我有这个代码，我怎么能让它接受所有典型的图像格式?Png, jpeg, jpg, gif ?
以下是我目前所了解到的:
public void EncryptFile()
{
OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
dialog.InitialDirectory = @"C:\";
dialog.Title = "Please select an image file to encrypt.";
if (dialog.ShowDialog() == DialogResult.OK)
{
//Encrypt the selected file. I'll do this later. :)
}
}
注意，过滤器被设置为.txt文件。我可以更改为PNG，但其他类型呢?
当前回答
从文档中，你需要的过滤器语法如下:
Office Files|*.doc;*.xls;*.ppt
例如，图像文件|*.jpg;*.jpeg;*.png;....
其他回答
对于图像，您可以从GDI (System.Drawing)获得可用的编解码器，并通过一些工作来构建您的列表。这将是最灵活的方式。
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
这是极端的，但是我使用名为FILE_TYPES的2列数据库表构建了一个动态的、数据库驱动的过滤器，字段名为EXTENSION和DOCTYPE:
---------------------------------
| EXTENSION | DOCTYPE |
---------------------------------
| .doc | Document |
| .docx | Document |
| .pdf | Document |
| ... | ... |
| .bmp | Image |
| .jpg | Image |
| ... | ... |
---------------------------------
显然，我有许多不同的类型和扩展，但在本例中我将其简化。这是我的函数:
private static string GetUploadFilter()
{
// Desired format:
// "Document files (*.doc, *.docx, *.pdf)|*.doc;*.docx;*.pdf|"
// "Image files (*.bmp, *.jpg)|*.bmp;*.jpg|"
string filter = String.Empty;
string nameFilter = String.Empty;
string extFilter = String.Empty;
// Used to get extensions
DataTable dt = new DataTable();
dt = DataLayer.Get_DataTable("SELECT * FROM FILE_TYPES ORDER BY EXTENSION");
// Used to cycle through doctype groupings ("Images", "Documents", etc.)
DataTable dtDocTypes = new DataTable();
dtDocTypes = DataLayer.Get_DataTable("SELECT DISTINCT DOCTYPE FROM FILE_TYPES ORDER BY DOCTYPE");
// For each doctype grouping...
foreach (DataRow drDocType in dtDocTypes.Rows)
{
nameFilter = drDocType["DOCTYPE"].ToString() + " files (";
// ... add its associated extensions
foreach (DataRow dr in dt.Rows)
{
if (dr["DOCTYPE"].ToString() == drDocType["DOCTYPE"].ToString())
{
nameFilter += "*" + dr["EXTENSION"].ToString() + ", ";
extFilter += "*" + dr["EXTENSION"].ToString() + ";";
}
}
// Remove endings put in place in case there was another to add, and end them with pipe characters:
nameFilter = nameFilter.TrimEnd(' ').TrimEnd(',');
nameFilter += ")|";
extFilter = extFilter.TrimEnd(';');
extFilter += "|";
// Add the name and its extensions to our main filter
filter += nameFilter + extFilter;
extFilter = ""; // clear it for next round; nameFilter will be reset to the next DOCTYPE on next pass
}
filter = filter.TrimEnd('|');
return filter;
}
private void UploadFile(string fileType, object sender)
{
Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
string filter = GetUploadFilter();
dlg.Filter = filter;
if (dlg.ShowDialog().Value == true)
{
string fileName = dlg.FileName;
System.IO.FileStream fs = System.IO.File.OpenRead(fileName);
byte[] array = new byte[fs.Length];
// This will give you just the filename
fileName = fileName.Split('\\')[fileName.Split('\\').Length - 1];
...
应该生成如下所示的过滤器:
写出应用程序需要的类型。(ref FileDialog.Filter)。以下是最常见的图像格式。
private static string GetImageFilter()
{
return
"All Files (*.*)|*.*" +
"|All Pictures (*.emf;*.wmf;*.jpg;*.jpeg;*.jfif;*.jpe;*.png;*.bmp;*.dib;*.rle;*.gif;*.emz;*.wmz;*.tif;*.tiff;*.svg;*.ico)" +
"|*.emf;*.wmf;*.jpg;*.jpeg;*.jfif;*.jpe;*.png;*.bmp;*.dib;*.rle;*.gif;*.emz;*.wmz;*.tif;*.tiff;*.svg;*.ico" +
"|Windows Enhanced Metafile (*.emf)|*.emf" +
"|Windows Metafile (*.wmf)|*.wmf" +
"|JPEG File Interchange Format (*.jpg;*.jpeg;*.jfif;*.jpe)|*.jpg;*.jpeg;*.jfif;*.jpe" +
"|Portable Network Graphics (*.png)|*.png" +
"|Bitmap Image File (*.bmp;*.dib;*.rle)|*.bmp;*.dib;*.rle" +
"|Compressed Windows Enhanced Metafile (*.emz)|*.emz" +
"|Compressed Windows MetaFile (*.wmz)|*.wmz" +
"|Tag Image File Format (*.tif;*.tiff)|*.tif;*.tiff" +
"|Scalable Vector Graphics (*.svg)|*.svg" +
"|Icon (*.ico)|*.ico";
}
示例使用
设置FilterIndex = 2以预选“所有图片”。不要设置openFileDialog。除非你有一个很好的理由。
void OpenImageFile()
{
var openFileDialog = new OpenFileDialog
{
Filter = GetImageFilter(),
FilterIndex = 2,
RestoreDirectory = true
};
DialogResult result = openFileDialog.ShowDialog();
// do something with your file
// bool resultOk = (result == System.Windows.Forms.DialogResult.OK);
// string filePath = openFileDialog.FileName;
// ...
}
使用此方法返回一个与Filter兼容的字符串，该字符串由支持当前系统理解的图像格式的ImageCodecInfo构建。
/// <summary>
/// Get the Filter string for all supported image types.
/// To be used in the FileDialog class Filter Property.
/// </summary>
/// <returns></returns>
public static string GetImageFilter()
{
string imageExtensions = string.Empty;
string separator = "";
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
Dictionary<string, string> imageFilters = new Dictionary<string, string>();
foreach (ImageCodecInfo codec in codecs)
{
imageExtensions = $"{imageExtensions}{separator}{codec.FilenameExtension.ToLower()}";
separator = ";";
imageFilters.Add($"{codec.FormatDescription} files ({codec.FilenameExtension.ToLower()})", codec.FilenameExtension.ToLower());
}
string result = string.Empty;
separator = "";
foreach (KeyValuePair<string, string> filter in imageFilters)
{
result += $"{separator}{filter.Key}|{filter.Value}";
separator = "|";
}
if (!string.IsNullOrEmpty(imageExtensions))
{
result += $"{separator}Image files|{imageExtensions}";
}
return result;
}
结果如下所示:
从文档中，你需要的过滤器语法如下:
Office Files|*.doc;*.xls;*.ppt
例如，图像文件|*.jpg;*.jpeg;*.png;....
