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I got 2 questions:
1. Why does this code rotates bitmap only once? I mean if i have 2 different hbitmaps when i use this function to rotate the first one - everithing is just fine. But when i use it for the second time - no rotation performed. Am i not releasing smth properly?
2. Why the commented code does not work?

Texture* Texture::Rotate90(HDC dc) {
//	/*
	HDC dcsrc = CreateCompatibleDC(dc);
	HDC dcdst = CreateCompatibleDC(dc);
	HBITMAP src = (HBITMAP)SelectObject(dcsrc, hbmp);
	HBITMAP ret = CreateBitmap(bmp.bmWidth,bmp.bmHeight,bmp.bmPlanes,bmp.bmBitsPixel, 0);
	HBITMAP dst = (HBITMAP)SelectObject(dcdst, ret);
	for (int i=0; i<bmp.bmWidth; i++)
		for (int j=0; j<bmp.bmHeight; j++)
			SetPixel(dcdst, i, j, GetPixel(dcsrc, j, i));
	SelectObject(dcsrc,src);
	SelectObject(dcdst,dst);
	DeleteDC(dcsrc);
	DeleteDC(dcdst);
	return new Texture(&ret);
//	*/
	/*
	HBITMAP old = (HBITMAP)SelectObject(dc, hbmp);
	for (int i=0; i<bmp.bmHeight; i++)
		for (int j=0; j<bmp.bmWidth; j++) {
			COLORREF c = GetPixel(dc, i, j);
			SetPixel(dc, i, j, GetPixel(dc, j, i));
			SetPixel(dc, j, i, c);
		}
	SelectObject(dc, old);
	return 0;
	*/
}

ps bmp is the BITMAP structure that holds correct data and hbmp is correct hbitmap
pps hbitmaps are squares always
ppps i do know that it is bad to use the SetPixel for that purpose

Posted 4-Aug-10 14:01pm

judgemaker

Updated 5-Aug-10 12:19pm

v2

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Comments

Alan N 5-Aug-10 20:34pm

What do you mean, the code does not define smth!

3 solutions

Solution 1

Your problem is probably that you don't pass in the rotated bitmap to rotate again.

Of course, Get/SetPixel are very slow and should be avoided. I dunno why the commented out code 'does not work', what did you want it to do, and what DOES it do ?

Posted 5-Aug-10 19:43pm

Christian Graus

Solution 2

Your problem is probably that you don't pass in the rotated bitmap to rotate again.

MIDL

gmRectVertical = CreateTexture(IDB_BITMAP1);
gmRectHorizontal = gs->Rotate90(gmRectVertical);

gmRectCornerTL = CreateTexture(IDB_BITMAP2);
gmRectCornerTR = gs->Rotate90(gmRectCornerTL);
gmRectCornerBR = gs->Rotate90(gmRectCornerTR);
gmRectCornerBL = gs->Rotate90(gmRectCornerBR);

This is a code where i create textures. The gmRectVertical is loaded from resources and is displayed just fine. gmRectHorizontal is created with the function Rotate90 i implemented through the following function to be exact

C#

Texture* GameScreen::Rotate90(Texture*t) {
    return t->Rotate90(bmp_dc);
}

and works too. The gmRectCornerTL is created next and the gmRectCornerTR is created with Rotate90 but is not rotated. As well as next gmRectCornerBR and gmRectCornerBL.

But!

I just tried to rotate IDB_BITMAP2 first:

MIDL

gmRectVertical = CreateTexture(IDB_BITMAP2);
gmRectHorizontal = gs->Rotate90(gmRectVertical);

gmRectCornerTL = CreateTexture(IDB_BITMAP1);
gmRectCornerTR = gs->Rotate90(gmRectCornerTL);
gmRectCornerBR = gs->Rotate90(gmRectCornerTR);
gmRectCornerBL = gs->Rotate90(gmRectCornerBR);

And IDB_BITMAP2 did not rotate anyway but the IDB_BITMAP1 rotated 4 times just fine. Both bitmaps are bmp files 32*32 size and 16 bits per pixel. I am confused what can it be:confused:

Of course, Get/SetPixel are very slow and should be avoided. I dunno why the commented out code 'does not work', what did you want it to do, and what DOES it do ?

To rotate a bitmap in the not commented out code i create 2 dc's. One for reading from bitmap and another - for writting. In the commented code i wanted to rotate a bitmap in the same dc. All i needed is to swap bits symmetrically to the diagonal that starts in point 0; 0 and ends in point 32; 32.

what DOES it do ?

Here is a code how i tested it:

gmRectHorizontal = new Texture(*gmRectVertical);
gs->Rotate90(gmRectHorizontal);

so i wanted a Texture could rotate itself but gmRectHorizontal did not rotate and looks just like gmRectVertical

Posted 7-Aug-10 10:04am

judgemaker

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Niklas L · Accepted Answer · 2010-08-07T21:55:00

Solution 3

The commented code doesn't work because you are swapping each pair of pixels twice, thus swapping it back again.

Posted 7-Aug-10 21:55pm

Niklas L

Comments

judgemaker 8-Aug-10 18:30pm

Wow right! Thanks!

judgemaker 8-Aug-10 18:33pm

HBITMAP old = (HBITMAP)SelectObject(dc, hbmp);
for (int i=0; i