DropFiles

Visual C++ 2005 Express Edition
Windows Server 2003 SP1 Platform SDK
Windowsアプリケーション / 空のプロジェクト

CreateWindowExでWS_EX_ACCEPTFILESを指定する。

WM_DROPFILESでDragFinish((HDROP)wParam);を必ず行う。

ドラッグ・アンド・ドロップ

DropFiles.c

// マルチバイト文字セット

#pragma warning(disable:4996)

#include <windows.h>

#define APPNAME	"DropFiles"

// グローバル変数
static HINSTANCE	g_hInstance;
static char			*g_pcFile = NULL;

// プロトタイプ宣言
LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
void OnPaint(HWND hWnd);
void OnDropFiles(HWND hWnd, WPARAM wParam);
void SetTitle(HWND hWnd);

int WINAPI WinMain(
	HINSTANCE	hInstance,
	HINSTANCE	hPrevInstance,
	LPSTR		lpCmdLine,
	int			nCmdShow)
{
	char acAppName[] = APPNAME;
	WNDCLASSEX	wcex;
	HWND	hWnd;
	MSG		msg;

g_hInstance = hInstance;

if (lpCmdLine[0] != '\0') {
		g_pcFile = _strdup(lpCmdLine);
	}

wcex.cbSize			= sizeof(WNDCLASSEX);
	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= g_hInstance;
	wcex.hIcon			= LoadIcon(NULL, IDI_APPLICATION);
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW + 1);
	wcex.lpszMenuName	= NULL;
	wcex.lpszClassName	= acAppName;
	wcex.hIconSm		= LoadIcon(NULL, IDI_APPLICATION);
	RegisterClassEx(&wcex);

hWnd = CreateWindowEx(
		WS_EX_ACCEPTFILES,	// ExStyle
		acAppName,			// ClassName
		NULL,			// WindowName
		WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT,		// x
		CW_USEDEFAULT,		// y
		CW_USEDEFAULT,		// Width
		CW_USEDEFAULT,		// Height
		NULL,				// WndParent
		NULL,				// Menu
		g_hInstance,
		NULL);				// Param
	if (hWnd == NULL) {
		return 0;
	}

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

while (GetMessage(&msg, NULL, 0, 0)) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch (uMsg) {
	case WM_PAINT:
		OnPaint(hWnd);
		break;
	case WM_DROPFILES:
		OnDropFiles(hWnd, wParam);
		DragFinish((HDROP)wParam);
		break;
	case WM_CREATE:
		SetTitle(hWnd);
		break;
	case WM_DESTROY:
		if (g_pcFile != NULL) {
			free(g_pcFile);
		}
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, uMsg, wParam, lParam);
	}
	return 0;
}

void OnPaint(HWND hWnd)
{
	PAINTSTRUCT	ps;
	HDC		hdc;

hdc = BeginPaint(hWnd, &ps);

if (g_pcFile != NULL) {
		TextOut(hdc, 0, 0, g_pcFile, (int)strlen(g_pcFile));
	}

EndPaint(hWnd, &ps);
}

void OnDropFiles(HWND hWnd, WPARAM wParam)
{
	HDROP	hDrop;
	UINT	uiLen;

hDrop = (HDROP)wParam;
	uiLen = DragQueryFile(hDrop, 0, NULL, 0) + 1;

if (g_pcFile != NULL) {
		free(g_pcFile);
	}
	g_pcFile = (char *)malloc(uiLen);
	if (g_pcFile != NULL) {
		DragQueryFile(hDrop, 0, g_pcFile, uiLen);
	}

SetTitle(hWnd);
	InvalidateRect(hWnd, NULL, TRUE);
}

void SetTitle(HWND hWnd)
{
	char	acFname[_MAX_FNAME];
	char	acExt[_MAX_EXT];
	char	acTitle[512];

if (g_pcFile != NULL) {
		_splitpath(g_pcFile, NULL, NULL, acFname, acExt);
		strcpy(acTitle, acFname);
		strcat(acTitle, acExt);
	} else {
		strcpy(acTitle, "無題");
	}
	strcat(acTitle, " - "APPNAME);
	SetWindowText(hWnd, acTitle);
}