Windows-classic-samples/Samples/Win7Samples/Touch/MTScratchpadWMTouch/cpp/MTScratchpadWMTouch.cpp

// 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.

// MTScratchpadWMTouch application.
// Description:
//  Inside the application window, user can draw using multiple fingers
//  at the same time. The trace of each finger is drawn using different
//  color. The primary finger trace is always drawn in black, and the
//  remaining traces are drawn by rotating through the following colors:
//  red, blue, green, magenta, cyan and yellow.
//
// Purpose:
//  This sample demonstrates handling of the multi-touch input inside
//  a Win32 application using WM_TOUCH window message:
//  - Registering a window for multi-touch using RegisterTouchWindow,
//    IsTouchWindow.
//  - Handling WM_TOUCH messages and unpacking their parameters using
//    GetTouchInputInfo and CloseTouchInputHandle; reading touch contact
//    data from the TOUCHINPUT structure.
//  - Unregistering a window for multi-touch using UnregisterTouchWindow.
//  In addition, the sample also shows how to store and draw strokes
//  entered by user, using the helper classes CStroke and
//  CStrokeCollection.
//
// MTScratchpadWMTouch.cpp : Defines the entry point for the application.

// Windows header files
#include <windows.h>
#include <windowsx.h>

// C RunTime header files
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <assert.h>
#define ASSERT assert

// Application header files
#include "resource.h"
#include "Stroke.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE g_hInst;                              // Current module instance
WCHAR g_wszTitle[MAX_LOADSTRING];               // The title bar text
WCHAR g_wszWindowClass[MAX_LOADSTRING];         // The main window class name
CStrokeCollection g_StrkColFinished;            // Finished strokes, the finger has been lifted
CStrokeCollection g_StrkColDrawing;             // Strokes that are currently being drawn

///////////////////////////////////////////////////////////////////////////////
// Drawing and WM_TOUCH helpers

// Returns color for the newly started stroke.
// in:
//      bPrimaryContact     boolean, whether the contact is the primary contact
// returns:
//      COLORREF, color of the stroke
COLORREF GetTouchColor(bool bPrimaryContact)
{
    static int g_iCurrColor = 0;    // Rotating secondary color index
    static COLORREF g_arrColor[] =  // Secondary colors array
    {
        RGB(255, 0, 0),             // Red
        RGB(0, 255, 0),             // Green
        RGB(0, 0, 255),             // Blue
        RGB(0, 255, 255),           // Cyan
        RGB(255, 0, 255),           // Magenta
        RGB(255, 255, 0)            // Yellow
    };

    COLORREF color;
    if (bPrimaryContact)
    {
        // The primary contact is drawn in black.
        color = RGB(0,0,0);         // Black
    }
    else
    {
        // Take current secondary color.
        color = g_arrColor[g_iCurrColor];

        // Move to the next color in the array.
        g_iCurrColor = (g_iCurrColor + 1) % (sizeof(g_arrColor)/sizeof(g_arrColor[0]));
    }

    return color;
}

// Extracts contact point in client area coordinates (pixels) from a TOUCHINPUT
// structure. TOUCHINPUT structure uses 100th of a pixel units.
// in:
//      hWnd        window handle
//      ti          TOUCHINPUT structure (info about contact)
// returns:
//      POINT with contact coordinates
POINT GetTouchPoint(HWND hWnd, const TOUCHINPUT& ti)
{
    POINT pt;
    pt.x = ti.x / 100;
    pt.y = ti.y / 100;
    ScreenToClient(hWnd, &pt);
    return pt;
}

// Extracts contact ID from a TOUCHINPUT structure.
// in:
//      ti          TOUCHINPUT structure (info about contact)
// returns:
//      ID assigned to the contact
inline int GetTouchContactID(const TOUCHINPUT& ti)
{
    return ti.dwID;
}

///////////////////////////////////////////////////////////////////////////////
// WM_TOUCH message handlers

// Handler for touch-down message.
// Starts a new stroke and assigns a color to it.
// in:
//      hWnd        window handle
//      ti          TOUCHINPUT structure (info about contact)
void OnTouchDownHandler(HWND hWnd, const TOUCHINPUT& ti)
{
    // Extract contact info: point of contact and ID
    POINT pt = GetTouchPoint(hWnd, ti);
    int iCursorId = GetTouchContactID(ti);

    // We have just started a new stroke, which must have an ID value unique
    // among all the strokes currently being drawn. Check if there is a stroke
    // with the same ID in the collection of the strokes in drawing.
    ASSERT(g_StrkColDrawing.FindStrokeById(iCursorId) == -1);

    // Create new stroke, add point and assign a color to it.
    CStroke* pStrkNew = new CStroke;
    pStrkNew->Add(pt);
    pStrkNew->SetColor(GetTouchColor((ti.dwFlags & TOUCHEVENTF_PRIMARY) != 0));
    pStrkNew->SetId(iCursorId);

    // Add new stroke to the collection of strokes in drawing.
    g_StrkColDrawing.Add(pStrkNew);
}

// Handler for touch-move message.
// Adds a point to the stroke in drawing and draws new stroke segment.
// in:
//      hWnd        window handle
//      ti          TOUCHINPUT structure (info about contact)
void OnTouchMoveHandler(HWND hWnd, const TOUCHINPUT& ti)
{
    // Extract contact info: contact ID
    int iCursorId = GetTouchContactID(ti);

    // Find the stroke in the collection of the strokes in drawing.
    int iStrk = g_StrkColDrawing.FindStrokeById(iCursorId);
    ASSERT((iStrk >= 0) && (iStrk < g_StrkColDrawing.Count()));

    // Extract contact info: contact point
    POINT pt;
    pt = GetTouchPoint(hWnd, ti);

    // Add contact point to the stroke
    g_StrkColDrawing[iStrk]->Add(pt);

    // Partial redraw: only the last line segment
    HDC hDC = GetDC(hWnd);
    g_StrkColDrawing[iStrk]->DrawLast(hDC);
    ReleaseDC(hWnd, hDC);
}

// Handler for touch-up message.
// Finishes the stroke and moves it to the collection of finished strokes.
// in:
//      hWnd        window handle
//      ti          TOUCHINPUT structure (info about contact)
void OnTouchUpHandler(HWND hWnd, const TOUCHINPUT& ti)
{
    // Extract contact info: contact ID
    int iCursorId = GetTouchContactID(ti);

    // Find the stroke in the collection of the strokes in drawing.
    int iStrk = g_StrkColDrawing.FindStrokeById(iCursorId);
    ASSERT((iStrk >= 0) && (iStrk < g_StrkColDrawing.Count()));

    // Add this stroke to the collection of finished strokes.
    g_StrkColFinished.Add(g_StrkColDrawing[iStrk]);

    // Remove this stroke from the collection of strokes in drawing.
    g_StrkColDrawing.Remove(iStrk);

    // Request full redraw.
    InvalidateRect(hWnd, NULL, FALSE);
}

///////////////////////////////////////////////////////////////////////////////
// Application framework

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

// Win32 application main entry point function.
// This function is generated by Visual Studio app wizard.
// in:
//      hInstance       handle of the application instance
//      hPrevInstance   not used, always NULL
//      lpCmdLine       command line for the application, null-terminated string
//      nCmdShow        how to show the window
int APIENTRY wWinMain(HINSTANCE hInstance,
                     HINSTANCE /* hPrevInstance */,
                     LPWSTR    /* lpCmdLine */,
                     int       nCmdShow)
{
    MSG msg;

    // Initialize global strings
    LoadString(hInstance, IDS_APP_TITLE, g_wszTitle, MAX_LOADSTRING);
    LoadString(hInstance, IDC_MTSCRATCHPADWMTOUCH, g_wszWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

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

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

    return (int) msg.wParam;
}

// Registers the window class of the application.
// This function is generated by Visual Studio app wizard.
// This function and its usage are only necessary if you want this code
// to be compatible with Win32 systems prior to the 'RegisterClassEx'
// function that was added to Windows 95. It is important to call this function
// so that the application will get 'well formed' small icons associated
// with it.
// in:
//      hInstance       handle to the instance of the application
// returns:
//      class atom that uniquely identifies the window class
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEX 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          = 0;
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = g_wszWindowClass;
    wcex.hIconSm        = 0;

    return RegisterClassEx(&wcex);
}

// Saves instance handle and creates main window
// This function is generated by Visual Studio app wizard; added code for
// registering the app window for multi-touch.
// In this function, we save the instance handle in a global variable,
// create and display the main program window, and also register the window
// for receiving multi-touch messages.
// in:
//      hInstance       handle to the instance of the application
//      nCmdShow        how to show the window
// returns:
//      boolean, succeeded or failed to create the window
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    HWND hWnd;

    g_hInst = hInstance; // Store instance handle in our global variable

    // Create the application window
    hWnd = CreateWindow(g_wszWindowClass, g_wszTitle, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
    if (!hWnd)
    {
        return FALSE;
    }

    // Register application window for receiving multi-touch input. Use default settings.
    if (!RegisterTouchWindow(hWnd, 0))
    {
        MessageBox(hWnd, L"Cannot register application window for multi-touch input", L"Error", MB_OK);
        return FALSE;
    }
    ASSERT(IsTouchWindow(hWnd, NULL));

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

    return TRUE;
}

// Processes messages for the main window:
//      WM_COMMAND  - process the application menu
//      WM_PAINT    - paint the main window
//      WM_TOUCH    - multi-touch message
//      WM_DESTROY  - post a quit message and return
// This function is generated by Visual Studio app wizard; added WM_PAINT, WM_TOUCH
// and WM_DESTROY code.
// in:
//      hWnd        window handle
//      message     message code
//      wParam      message parameter (message-specific)
//      lParam      message parameter (message-specific)
// returns:
//      the result of the message processing and depends on the message sent
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId;
    PAINTSTRUCT ps;
    HDC hdc;

    switch (message)
    {
        case WM_COMMAND:
            wmId = LOWORD(wParam);
            // Parse the menu selections:
            switch (wmId)
            {
                case IDM_EXIT:
                    DestroyWindow(hWnd);
                    break;
                default:
                    return DefWindowProc(hWnd, message, wParam, lParam);
            }
            break;

        case WM_PAINT:
            hdc = BeginPaint(hWnd, &ps);
            // Full redraw: draw complete collection of finished strokes and
            // also all the strokes that are currently in drawing.
            g_StrkColFinished.Draw(hdc);
            g_StrkColDrawing.Draw(hdc);
            EndPaint(hWnd, &ps);
            break;

        // WM_TOUCH message handlers
        case WM_TOUCH:
            {
                // WM_TOUCH message can contain several messages from different contacts
                // packed together.
                // Message parameters need to be decoded:
                unsigned int numInputs = (unsigned int) wParam; // Number of actual per-contact messages
                TOUCHINPUT* ti = new TOUCHINPUT[numInputs]; // Allocate the storage for the parameters of the per-contact messages
                if (ti == NULL)
                {
                    break;
                }
                // Unpack message parameters into the array of TOUCHINPUT structures, each
                // representing a message for one single contact.
                if (GetTouchInputInfo((HTOUCHINPUT)lParam, numInputs, ti, sizeof(TOUCHINPUT)))
                {
                    // For each contact, dispatch the message to the appropriate message
                    // handler.
                    for (unsigned int i = 0; i < numInputs; ++i)
                    {
                        if (ti[i].dwFlags & TOUCHEVENTF_DOWN)
                        {
                            OnTouchDownHandler(hWnd, ti[i]);
                        }
                        else if (ti[i].dwFlags & TOUCHEVENTF_MOVE)
                        {
                            OnTouchMoveHandler(hWnd, ti[i]);
                        }
                        else if (ti[i].dwFlags & TOUCHEVENTF_UP)
                        {
                            OnTouchUpHandler(hWnd, ti[i]);
                        }
                    }
                }
                CloseTouchInputHandle((HTOUCHINPUT)lParam);
                delete [] ti;
            }
            break;

        case WM_DESTROY:
            // Clean up of application data: unregister window for multi-touch.
            if (!UnregisterTouchWindow(hWnd))
            {
                MessageBox(NULL, L"Cannot unregister application window for touch input", L"Error", MB_OK);
            }
            ASSERT(!IsTouchWindow(hWnd, NULL));
            // Destroy all the strokes
            {
                int i;
                for (i = 0; i < g_StrkColDrawing.Count(); ++i)
                {
                    delete g_StrkColDrawing[i];
                }
                for (i = 0; i < g_StrkColFinished.Count(); ++i)
                {
                    delete g_StrkColFinished[i];
                }
            }
            PostQuitMessage(0);
            break;

        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}