如何在C＃中创建图像的多个图像缩略图。
条件：
1.图像质量不应该影响。
2.缩略图大小应该不相同。
答案 0 :(得分：1)
如果您使用的是asp.net mvc，那么您可以尝试内置的WebImage类。更多信息可以在这里找到：http://msdn.microsoft.com/en-us/library/system.web.helpers.webimage(v=vs.111).aspx
为了更专业的使用，你想要控制一切，你可以使用：http://imageresizing.net/这个套件非常先进，具有很多图像大小调整功能。
还有很多选项可用于编写自己的代码，可以在此处找到一个示例：http://www.codeproject.com/Articles/191424/Resizing-an-Image-On-The-Fly-using-NET
我的建议是：“不要试图再次发明轮子”，那里有很多好的解决方案。
希望这可以帮助你。
答案 1 :(得分：0)
using System.ComponentModel;
using System.Web.UI;
/// <summary>
/// An abstract ImageFilter class.
/// </summary>
public abstract class ImageFilter
{
/// <summary>
/// Processes the image with current filter.
/// </summary>
/// <param name="image">The image to process.</param>
/// <returns>Returns a Image after applying current filter.</returns>
public abstract System.Drawing.Image Process(System.Drawing.Image image);
/// <summary>
/// Returns a <see cref="System.String"/> that represents this instance.
/// </summary>
/// <returns>
/// A <see cref="System.String"/> that represents this instance.
/// </returns>
public override string ToString()
{
return "Image Filter";
}
}
public class ResizeFilter : ImageFilter
{
private int x = -1;
private int y = -1;
private int height;
private int width;
private InterpolationMode interpolationMode = InterpolationMode.Bicubic;
private ResizeMode resizeMode = ResizeMode.Fit;
[DefaultValue(-1)]
[Category("Behavior")]
public int X
{
get
{
return this.x;
}
set
{
if (value < 0)
{
value = -1;
}
x = value;
}
}
[DefaultValue(-1)]
[Category("Behavior")]
public int Y
{
get
{
return this.y;
}
set
{
if (value < -1)
{
value = -1;
}
y = value;
}
}
/// <summary>
/// Gets or sets a value indicating whether disable transparency.
/// </summary>
/// <value>
/// <see langword="true"/> if disable transparency; otherwise, <see langword="false"/>.
/// </value>
/// <author>Anwar</author>
/// <datetime>3/4/2011 5:37 PM</datetime>
[DefaultValue(false), Category("Behavior")]
public bool DisableTransparency { get; set; }
/// <summary>
/// Gets or sets the maximum height of the resulting image.
/// </summary>
/// <value>The height of the resulting image.</value>
[DefaultValue(0)]
[Category("Behavior")]
public int Height
{
get
{
return this.height;
}
set
{
CheckValue(value);
this.height = value;
}
}
/// <summary>
/// Gets or sets the interpolation mode used for resizing images. The default is HighQualityBicubic.
/// </summary>
/// <value>The interpolation mode.</value>
[DefaultValue(InterpolationMode.HighQualityBicubic)]
[Category("Behavior")]
public InterpolationMode InterpolationMode
{
get { return this.interpolationMode; }
set { this.interpolationMode = value; }
}
/// <summary>
/// Gets or sets the resize mode. The default value is Fit.
/// </summary>
/// <value>The image resize mode.</value>
[DefaultValue(ResizeMode.Fit)]
[Category("Behavior")]
public ResizeMode ResizeMode
{
get { return this.resizeMode; }
set { this.resizeMode = value; }
}
/// <summary>
/// Gets or sets the maximum width of the resulting image.
/// </summary>
/// <value>The width of the image..</value>
[DefaultValue(0)]
[Category("Behavior")]
public int Width
{
get
{
return this.width;
}
set
{
CheckValue(value);
this.width = value;
}
}
/// <summary>
/// Processes the image with current filter.
/// </summary>
/// <param name="image">The image to process.</param>
/// <returns>Returns a Image after applying current filter.</returns>
public override Image Process(Image image)
{
int scaledHeight = (int)(image.Height * (this.Width / (float)image.Width));
int scaledWidth = (int)(image.Width * (this.Height / (float)image.Height));
switch (this.ResizeMode)
{
case ResizeMode.Fit:
return this.FitImage(image, scaledHeight, scaledWidth);
case ResizeMode.Crop:
return this.CropImage(image, scaledHeight, scaledWidth);
default:
Debug.Fail("Should not reach this");
break;
}
return null;
}
/// <summary>
/// Returns a <see cref="System.String"/> that represents this instance.
/// </summary>
/// <returns>
/// A <see cref="System.String"/> that represents this instance.
/// </returns>
public override string ToString()
{
return "Resize Filter";
}
private static void CheckValue(int value)
{
if (value < 0)
{
throw new ArgumentOutOfRangeException("value");
}
}
private Image CropImage(Image img, int scaledHeight, int scaledWidth)
{
int resizeWidth;
int resizeHeight;
if (this.Width != 0 && this.Height != 0)
{
resizeWidth = this.Width;
resizeHeight = this.Height;
}
else if (this.Height == 0)
{
resizeWidth = this.Width;
resizeHeight = scaledHeight;
}
else if (this.Width == 0)
{
resizeWidth = scaledWidth;
resizeHeight = this.Height;
}
else
{
if (this.Width / (float)img.Width > this.Height / (float)img.Height)
{
resizeWidth = this.Width;
resizeHeight = scaledHeight;
}
else
{
resizeWidth = scaledWidth;
resizeHeight = this.Height;
}
}
Bitmap newImage = new Bitmap(this.Width, this.Height);
using (Graphics graphics = Graphics.FromImage(newImage))
{
this.SetupGraphics(graphics);
if (this.DisableTransparency)
{
graphics.FillRectangle(new SolidBrush(Color.White), 0, 0, resizeWidth, resizeHeight);
}
int srcX = this.X;
int srcY = this.Y;
if (srcX == -1)
{
srcX = (this.Width - resizeWidth) / 2;
}
if (srcY == -1)
{
srcY = (this.Height - resizeHeight) / 2;
}
graphics.DrawImage(img, new Rectangle(0, 0, resizeWidth, resizeHeight), srcX, srcY, resizeWidth, resizeHeight, GraphicsUnit.Pixel);
}
return newImage;
}
private Image FitImage(Image img, int scaledHeight, int scaledWidth)
{
int resizeWidth;
int resizeHeight;
if (this.Width != 0 && this.Height != 0)
{
resizeWidth = this.Width;
resizeHeight = this.Height;
}
else if (this.Height == 0)
{
resizeWidth = this.Width;
resizeHeight = scaledHeight;
}
else if (this.Width == 0)
{
resizeWidth = scaledWidth;
resizeHeight = this.Height;
}
else
{
if (this.Width / (float)img.Width < this.Height / (float)img.Height)
{
resizeWidth = this.Width;
resizeHeight = scaledHeight;
}
else
{
resizeWidth = scaledWidth;
resizeHeight = this.Height;
}
}
Bitmap newimage = new Bitmap(resizeWidth, resizeHeight);
using (Graphics gra = Graphics.FromImage(newimage))
{
if (DisableTransparency)
{
gra.FillRectangle(new SolidBrush(Color.White), 0, 0, resizeWidth, resizeHeight);
}
this.SetupGraphics(gra);
gra.DrawImage(img, 0, 0, resizeWidth, resizeHeight);
}
return newimage;
}
private void SetupGraphics(Graphics graphics)
{
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighSpeed;
graphics.InterpolationMode = this.InterpolationMode;
}
}
////Seprate this enum in your different class ResizeMode.cs
/// <summary>
/// Image Resize Modes.
/// </summary>
public enum ResizeMode
{
/// <summary>
/// Fit mode maintains the aspect ratio of the original image while ensuring that the dimensions of the result
/// do not exceed the maximum values for the resize transformation.
/// </summary>
Fit,
/// <summary>
/// Crop resizes the image and removes parts of it to ensure that the dimensions of the result are exactly
/// as specified by the transformation.
/// </summary>
Crop
}
///Your Controller Code
public class HomeController : Controller
{
//
// GET: /Home/
public ActionResult Index()
{
return View();
}
[HttpPost]
public ActionResult ImportImage()
{
var postedFile = Request.Files["FileUpload1"];
if (postedFile != null && postedFile.ContentLength > 0 )
{
MemoryStream ms=new MemoryStream();
postedFile.InputStream.CopyTo(ms);
Image image=new Bitmap(ms);
Guid newImageName=Guid.NewGuid();
string newNameToImage = newImageName.ToString() + Path.GetExtension(postedFile.FileName);
ResizeFilter resizeFilter=new ResizeFilter {Height = 0, Width = 75};
using (Image thumbnailImage = resizeFilter.Process(image))
{
var imagePath = Path.Combine(Server.MapPath("~/Content/Images"), newNameToImage);
thumbnailImage.Save(imagePath);
}
resizeFilter.Width = 350;
resizeFilter.Height = 0;
newImageName = Guid.NewGuid();
newNameToImage = newImageName.ToString() + Path.GetExtension(postedFile.FileName);
using (Image middleImage = resizeFilter.Process(image))
{
var imagePath = Path.Combine(Server.MapPath("~/Content/Images"), newNameToImage);
middleImage.Save(imagePath);
}
}
return RedirectToAction("Index");
}
}
///View Coding
@{
ViewBag.Title = "Index";
}
@using (Html.BeginForm("ImportImage", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
<input type="file" name="FileUpload1" id="FileUpload1" />
<input type="submit" id="submit" />
}