Image tmp_Image = (System.Web.UI.WebControls.Image)e.Row.Cells[2].FindControl("Image1");
                if (!System.Convert.IsDBNull(DataBinder.Eval(e.Row.DataItem, "image")))
                {
                    
                    byte[] photo = (DataBinder.Eval(e.Row.DataItem, "image") as Binary).ToArray();
                    
                    System.Drawing.Image img = CreateImage(photo);
                    System.Drawing.Image aPhoto = CreateThumb(img, 60, 60, Color.Purple);


                    string strPath = "~/images/" + strPersonName.Trim() + ".JPG";
                    string strPhotoPath = Server.MapPath(strPath);
                    //保存图片文件
                    aPhoto.Save(strPhotoPath);
                    tmp_Image.ImageUrl = strPath;
                }    

            }
        }
        protected System.Drawing.Image CreateImage(Byte[] pBytes)
        {
            MemoryStream aStream = new MemoryStream(pBytes);
            System.Drawing.Image rImg = System.Drawing.Image.FromStream(aStream);
            aStream.Close();
            return rImg;
        }

        protected System.Drawing.Image CreateThumb(System.Drawing.Image pSource, int pWidth, int pHeight, Color pBkColor)
        {
            int aWidth = pSource.Width;
            int aHeight = pSource.Height;

            double xScale = (aWidth * 1.0) / pWidth;
            double yScale = (aHeight * 1.0) / pHeight;
            double mScale = xScale;
            bool fitX = true;
            if (yScale > xScale)
            {
                mScale = yScale;
                fitX = false;
            }
            int offset = 0;
            if (fitX)
                offset = (int)(pHeight - aHeight / mScale) / 2;
            else
                offset = (int)(pWidth - aWidth / mScale) / 2;

            int rWidth = (int)(aWidth / mScale);
            int rHeight = (int)(aHeight / mScale);

            System.Drawing.Image rImg = new Bitmap(pWidth, pHeight);
            Graphics aGC = Graphics.FromImage(rImg);
            aGC.Clear(pBkColor);
            if (fitX)
            {
                int x = 0;
                int y = offset;
                aGC.DrawImage(pSource, x, y, rWidth, rHeight);
            }
            else
            {
                int x = offset;
                int y = 0;
                aGC.DrawImage(pSource, x, y, rWidth, rHeight);
            }
            return rImg;
        }
        /// <summary>
        /// PageChanging
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void List_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            productsList.PageIndex = e.NewPageIndex;
            InitProductsList();
        }