entityMap|blocks|key|6i88h|text|你有没有看过MSDN+[this+MSDN+article](http://msdn.microsoft.com/en-us/library/system.drawing.bitmap.aspx)+]|type|unstyled|depth|inlineStyleRanges|entityRanges|data|a9rc3|什么？它描述了Bitmap类，它是一个用于处理由像素数据定义的图像的对象。System.Drawing.Image为它提供了额外的功能。HTH^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|E|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|F|9|@]|A|@]|B|$]]]]

Have you taken a look at <a href="http://msdn.microsoft.com/en-us/library/system.drawing.bitmap.aspx" rel="nofollow">this MSDN article</a>? It describes the Bitmap class, which is an object used to work with images defined by pixel data. System.Drawing.Image provides additional functionality for it. HTH

entityMap|blocks|key|8oa72|text|不是100%25确定您在这里想要什么，但如果您想要使用graphics类进行绘制，然后保存到文件，您必须从Bitmap文件中获取Graphics对象，然后在完成后保存位图。你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|afngl|Bitmap+bitmap+=+new+Bitmap(bWidth,+bHeight);
++Graphics+g+=+Graphics.FromImage(bitmap);
++//do+all+your+operations+on+g+here.
++bitmap.Save(fileName,+imageFormat);|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

Not 100% sure what you want here, but if you want to use the graphics class to draw, and then save to file, you have to obtain the Graphics object from a Bitmap file, and then save the bitmap after you are done. You can do that like this:

<pre><code> Bitmap bitmap = new Bitmap(bWidth, bHeight);
 Graphics g = Graphics.FromImage(bitmap);
 //do all your operations on g here.
 bitmap.Save(fileName, imageFormat);
</code></pre>

entityMap|blocks|key|6ej42|text|我不太确定我是否理解你的要求，因为你的问题很不清楚。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|l35g|如果您想知道如何保存Graphics对象转换为位图，那么答案是没有直接的方法可以做到这一点。在Graphics对象是单向操作。|offset|length|style|CODE|6c8vn|更好的选择是创建一个新的Bitmap对象，则获取一个Graphics对象，并直接在其上绘制。下面的代码是一个示例，说明了如何做到这一点：|blqvu|//+Create+a+new+bitmap+object
using+(Bitmap+bmp+=+new+Bitmap(200,+300))
{
++++//+Obtain+a+Graphics+object+from+that+bitmap
++++using+(Graphics+g+=+Graphics.FromImage(bmp))
++++{
++++++++//+Draw+onto+the+bitmap+here
++++++++//+....
++++++++g.DrawRectangle(Pens.Red,+10,+10,+50,+50);
++++}

++++//+Save+the+bitmap+to+a+file+on+disk,+or+do+whatever+else+with+it
++++//+...
++++bmp.Save("C:\\MyImage.bmp");
}|code-block|syntax|javascript^0|0|A|8|1B|8|0|C|6|Q|8|0^^$0|$]|1|@$2|3|4|5|6|7|8|P|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|Q|9|@$E|R|F|S|G|H]|$E|T|F|U|G|H]]|A|@]|B|$]]|$2|I|4|J|6|7|8|V|9|@$E|W|F|X|G|H]|$E|Y|F|Z|G|H]]|A|@]|B|$]]|$2|K|4|L|6|M|8|10|9|@]|A|@]|B|$N|O]]]]

I'm not really sure if I understand what you're asking for, as your question is very unclear. 

If you want to know how to save the contents of a <code>Graphics</code> object to a bitmap, then the answer is that there's no direct approach for doing so. Drawing on a <code>Graphics</code> object is a one-way operation. 

The better option is to create a new <code>Bitmap</code> object, obtain a <code>Graphics</code> object for that bitmap, and draw directly onto it. The following code is an example of how you might do that:

<pre><code>// Create a new bitmap object
using (Bitmap bmp = new Bitmap(200, 300))
{
 // Obtain a Graphics object from that bitmap
 using (Graphics g = Graphics.FromImage(bmp))
 {
 // Draw onto the bitmap here
 // ....
 g.DrawRectangle(Pens.Red, 10, 10, 50, 50);
 }

 // Save the bitmap to a file on disk, or do whatever else with it
 // ...
 bmp.Save("C:\\MyImage.bmp");
}
</code></pre>

entityMap|blocks|key|a514|text|这段代码适用于我正在转换图像>>位图>>字节>>+Base64字符串的地方。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|elqta|System.Drawing.Image+originalImage+=+//your+image

//Create+empty+bitmap+image+of+original+size

Bitmap+tempBmp+=+new+Bitmap(originalImage.Width,+originalImage.Height);

Graphics+g+=+Graphics.FromImage(tempBmp);

//draw+the+original+image+on+tempBmp

g.DrawImage(originalImage,+0,+0,+originalImage.Width,+originalImage.Height);

//dispose+originalImage+and+Graphics+so+the+file+is+now+free

g.Dispose();

originalImage.Dispose();

using+(MemoryStream+ms+=+new+MemoryStream())
{
++++//+Convert+Image+to+byte[]
++++tempBmp.Save(ms,+System.Drawing.Imaging.ImageFormat.Jpeg);
++++//dpgraphic.image.Save(ms,+System.Drawing.Imaging.ImageFormat.Bmp);
++++byte[]+imageBytes+=+ms.ToArray();

++++//+Convert+byte[]+to+Base64+String
++++string+strImage+=+Convert.ToBase64String(imageBytes);
++++sb.AppendFormat(strImage);
}|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

This code working for me where I am converting image >> bitmap >> byte >> Base64 String.

<pre><code>System.Drawing.Image originalImage = //your image

//Create empty bitmap image of original size

Bitmap tempBmp = new Bitmap(originalImage.Width, originalImage.Height);

Graphics g = Graphics.FromImage(tempBmp);

//draw the original image on tempBmp

g.DrawImage(originalImage, 0, 0, originalImage.Width, originalImage.Height);

//dispose originalImage and Graphics so the file is now free

g.Dispose();

originalImage.Dispose();

using (MemoryStream ms = new MemoryStream())
{
 // Convert Image to byte[]
 tempBmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
 //dpgraphic.image.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
 byte[] imageBytes = ms.ToArray();

 // Convert byte[] to Base64 String
 string strImage = Convert.ToBase64String(imageBytes);
 sb.AppendFormat(strImage);
}
</code></pre>

entityMap|blocks|key|4a6l5|text|你可以得到他的hdc，这是一个指向表面缓冲区的指针，并最终使用bitblt函数将他的内容复制到另一个hdc。这样，您就可以在位图上创建绘图图面的副本。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|788ic|enum+TernaryRasterOperations+:+uint
{
++++///+dest+=+source
++++SRCCOPY+=+0x00CC0020,
++++///+dest+=+source+OR+dest
++++SRCPAINT+=+0x00EE0086,
++++///+dest+=+source+AND+dest
++++SRCAND+=+0x008800C6,
++++///+dest+=+source+XOR+dest
++++SRCINVERT+=+0x00660046,
++++///+dest+=+source+AND+(NOT+dest)
++++SRCERASE+=+0x00440328,
++++///+dest+=+(NOT+source)
++++NOTSRCCOPY+=+0x00330008,
++++///+dest+=+(NOT+src)+AND+(NOT+dest)
++++NOTSRCERASE+=+0x001100A6,
++++///+dest+=+(source+AND+pattern)
++++MERGECOPY+=+0x00C000CA,
++++///+dest+=+(NOT+source)+OR+dest
++++MERGEPAINT+=+0x00BB0226,
++++///+dest+=+pattern
++++PATCOPY+=+0x00F00021,
++++///+dest+=+DPSnoo
++++PATPAINT+=+0x00FB0A09,
++++///+dest+=+pattern+XOR+dest
++++PATINVERT+=+0x005A0049,
++++///+dest+=+(NOT+dest)
++++DSTINVERT+=+0x00550009,
++++///+dest+=+BLACK
++++BLACKNESS+=+0x00000042,
++++///+dest+=+WHITE
++++WHITENESS+=+0x00FF0062,
++++///+
++++///+Capture+window+as+seen+on+screen.++This+includes+layered+windows+
++++///+such+as+WPF+windows+with+AllowsTransparency="true"
++++///+
++++CAPTUREBLT+=+0x40000000
}

[DllImport("gdi32.dll",+EntryPoint+=+"BitBlt",+SetLastError+=+true)]
[return:+MarshalAs(UnmanagedType.Bool)]
static+extern+bool+BitBlt([In]+IntPtr+hdc,+int+nXDest,+int+nYDest,+int+nWidth,+int+nHeight,+[In]+IntPtr+hdcSrc,+int+nXSrc,+int+nYSrc,+TernaryRasterOperations+dwRop);

public+static+Bitmap+CopyGraphicsContent(Graphics+source,+Rectangle+rect)
{
++++Bitmap+bmp+=+new+Bitmap(rect.Width,+rect.Height);

++++using+(Graphics+dest+=+Graphics.FromImage(bmp))
++++{
++++++++IntPtr+hdcSource+=+source.GetHdc();
++++++++IntPtr+hdcDest+=+dest.GetHdc();

++++++++BitBlt(hdcDest,+0,+0,+rect.Width,+rect.Height,+hdcSource,+rect.X,+rect.Y,+TernaryRasterOperations.SRCCOPY);

++++++++source.ReleaseHdc(hdcSource);
++++++++dest.ReleaseHdc(hdcDest);
++++}

++++return+bmp;
}|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

You can get his hdc that's a pointer to the surface buffer, and eventually copy his content to another hdc with bitblt function. This way you can create a copy of the drawing surface on a bitmap.

<pre><code>enum TernaryRasterOperations : uint
{
 /// &lt;summary&gt;dest = source&lt;/summary&gt;
 SRCCOPY = 0x00CC0020,
 /// &lt;summary&gt;dest = source OR dest&lt;/summary&gt;
 SRCPAINT = 0x00EE0086,
 /// &lt;summary&gt;dest = source AND dest&lt;/summary&gt;
 SRCAND = 0x008800C6,
 /// &lt;summary&gt;dest = source XOR dest&lt;/summary&gt;
 SRCINVERT = 0x00660046,
 /// &lt;summary&gt;dest = source AND (NOT dest)&lt;/summary&gt;
 SRCERASE = 0x00440328,
 /// &lt;summary&gt;dest = (NOT source)&lt;/summary&gt;
 NOTSRCCOPY = 0x00330008,
 /// &lt;summary&gt;dest = (NOT src) AND (NOT dest)&lt;/summary&gt;
 NOTSRCERASE = 0x001100A6,
 /// &lt;summary&gt;dest = (source AND pattern)&lt;/summary&gt;
 MERGECOPY = 0x00C000CA,
 /// &lt;summary&gt;dest = (NOT source) OR dest&lt;/summary&gt;
 MERGEPAINT = 0x00BB0226,
 /// &lt;summary&gt;dest = pattern&lt;/summary&gt;
 PATCOPY = 0x00F00021,
 /// &lt;summary&gt;dest = DPSnoo&lt;/summary&gt;
 PATPAINT = 0x00FB0A09,
 /// &lt;summary&gt;dest = pattern XOR dest&lt;/summary&gt;
 PATINVERT = 0x005A0049,
 /// &lt;summary&gt;dest = (NOT dest)&lt;/summary&gt;
 DSTINVERT = 0x00550009,
 /// &lt;summary&gt;dest = BLACK&lt;/summary&gt;
 BLACKNESS = 0x00000042,
 /// &lt;summary&gt;dest = WHITE&lt;/summary&gt;
 WHITENESS = 0x00FF0062,
 /// &lt;summary&gt;
 /// Capture window as seen on screen. This includes layered windows 
 /// such as WPF windows with AllowsTransparency="true"
 /// &lt;/summary&gt;
 CAPTUREBLT = 0x40000000
}

[DllImport("gdi32.dll", EntryPoint = "BitBlt", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool BitBlt([In] IntPtr hdc, int nXDest, int nYDest, int nWidth, int nHeight, [In] IntPtr hdcSrc, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);

public static Bitmap CopyGraphicsContent(Graphics source, Rectangle rect)
{
 Bitmap bmp = new Bitmap(rect.Width, rect.Height);

 using (Graphics dest = Graphics.FromImage(bmp))
 {
 IntPtr hdcSource = source.GetHdc();
 IntPtr hdcDest = dest.GetHdc();

 BitBlt(hdcDest, 0, 0, rect.Width, rect.Height, hdcSource, rect.X, rect.Y, TernaryRasterOperations.SRCCOPY);

 source.ReleaseHdc(hdcSource);
 dest.ReleaseHdc(hdcDest);
 }

 return bmp;
}
</code></pre>

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://docs.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-getobjectw|1|https://docs.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-dibsection|2|https://docs.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapinfoheader|blocks|key|7cock|text|因为9年后没有人回答这个实际问题...|unstyled|depth|inlineStyleRanges|entityRanges|febv4|//+System.Windows.Forms.Internal.IntUnsafeNativeMethods
[DllImport("gdi32.dll",+CharSet+=+CharSet.Auto,+EntryPoint+=+"GetCurrentObject",+ExactSpelling+=+true,+SetLastError+=+true)]
public+static+extern+IntPtr+IntGetCurrentObject(HandleRef+hDC,+int+uObjectType);


IntPtr+hdc+=+graphics.GetHdc();
//+This+is+a+HBITMAP,+which+is+the+actual+buffer+that+is+being+drawn+to+by+hdc.
IntPtr+hbitmap+=+IntGetCurrentObject(new+HandleRef(null,+hdc),+7+/*OBJ_BITMAP*/);
//+You+can+create+a+Gdiplus::Bitmap+object+from+this,+but+it+will+copy+all+image+data.
//Bitmap+bitmap+=+Image.FromHbitmap(hbitmap);
//+To+manipulate+the+actual+bitmap+pixel+data+directly,+see+below.

//+Put+these+in+finally:
//bitmap.Dispose();
//+NOTE:+You+cannot+use+the+graphics+object+before+ReleaseHdc+is+called.
graphics.ReleaseHdc(hdc);|code-block|syntax|javascript|10ol8|要获取实际的位图比特，请执行以下操作，你必须先了解一些关于GDI位图的知识。有所谓的设备相关位图(DDB，或者通常只是API中的“位图”)，以及与设备无关的位图(DIB)。对这种差异的完整解释超出了这个答案的范围。|3m0ar|如果您使用|4s933|this.SetStyle(ControlStyles.OptimizedDoubleBuffer,+true);|offset|length|style|CODE|618kj|中的图形对象OnPaint将使用DIB，否则将使用DDB。|6j1rm|如果你的HBITMAP是一个DDB，您不能直接读/写像素数据(尽管在技术上是可行的，但Windows没有提供这样做的方法)。你必须使用GetDIBits使用特定格式将它们复制到与设备无关的缓冲区，然后SetDIBits把它们复制回去。|40eqe|如果你的HBITMAP是一个DIB，然后您可以获得实际的像素位(作为指针)，并使用以下命令直接在内存中读/写它们`GetObject`(请不要与GetCurrentObject)：|ft5q6|[DllImport("gdi32.dll")]
static+extern+unsafe+int+GetObject(IntPtr+hobj,+int+cb,+void*+data);

[StructLayout(LayoutKind.Sequential)]
unsafe+struct+BITMAP
{
++++int++++++++bmType;
++++int++++++++bmWidth;
++++int++++++++bmHeight;
++++int++++++++bmWidthBytes;
++++ushort+++++bmPlanes;
++++ushort+++++bmBitsPixel;
++++void*++++++bmBits;
}

BITMAP+BitmapDesc+=+new+BITMAP();
GetObject(hbitmap,+sizeof(BITMAP),+&BitmapDesc);|tjo0|BITMAP.bmBits将会是null如果是DDB，那么它将是一个有效的内存地址；如果它是一个DIB，那么它将是一个有效的内存地址。如果您只想复制此数据，可以直接使用bmBits；总长度为bmHeight+*+bmWidthBytes..。|37gec|如果你真的想要操作内存中的像素数据，你需要知道DIB的确切像素格式，以便正确地操作它。像素格式有多种可能(每像素的位数为1/4/8/16/24/32、RGB与BGR、调色板等)。如果你真的想要支持所有的东西，那就需要做大量的工作..。|e8amu|要做到这一点，要知道当被赋予一个HBITMAP、GetObject函数将接受一个BITMAP结构(如上面的代码示例所示)或一个`DIBSECTION`结构。请注意DIBSECTION以一个BITMAP，这使得两个结构兼容。如果HBITMAP是DIB，那么GetObject将填写有效的(非空)bmBits指针，它还将填充DIBSECTION%25s`BITMAPINFOHEADER`结构，然后可以使用它来检查DIB的像素格式。|5isms|检查BITMAPINFOHEADER会很痛苦。^0|0|0|0|0|0|1L|0|6|7|0|4|7|E|3|1V|9|2S|9|0|4|7|E|3|20|G|1K|B|0|0|0|0|D|G|4|2C|6|2N|N|0|0|G|7|O|9|14|6|29|A|2M|6|35|7|3J|9|42|6|4G|A|1R|C|1|4S|I|2|0|2|G^^$0|$1|$2|3|4|5|6|$7|8]]|9|$2|3|4|5|6|$7|A]]|B|$2|3|4|5|6|$7|C]]]|D|@$E|F|G|H|2|I|J|1H|K|@]|L|@]|6|$]]|$E|M|G|N|2|O|J|1I|K|@]|L|@]|6|$P|Q]]|$E|R|G|S|2|I|J|1J|K|@]|L|@]|6|$]]|$E|T|G|U|2|I|J|1K|K|@]|L|@]|6|$]]|$E|V|G|W|2|I|J|1L|K|@$X|1M|Y|1N|Z|10]]|L|@]|6|$]]|$E|11|G|12|2|I|J|1O|K|@$X|1P|Y|1Q|Z|10]]|L|@]|6|$]]|$E|13|G|14|2|I|J|1R|K|@$X|1S|Y|1T|Z|10]|$X|1U|Y|1V|Z|10]|$X|1W|Y|1X|Z|10]|$X|1Y|Y|1Z|Z|10]]|L|@]|6|$]]|$E|15|G|16|2|I|J|20|K|@$X|21|Y|22|Z|10]|$X|23|Y|24|Z|10]|$X|25|Y|26|Z|10]]|L|@$X|27|Y|28|E|29]]|6|$]]|$E|17|G|18|2|O|J|2A|K|@]|L|@]|6|$P|Q]]|$E|19|G|1A|2|I|J|2B|K|@$X|2C|Y|2D|Z|10]|$X|2E|Y|2F|Z|10]|$X|2G|Y|2H|Z|10]|$X|2I|Y|2J|Z|10]]|L|@]|6|$]]|$E|1B|G|1C|2|I|J|2K|K|@]|L|@]|6|$]]|$E|1D|G|1E|2|I|J|2L|K|@$X|2M|Y|2N|Z|10]|$X|2O|Y|2P|Z|10]|$X|2Q|Y|2R|Z|10]|$X|2S|Y|2T|Z|10]|$X|2U|Y|2V|Z|10]|$X|2W|Y|2X|Z|10]|$X|2Y|Y|2Z|Z|10]|$X|30|Y|31|Z|10]|$X|32|Y|33|Z|10]]|L|@$X|34|Y|35|E|36]|$X|37|Y|38|E|39]]|6|$]]|$E|1F|G|1G|2|I|J|3A|K|@$X|3B|Y|3C|Z|10]]|L|@]|6|$]]]]

Since nobody answered the actual question after 9 years...
<pre><code>// System.Windows.Forms.Internal.IntUnsafeNativeMethods
[DllImport(&quot;gdi32.dll&quot;, CharSet = CharSet.Auto, EntryPoint = &quot;GetCurrentObject&quot;, ExactSpelling = true, SetLastError = true)]
public static extern IntPtr IntGetCurrentObject(HandleRef hDC, int uObjectType);


IntPtr hdc = graphics.GetHdc();
// This is a HBITMAP, which is the actual buffer that is being drawn to by hdc.
IntPtr hbitmap = IntGetCurrentObject(new HandleRef(null, hdc), 7 /*OBJ_BITMAP*/);
// You can create a Gdiplus::Bitmap object from this, but it will copy all image data.
//Bitmap bitmap = Image.FromHbitmap(hbitmap);
// To manipulate the actual bitmap pixel data directly, see below.

// Put these in finally:
//bitmap.Dispose();
// NOTE: You cannot use the graphics object before ReleaseHdc is called.
graphics.ReleaseHdc(hdc);
</code></pre>
To get to the actual bitmap bits, you have to know something about GDI bitmaps first. There are so-called device-dependent bitmaps (DDB, or often simply just &quot;Bitmap&quot; in the API), and device-independent bitmaps (DIB). A full explanation of the difference would be out of scope for this answer.
If you use <code>this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);</code>, then the graphics object in <code>OnPaint</code> will use a DIB, otherwise it will use a DDB.
If your <code>HBITMAP</code> is a <code>DDB</code>, you cannot read/write the pixel data directly (even though it's technically possible, Windows exposes no way to do it). You have to use <code>GetDIBits</code> to copy them to a device independent buffer, using a particular format, and then <code>SetDIBits</code> to copy them back.
If your <code>HBITMAP</code> is a <code>DIB</code>, then you can get the actual pixel bits (as a pointer), and read/write them directly in memory using <a href="https://docs.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-getobjectw" rel="nofollow noreferrer"><code>GetObject</code></a> (not to be confused with <code>GetCurrentObject</code>):
<pre><code>[DllImport(&quot;gdi32.dll&quot;)]
static extern unsafe int GetObject(IntPtr hobj, int cb, void* data);

[StructLayout(LayoutKind.Sequential)]
unsafe struct BITMAP
{
 int bmType;
 int bmWidth;
 int bmHeight;
 int bmWidthBytes;
 ushort bmPlanes;
 ushort bmBitsPixel;
 void* bmBits;
}

BITMAP BitmapDesc = new BITMAP();
GetObject(hbitmap, sizeof(BITMAP), &amp;BitmapDesc);
</code></pre>
<code>BITMAP.bmBits</code> will be <code>null</code> if it was a DDB, and it will be a valid memory address if it's a DIB. If you just want to copy this data, you can directly use <code>bmBits</code>; the total length is <code>bmHeight * bmWidthBytes</code>.
If you actually want to manipulate pixel data in memory, you need to know the exact pixel format of the DIB in order to manipulate it correctly. There are many possibilities what the pixel format can be (number of bits per pixel 1/4/8/16/24/32, RGB vs BGR, palettes, etc). It's a lot of work if you really want to support everything.
To do that, know that when being given an <code>HBITMAP</code>, the <code>GetObject</code> function will either accept a <code>BITMAP</code> struct (as shown in the code example above), or a <a href="https://docs.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-dibsection" rel="nofollow noreferrer"><code>DIBSECTION</code></a> struct. Note that <code>DIBSECTION</code> starts with a <code>BITMAP</code>, this makes the two structs compatible. Iff the <code>HBITMAP</code> is a DIB, then <code>GetObject</code> will fill in a valid (non-null) <code>bmBits</code> pointer, and it will also fill in the <code>DIBSECTION</code>'s <a href="https://docs.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapinfoheader" rel="nofollow noreferrer"><code>BITMAPINFOHEADER</code></a> struct, which you can then use to inspect the pixel format of the DIB. Examining the <code>BITMAPINFOHEADER</code> will be painful.

entityMap|blocks|key|7650k|text|到目前为止，@dialer在这个帖子中有最好的答案。作为一个额外的例子，这里是如何从图形或任何硬件到C#中的Emgu.CV+Mat中获取位。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|6c1pu|struct+BITMAP
++++{
++++++++public+Int32+bmType;
++++++++public+Int32+bmWidth;
++++++++public+Int32+bmHeight;
++++++++public+Int32+bmWidthBytes;
++++++++public+Int16+bmPlanes;
++++++++public+Int16+bmBitsPixel;
++++++++public+IntPtr+bmBits;
++++}

++++[StructLayout(LayoutKind.Sequential,+Pack+=+4)]
++++struct+BITMAPINFOHEADER
++++{
++++++++public+int+biSize;
++++++++public+int+biWidth;
++++++++public+int+biHeight;
++++++++public+Int16+biPlanes;
++++++++public+Int16+biBitCount;
++++++++public+int+biCompression;
++++++++public+int+biSizeImage;
++++++++public+int+biXPelsPerMeter;
++++++++public+int+biYPelsPerMeter;
++++++++public+int+biClrUsed;
++++++++public+int+bitClrImportant;
++++}

++++[DllImport("user32.dll",+SetLastError=true)]
++++static+extern+IntPtr+GetDC(IntPtr+hWnd);

++++//+System.Windows.Forms.Internal.IntUnsafeNativeMethods
++++[DllImport("gdi32.dll",+CharSet+=+CharSet.Auto,+EntryPoint+=+"GetCurrentObject",+ExactSpelling+=+true,+SetLastError+=+true)]
++++static+extern+IntPtr+IntGetCurrentObject(HandleRef+hDC,+int+uObjectType);
++++
++++[DllImport("gdi32.dll",+CharSet+=+CharSet.Auto,+EntryPoint+=+"GetObject")]
++++static+extern+int+GetObjectBitmap(IntPtr+hObject,+int+nCount,+ref+BITMAP+lpObject);

++++[DllImport("gdi32.dll",+EntryPoint+=+"GetDIBits")]
++++static+extern+int+GetDIBits(IntPtr+hdc,+IntPtr+hbmp,+int+uStartScan,+int+cScanLines,+
++++++++++++++++++++++++++++++++IntPtr+lpvBits,+ref+BITMAPINFOHEADER+lpbi,+int+uUsage);

++++///+Gets+GDI+HDC+as+an+Emgu.CV.Mat+image+as+BGRA
++++///+GDI+HDC
++++///+Destination+Mat+which+will+receive+the+window+contents+image
++++///+If+TRUE,+pixel+will+be+flipped+vertically
++++///+TRUE+if+image+was+copied+successfully
++++public+static+bool+GetHdcAsMat(IntPtr+hdc,+ref+Mat+destination,+bool+verticalFlip)
++++{
++++++++try
++++++++{
++++++++++++//+This+is+a+HBITMAP,+which+is+the+actual+buffer+that+is+being+drawn+to+by+hdc.
++++++++++++IntPtr+hbitmap+=+IntGetCurrentObject(new+HandleRef(null,+hdc),+7+/*OBJ_BITMAP*/);

++++++++++++//+Get+width,+height+and+the+address+of+the+pixel+data+for+the+native+HBitmap
++++++++++++BITMAP+info+=+new+BITMAP();
++++++++++++if+(0+==+GetObjectBitmap(hbitmap,+Marshal.SizeOf(info),+ref+info))
++++++++++++++++return+false;

++++++++++++//+if+the+image+is+a+DIB,+we+can+copy+the+bits+directly+from+bmBits
++++++++++++if+(info.bmBits+!=+IntPtr.Zero)
++++++++++++{
++++++++++++++++//+data+view+of+the+DIB+bits,+no+allocations
++++++++++++++++Mat+view+=+new+Mat(info.bmHeight,+info.bmWidth,+DepthType.Cv8U,+4,+
+++++++++++++++++++++++++++++++++++info.bmBits,+info.bmWidth+*+4);

++++++++++++++++if+(verticalFlip)+//+copy+flipped:
++++++++++++++++++++CvInvoke.Flip(view,+destination,+FlipType.Vertical);
++++++++++++++++else+//+copy+directly:
++++++++++++++++++++view.CopyTo(destination);+//+automatically+resize+destination
++++++++++++++++return+true;
++++++++++++}

++++++++++++//+otherwise,+use+GetDIBits+to+get+the+bitmap+from+the+GPU
++++++++++++//+a+copy+is+always+needed+to+get+the+data+from+GPU+to+system+memory

++++++++++++if+(destination.Width+!=+info.bmWidth+%7C%7C
++++++++++++++++destination.Height+!=+info.bmHeight)
++++++++++++{
++++++++++++++++destination.Dispose();
++++++++++++++++destination+=+new+Mat(info.bmHeight,+info.bmWidth,+DepthType.Cv8U,+4);
++++++++++++}

++++++++++++var+desired+=+new+BITMAPINFOHEADER();
++++++++++++desired.biSize+=+Marshal.SizeOf(desired);
++++++++++++desired.biWidth+=+info.bmWidth;
++++++++++++desired.biHeight+=+verticalFlip+?+-info.bmHeight+:+info.bmHeight;
++++++++++++desired.biPlanes+=+1;
++++++++++++desired.biBitCount+=+info.bmBitsPixel;

++++++++++++//+Copy+bits+into+destination
++++++++++++IntPtr+dest+=+destination.DataPointer;
++++++++++++return+0+!=+GetDIBits(hdc,+hbitmap,+0,+destination.Height,+dest,+ref+desired,+0);
++++++++}
++++++++catch
++++++++{
++++++++++++return+false;
++++++++}
++++}
++++
++++///+Gets+window+contents+as+an+Emgu.CV.Mat+image+as+BGRA
++++///+Handle+to+desired+window
++++///+Destination+Mat+which+will+receive+the+window+contents+image
++++///+If+TRUE,+pixel+will+be+flipped+vertically
++++///+TRUE+if+image+was+copied+successfully
++++public+static+bool+GetWindowAsMat(IntPtr+hwnd,+ref+Mat+destination,+bool+verticalFlip)
++++{
++++++++IntPtr+hdc+=+GetDC(hwnd);+//+private+DC+does+not+need+to+be+released
++++++++return+GetHdcAsMat(hdc,+ref+destination,+verticalFlip);
++++}

++++///+Gets+GDI+Graphics+contents+as+an+Emgu.CV.Mat+image+as+BGRA
++++///+.NET+GDI+Graphics+instance
++++///+Destination+Mat+which+will+receive+the+window+contents+image
++++///+If+TRUE,+pixel+will+be+flipped+vertically
++++///+TRUE+if+image+was+copied+successfully
++++public+static+bool+GetGraphicsAsMat(Graphics+graphics,+ref+Mat+destination,+bool+verticalFlip)
++++{
++++++++IntPtr+hdc+=+graphics.GetHdc();
++++++++try
++++++++{
++++++++++++return+GetHdcAsMat(hdc,+ref+destination,+verticalFlip);
++++++++}
++++++++finally
++++++++{
++++++++++++//+NOTE:+You+cannot+use+the+graphics+object+before+ReleaseHdc+is+called.
++++++++++++graphics.ReleaseHdc(hdc);
++++++++}
++++}|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

@dialer Has the best answer in this thread so far. As an additional example, here is how to get bits from Graphics or any HWND into Emgu.CV Mat in C#.
<pre><code> struct BITMAP
 {
 public Int32 bmType;
 public Int32 bmWidth;
 public Int32 bmHeight;
 public Int32 bmWidthBytes;
 public Int16 bmPlanes;
 public Int16 bmBitsPixel;
 public IntPtr bmBits;
 }

 [StructLayout(LayoutKind.Sequential, Pack = 4)]
 struct BITMAPINFOHEADER
 {
 public int biSize;
 public int biWidth;
 public int biHeight;
 public Int16 biPlanes;
 public Int16 biBitCount;
 public int biCompression;
 public int biSizeImage;
 public int biXPelsPerMeter;
 public int biYPelsPerMeter;
 public int biClrUsed;
 public int bitClrImportant;
 }

 [DllImport(&quot;user32.dll&quot;, SetLastError=true)]
 static extern IntPtr GetDC(IntPtr hWnd);

 // System.Windows.Forms.Internal.IntUnsafeNativeMethods
 [DllImport(&quot;gdi32.dll&quot;, CharSet = CharSet.Auto, EntryPoint = &quot;GetCurrentObject&quot;, ExactSpelling = true, SetLastError = true)]
 static extern IntPtr IntGetCurrentObject(HandleRef hDC, int uObjectType);
 
 [DllImport(&quot;gdi32.dll&quot;, CharSet = CharSet.Auto, EntryPoint = &quot;GetObject&quot;)]
 static extern int GetObjectBitmap(IntPtr hObject, int nCount, ref BITMAP lpObject);

 [DllImport(&quot;gdi32.dll&quot;, EntryPoint = &quot;GetDIBits&quot;)]
 static extern int GetDIBits(IntPtr hdc, IntPtr hbmp, int uStartScan, int cScanLines, 
 IntPtr lpvBits, ref BITMAPINFOHEADER lpbi, int uUsage);

 /// &lt;summary&gt;Gets GDI HDC as an Emgu.CV.Mat image as BGRA&lt;/summary&gt;
 /// &lt;param name=&quot;hdc&quot;&gt;GDI HDC&lt;/param&gt;
 /// &lt;param name=&quot;destination&quot;&gt;Destination Mat which will receive the window contents image&lt;/param&gt;
 /// &lt;param name=&quot;verticalFlip&quot;&gt;If TRUE, pixel will be flipped vertically&lt;/param&gt;
 /// &lt;returns&gt;TRUE if image was copied successfully&lt;/returns&gt;
 public static bool GetHdcAsMat(IntPtr hdc, ref Mat destination, bool verticalFlip)
 {
 try
 {
 // This is a HBITMAP, which is the actual buffer that is being drawn to by hdc.
 IntPtr hbitmap = IntGetCurrentObject(new HandleRef(null, hdc), 7 /*OBJ_BITMAP*/);

 // Get width, height and the address of the pixel data for the native HBitmap
 BITMAP info = new BITMAP();
 if (0 == GetObjectBitmap(hbitmap, Marshal.SizeOf(info), ref info))
 return false;

 // if the image is a DIB, we can copy the bits directly from bmBits
 if (info.bmBits != IntPtr.Zero)
 {
 // data view of the DIB bits, no allocations
 Mat view = new Mat(info.bmHeight, info.bmWidth, DepthType.Cv8U, 4, 
 info.bmBits, info.bmWidth * 4);

 if (verticalFlip) // copy flipped:
 CvInvoke.Flip(view, destination, FlipType.Vertical);
 else // copy directly:
 view.CopyTo(destination); // automatically resize destination
 return true;
 }

 // otherwise, use GetDIBits to get the bitmap from the GPU
 // a copy is always needed to get the data from GPU to system memory

 if (destination.Width != info.bmWidth ||
 destination.Height != info.bmHeight)
 {
 destination.Dispose();
 destination = new Mat(info.bmHeight, info.bmWidth, DepthType.Cv8U, 4);
 }

 var desired = new BITMAPINFOHEADER();
 desired.biSize = Marshal.SizeOf(desired);
 desired.biWidth = info.bmWidth;
 desired.biHeight = verticalFlip ? -info.bmHeight : info.bmHeight;
 desired.biPlanes = 1;
 desired.biBitCount = info.bmBitsPixel;

 // Copy bits into destination
 IntPtr dest = destination.DataPointer;
 return 0 != GetDIBits(hdc, hbitmap, 0, destination.Height, dest, ref desired, 0);
 }
 catch
 {
 return false;
 }
 }
 
 /// &lt;summary&gt;Gets window contents as an Emgu.CV.Mat image as BGRA&lt;/summary&gt;
 /// &lt;param name=&quot;hwnd&quot;&gt;Handle to desired window&lt;/param&gt;
 /// &lt;param name=&quot;destination&quot;&gt;Destination Mat which will receive the window contents image&lt;/param&gt;
 /// &lt;param name=&quot;verticalFlip&quot;&gt;If TRUE, pixel will be flipped vertically&lt;/param&gt;
 /// &lt;returns&gt;TRUE if image was copied successfully&lt;/returns&gt;
 public static bool GetWindowAsMat(IntPtr hwnd, ref Mat destination, bool verticalFlip)
 {
 IntPtr hdc = GetDC(hwnd); // private DC does not need to be released
 return GetHdcAsMat(hdc, ref destination, verticalFlip);
 }

 /// &lt;summary&gt;Gets GDI Graphics contents as an Emgu.CV.Mat image as BGRA&lt;/summary&gt;
 /// &lt;param name=&quot;graphics&quot;&gt;.NET GDI Graphics instance&lt;/param&gt;
 /// &lt;param name=&quot;destination&quot;&gt;Destination Mat which will receive the window contents image&lt;/param&gt;
 /// &lt;param name=&quot;verticalFlip&quot;&gt;If TRUE, pixel will be flipped vertically&lt;/param&gt;
 /// &lt;returns&gt;TRUE if image was copied successfully&lt;/returns&gt;
 public static bool GetGraphicsAsMat(Graphics graphics, ref Mat destination, bool verticalFlip)
 {
 IntPtr hdc = graphics.GetHdc();
 try
 {
 return GetHdcAsMat(hdc, ref destination, verticalFlip);
 }
 finally
 {
 // NOTE: You cannot use the graphics object before ReleaseHdc is called.
 graphics.ReleaseHdc(hdc);
 }
 }
</code></pre>

I want to know what the intermediate state of the buffer where the Graphics object is drawing some stuff. How do I get hold of the bitmap or the image that it is drawing on?

How to get the bitmap/image from a Graphics object in C#?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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 我想知道Graphics对象正在绘制一些东西的缓冲区的中间状态是什么。如何获取位图或它正在绘制的图像？

问如何在C#中从Graphics对象中获取位图/图像？
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