//***********************************************************************//
// //
// - "Talk to me like I'm a 3 year old!" Programming Lessons - //
// //
// $Author: Ben Humphrey digiben@gametutorials.com //
// //
// $Program: DragAndDrop //
// //
// $Description: Recognizes files that are drag and dropped //
// //
//***********************************************************************//
#include <iostream> // Include the standard C++ file
#include <windows.h> // We need to include windows.h
using namespace std; // Include the standard namespace
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
//
// This tutorial shows you how to add functionality to Win32 programs so
// that the user can drag and drop files onto your applications. Just to
// simplify the code as much as possible we will have this tutorial just
// print out the file names that were drag onto the application in a message
// box.
//
// The basic things that you need in order to allow drag and dropped files is
// the following:
//
// 1) "CreateWindowEx()" instead of "CreateWindow()"
// 2) Add WS_EX_ACCEPTFILES as the "Ex" style
// 3) Handle the WM_DROPFILES windows message in the WndProc()
// 4) Convert the wParam from the WM_DROPFILES message to an HDROP
// 5) Call DragQueryFile() to get how many files were drag and dropped
// 6) Call DragQueryFile() for as many files were drop to get each file name
// 7) Call DragFinish() to destroy the extra allocated memory
//
// That it! Simple huh? Most professional applications should be able to
// handle this functionality so be sure to add this to your programming tool
// belt.
//
// The code for this tutorial was taken primarily from the base code of the
// "Animation" tutorial, but has been stripped down considerably so there will
// be no "NEW" tags.
//
// Check out the simple code below for more explanation.
//
//
// Create a define for our window height
#define HEIGHT 480
// Create a define for our window width
#define WIDTH 640
// This function takes in a wParam from the WM_DROPFILES message and
// prints all the files to a message box.
void HandleFiles(WPARAM wParam)
{
// DragQueryFile() takes a LPWSTR for the name so we need a TCHAR string
TCHAR szName[MAX_PATH];
// Here we cast the wParam as a HDROP handle to pass into the next functions
HDROP hDrop = (HDROP)wParam;
// This functions has a couple functionalities. If you pass in 0xFFFFFFFF in
// the second parameter then it returns the count of how many filers were drag
// and dropped. Otherwise, the function fills in the szName string array with
// the current file being queried.
int count = DragQueryFile(hDrop, 0xFFFFFFFF, szName, MAX_PATH);
// Here we go through all the files that were drag and dropped then display them
for(int i = 0; i < count; i++)
{
// Grab the name of the file associated with index "i" in the list of files dropped.
// Be sure you know that the name is attached to the FULL path of the file.
DragQueryFile(hDrop, i, szName, MAX_PATH);
// Bring up a message box that displays the current file being processed
MessageBox(GetForegroundWindow(), szName, "Current file received", MB_OK);
}
// Finally, we destroy the HDROP handle so the extra memory
// allocated by the application is released.
DragFinish(hDrop);
}
// Here is the WndProc that handles all the messages
LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
// Check which message was passed in
switch (iMsg)
{
// This is the message given when people drag files to the window
case WM_DROPFILES:
// Call our function we created to display all the files.
// We pass the wParam because it's the HDROP handle.
HandleFiles(wParam);
break;
// This message is sent when the window is destroyed
case WM_DESTROY:
// Tell our main program loop to quit
PostQuitMessage(0);
break;
}
// Process/handle the default messages
return DefWindowProc (hwnd, iMsg, wParam, lParam);
}
// This creates our window and handles our main loop
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
// Create the handle to the window.
HWND hwnd;
// Create the variable to hold the window messages
MSG msg;
// Create the structure that holds the attributes of the window.
WNDCLASSEX wndclass = {sizeof (wndclass), CS_HREDRAW | CS_VREDRAW, WndProc, 0, 0, hInstance,
LoadIcon (NULL, IDI_WINLOGO), LoadCursor (NULL, IDC_ARROW), (HBRUSH) GetStockObject (WHITE_BRUSH),
NULL, "GameTutorials", LoadIcon (NULL, IDI_WINLOGO)};
// Register the window class with the operating system
RegisterClassEx (&wndclass);
// This is the style that we need to add to our CreateWindowEx() function to accept files
DWORD dwStyleEx = WS_EX_ACCEPTFILES;
// Now, we actually create the window
hwnd = CreateWindowEx(dwStyleEx, // The style for accepting files
"GameTutorials", // Window class name
"DragAndDrop - Drag files to me!", // Window's Title
WS_OVERLAPPEDWINDOW, // Window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
WIDTH, // Here we pass in our desired width (800)
HEIGHT, // Here we pass in our desired height (600)
NULL, // This is the parent window handle.
NULL, // This is the window menu handle
hInstance, // This is the programs instance handle.
NULL); // We don't want to pass any extra data in, so NULL
// This shows our window.
ShowWindow (hwnd, iCmdShow);
// This pretty much paints our window to the screen.
UpdateWindow (hwnd);
// Here is our main loop.
while (1)
{
// Check if there is a window message and remove it from the queue
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
// If the message was to quit, break out of the while loop
if(msg.message == WM_QUIT) break;
// This Translates messages so windows understands them.
TranslateMessage (&msg);
// This sends the messages to the WndProc().
DispatchMessage (&msg);
}
else
{
Sleep(1);
}
}
// Unregister the window class with the operating system
UnregisterClass("GameTutorials",hInstance);
// Quit the program
return (int)msg.wParam ;
}