// GDI_CapturingAnImage.cpp : Defines the entry point for the application.
//

#include "framework.h"
#include "GDI_CapturingAnImage.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;                                // current instance
WCHAR szTitle[MAX_LOADSTRING];                  // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING];            // the main window class name

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
	_In_opt_ HINSTANCE hPrevInstance,
	_In_ LPWSTR    lpCmdLine,
	_In_ int       nCmdShow)
{
	UNREFERENCED_PARAMETER(hPrevInstance);
	UNREFERENCED_PARAMETER(lpCmdLine);

	// TODO: Place code here.

	// Initialize global strings
	LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadStringW(hInstance, IDC_GDICAPTURINGANIMAGE, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance(hInstance, nCmdShow))
	{
		return FALSE;
	}

	HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_GDICAPTURINGANIMAGE));

	MSG msg;

	// Main message loop:
	while (GetMessage(&msg, nullptr, 0, 0))
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return (int)msg.wParam;
}

//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEXW wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style = CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc = WndProc;
	wcex.cbClsExtra = 0;
	wcex.cbWndExtra = 0;
	wcex.hInstance = hInstance;
	wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_GDICAPTURINGANIMAGE));
	wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
	wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
	wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_GDICAPTURINGANIMAGE);
	wcex.lpszClassName = szWindowClass;
	wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

	return RegisterClassExW(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
	hInst = hInstance; // Store instance handle in our global variable

	HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

	if (!hWnd)
	{
		return FALSE;
	}

	ShowWindow(hWnd, nCmdShow);
	UpdateWindow(hWnd);

	return TRUE;
}

// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.
//
// Copyright (c) Microsoft Corporation. All rights reserved

//
//   FUNCTION: CaptureAnImage(HWND hWnd)
//
//   PURPOSE: Captures a screenshot into a window ,and then saves it in a .bmp file.
//
//   COMMENTS: 
//
//      Note: This function attempts to create a file called captureqwsx.bmp 
//        

int CaptureAnImage(HWND hWnd)
{
	HDC hdcScreen;
	HDC hdcWindow;
	HDC hdcMemDC = NULL;
	HBITMAP hbmScreen = NULL;
	BITMAP bmpScreen;
	DWORD dwBytesWritten = 0;
	DWORD dwSizeofDIB = 0;
	HANDLE hFile = NULL;
	char* lpbitmap = NULL;
	HANDLE hDIB = NULL;
	DWORD dwBmpSize = 0;

	// Retrieve the handle to a display device context for the client 
	// area of the window. 
	HWND mhWnd = FindWindow(NULL, L"Untitled - Notepad");
	hdcScreen = GetDC(mhWnd);
	hdcWindow = GetDC(hWnd);

	// Create a compatible DC, which is used in a BitBlt from the window DC.
	hdcMemDC = CreateCompatibleDC(hdcWindow);

	if (!hdcMemDC)
	{
		MessageBox(hWnd, L"CreateCompatibleDC has failed", L"Failed", MB_OK);
		goto done;
	}

	// Get the client area for size calculation.
	RECT rcClient;
	GetClientRect(hWnd, &rcClient);
	RECT rcSrcWnd;
	GetClientRect(mhWnd, &rcSrcWnd);
	// This is the best stretch mode.
	SetStretchBltMode(hdcWindow, HALFTONE);

	// The source DC is the entire screen, and the destination DC is the current window (HWND).
	if (!StretchBlt(hdcWindow,
		rcClient.left, rcClient.top,
		rcClient.right, rcClient.bottom,
		hdcScreen,
		0, 0-2 * GetSystemMetrics(SM_CYCAPTION),
		rcSrcWnd.right- rcSrcWnd.left, rcSrcWnd.bottom- rcSrcWnd.top,
		/*GetSystemMetrics(SM_CXSCREEN),
		GetSystemMetrics(SM_CYSCREEN),*/
		SRCCOPY))
	{
		MessageBox(hWnd, L"StretchBlt has failed", L"Failed", MB_OK);
		goto done;
	}

	// Create a compatible bitmap from the Window DC.
	hbmScreen = CreateCompatibleBitmap(hdcWindow, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top);

	if (!hbmScreen)
	{
		MessageBox(hWnd, L"CreateCompatibleBitmap Failed", L"Failed", MB_OK);
		goto done;
	}

	// Select the compatible bitmap into the compatible memory DC.
	SelectObject(hdcMemDC, hbmScreen);

	// Bit block transfer into our compatible memory DC.
	if (!BitBlt(hdcMemDC,
		0, 0,
		rcClient.right - rcClient.left, rcClient.bottom - rcClient.top,
		hdcWindow,
		0, 0,
		SRCCOPY))
	{
		MessageBox(hWnd, L"BitBlt has failed", L"Failed", MB_OK);
		goto done;
	}

	// Get the BITMAP from the HBITMAP.
	GetObject(hbmScreen, sizeof(BITMAP), &bmpScreen);

	BITMAPFILEHEADER   bmfHeader;
	BITMAPINFOHEADER   bi;

	bi.biSize = sizeof(BITMAPINFOHEADER);
	bi.biWidth = bmpScreen.bmWidth;
	bi.biHeight = bmpScreen.bmHeight;
	bi.biPlanes = 1;
	bi.biBitCount = 32;
	bi.biCompression = BI_RGB;
	bi.biSizeImage = 0;
	bi.biXPelsPerMeter = 0;
	bi.biYPelsPerMeter = 0;
	bi.biClrUsed = 0;
	bi.biClrImportant = 0;

	dwBmpSize = ((bmpScreen.bmWidth * bi.biBitCount + 31) / 32) * 4 * bmpScreen.bmHeight;

	// Starting with 32-bit Windows, GlobalAlloc and LocalAlloc are implemented as wrapper functions that 
	// call HeapAlloc using a handle to the process's default heap. Therefore, GlobalAlloc and LocalAlloc 
	// have greater overhead than HeapAlloc.
	hDIB = GlobalAlloc(GHND, dwBmpSize);
	lpbitmap = (char*)GlobalLock(hDIB);

	// Gets the "bits" from the bitmap, and copies them into a buffer 
	// that's pointed to by lpbitmap.
	GetDIBits(hdcWindow, hbmScreen, 0,
		(UINT)bmpScreen.bmHeight,
		lpbitmap,
		(BITMAPINFO*)& bi, DIB_RGB_COLORS);

	// A file is created, this is where we will save the screen capture.
	hFile = CreateFile(L"captureqwsx.bmp",
		GENERIC_WRITE,
		0,
		NULL,
		CREATE_ALWAYS,
		FILE_ATTRIBUTE_NORMAL, NULL);

	// Add the size of the headers to the size of the bitmap to get the total file size.
	dwSizeofDIB = dwBmpSize + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

	// Offset to where the actual bitmap bits start.
	bmfHeader.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER);

	// Size of the file.
	bmfHeader.bfSize = dwSizeofDIB;

	// bfType must always be BM for Bitmaps.
	bmfHeader.bfType = 0x4D42; // BM.

	WriteFile(hFile, (LPSTR)& bmfHeader, sizeof(BITMAPFILEHEADER), &dwBytesWritten, NULL);
	WriteFile(hFile, (LPSTR)& bi, sizeof(BITMAPINFOHEADER), &dwBytesWritten, NULL);
	WriteFile(hFile, (LPSTR)lpbitmap, dwBmpSize, &dwBytesWritten, NULL);

	// Unlock and Free the DIB from the heap.
	GlobalUnlock(hDIB);
	GlobalFree(hDIB);

	// Close the handle for the file that was created.
	CloseHandle(hFile);

	// Clean up.
done:
	DeleteObject(hbmScreen);
	DeleteObject(hdcMemDC);
	ReleaseDC(NULL, hdcScreen);
	ReleaseDC(hWnd, hdcWindow);

	return 0;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE: Processes messages for the main window.
//
//  WM_COMMAND  - process the application menu
//  WM_PAINT    - Paint the main window
//  WM_DESTROY  - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
	case WM_COMMAND:
	{
		int wmId = LOWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
	}
	break;
	case WM_PAINT:
	{

		PAINTSTRUCT ps;
		HDC hdc = BeginPaint(hWnd, &ps);
		CaptureAnImage(hWnd);
		EndPaint(hWnd, &ps);
	}
	break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	UNREFERENCED_PARAMETER(lParam);
	switch (message)
	{
	case WM_INITDIALOG:
		return (INT_PTR)TRUE;

	case WM_COMMAND:
		if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
		{
			EndDialog(hDlg, LOWORD(wParam));
			return (INT_PTR)TRUE;
		}
		break;
	}
	return (INT_PTR)FALSE;
}