Convert LPVOID bitmap pointer to QPixmap - c++

Question

I am trying to load in a BMP image from a resources folder into a QPixmap object. However, I can't read the bytes even though rewriting those bytes to a new file makes a correct copy of the original. Here is my loading method:
QPixmap* GUIMain::loadImage(int name) {
// Resource loading, works fine
HRSRC rc = FindResource(NULL, MAKEINTRESOURCE(name), RT_BITMAP);
if (rc == NULL) {
printf("INVALID RESOURCE ADDRESS (%i)\n", name);
return new QPixmap();
}
HGLOBAL rcData = LoadResource(NULL, rc);
LPVOID data = LockResource(rcData);
DWORD data_size = SizeofResource(NULL, rc);
// Rewrite file to new file, works fine
ofstream output("E:\\" + to_string(name) + ".bmp", std::ios::binary);
BITMAPFILEHEADER bfh = { 'MB', 54 + data_size, 0, 0, 54 };
output.write((char*)&bfh, sizeof(bfh));
output.write((char*)data, data_size);
output.close();
// Need to return, can't get bytes working
return new QPixmap(/*?*/);
}
This method is called with the definitions from the resource.h file.
I have tried to use a stringstream with the same calls as the ofstream, followed by using that stream as a source for the QPixmap, but the stream didn't produce the same output.
Here are the relevant parts of my resource.h file:
#define IDB_BITMAP1 101
#define IDB_BITMAP2 102
Here is my Resource.rc file:
IDB_BITMAP1 BITMAP "E:\\Downloads\\onIcon.bmp"
IDB_BITMAP2 BITMAP "E:\\Downloads\\offIcon.bmp"
I know I should be using the Qt tools for resource management, but I don't have the capabilities to do so.

Answer 1

You can use QPixmap::loadFromData(...) to create a QPixmap from bytes in bmp format, but you also need to not declare the resource as "BITMAP" in the .rc file.
Bitmap resources are intended to be used with LoadBitmap(...) or LoadImage(...) and are stored in the .exe with the bitmap header stripped off. (Raymond Chen discusses this here) Since you are not using LoadBitmap set the type of the resources to be arbitrary binary data, e.g.
IDB_BITMAP1 RCDATA "E:\\Downloads\\onIcon.bmp"
and then implement your image loading routine as below:
QPixmap* GUIMain::loadImage(int name) {
// ...
HGLOBAL rcData = LoadResource(NULL, rc);
LPVOID data = LockResource(rcData);
DWORD data_size = SizeofResource(NULL, rc);
QPixmap* pm = new QPixmap();
pm->loadFromData( static_cast<uchar*>(data), data_size, "bmp");
return pm;
}