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
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:
其他回答
对于那些不想每次都记住语法的人，这里有一个简单的封装:
public class FileDialogFilter : List<string>
{
public string Explanation { get; }
public FileDialogFilter(string explanation, params string[] extensions)
{
Explanation = explanation;
AddRange(extensions);
}
public string GetFileDialogRepresentation()
{
if (!this.Any())
{
throw new ArgumentException("No file extension is defined.");
}
StringBuilder builder = new StringBuilder();
builder.Append(Explanation);
builder.Append(" (");
builder.Append(String.Join(", ", this));
builder.Append(")");
builder.Append("|");
builder.Append(String.Join(";", this));
return builder.ToString();
}
}
public class FileDialogFilterCollection : List<FileDialogFilter>
{
public string GetFileDialogRepresentation()
{
return String.Join("|", this.Select(filter => filter.GetFileDialogRepresentation()));
}
}
用法:
FileDialogFilter filterImage = new FileDialogFilter("Image Files", "*.jpeg", "*.bmp");
FileDialogFilter filterOffice = new FileDialogFilter("Office Files", "*.doc", "*.xls", "*.ppt");
FileDialogFilterCollection filters = new FileDialogFilterCollection
{
filterImage,
filterOffice
};
OpenFileDialog fileDialog = new OpenFileDialog
{
Filter = filters.GetFileDialogRepresentation()
};
fileDialog.ShowDialog();
只是一个关于使用字符串的necrocomment。Join和LINQ。
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
dlgOpenMockImage.Filter = string.Format("{0}| All image files ({1})|{1}|All files|*",
string.Join("|", codecs.Select(codec =>
string.Format("{0} ({1})|{1}", codec.CodecName, codec.FilenameExtension)).ToArray()),
string.Join(";", codecs.Select(codec => codec.FilenameExtension).ToArray()));
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:
要过滤图像文件，请使用下面的代码示例。
//Create a new instance of openFileDialog
OpenFileDialog res = new OpenFileDialog();
//Filter
res.Filter = "Image Files|*.jpg;*.jpeg;*.png;*.gif;*.tif;...";
//When the user select the file
if (res.ShowDialog() == DialogResult.OK)
{
//Get the file's path
var filePath = res.FileName;
//Do something
....
}
下面是一个ImageCodecInfo建议的例子(在VB中):
Imports System.Drawing.Imaging
...
Dim ofd as new OpenFileDialog()
ofd.Filter = ""
Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders()
Dim sep As String = String.Empty
For Each c As ImageCodecInfo In codecs
Dim codecName As String = c.CodecName.Substring(8).Replace("Codec", "Files").Trim()
ofd.Filter = String.Format("{0}{1}{2} ({3})|{3}", ofd.Filter, sep, codecName, c.FilenameExtension)
sep = "|"
Next
ofd.Filter = String.Format("{0}{1}{2} ({3})|{3}", ofd.Filter, sep, "All Files", "*.*")
它是这样的:
