于是,只能自己动手了。微信朋友圈的缩略图片也是这样的模式,处理方法不同。
先看看效果图:
前端测试的布局:
- <div style="background-color:#7eb8ba;">
- 原图:<asp:Image ID="imgtest" runat="server" ImageUrl="~/ee.jpg" Height="700" />
- 裁剪后:<asp:Image ID="Image1" runat="server" />
- </div>
- <ul>
- <li>原图宽度:<asp:TextBox ID="TextBox8" runat="server"></asp:TextBox></li>
- <li>原图高度:<asp:TextBox ID="TextBox9" runat="server"></asp:TextBox></li>
- <li>缩放后宽度:<asp:TextBox ID="TextBox10" runat="server"></asp:TextBox></li>
- <li>缩放后高度:<asp:TextBox ID="TextBox11" runat="server"></asp:TextBox></li>
- <li>x轴移位:<asp:TextBox ID="TextBox12" runat="server"></asp:TextBox></li>
- <li>裁剪后图片路径:<asp:TextBox ID="TextBox13" runat="server"></asp:TextBox></li>
- <li><asp:Button ID="TextBox7" runat="server" Text="裁剪图片" OnClick="TextBox7_Click"></asp:Button></li>
- </ul>
后端代码:
- protected void TextBox7_Click(object sender, EventArgs e)
- {
- System.IO.FileStream file = System.IO.File.Open("E:/Project/Test/Web/ee.jpg", System.IO.FileMode.Open);//原图暂时固定路径的
- System.IO.Stream strea = file;
- MakeSmallImg(strea, "E:/Project/Test/Web/1.jpg", 200, 200);//生成后的缩略图也固定路径的
- file.Close();
- }
- /// <summary>
- /// 生成缩略图
- /// 对于宽高不同的情况,从中间部分裁剪
- ///注:缩略图大小控制在模版区域内
- /// </summary>
- /// <param name="fromFileStream">源图文件流</param>
- /// <param name="fileSaveUrl">缩略图存放地址</param>
- /// <param name="templateWidth">缩略图的宽度</param>
- /// <param name="templateHeight">缩略图的高度</param>
- private void MakeSmallImg(System.IO.Stream fromFileStream, string fileSaveUrl, System.Double templateWidth, System.Double templateHeight)
- {
- //从文件取得图片对象,并使用流中嵌入的颜色管理信息
- System.Drawing.Image myImage = System.Drawing.Image.FromStream(fromFileStream, true);
- TextBox8.Text = myImage.Width.ToString();
- TextBox9.Text = myImage.Height.ToString();
- //缩略图宽、高
- System.Double newWidth = myImage.Width, newHeight = myImage.Height;
- //宽度大于高度的横图 ,以宽度为准,这样才能裁剪中间部分
- int x = 0, y = 0;
- if (myImage.Width >= myImage.Height)
- {
- if (myImage.Width > templateWidth)//仅处理缩小的情况
- {
- //高按模版,宽按比例缩放
- //原高度除以新高度,得到缩小的比例,新宽度乘以比例,得到新图片应该的宽度,(老宽度-新宽度)/2,得到应该移位的宽度
- x = Convert.ToInt32(myImage.Width - templateWidth * (myImage.Height / templateHeight)) / 2;
- newHeight = templateHeight;
- newWidth = myImage.Width * (newHeight / myImage.Height);
- TextBox10.Text = newWidth.ToString();//测试用,可删除
- TextBox11.Text = newHeight.ToString();//测试用,可删除
- TextBox12.Text = x.ToString();//测试用,可删除
- }
- }
- //高大于模版的竖图
- else
- {
- if (myImage.Height > templateHeight)//仅处理缩小的情况
- {
- //宽按模版,高按比例缩放
- y = Convert.ToInt32(myImage.Height - templateHeight * (myImage.Width / templateWidth)) / 2;
- newWidth = templateWidth;
- newHeight = (newWidth * myImage.Height) / myImage.Width;
- TextBox10.Text = newWidth.ToString();//测试用,可删除
- TextBox11.Text = newHeight.ToString();//测试用,可删除
- TextBox12.Text = x.ToString();//测试用,可删除
- }
- }
- //新建一个bmp图片
- System.Drawing.Image bitmap = new System.Drawing.Bitmap((int)templateWidth, (int)templateHeight);
- //新建一个画板
- System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
- //设置高质量插值法
- g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
- //设置高质量,低速度呈现平滑程度
- g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
- //清空一下画布
- g.Clear(Color.White);
- //在指定位置画图
- g.DrawImage(myImage, new System.Drawing.Rectangle(0, 0, (int)newWidth, (int)newHeight),
- new System.Drawing.Rectangle(x,y, myImage.Width, myImage.Height),//这是移位,保证裁剪的是图片的中间部分
- System.Drawing.GraphicsUnit.Pixel);
- //文字水印
- //System.Drawing.Graphics G=System.Drawing.Graphics.FromImage(bitmap);
- //System.Drawing.Font f=new Font("宋体",10);
- //System.Drawing.Brush b=new SolidBrush(Color.Black);
- //G.DrawString("abc",f,b,10,10);
- //G.Dispose();
- ///图片水印
- //System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath("pic/1.gif"));
- //Graphics a = Graphics.FromImage(bitmap);
- //a.DrawImage(copyImage, new Rectangle(bitmap.Width-copyImage.Width,bitmap.Height-copyImage.Height,copyImage.Width, copyImage.Height),0,0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
- //copyImage.Dispose();
- //a.Dispose();
- //copyImage.Dispose();
- //保存缩略图
- bitmap.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
- TextBox13.Text = fileSaveUrl;//测试用,可删除
- Image1.ImageUrl = "1.jpg";//测试用,可删除
- g.Dispose();
- myImage.Dispose();
- bitmap.Dispose();
- }