Saving bitmap problems in winapi - c++

Question

It writes to my BITMAP.bmp file but when I try to view it in Windows Photo Viewer It says "Windows Photo Viewer can't open this picture because the file appears to be damaged, corrupted, or is too large." I know I probably should have put the functions into header files but I haven't ever really delved deeply enough into a project to really make header files so I forgot how. If anyone knows the size limit for pictures in Windows Photo Viewer I would be very thankful. And I got some of these functions from MSDN(unashamed). The error handling could be better but I don't have errorhandler.h. I am not completely sure how all of the functions work because as I said I used some code from MSDN.
I would be greatly appreciative of anyone that can help me. :)
#include <errorrep.h>
#include <windows.h>
#include <iostream>
using namespace std;
namespace Globals{
HBITMAP hBitmap;
HDC hScreen;
}
using namespace Globals;
void GetScreenShot(void)
{
int x1, y1, x2, y2, w, h;
LPSIZE lpSize;
LPVOID lpvBits;
// get screen dimensions
x1 = GetSystemMetrics(SM_XVIRTUALSCREEN);
x2 = GetSystemMetrics(SM_CXVIRTUALSCREEN);
y1 = GetSystemMetrics(SM_YVIRTUALSCREEN);
y2 = GetSystemMetrics(SM_CYVIRTUALSCREEN);
w = x2-x1;
h = y2-y1;
// copy screen to bitmap
hScreen = GetDC(NULL);
HDC hDC = CreateCompatibleDC(hScreen);
hBitmap = CreateCompatibleBitmap(hScreen, w, h);
HGDIOBJ old_obj = SelectObject(hDC, hBitmap);
BOOL bRet = BitBlt(hDC, 0, 0, w, h, hScreen, x1, y1, SRCCOPY);
GetBitmapDimensionEx(hBitmap, lpSize);
GetBitmapBits(hBitmap, (LONG)lpSize, lpvBits);
// save bitmap to clipboard
OpenClipboard(NULL);
EmptyClipboard();
SetClipboardData(CF_BITMAP, hBitmap);
CloseClipboard();
// clean up
SelectObject(hDC, old_obj);
/*DeleteDC(hDC);
ReleaseDC(NULL, hScreen);
DeleteObject(hBitmap);*/
}
PBITMAPINFO CreateBitmapInfoStruct(/*HWND hwnd, */HBITMAP hBmp)
{
BITMAP bmp;
PBITMAPINFO pbmi;
WORD cClrBits;
// Retrieve the bitmap color format, width, and height.
if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
//errhandler("GetObject", hwnd);
cout << "Error: CreateBitmapInfoStruct" << endl;
// Convert the color format to a count of bits.
cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel);
if (cClrBits == 1)
cClrBits = 1;
else if (cClrBits <= 4)
cClrBits = 4;
else if (cClrBits <= 8)
cClrBits = 8;
else if (cClrBits <= 16)
cClrBits = 16;
else if (cClrBits <= 24)
cClrBits = 24;
else cClrBits = 32;
// Allocate memory for the BITMAPINFO structure. (This structure
// contains a BITMAPINFOHEADER structure and an array of RGBQUAD
// data structures.)
if (cClrBits < 24)
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER) +
sizeof(RGBQUAD) * (1<< cClrBits));
// There is no RGBQUAD array for these formats: 24-bit-per-pixel or 32-bit-per-pixel
else
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER));
// Initialize the fields in the BITMAPINFO structure.
pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;
if (cClrBits < 24)
pbmi->bmiHeader.biClrUsed = (1<<cClrBits);
// If the bitmap is not compressed, set the BI_RGB flag.
pbmi->bmiHeader.biCompression = BI_RGB;
// Compute the number of bytes in the array of color
// indices and store the result in biSizeImage.
// The width must be DWORD aligned unless the bitmap is RLE
// compressed.
pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8
* pbmi->bmiHeader.biHeight;
// Set biClrImportant to 0, indicating that all of the
// device colors are important.
pbmi->bmiHeader.biClrImportant = 0;
return pbmi;
}
void CreateBMPFile(/*HWND hwnd, */LPTSTR pszFile, PBITMAPINFO pbi,
HBITMAP hBMP, HDC hDC)
{
HANDLE hf; // file handle
BITMAPFILEHEADER hdr; // bitmap file-header
PBITMAPINFOHEADER pbih; // bitmap info-header
LPBYTE lpBits; // memory pointer
DWORD dwTotal; // total count of bytes
DWORD cb; // incremental count of bytes
BYTE *hp; // byte pointer
DWORD dwTmp;
pbih = (PBITMAPINFOHEADER) pbi;
lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage);
if (!lpBits)
//errhandler("GlobalAlloc", hwnd);
cout << "!lpBits" << endl;
// Retrieve the color table (RGBQUAD array) and the bits
// (array of palette indices) from the DIB.
if (!GetDIBits(hDC, hBMP, 0, (WORD) pbih->biHeight, lpBits, pbi,
DIB_RGB_COLORS))
{
//errhandler("GetDIBits", hwnd);
cout << "Error 1" << endl;
}
// Create the .BMP file.
hf = CreateFile(pszFile,
GENERIC_READ | GENERIC_WRITE,
(DWORD) 0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
(HANDLE) NULL);
if (hf == INVALID_HANDLE_VALUE)
//errhandler("CreateFile", hwnd);
hdr.bfType = 0x4d42; // 0x42 = "B" 0x4d = "M"
// Compute the size of the entire file.
hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof(RGBQUAD) + pbih->biSizeImage);
hdr.bfReserved1 = 0;
hdr.bfReserved2 = 0;
// Compute the offset to the array of color indices.
hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof (RGBQUAD);
// Copy the BITMAPFILEHEADER into the .BMP file.
if (!WriteFile(hf, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER),
(LPDWORD) &dwTmp, NULL))
{
//errhandler("WriteFile", hwnd);
cout << "!WriteFile" << endl;
}
// Copy the BITMAPINFOHEADER and RGBQUAD array into the file.
if (!WriteFile(hf, (LPVOID) pbih, sizeof(BITMAPINFOHEADER)
+ pbih->biClrUsed * sizeof (RGBQUAD),
(LPDWORD) &dwTmp, ( NULL)))
//errhandler("WriteFile", hwnd);
cout << "!WriteFile" << endl;
// Copy the array of color indices into the .BMP file.
dwTotal = cb = pbih->biSizeImage;
hp = lpBits;
if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL))
//errhandler("WriteFile", hwnd);
cout << "if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL))" << endl;
// Close the .BMP file.
if (!CloseHandle(hf))
//errhandler("CloseHandle", hwnd);
// Free memory.
GlobalFree((HGLOBAL)lpBits);
}
int main() {
cout << "ScreenShot - Takes a screen shot\nScreen shot will be put in your clipboard"
"\nThere will be 10 seconds before it takes the screen shot\n" << endl;
string input;
do
{
cin >> input;
if(input == "ScreenShot")
{
/*for(int i=1; i<11; i++)
{
Sleep(1000);
cout << i << endl;
if(i == 10)
{
break;
}
}*/
GetScreenShot();
PBITMAPINFO pbmi = CreateBitmapInfoStruct(hBitmap);
CreateBMPFile("C:\\Users\\Owner\\Desktop\\BITMAP.bmp", pbmi, hBitmap, hScreen);
cout << "ScreenShot taken!" << endl;
cin.ignore(2);
Sleep(3000);
break;
}
else
{
cout << "Invalid command." << endl;
}
} while(true);
return 0;
}

Answer 1

Passing uninitialized values to GetBitmapDimensionEx and GetBitmapBits doesn't seems good, so delete them since they doesn't seem to be used.
void GetScreenShot(void)
{
int x1, y1, x2, y2, w, h;
// get screen dimensions
x1 = GetSystemMetrics(SM_XVIRTUALSCREEN);
x2 = GetSystemMetrics(SM_CXVIRTUALSCREEN);
y1 = GetSystemMetrics(SM_YVIRTUALSCREEN);
y2 = GetSystemMetrics(SM_CYVIRTUALSCREEN);
w = x2-x1;
h = y2-y1;
// copy screen to bitmap
hScreen = GetDC(NULL);
HDC hDC = CreateCompatibleDC(hScreen);
hBitmap = CreateCompatibleBitmap(hScreen, w, h);
HGDIOBJ old_obj = SelectObject(hDC, hBitmap);
BOOL bRet = BitBlt(hDC, 0, 0, w, h, hScreen, x1, y1, SRCCOPY);
// save bitmap to clipboard
OpenClipboard(NULL);
EmptyClipboard();
SetClipboardData(CF_BITMAP, hBitmap);
CloseClipboard();
// clean up
SelectObject(hDC, old_obj);
/*DeleteDC(hDC);
ReleaseDC(NULL, hScreen);
DeleteObject(hBitmap);*/
}
Then, set hdr.bfType even where hf != INVALID_HANDLE_VALUE.
change
if (hf == INVALID_HANDLE_VALUE)
//errhandler("CreateFile", hwnd);
hdr.bfType = 0x4d42; // 0x42 = "B" 0x4d = "M"
to
if (hf == INVALID_HANDLE_VALUE)
{
//errhandler("CreateFile", hwnd);
}
hdr.bfType = 0x4d42; // 0x42 = "B" 0x4d = "M"
(add braces)
Using LPCTSTR instead of LPTSTR for type of pszFile, which is an argument of CreateBMPFile is also good
to avoid compiler warning when a string literal is passed.