Pan Xiaolong Gu Yuming
---- Screen interception is something that is more interested. Although there are now many applications such as Hypersnap can be used to intercept the screen screen you like, but if you can add this function to your own program, It is more powerful to use it.
---- The following uses VC to gradually introduce the implementation process under Windows 95. First we want to determine the area intercepted in the screen, define using the LPRect structure. You can intercept a window, or the entire screen. The following code copies the selected screen area In place.
HbitMap CopyScreenTOBITMAP (LPRECT LPRECT)
// LPRECT represents the selected area
{
HDC HSCRDC, HMEMDC;
// Screen and Memory Device Description Table
Hbitmap hbitmap, holdbitmap;
// bit map handle
INT NX, NY, NX2, NY2;
// Select region coordinates
INT NWIDTH, NHEIGHT;
// bitmap width and height
Int xscrn, yscrn;
// Screen Resolution
/ / Make sure the selected area is not empty rectangle
IF (IsRectempty (LPRECT))
Return NULL;
/ / Create a device description table for the screen
HSCRDC = CREATEDC ("Display", NULL, NULL, NULL;
/ / Create a compatible memory device description for the screen device description table
HMEMDC = CREATECOMPATIBLEDC (HSCRDC);
/ / Get selected area coordinates
Nx = lprect-> left;
NY = lpRect-> TOP;
NX2 = lpRect-> Right;
NY2 = LPRECT-> BOTTOM;
// Get the screen resolution
Xscrn = getDeviceCaps (HSCRDC, Horzres);
YSCRN = GetDeviceCaps (HSCRDC, Vertres);
/ / Ensure that the selected area is visible
IF (NX <0)
Nx = 0;
IF (NY <0)
NY = 0;
IF (nx2> xscrn)
NX2 = xscrn;
IF (NY2> YSCRN)
NY2 = YSCRN;
NWIDTH = NX2 - NX;
NHEIGHT = NY2 - NY;
// Create a bitmap compatible with the screen device description table
hbitmap = createcompatibleBitmap
(HSCRDC, NWIDTH, NHEIGHT);
/ / Put the new bitmap in the memory device descriptor table
HoldbitMap = SELECTOBJECT (HMEMDC, HBitmap);
/ / Copy the screen device description table to the memory device descriptor table
Bitblt (Hmemdc, 0, 0, NWIDTH, NHEIGHT,
HSCRDC, NX, NY, SRCCOPY;
/ / Get the handle of the screen bitmap
Hbitmap = selectObject (HMEMDC, Holdbitmap);
// Clear
Deletedc (HSCRDC);
Deletedc (HMEMDC);
// Return the bitmap section
Return hbitmap;
}
After getting the screen bitmap handle, we
You can paste the screen content onto the clipboard.
OpenClipboard (hwnd))
// hwnd is the program window handle
{
// Empty clipboard
EMPTYCLIPBOARD ();
// Paste the screen content into the clipboard,
Hbitmap is the screen bitmap handle
SetClipboardData (cf_bitmap, hbitmap);
// Close the clipboard
CloseClipboard ();
}
We can also save the screen content to disk files in a bitmap format.
Int SaveBitmaptofile (Hbitmap Hbitmap,
LPSTR LPFILENAME) // hbitmap for the screen bitmap handle {// lpfilename is a bitmap file name
HDC HDC;
// Device Description Table
INT IBITS;
/ / The number of items per pixel at the current display resolution
Word wbitcount;
////Bit of each pixel accounts for each pixel
/ / Define the palette size, the pixel byte size in the bit map,
Bitmap file size, write file byte
DWORD dwpalettesize = 0,
DWBMBITSSIZE,
DWDIBSIZE, DWWWWRITEN
Bitmap bitmap;
// bit map attribute structure
BitmapfileHeader BMFHDR;
// bitmap file head structure
BitmapInfoheader Bi;
// bitmap information head structure
LpbitmapInfoHeader LPBI;
/ (Pointing the bitmap information head structure
Handle FH, HDIB, HPAL, HOLDPAL = NULL
/ / Define files, allocate memory handles, palette handles
/ / Calculate the number of bytes per pixel per pixel
HDC = CREATEDC ("Display", NULL, NULL, NULL;
Ibits = getDeviceCaps (HDC, Bitspixel) *
GetDeviceCaps (HDC, Plaso);
Deletedc (HDC);
IF (iBITS <= 1)
Wbitcount = 1;
Else IF (iBITS <= 4)
Wbitcount = 4;
ELSE IF (iBITS <= 8)
Wbitcount = 8;
Else IF (iBITS <= 24)
Wbitcount = 24;
/ / Calculate the size of the palette
IF (wbitcount <= 8)
DWPALETESIZE = (1 SizeOf (RGBQUAD); / / Set the bitmap information head structure GetObject (HbitMap, Sizeof (Bitmap), (LPSTR) & Bitmap; bi.bisize = sizeof (bitmapinfohead); bi.biwidth = bitmap.bmwidth; bi.biheight = bitmap.bmheight; Bi.Biplanes = 1; Bi.biBitcount = WbitCount; Bi.Bicompression = BI_RGB; Bi.bisizeImage = 0; bi.bixpelspermeter = 0; Bi.biypelspermeter = 0; Bi.bi.biRused = 0; Bi.Biclrimportant = 0; DWBMBITSSIZE = ((bitmap.bmwidth * Wbitcount 31) / 32) * 4 * Bitmap.bmheight; / / Distribute memory for bitmap content HDIB = GLOBALLOC (GHND, DWBMBITSSIZE DWPALETESIZE SIZEOF (BitmapInfoHeader); LPBI = (LPbitMapInfoHeader) Globalock (HDIB); * lpbi = bi; // Process the palette hpal = getStockObject (Default_palette); IF (HPAL) { HDC = GetDC (NULL); Holdpal = SELECTPALETTTE (HDC, HPAL, FALSE); RealizePalette (HDC); } / / Get new pixel values under this palette GetDibits (HDC, Hbitmap, 0, (UINT) Bitmap.Bmheight, (LPSTR) LPBI SIZEOF (BitMapInfoHeader) DWPALETESIZE, (BitMapInfoHeader *) LPBI, DIB_RGB_COLORS); // Restore palette IF (Holdpal) { SelectPalette (HDC, Holdpal, True); RealizePalette (HDC); ReleaseDC (NULL, HDC); } // Create a bitmap file FH = CREATEFILE (lpfilename, generic_write, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_ Flag_sequential_scan, null); IF (fH == invalid_handle_value) Return False; / / Set the bitmap file header BMFHDR.BFTYPE = 0x4d42; // "BM" DWDIBSIZE = Sizeof (BitmapfileHeader) Sizeof (BitmapInfoHeader) DWPALETESIZE DWBMBITSSIZE; BMFHDR.BFSIZE = DWDIBSIZE; BMFHDR.BFRESERVED1 = 0; BMFHDR.BFRESERVED2 = 0; BMFHDR.BFOFFBITS = (DWORD) SIZEOF (BitmapFileHeader) (DWORD) SIZEOF (BitmapInfoHeader) DWPALETESIZE; // Write the bitmap file header Writefile (FH, (LPSTR) & BMFHDR, SIZEOF (BitmapfileHeader), & dwwritten, null; / / Write the rest of the file Writefile (FH, (LPSTR) LPBI, DWDIBSIZE, & dwwritten, null; // Clear GlobalUnlock (HDIB); GlobalFree (HDIB); CloseHandle (FH); }
