I'm creating a game, in which a lot of drawing is done during the WM_PAINT message. There are several different places where the window is invalidated, forcing it to redraw. I have everything draw to an offscreen DC and then draw that to the window - to create non-flickering "frames".
However, every once in a while, everything suddenly starts being drawn incorrectly. Out of five bitmaps I use, the first three keep drawing more or less (but not completely) correctly. As in, all of the color information is correct for these three. The other two, which are drawn after these three, are drawn with the wrong colors - I think that white is still drawing as white, but everything else is being drawn as grey. And I'm not talking greyscale, I mean that everything except white is the same color - grey.
Also, when this starts happening, oftentimes everything is drawn too high - by about 20 to 30 pixels. Furthermore, fonts and message boxes stop working - all text is drawn in the default font (but, oddly, the correct color), and message boxes only appear briefly, with no text, and then disappear - but must be dismissed like regular (you have to press enter or else if you click on the main window, it does what it normally does when there's a message box open taking input - flashes and pings the error tone). So everything is royally screwed up.
I've been working on this project for a while now, and I've only begun seeing this error recently - although I haven't modified the piece of code below literally at all. It's really hard to test what could be doing this, because it only seems to happen once in a while.
Here's the code in my WM_CREATE and WM_PAINT in WndProc:
case WM_CREATE:
{
hdc = GetDC(hWnd);
hdcmem = CreateCompatibleDC(hdc);
RECT rc;
GetClientRect(hWnd, &rc);
hdcbm = CreateCompatibleBitmap(hdc, rc.right, rc.bottom);
hbcmem = CreateCompatibleDC(hdcmem);
hdcbmold = (HBITMAP)SelectObject(hdcmem, hdcbm);
// Load bitmaps
bg = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_BACKGROUND));
mainCont = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_GAME_CONT));
if(bg == NULL || mainCont == NULL)
ThrowError("A bitmap failed to load.");
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
BeginPaint(hWnd, &ps);
// Background
hdcold = (HBITMAP)SelectObject(hbcmem, bg);
BitBlt(hdcmem, 0, 0, 237, 196, hbcmem, 0, 0, SRCCOPY);
BitBlt(hdcmem, 237, 0, 237, 196, hbcmem, 0, 0, SRCCOPY);
BitBlt(hdcmem, 237 * 2, 0, 237, 196, hbcmem, 0, 0, SRCCOPY);
BitBlt(hdcmem, 0, 196, 237, 196, hbcmem, 0, 0, SRCCOPY);
BitBlt(hdcmem, 237, 196, 237, 196, hbcmem, 0, 0, SRCCOPY);
BitBlt(hdcmem, 237 * 2, 196, 237, 196, hbcmem, 0, 0, SRCCOPY);
// Main Game Container
hdcold = (HBITMAP)SelectObject(hbcmem, mainCont);
BitBlt(hdcmem, 26, 26, 300, 300, hbcmem, 0, 0, SRCCOPY);
// Side Info
HBITMAP side = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SIDEINFO));
hdcold = (HBITMAP)SelectObject(hbcmem, side);
BitBlt(hdcmem, 339, 26, 154, 300, hbcmem, 0, 0, SRCCOPY);
DrawLevelNumber(game.map.levelnumber);
if (color)
sprites = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_COLOR_SPRITES));
else sprites = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_BLACKWHITE_SPRITES));
hdcold = (HBITMAP)SelectObject(hbcmem, sprites);
// Find x and y coordinate for the top left of the visible screen
int x = game.player.x, y = game.player.y, ypos = 0;
if (x < 4) x = 4;
if (x > 27) x = 27;
if (y < 4) y = 4;
if (y > 27) y = 27;
x -= 4;
y -= 4;
// Draw lower layer
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
if (game.map.Layer_Two[x + i][y + j] != 0)
{
int xpos = game.get_pos(game.map.Layer_Two[x + i][y + j].get(), ypos, false);
BitBlt(hdcmem, (i * 32) + 32, (j * 32) + 32, 32, 32, hbcmem, xpos, ypos, SRCCOPY);
}
}
}
// Draw upper layer
for (int i = 0; i < 9; i++)
{
for (int j = 0; j < 9; j++)
{
if ((game.map.Layer_Two[x + i][y + j] != 0 && game.map.Layer_One[x + i][y + j] >= 64 && game.map.Layer_One[x + i][y + j] <= 111))
{
int xpos = game.get_pos(game.map.Layer_One[x + i][y + j].get(), ypos, true);
BitBlt(hdcmem, (i * 32) + 32, (j * 32) + 32, 32, 32, hbcmem, xpos + 96, ypos, SRCPAINT);
BitBlt(hdcmem, (i * 32) + 32, (j * 32) + 32, 32, 32, hbcmem, xpos, ypos, SRCAND);
} else {
int xpos = game.get_pos(game.map.Layer_One[x + i][y + j].get(), ypos, false);
BitBlt(hdcmem, (i * 32) + 32, (j * 32) + 32, 32, 32, hbcmem, xpos, ypos, SRCCOPY);
}
}
}
// If it isn't started, show title
if (!game.started)
{
HDC tmphdc = CreateCompatibleDC(hdcmem);
HDC tmp = CreateCompatibleDC(tmphdc);
RECT rc;
GetClientRect(hWnd, &rc);
string str = game.map.leveltitle.substr(0, game.map.leveltitle.length() - 1);
TCHAR* tch = new TCHAR[str.length()];
mbstowcs_s(NULL, tch, _tcslen(tch), str.c_str(), str.length());
HFONT font = CreateFont(25, 0, 0, 0, FW_BOLD, false, false, false, ANSI_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, FF_DONTCARE, NULL);
SelectObject(tmp, font);
DrawText(tmp, tch, str.length(), &rc, DT_CALCRECT);
rc.right += 16;
HBITMAP tmpbm = CreateCompatibleBitmap(hdcmem, rc.right, rc.bottom);
HBITMAP tmpold = (HBITMAP)SelectObject(tmphdc, tmpbm);
HBRUSH hbr = CreateSolidBrush(RGB(255, 255, 255));
HPEN pen = CreatePen(PS_SOLID, 1, RGB(255, 255, 255));
SelectObject(hdcmem, pen);
SelectObject(hdcmem, hbr);
Rectangle(hdcmem, 176 - (rc.right / 2), 243, 177 + (rc.right / 2), 248);
hbr = CreateSolidBrush(RGB(128, 128, 128));
pen = CreatePen(PS_SOLID, 1, RGB(128, 128, 128));
SelectObject(hdcmem, pen);
SelectObject(hdcmem, hbr);
Rectangle(hdcmem, 176 - (rc.right / 2), 294, 177 + (rc.right / 2), 299);
HBITMAP left = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_LEFT));
hdcold = (HBITMAP)SelectObject(hbcmem, left);
BitBlt(hdcmem, 176 - (rc.right / 2) - 4, 243, 4, 56, hbcmem, 0, 0, SRCCOPY);
HBITMAP right = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_RIGHT));
hdcold = (HBITMAP)SelectObject(hbcmem, right);
BitBlt(hdcmem, 176 + (rc.right / 2) + ((rc.right % 2) != 0), 243, 4, 56, hbcmem, 0, 0, SRCCOPY);
SelectObject(tmphdc, font);
SetTextColor(tmphdc, RGB(255, 255, 0));
SetBkColor(tmphdc, RGB(0, 0, 0));
DrawText(tmphdc, tch, str.length(), &rc, DT_CENTER);
BITMAP structBitmapHeader;
memset( &structBitmapHeader, 0, sizeof(BITMAP) );
HGDIOBJ hBitmap = GetCurrentObject(tmphdc, OBJ_BITMAP);
GetObject(hBitmap, sizeof(BITMAP), &structBitmapHeader);
BitBlt(hdcmem, 176 - (rc.right / 2), 247, structBitmapHeader.bmWidth, structBitmapHeader.bmHeight, tmphdc, 0, 0, SRCCOPY);
DeleteDC(tmphdc);
DeleteDC(tmp);
}
// If paused
if (game.paused)
{
RECT rc;
rc.top = 32;
rc.left = 32;
rc.bottom = 330;
rc.right = 330;
BitBlt(hdcmem, 32, 32, 288, 288, NULL, 0, 0, BLACKNESS);
HFONT font = CreateFont(50, 0, 0, 0, FW_NORMAL, false, false, false, ANSI_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, FF_DONTCARE, NULL);
SelectObject(hdcmem, font);
SetTextColor(hdcmem, RGB(255, 0, 0));
SetBkColor(hdcmem, RGB(0, 0, 0));
DrawText(hdcmem, L"PAUSED", 6, &rc, (DT_CENTER + DT_SINGLELINE + DT_VCENTER));
}
nums = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_NUMBERS));
hdcold = (HBITMAP)SelectObject(hbcmem, nums);
for (int i = 100; i > 0; i /= 10) // coins and time left
{
int tmp;
if (i == 100)
tmp = game.coinsleft / 100;
if (i == 10)
tmp = ((game.coinsleft % 100) - (game.coinsleft % 10)) / 10;
if (i == 1)
tmp = game.coinsleft % 10;
if (game.coinsleft < i && i > 1)
tmp = 10;
int ypos = game.get_num_pos(tmp, (game.coinsleft == 0));
BitBlt(hdcmem, 417 + ((3 - (int)floor(log10((double)i)) * 17)), 215, 17, 23, hbcmem, 0, ypos, SRCCOPY);
if (i == 100)
tmp = game.timeleft / 100;
if (i == 10)
tmp = ((game.timeleft % 100) - (game.timeleft % 10)) / 10;
if (i == 1)
tmp = game.timeleft % 10;
if (game.timeleft < i && i > 1)
tmp = 10;
if (game.map.timelimit == 0)
tmp = 11;
ypos = game.get_num_pos(tmp, (game.timeleft < 16 || game.map.timelimit == 0));
BitBlt(hdcmem, 369 + ((3 - (int)floor(log10((double)i))) * 17), 125, 17, 23, hbcmem, 0, ypos, SRCCOPY);
}
if (game.onhint)
{
HBITMAP sidebg = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SIDEBG));
hdcold = (HBITMAP)SelectObject(hbcmem, sidebg);
BitBlt(hdcmem, 353, 165, 127, 146, hbcmem, 0, 0, SRCCOPY);
HFONT font = CreateFont(18, 0, 0, 0, FW_BOLD, true, false, false, ANSI_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, FF_DONTCARE, NULL);
SelectObject(hdcmem, font);
SetTextColor(hdcmem, RGB(0, 255, 255));
SetBkColor(hdcmem, RGB(0, 0, 0));
RECT rc;
rc.top = 168;
rc.left = 356;
rc.bottom = 308;
rc.right = 477;
string str = "Hint: " + game.map.hint;
TCHAR* tch = new TCHAR[str.length()];
mbstowcs_s(NULL, tch, _tcslen(tch), str.c_str(), str.length());
DrawText(hdcmem, tch, str.length(), &rc, DT_CENTER + DT_WORDBREAK);
} else {
hdcold = (HBITMAP)SelectObject(hbcmem, sprites); // LOWER SIDE INFO
if (game.player.key1 > 0)
BitBlt(hdcmem, 352, 247, 32, 32, hbcmem, 192, 160, SRCCOPY);
else BitBlt(hdcmem, 352, 247, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.key2 > 0)
BitBlt(hdcmem, 384, 247, 32, 32, hbcmem, 192, 128, SRCCOPY);
else BitBlt(hdcmem, 384, 247, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.key3 > 0)
BitBlt(hdcmem, 416, 247, 32, 32, hbcmem, 192, 224, SRCCOPY);
else BitBlt(hdcmem, 416, 247, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.key4)
BitBlt(hdcmem, 448, 247, 32, 32, hbcmem, 192, 192, SRCCOPY);
else BitBlt(hdcmem, 448, 247, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.mod1)
BitBlt(hdcmem, 352, 279, 32, 32, hbcmem, 192, 256, SRCCOPY);
else BitBlt(hdcmem, 352, 279, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.mod2)
BitBlt(hdcmem, 384, 279, 32, 32, hbcmem, 192, 288, SRCCOPY);
else BitBlt(hdcmem, 384, 279, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.mod3)
BitBlt(hdcmem, 416, 279, 32, 32, hbcmem, 192, 320, SRCCOPY);
else BitBlt(hdcmem, 416, 279, 32, 32, hbcmem, 0, 0, SRCCOPY);
if (game.player.mod4)
BitBlt(hdcmem, 448, 279, 32, 32, hbcmem, 192, 352, SRCCOPY);
else BitBlt(hdcmem, 448, 279, 32, 32, hbcmem, 0, 0, SRCCOPY);
}
BitBlt(hdc, 0, 0, 518, 401, hdcmem, 0, 0, SRCCOPY);
EndPaint(hWnd, &ps);
}
break;
case WM_DESTROY:
SelectObject(hdc,hdcold);
DeleteDC(hdcmem);
DeleteDC(hbcmem);
ReleaseDC(hWnd, hdc);
DeleteObject(bg);
PostQuitMessage(0);
break;
I'd also really appreciate any advice/criticism anyone could provide on syntax, efficiency and/or better ways of doing things in my code. I'm pretty new to Win32.
