WPF CreateBitmapSourceFromHBitmap（）內存泄漏

Question

我需要逐個像素繪製圖像並將其顯示在WPF中。我試圖通過使用System.Drawing.Bitmap，然後使用CreateBitmapSourceFromHBitmap()爲WPF圖像控件創建BitmapSource來做到這一點。我有一個內存泄漏的地方，因爲當重複調用CreateBitmapSourceFromBitmap()時，內存使用量會增加，直到應用程序結束纔會停止。如果我不打電話CreateBitmapSourceFromBitmap()內存使用情況沒有明顯變化。

for (int i = 0; i < 100; i++) 
{ 
    var bmp = new System.Drawing.Bitmap(1000, 1000); 
    var source = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
     bmp.GetHbitmap(), IntPtr.Zero, Int32Rect.Empty, 
     System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions()); 
    source = null; 
    bmp.Dispose(); 
    bmp = null; 
} 

我該怎麼做才能釋放BitmapSource內存？

Answer 1

MSDN聲明：對於Bitmap.GetHbitmap()：您負責調用GDI DeleteObject方法釋放GDI位圖對象使用的內存。因此使用下面的代碼：

// at class level 
[System.Runtime.InteropServices.DllImport("gdi32.dll")] 
public static extern bool DeleteObject(IntPtr hObject); 

// your code 
using (System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(1000, 1000)) 
{ 
    IntPtr hBitmap = bmp.GetHbitmap(); 

    try 
    { 
     var source = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions()); 
    } 
    finally 
    { 
     DeleteObject(hBitmap); 
    } 
} 

我也由一個using語句替換您的通話Dispose()。

Answer 2

每當與非託管處理處理它可以是一個好主意，用「安全處理」包裝：

public class SafeHBitmapHandle : SafeHandleZeroOrMinusOneIsInvalid 
{ 
    [SecurityCritical] 
    public SafeHBitmapHandle(IntPtr preexistingHandle, bool ownsHandle) 
     : base(ownsHandle) 
    { 
     SetHandle(preexistingHandle); 
    } 

    protected override bool ReleaseHandle() 
    { 
     return GdiNative.DeleteObject(handle) > 0; 
    } 
} 

構建一個像這樣只要你表面的句柄（理想情況下你的API永遠不會暴露的IntPtr ，他們總是返回安全把手）：

IntPtr hbitmap = bitmap.GetHbitmap(); 
var handle = new SafeHBitmapHandle(hbitmap , true); 

並使用它像這樣：

using (handle) 
{ 
    ... Imaging.CreateBitmapSourceFromHBitmap(handle.DangerousGetHandle(), ...) 
} 

SafeHandle基礎爲您提供自動一次性/終結器模式，您只需重寫ReleaseHandle方法即可。

Answer 3

我有相同的要求和問題（內存泄漏）。我實現了與標記爲答案相同的解決方案。但是，儘管解決方案有效，但它對性能造成了令人難以接受的衝擊。運行在i7上，我的測試應用程序看到一個穩定的30-40％的CPU，200-400MB的RAM增加，垃圾收集器運行幾乎每毫秒。

由於我在做視頻處理，我需要更好的性能。我想出了以下內容，所以我想分享一下。

可重複使用的全局對象

//set up your Bitmap and WritableBitmap as you see fit 
Bitmap colorBitmap = new Bitmap(..); 
WriteableBitmap colorWB = new WriteableBitmap(..); 

//choose appropriate bytes as per your pixel format, I'll cheat here an just pick 4 
int bytesPerPixel = 4; 

//rectangles will be used to identify what bits change 
Rectangle colorBitmapRectangle = new Rectangle(0, 0, colorBitmap.Width, colorBitmap.Height); 
Int32Rect colorBitmapInt32Rect = new Int32Rect(0, 0, colorWB.PixelWidth, colorWB.PixelHeight); 

轉換碼

private void ConvertBitmapToWritableBitmap() 
{ 
    BitmapData data = colorBitmap.LockBits(colorBitmapRectangle, ImageLockMode.WriteOnly, colorBitmap.PixelFormat); 

    colorWB.WritePixels(colorBitmapInt32Rect, data.Scan0, data.Width * data.Height * bytesPerPixel, data.Stride); 

    colorBitmap.UnlockBits(data); 
} 

實施例

//do stuff to your bitmap 
ConvertBitmapToWritableBitmap(); 
Image.Source = colorWB; 

結果是一個穩定的10-13％CPU，70-150MB RAM，垃圾收集器只在6分鐘內運行兩次。

Answer 4

這是一篇很棒的貼子，雖然有了所有的意見和建議，但花了我一個小時才弄清楚這些作品。所以這裏是一個調用來獲得帶有SafeHandles的BitMapSource，然後用它來創建一個.PNG圖像文件的例子。最底層是「使用」和一些參考文獻。當然，沒有一個信用是我的，我只是抄寫員。

private static BitmapSource CopyScreen() 
{ 
    var left = Screen.AllScreens.Min(screen => screen.Bounds.X); 
    var top = Screen.AllScreens.Min(screen => screen.Bounds.Y); 
    var right = Screen.AllScreens.Max(screen => screen.Bounds.X + screen.Bounds.Width); 
    var bottom = Screen.AllScreens.Max(screen => screen.Bounds.Y + screen.Bounds.Height); 
    var width = right - left; 
    var height = bottom - top; 

    using (var screenBmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb)) 
    { 
     BitmapSource bms = null; 

     using (var bmpGraphics = Graphics.FromImage(screenBmp)) 
     { 
      IntPtr hBitmap = new IntPtr(); 
      var handleBitmap = new SafeHBitmapHandle(hBitmap, true); 

      try 
      { 
       bmpGraphics.CopyFromScreen(left, top, 0, 0, new System.Drawing.Size(width, height)); 

       hBitmap = screenBmp.GetHbitmap(); 

       using (handleBitmap) 
       { 
        bms = Imaging.CreateBitmapSourceFromHBitmap(
         hBitmap, 
         IntPtr.Zero, 
         Int32Rect.Empty, 
         BitmapSizeOptions.FromEmptyOptions()); 

       } // using 

       return bms; 
      } 
      catch (Exception ex) 
      { 
       throw new ApplicationException($"Cannot CopyFromScreen. Err={ex}"); 
      } 

     } // using bmpGraphics 
    } // using screen bitmap 
} // method CopyScreen 

這裏是使用，也是 「安全處理」 類：

private void buttonTestScreenCapture_Click(object sender, EventArgs e) 
{ 
    try 
    { 
     BitmapSource bms = CopyScreen(); 
     BitmapFrame bmf = BitmapFrame.Create(bms); 

     PngBitmapEncoder encoder = new PngBitmapEncoder(); 
     encoder.Frames.Add(bmf); 

     string filepath = @"e:\(test)\test.png"; 
     using (Stream stm = File.Create(filepath)) 
     { 
      encoder.Save(stm); 
     } 
    } 
    catch (Exception ex) 
    { 
     MessageBox.Show($"Err={ex}"); 
    } 
} 

public class SafeHBitmapHandle : SafeHandleZeroOrMinusOneIsInvalid 
{ 
    [System.Runtime.InteropServices.DllImport("gdi32.dll")] 
    public static extern int DeleteObject(IntPtr hObject); 

    [SecurityCritical] 
    public SafeHBitmapHandle(IntPtr preexistingHandle, bool ownsHandle) 
     : base(ownsHandle) 
    { 
     SetHandle(preexistingHandle); 
    } 

    protected override bool ReleaseHandle() 
    { 
     return DeleteObject(handle) > 0; 
    } 
} 

最後看看我的 'usings'：

using System; 
using System.Linq; 
using System.Drawing; 
using System.Windows.Forms; 
using System.Windows.Media.Imaging; 
using System.Windows.Interop; 
using System.Windows; 
using System.IO; 
using Microsoft.Win32.SafeHandles; 
using System.Security; 

的DLL文件引用包括： * PresentationCore * System.Core * System.Deployment * System.Drawing * Windo wsBase