WPF - converting Bitmap to ImageSource

问题:

I need to convert a System.Drawing.Bitmap into System.Windows.Media.ImageSource class in order to bind it into a HeaderImage control of a WizardPage (Extended WPF toolkit). The bitmap is set as a resource of the assembly I write. It is being referenced like that:

     public Bitmap GetBitmap
     {
         get
         {
             Bitmap bitmap = new Bitmap(Resources.my_banner);
             return bitmap;
         }
     }

     public ImageSource HeaderBitmap
     {
         get
         {
             ImageSourceConverter c = new ImageSourceConverter();
             return (ImageSource) c.ConvertFrom(GetBitmap);
         }
     }

The converter was found by me here: http://www.codeproject.com/Questions/621920/How-to-convert-Bitmap-to-ImageSource I get a NullReferenceException at

return (ImageSource) c.ConvertFrom(Resources.my_banner); How can i initialize ImageSource in order to avoid this exception? Or is there another way? I want to use it afterwards like:

        <xctk:WizardPage x:Name="StartPage" Height="500" Width="700"
                     HeaderImage="{Binding HeaderBitmap}" Enter="StartPage_OnEnter"

Thanks in advance for any answers.

回答1:

For others, this works:

    //If you get 'dllimport unknown'-, then add 'using System.Runtime.InteropServices;'
    [DllImport("gdi32.dll", EntryPoint = "DeleteObject")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool DeleteObject([In] IntPtr hObject);

    public ImageSource ImageSourceForBitmap(Bitmap bmp)
    {
        var handle = bmp.GetHbitmap();
        try
        {
            return Imaging.CreateBitmapSourceFromHBitmap(handle, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
        }
        finally { DeleteObject(handle); }               
    }

回答2:

For the benefit of searchers, I created a quick converter based on a this more detailed solution.

No problems so far.

using System;
using System.Drawing;
using System.IO;
using System.Windows.Media.Imaging;

namespace XYZ.Helpers
{
    public class ConvertBitmapToBitmapImage
    {
        /// <summary>
        /// Takes a bitmap and converts it to an image that can be handled by WPF ImageBrush
        /// </summary>
        /// <param name="src">A bitmap image</param>
        /// <returns>The image as a BitmapImage for WPF</returns>
        public BitmapImage Convert(Bitmap src)
        {
            MemoryStream ms = new MemoryStream();
            ((System.Drawing.Bitmap)src).Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
            BitmapImage image = new BitmapImage();
            image.BeginInit();
            ms.Seek(0, SeekOrigin.Begin);
            image.StreamSource = ms;
            image.EndInit();
            return image;
        }
    }
}

回答3:

I do not believe that ImageSourceConverter will convert from a System.Drawing.Bitmap. However, you can use the following:

public static BitmapSource CreateBitmapSourceFromGdiBitmap(Bitmap bitmap)
{
    if (bitmap == null)
        throw new ArgumentNullException("bitmap");

    var rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);

    var bitmapData = bitmap.LockBits(
        rect,
        ImageLockMode.ReadWrite,
        PixelFormat.Format32bppArgb);

    try
    {
        var size = (rect.Width * rect.Height) * 4;

        return BitmapSource.Create(
            bitmap.Width,
            bitmap.Height,
            bitmap.HorizontalResolution,
            bitmap.VerticalResolution,
            PixelFormats.Bgra32,
            null,
            bitmapData.Scan0,
            size,
            bitmapData.Stride);
    }
    finally
    {
        bitmap.UnlockBits(bitmapData);
    }
}

This solution requires the source image to be in Bgra32 format; if you are dealing with other formats, you may need to add a conversion.

回答4:

dethSwatch - Thank you for your answer above! It helped tremendously! After implementing it I was getting the desired behavior but I found I was getting a memory/handle issue in another section of my program. I changed the code as follows, making it a little more verbose and the issue went away. Thank you again!

    [DllImport("gdi32.dll", EntryPoint = "DeleteObject")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool DeleteObject([In] IntPtr hObject);

    public ImageSource ImageSourceForBitmap(Bitmap bmp)
    {
        var handle = bmp.GetHbitmap();
        try
        {
            ImageSource newSource = Imaging.CreateBitmapSourceFromHBitmap(handle, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());

            DeleteObject(handle);
            return newSource;
        }
        catch (Exception ex)
        {
            DeleteObject(handle);
            return null;
        }
    }

回答5:

The simpliest solution for me:

ImageBrush myBrush = new ImageBrush();
var bitmap = System.Drawing.Image.FromFile("pic1.bmp");
Bitmap bitmap = new System.Drawing.Bitmap(image);//it is in the memory now
var bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(bitmap.GetHbitmap(),IntPtr.Zero,Int32Rect.Empty,BitmapSizeOptions.FromEmptyOptions());
myBrush.ImageSource = bitmapSource;
cover.MainGrid.Background = myBrush;
cover.Show();
bitmap.Dispose();