所以我的逻辑是有缺陷的,我需要一个更好的和正确的方式在我的C#应用程序来调整图像C#GDI +图片缩放功能
我需要类似于此设置函数
public void ResizeImageForWeb(string OriginalFile, string NewFile, int MaxWidth, int MaxHeight, int Quality)
{
// Resize Code
}
基本上,我是一名网页设计师,无法尝试编写桌面应用程序。
所以我的逻辑是有缺陷的,我需要一个更好的和正确的方式在我的C#应用程序来调整图像C#GDI +图片缩放功能
我需要类似于此设置函数
public void ResizeImageForWeb(string OriginalFile, string NewFile, int MaxWidth, int MaxHeight, int Quality)
{
// Resize Code
}
基本上,我是一名网页设计师,无法尝试编写桌面应用程序。
这是我用来调整图像大小的代码,用户上传的图像可能会创建缩略图或者只是为了强制执行大小限制。它不涉及图像质量,但它是一个开始。
// uses System.Drawing namespace
public class ImageResizer
{
public bool ResizeImage(string fullFileName, int maxHeight, int maxWidth)
{
return this.ResizeImage(fullFileName, maxHeight, maxWidth, fullFileName);
}
public bool ResizeImage(string fullFileName, int maxHeight, int maxWidth, string newFileName)
{
using (Image originalImage = Image.FromFile(fullFileName))
{
int height = originalImage.Height;
int width = originalImage.Width;
int newHeight = maxHeight;
int newWidth = maxWidth;
if (height > maxHeight || width > maxWidth)
{
if (height > maxHeight)
{
newHeight = maxHeight;
float temp = ((float)width/(float)height) * (float)maxHeight;
newWidth = Convert.ToInt32(temp);
height = newHeight;
width = newWidth;
}
if (width > maxWidth)
{
newWidth = maxWidth;
float temp = ((float)height/(float)width) * (float)maxWidth;
newHeight = Convert.ToInt32(temp);
}
Image.GetThumbnailImageAbort abort = new Image.GetThumbnailImageAbort(ThumbnailCallback);
using (Image resizedImage = originalImage.GetThumbnailImage(newWidth, newHeight, abort, System.IntPtr.Zero))
{
resizedImage.Save(newFileName);
}
return true;
}
else if (fullFileName != newFileName)
{
// no resizing necessary, but need to create new file
originalImage.Save(newFileName);
}
}
return false;
}
private bool ThumbnailCallback()
{
return false;
}
}
当它只有800像素宽,任何方式来缩小一个1.8 MB的图像为1MB的图像文件的大小? – Landmine 2010-05-18 23:17:18
也许看看其他重载的Save方法 http://msdn.microsoft.com/en-us/library/8ex6sdew(v=VS.100).aspx http://msdn.microsoft.com/en-us /library/ytz20d80(v=VS.100).aspx – 2010-05-18 23:28:30
图片质量很糟糕!调整大小很好,但不能使用这个。 – Landmine 2010-05-19 00:10:21
使用Graphics.DrawImage()。 GetThumbnailImage()将从jpeg文件返回一个120x120(或更小)的嵌入缩略图。对于超过这个尺寸的任何东西将是可怕的。
请参阅http://nathanaeljones.com/163/20-image-resizing-pitfalls/以了解适用的设置。
我肯定不会使用GetThumbnailImage,因为它会令人震惊 - 对于不使用DX或OpenL等的良好分辨率,我会使用类似下面的内容(从我自己的图形库中,我用在许多Windows应用程序 - 我有之前共享过几次,所以可能会有变体浮在网上)。这里有3个方法 - GetNonIndexedPixelFormat方法用于在传递的像素格式无法处理时阻止GDI崩溃(注释解释它)。第一个允许缩放一个因子(缩放),最后一个允许固定尺寸缩放,同时保持纵横比(但如果您想改变它的话,可以很容易地修改)。享受:
/// <summary>
/// Scale Image By A Percentage - Scale Factor between 0 and 1.
/// </summary>
/// <param name="originalImg">Image: Image to scale</param>
/// <param name="ZoomFactor">Float: Sclae Value - 0 to 1 are the usual values</param>
/// <returns>Image: Scaled Image</returns>
public static Image ScaleByPercent(Image originalImg, float ZoomFactor)
{
int destWidth = (int)((float)originalImg.Width * ZoomFactor);
int destHeight = (int)((float)originalImg.Height * ZoomFactor);
Bitmap bmPhoto = new Bitmap(destWidth, destHeight, GetNonIndexedPixelFormat(originalImg)); // PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(originalImg.HorizontalResolution, originalImg.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(originalImg,
new Rectangle(0, 0, destWidth, destHeight),
new Rectangle(0, 0, originalImg.Width, originalImg.Height),
GraphicsUnit.Pixel);
grPhoto.Dispose();
return bmPhoto;
}
/// <summary>
/// Gets the closest non-indexed pixel format
/// </summary>
/// <param name="originalImage">Image: Original image</param>
/// <returns>PixelFormat: Closest non-pixel image format</returns>
public static PixelFormat GetNonIndexedPixelFormat(Image originalImage)
{
/*
* These formats cause an error when creating a GDI Graphics Oblect, so must be converted to non Indexed
* Error is "A graphics object cannot be created from an image that has an indexed pixel format"
*
PixelFormat.Undefined
PixelFormat.DontCare
PixelFormat.1bppIndexed
PixelFormat.4bppIndexed
PixelFormat.8bppIndexed
PixelFormat.16bppGrayScale
PixelFormat.16bppARGB1555
*
* An attempt is made to use the closest (i.e. smallest fitting) format that will hold the palette.
*/
switch (originalImage.PixelFormat)
{
case PixelFormat.Undefined:
//This is also the same Enumation as PixelFormat.DontCare:
return PixelFormat.Format24bppRgb;
case PixelFormat.Format1bppIndexed:
return PixelFormat.Format16bppRgb555;
case PixelFormat.Format4bppIndexed:
return PixelFormat.Format16bppRgb555;
case PixelFormat.Format8bppIndexed:
return PixelFormat.Format16bppRgb555;
case PixelFormat.Format16bppGrayScale:
return PixelFormat.Format16bppArgb1555;
case PixelFormat.Format32bppArgb:
return PixelFormat.Format24bppRgb;
default:
return originalImage.PixelFormat;
}
}
/// <summary>
/// Resize image keeping aspect ratio.
/// </summary>
/// <param name="originalImg">Image: Image to scale</param>
/// <param name="Width">Int: Required width in pixels</param>
/// <param name="Height">Int: Required height in pixels</param>
/// <param name="BackgroundColour">Color: Background colour</param>
/// <returns>Image: Scaled Image</returns>
public static Image Resize(Image originalImg, int Width, int Height, Color BackgroundColour)
{
int destX = 0;
int destY = 0;
float nPercent = 0f;
float nPercentW = ((float)Width/(float)originalImg.Width);
float nPercentH = ((float)Height/(float)originalImg.Height);
if (nPercentH < nPercentW)
{
nPercent = nPercentH;
destX = System.Convert.ToInt16(((float)Width - ((float)originalImg.Width * nPercent))/2f);
}
else
{
nPercent = nPercentW;
destY = System.Convert.ToInt16(((float)Height - ((float)originalImg.Height * nPercent))/2f);
}
int destWidth = (int)(originalImg.Width * nPercent);
int destHeight = (int)(originalImg.Height * nPercent);
Bitmap bmPhoto = new Bitmap(Width, Height, GetNonIndexedPixelFormat(originalImg)); // PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(originalImg.HorizontalResolution, originalImg.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.Clear(BackgroundColour);
grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(originalImg,
new Rectangle(destX, destY, destWidth, destHeight),
new Rectangle(0, 0, originalImg.Width, originalImg.Height), GraphicsUnit.Pixel);
grPhoto.Dispose();
return bmPhoto;
}
+1用于报告此处的代码,而不链接到可能随时间过期的外部资源。事实上,接受的答案中的链接不再起作用。 谢谢。 – vaitrafra 2016-09-24 13:40:22
什么是'int Quality'? – SLaks 2010-05-18 23:10:29
图像质量,1到100如何压缩jpg – Landmine 2010-05-18 23:15:39
请注意,您问的是使用C#编写的GDI +调整大小函数,而不是C#调整大小函数。 – 2010-05-18 23:29:08