WPF - Load Font from Stream?

问题

I have a MemoryStream with the contents of a Font File (.ttf) and I would like to be able to create a FontFamily WPF object from that stream WITHOUT writing the contents of the stream to disk. I know this is possible with a System.Drawing.FontFamily but I cannot find out how to do it with System.Windows.Media.FontFamily.

Note: I will only have the stream, so I can't pack it as a resource in the application and because of disk permissions issues, will not be able to write the font file to disk for reference as "content"

UPDATE:

The API docs how describe how an application resource can be used, though it is not clear to me whether that is an Embedded resource in the assembly or a file on disk.

You can use a base URI value when you reference a font that is packaged as part of the application. For example, the base URI value can be a "pack://application" URI, which lets you reference fonts that are packaged as application resources. The following code example shows a font reference that is composed of a base URI value and a relative URI value.

回答1:

The best approach I could think of, was to save the oldFont to a temp directory, and immediately load it using the newFont constructor that accepts a uri.

回答2:

There is a similar question here, which contains a supposed solution by converting a System.Drawing.FontFamily to a WPF font family, all in memory without any file IO:

public static void Load(MemoryStream stream)
{
    byte[] streamData = new byte[stream.Length];
    stream.Read(streamData, 0, streamData.Length);
    IntPtr data = Marshal.AllocCoTaskMem(streamData.Length); // Very important.
    Marshal.Copy(streamData, 0, data, streamData.Length);
    PrivateFontCollection pfc = new PrivateFontCollection();
    pfc.AddMemoryFont(data, streamData.Length);
    MemoryFonts.Add(pfc); // Your own collection of fonts here.
    Marshal.FreeCoTaskMem(data); // Very important.
}

public static System.Windows.Media.FontFamily LoadFont(int fontId)
{
    if (!Exists(fontId))
    {
        return null;
    }
    /*
    NOTE:
    This is basically how you convert a System.Drawing.FontFamily to System.Windows.Media.FontFamily, using PrivateFontCollection.
    */
    return new System.Windows.Media.FontFamily(MemoryFonts[fontId].Families[0].Name);
}

This seems to use the System.Drawing.PrivateFontCollection(^) to add a System.Drawing.Font created from a MemoryStream and then use the Families[0].Name of that font to pass into the System.Windows.Media.FontFamily constructor. I assume the family name would then be a URI to the instance of that font in the PrivateFontCollection but you'd probably have to try it out.

来源：https://stackoverflow.com/questions/44394/wpf-load-font-from-stream

标签

wpf

fonts

stream