Loading an image from a .rc file

[Prominence256]

I'm trying to upgrade my screensaver from using Shapes to using actual images. I have it working and everything, but I was wondering if there was a way to set an sf::Image from an image saved in a .rc file, that way my screensaver's just one file.

[Laurent]

Get a pointer to the contents of your resource and use LoadFromMemory.

[Prominence256]

Do you have an example of this? This is what I tried and it didn't work:

Code: [Select]

Image zero;
HBITMAP img = LoadBitmap(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_BITMAP0));
zero.LoadFromMemory((const char*) img, sizeof(img));

[Laurent]

I don't know how to do, but it's a little bit more complicated than this. Read carefully the MSDN doc and tutorials.

[Groogy]

my guess is that the "sizeof" is wrong. The BITMAP variable is more or less a pointer/reference to the data. Just like if you would use sizeof(sf::Image) you would not get the amount of bytes the image data consist of but you would get the byte size of the instance sf::Image.

You'll have to acquire the size somehow else.

Never used BITMAP myself before, just an educated guess ^^

[JAssange]

Bitmaps are stored in memory like this under Windows.

[Disch]

Acquiring a pointer to resource data is a multi-step process.

1)  FindResource to find it
2)  LoadReourse to get a handle to it
3)  LockResource to get the data pointer


After that I'm not sure how you free the resource as there doesn't seem to be an UnlockResource function.  You can search MSDN for details on all these functions.

[Prominence256]

Thanks, and according to MSDN LockResource doens't actually lock anything as of XP.

But now my issue is what to put for the SizeInBytes in LoadFromMemory.

[JAssange]

Thanks, and according to MSDN LockResource doens't actually lock anything as of XP.

But now my issue is what to put for the SizeInBytes in LoadFromMemory.

Width * Height *4

[Disch]

Width * Height *4

No, he needs the size of the bitmap/whatever file.

To get the size of a resource,use SizeofResource:

http://msdn.microsoft.com/en-us/library/ms648048%28v=vs.85%29.aspx

[Prominence256]

I tried all of this together and the image showed up as a little white dot on the screen, also SFML printed this to the console:

Failed to load image from memory. Reason : Image not of any known type, or corrupt

This was my code:

Code: [Select]

Image zeroimg;
HRSRC hresource = FindResource(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_BITMAP1), RT_BITMAP);
HGLOBAL hglobal = LoadResource(GetModuleHandle(NULL), hresource);
LPVOID lpvoid = LockResource(hglobal);
zeroimg.LoadFromMemory((const char*) lpvoid, SizeofResource(GetModuleHandle(NULL), hresource));
Here's a link to the picture, I couldn't find an image host that doesn't convert the image to a png.

[JAssange]

Width * Height *4

No, he needs the size of the bitmap/whatever file.

To get the size of a resource,use SizeofResource:

http://msdn.microsoft.com/en-us/library/ms648048%28v=vs.85%29.aspx

But he said LoadFromMemory so I assume he means the SFML function, which only takes the pixels in ARGB format, which would be w*h*4.

[Prominence256]

I did mean the SFML function, but I get the same result with both width*height*4 and SizeofResource().

[JAssange]

I did mean the SFML function, but I get the same result with both width*height*4 and SizeofResource().

Then the pointer isn't to ARGB formatted pixel data. You can't just take the handle of the Bitmap resource, it has a DIB header and a color table, its a completely different format. You need to parse it into an array of ARGB bytes.

[Laurent]

LoadFromMemory takes a pointer to a bitmap file in memory (the same thing that you would have on your hard drive).

LoadFromPixels takes a pointer to an array of RGBA pixels.

Use the one that suits what your resource is