GDI sprite shown some time and disappear - c++

Question

I'm studying sprite drawing with GDI in Visual Studio 2013 with C++.
I can draw sprite using two bmp files, image with black background, and black mask. But after program start, sprite shown some time (about 15 second) and disappear. I can't find the reason.
Here is my code.
#include <Windows.h>
#include "resource.h"
using namespace std;
LRESULT WINAPI WinProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam);
HWND hWnd = 0;
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
MSG msg;
ZeroMemory(&msg, sizeof(msg));
WNDCLASS wc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hbrBackground = (HBRUSH)GetStockObject(NULL_BRUSH);
wc.hCursor = LoadCursor(hInst, MAKEINTRESOURCE(IDC_HAND));
wc.hIcon = LoadIcon(hInst, MAKEINTRESOURCE(IDI_ASTERISK));
wc.hInstance = hInst;
wc.lpfnWndProc = WinProc;
wc.lpszClassName = "ClassName";
wc.lpszMenuName = 0;
wc.style = CS_VREDRAW | CS_HREDRAW;
if (!RegisterClass(&wc))
MessageBox(0, "Class was not registered!", "Error", 0);
hWnd=CreateWindow("ClassName", "WindowName", WS_OVERLAPPEDWINDOW, 100, 100, 640, 480, 0, 0, hInst, 0);
if (hWnd==0)
MessageBox(0, "Window was not created!", "Error", 0);
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
while (msg.message!=WM_QUIT)
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
HDC hdc = GetDC(hWnd);
HDC hBuffDC = CreateCompatibleDC(hdc);
HDC hMemDC = CreateCompatibleDC(hdc);
HBITMAP hBuffBitmap = CreateCompatibleBitmap(hdc, 640, 480);
HBITMAP hSpriteBitmap = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_MASK));
SelectObject(hBuffDC, hBuffBitmap);
SelectObject(hBuffDC, (HBRUSH)GetStockObject(GRAY_BRUSH));
Rectangle(hBuffDC, 0, 0, 640, 480);
SelectObject(hMemDC, hSpriteBitmap);
BitBlt(hBuffDC, 0, 0, 640, 480, hMemDC, 0, 0, SRCAND);
hSpriteBitmap = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SPRITE));
SelectObject(hMemDC, hSpriteBitmap);
BitBlt(hBuffDC, 0, 0, 640, 480, hMemDC, 0, 0, SRCPAINT);
BitBlt(hdc, 0, 0, 640, 480, hBuffDC, 0, 0, SRCCOPY);
DeleteObject(hBuffBitmap);
DeleteObject(hSpriteBitmap);
DeleteDC(hMemDC);
DeleteDC(hBuffDC);
ReleaseDC(hWnd, hdc);
}
return 0;
}
LRESULT WINAPI WinProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_KEYDOWN:
switch (wParam)
{
case VK_ESCAPE:
DestroyWindow(hWnd);
break;
}
break;
case WM_CLOSE:
DestroyWindow(hWnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
images are just a black circle with white background (mask), and green circle with black background.

Answer 1

//Here is corrected code without memory leak and ReleaseDc return 1
#include <Windows.h>
#include "resource.h"
using namespace std;
LRESULT WINAPI WinProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam);
HWND hWnd = 0;
HDC hdc = 0;
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
MSG msg;
ZeroMemory(&msg, sizeof(msg));
WNDCLASS wc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hbrBackground = (HBRUSH)GetStockObject(GRAY_BRUSH);
wc.hCursor = LoadCursor(hInst, MAKEINTRESOURCE(IDC_HAND));
wc.hIcon = LoadIcon(hInst, MAKEINTRESOURCE(IDI_ASTERISK));
wc.hInstance = hInst;
wc.lpfnWndProc = WinProc;
wc.lpszClassName = "ClassName";
wc.lpszMenuName = 0;
wc.style = CS_VREDRAW | CS_HREDRAW;
if (!RegisterClass(&wc))
MessageBox(0, "Class was not registered!", "Error", 0);
hWnd=CreateWindow("ClassName", "WindowName", WS_OVERLAPPEDWINDOW, 100, 100, 640, 480, 0, 0, hInst, 0);
if (hWnd==0)
MessageBox(0, "Window was not created!", "Error", 0);
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
hdc = GetDC(hWnd);
while (msg.message!=WM_QUIT)
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
HDC hBuffDC = CreateCompatibleDC(hdc);
HDC hMemDC = CreateCompatibleDC(hdc);
HBITMAP hBuffBitmap = CreateCompatibleBitmap(hdc, 640, 480);
HBITMAP hSpriteBitmap = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SPRITE));
HBITMAP hMaskBitmap = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_MASK));
HBITMAP hOldBuffBitmap= (HBITMAP)SelectObject(hBuffDC, hBuffBitmap);
HBRUSH hOldBrush= (HBRUSH)SelectObject(hBuffDC, (HBRUSH)GetStockObject(GRAY_BRUSH));
Rectangle(hBuffDC, 0, 0, 640, 480);
HBITMAP hOldSpriteBitmap= (HBITMAP)SelectObject(hMemDC, hMaskBitmap);
BitBlt(hBuffDC, 0, 0, 640, 480, hMemDC, 0, 0, SRCAND);
SelectObject(hMemDC, hSpriteBitmap);
BitBlt(hBuffDC, 0, 0, 640, 480, hMemDC, 0, 0, SRCPAINT);
BitBlt(hdc, 0, 0, 640, 480, hBuffDC, 0, 0, SRCCOPY);
SelectObject(hBuffDC, hOldBuffBitmap);
SelectObject(hMemDC, hOldSpriteBitmap);
SelectObject(hBuffDC, hOldBrush);
DeleteObject(hBuffBitmap);
DeleteObject(hSpriteBitmap);
DeleteObject(hMaskBitmap);
DeleteDC(hMemDC);
DeleteDC(hBuffDC);
}
return 0;
}
LRESULT WINAPI WinProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_KEYDOWN:
switch (wParam)
{
case VK_ESCAPE:
DestroyWindow(hWnd);
break;
}
return 0;
case WM_CLOSE:
DestroyWindow(hWnd);
return 0;
case WM_DESTROY:
int Res = ReleaseDC(hWnd, hdc); //Release main window device context before destroying window
DWORD err = GetLastError();
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}