c语言获取当前程序内存，语言获取任意文件的缩略图

c语言获取当前程序内存，语言获取任意文件的缩略图

因为用shell取缩略图时，对于损坏的文件，读出来的图有黑边，所以就诞生了以下方法，不过这个效率要比用shell取的低3-4倍（耗时主要是在将黑色背景转为透明的过程）。

1.添加类WindowsThumbnailProvider

[csharp] view plain copy

1. [Flags]
2. public enum ThumbnailOptions
3. {
4. None = 0x00
5. BiggerSizeOk = 0x01
6. InMemoryOnly = 0x02
7. IconOnly = 0x04
8. ThumbnailOnly = 0x08
9. InCacheOnly = 0x10
10. }
12. public class WindowsThumbnailProvider
13. {
14. private const string IShellItem2Guid = "7E9FB0D3-919F-4307-AB2E-9B1860310C93";
16. [dllImport("shell32.dll" CharSet = CharSet.Unicode SetLastError = true)]
17. internal static extern int SHCreateItemFromParsingName(
18. [MarshalAs(UnmanagedType.LPWStr)] string path
19. // The following parameter is not used - binding context.
20. IntPtr pbc
21. ref Guid riid
22. [MarshalAs(UnmanagedType.Interface)] out IShellItem shellItem);
24. [DllImport("gdi32.dll")]
25. [return: MarshalAs(UnmanagedType.Bool)]
26. internal static extern bool DeleteObject(IntPtr hObject);
28. [ComImport]
29. [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
30. [Guid("43826d1e-e718-42ee-bc55-a1e261c37bfe")]
31. internal interface IShellItem
32. {
33. void BindToHandler(IntPtr pbc
34. [MarshalAs(UnmanagedType.LPStruct)]Guid bhid
35. [MarshalAs(UnmanagedType.LPStruct)]Guid riid
36. out IntPtr ppv);
38. void GetParent(out IShellItem ppsi);
39. void GetDisplayName(SIGDN sigdnName out IntPtr ppszName);
40. void GetAttributes(uint sfgaoMask out uint psfgaoAttribs);
41. void Compare(IShellItem psi uint hint out int piOrder);
42. };
44. internal enum SIGDN : uint
45. {
46. NORMALDISPLAY = 0
47. PARENTRELATIVEPARSING = 0x80018001
48. PARENTRELATIVEFORADDRESSBAR = 0x8001c001
49. DESKTOPABSOLUTEPARSING = 0x80028000
50. PARENTRELATIVEEDITING = 0x80031001
51. DESKTOPABSOLUTEEDITING = 0x8004c000
52. FILESYSPATH = 0x80058000
53. URL = 0x80068000
54. }
56. internal enum HResult
57. {
58. Ok = 0x0000
59. False = 0x0001
60. InvalidArguments = unchecked((int)0x80070057)
61. OutOfMemory = unchecked((int)0x8007000E)
62. NoInterface = unchecked((int)0x80004002)
63. Fail = unchecked((int)0x80004005)
64. ElementNotFound = unchecked((int)0x80070490)
65. TypeElementNotFound = unchecked((int)0x8002802B)
66. NoObject = unchecked((int)0x800401E5)
67. Win32ErrorCanceled = 1223
68. Canceled = unchecked((int)0x800704C7)
69. ResourceInUse = unchecked((int)0x800700AA)
70. AccessDenied = unchecked((int)0x80030005)
71. }
73. [ComImportAttribute()]
74. [GuidAttribute("bcc18b79-ba16-442f-80c4-8a59c30c463b")]
75. [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
76. internal interface IShellItemImageFactory
77. {
78. [PreserveSig]
79. HResult GetImage(
80. [In MarshalAs(UnmanagedType.Struct)] NativeSize size
81. [In] ThumbnailOptions flags
82. [Out] out IntPtr phbm);
83. }
85. [StructLayout(LayoutKind.Sequential)]
86. internal struct NativeSize
87. {
88. private int width;
89. private int height;
91. public int Width { set { width = value; } }
92. public int Height { set { height = value; } }
93. };
95. [StructLayout(LayoutKind.Sequential)]
96. public struct RGBQUAD
97. {
98. public byte rgbBlue;
99. public byte rgbGreen;
100. public byte rgbRed;
101. public byte rgbReserved;
102. }
104. public static Bitmap GetThumbnail(string fileName int width int height ThumbnailOptions options)
105. {
106. IntPtr hBitmap = GetHBitmap(Path.GetFullPath(fileName) width height options);
108. try
109. {
110. // return a System.Drawing.Bitmap from the hBitmap
111. return GetBitmapFromHBitmap(hBitmap);
112. }
113. finally
114. {
115. // delete HBitmap to avoid memory leaks
116. DeleteObject(hBitmap);
117. }
118. }
120. public static Bitmap GetBitmapFromHBitmap(IntPtr nativeHBitmap)
121. {
122. Bitmap bmp = Bitmap.FromHbitmap(nativeHBitmap);
124. if (Bitmap.GetPixelFormatSize(bmp.PixelFormat) < 32)
125. return bmp;
127. return CreateAlphaBitmap(bmp PixelFormat.Format32bppArgb);
128. }
130. public static Bitmap CreateAlphaBitmap(Bitmap srcBitmap PixelFormat targetPixelFormat)
131. {
132. Bitmap result = new Bitmap(srcBitmap.Width srcBitmap.Height targetPixelFormat);
134. Rectangle bmpBounds = new Rectangle(0 0 srcBitmap.Width srcBitmap.Height);
136. BitmapData srcData = srcBitmap.LockBits(bmpBounds ImageLockMode.ReadOnly srcBitmap.PixelFormat);
138. bool isAlplaBitmap = false;
140. try
141. {
142. for (int y = 0; y <= srcData.Height - 1; y )
143. {
144. for (int x = 0; x <= srcData.Width - 1; x )
145. {
146. Color pixelColor = Color.FromArgb(
147. Marshal.ReadInt32(srcData.Scan0 (srcData.Stride * y) (4 * x)));
149. if (pixelColor.A > 0 & pixelColor.A < 255)
150. {
151. isAlplaBitmap = true;
152. }
154. result.SetPixel(x y pixelColor);
155. }
156. }
157. }
158. finally
159. {
160. srcBitmap.UnlockBits(srcData);
161. }
163. if (isAlplaBitmap)
164. {
165. return result;
166. }
167. else
168. {
169. return srcBitmap;
170. }
171. }
173. private static IntPtr GetHBitmap(string fileName int width int height ThumbnailOptions options)
174. {
175. IShellItem nativeShellItem;
176. Guid shellItem2Guid = new Guid(IShellItem2Guid);
177. int retCode = SHCreateItemFromParsingName(fileName IntPtr.Zero ref shellItem2Guid out nativeShellItem);
179. if (retCode != 0)
180. throw Marshal.GetExceptionForHR(retCode);
182. NativeSize nativeSize = new NativeSize();
183. nativeSize.Width = width;
184. nativeSize.Height = height;
186. IntPtr hBitmap;
187. HResult hr = ((IShellItemImageFactory)nativeShellItem).GetImage(nativeSize options out hBitmap);
189. Marshal.ReleaseComObject(nativeShellItem);
191. if (hr == HResult.Ok) return hBitmap;
193. throw Marshal.GetExceptionForHR((int)hr);
194. }
195. }

2.使用方法：[csharp] view plain copy

1. int pic_size = 256;
3. Bitmap bm = WindowsThumbnailProvider.GetThumbnail(path pic_size pic_size ThumbnailOptions.None);