Lan*_*ine 1 c# gdi+ resize image
所以我的逻辑存在缺陷,我需要一种更好,更正确的方法来调整c#app中的图像大小
我需要一个类似于这个设置的功能
public void ResizeImageForWeb(string OriginalFile, string NewFile, int MaxWidth, int MaxHeight, int Quality)
{
// Resize Code
}
基本上,我是一个网页设计师,试图编写桌面应用程序.
这是我用来调整用户上传的图像的代码,用于创建缩略图或仅强制执行大小限制.它没有解决图像质量,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;
}
}
我当然不会使用GetThumbnailImage因为它会令人震惊 - 为了获得良好的分辨率而不使用DX或OpenL等,我会使用类似下面的内容(来自我在许多Windows应用程序中使用的图形库 - 我已经分享了一些之前的时间因此可能存在浮在网周围的变体).这里有3种方法 - GetNonIndexedPixelFormat方法用于在传递无法处理的像素格式时停止GDI崩溃(注释解释).第一个允许缩放因子(缩放),最后一个允许固定大小重新缩放,同时保持纵横比(但如果你想改变它,可以很容易地修改).请享用:
/// <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;
}