基本上,我的图像可能很大(高度和宽度都有几千个像素),宽度和高度可能会有很大差异。
我需要做的是以高约500像素的高度和宽度显示这些图像 - 但我想保持这些图像的纵横比完好无损,因此值非常接近。但是我对在原始宽度和高度上使用的计算有点困惑,以使它们达到正确的数字。
有什么想法吗?
答案 0 :(得分:0)
试试这个:
Size original = new Size(5000,4000);
double ratio = (double)original.Height/original.Width;
int resizePercent = 50;
int newWidth = Convert.ToInt32(original.Width*resizePercent/100);
int newHeight = Convert.ToInt32(newWidth * ratio);
Size resized = new Size(newWidth,newHeight);
当然,只需将原始变量设置为图像大小,然后确定调整大小百分比即可。如果你有这样的目标宽度,你可以计算调整大小百分比:
int targetWidth = 500;
int resizePercent = Convert.ToInt32((double)original.Width/targetWidth);
答案 1 :(得分:0)
几周前我遇到了这个问题。查看此文章http://www.4guysfromrolla.com/articles/012203-1.2.aspx
您创建一个通用处理程序(.ashx)来查找图像,调整图像大小并将其返回
以下是我最终使用的内容(您可以动态调整大小):
public void ProcessRequest (HttpContext context) {
TimeSpan refresh = new TimeSpan(168, 0, 0);
HttpContext.Current.Response.Cache.SetExpires(DateTime.Now.Add(refresh));
HttpContext.Current.Response.Cache.SetMaxAge(refresh);
HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.Public);
HttpContext.Current.Response.Cache.SetValidUntilExpires(true);
string dir = HttpContext.Current.Request.QueryString["dir"];
string img = HttpContext.Current.Request.QueryString["img"];
bool force = HttpContext.Current.Request.QueryString["force"] == "yes";
double w = 0;
double h = 0;
string path = null;
Image orig = null;
Image thumb = null;
//make sure we have a directory and image filename
if (string.IsNullOrEmpty(dir))
return;
//make sure that we allow access to that directory, could do some extra sneaky security stuff here if we had to... (only accept a DirectoryID so the user doesn't know the actual path)
switch (dir)
{
case "user":
dir = "assets/images/users";
if (string.IsNullOrEmpty(img) || img == "undefined") img = "0.jpg";
break;
break;
case "icon":
dir = "assets/images/icons";
break;
default:
dir = "assets/images";
break;
}
//make sure that the image filename is just a filename
if (img.IndexOf("/") > -1 | img.IndexOf("\\") > -1)
return;
//make sure the image exists
path = HttpContext.Current.Server.MapPath("~/" + dir + "/" + img);
if (System.IO.File.Exists(path))
{
orig = Image.FromFile(path);
}
else
{
return;
}
//if there is a max width or height
if (double.TryParse(HttpContext.Current.Request.QueryString["w"], out w) | double.TryParse(HttpContext.Current.Request.QueryString["h"], out h))
{
//thumb is the resized image
double s = 1;
if (w > 0 & h > 0)
{
double ratio = h / w;
if (orig.Height / (double)orig.Width > ratio)
{
if (orig.Height > h)
{
if (force)
s = w / (double)orig.Width;
else
s = h / (double)orig.Height;
}
}
else
{
if (orig.Width > w)
{
if (force)
s = h / (double)orig.Height;
else
s = w / (double)orig.Width;
}
}
}
else if (w > 0)
{
if (orig.Width > w)
{
s = w / (double)orig.Width;
}
}
else if (h > 0)
{
if (orig.Height > h)
{
s = h / (double)orig.Height;
}
}
//double flip gets it to lose the embedded thumbnail
//http://www.4guysfromrolla.com/articles/012203-1.2.aspx
orig.RotateFlip(RotateFlipType.Rotate180FlipNone);
orig.RotateFlip(RotateFlipType.Rotate180FlipNone);
thumb = orig.GetThumbnailImage(Convert.ToInt32(orig.Width * s), Convert.ToInt32(orig.Height * s), null, IntPtr.Zero);
if (force && w > 0 & h > 0)
thumb = cropImage(thumb, (int)w, (int)h);
}
else
{
//thumb is the image at it's original size
thumb = orig;
}
HttpContext.Current.Response.ContentType = "image/jpeg";
thumb.Save(HttpContext.Current.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
}
private Image cropImage(Image img, int w, int h)
{
if (w > img.Width && h > img.Height)
return img;
Rectangle cropArea = new Rectangle((img.Width - w) / 2, (img.Height - h) / 2, w, h);
Bitmap bmpImage = new Bitmap(img);
Bitmap bmpCrop = bmpImage.Clone(cropArea, bmpImage.PixelFormat);
return (Image)(bmpCrop);
}
public bool IsReusable {
get {
return false;
}
}