GUI C++ - 绘制多行？ 初学者问题

问题描述

我想探索 C++ GUI 编码。

我下载了下面的示例并想修改突出显示的输出：“

为了添加第二行“Test. 3,2,1.”，我必须做什么以及为什么要做。我的方法不起作用，只产生了第一行。

// HelloWindowsDesktop.cpp
// compile with: /D_UNICODE /DUNICODE /DWIN32 /D_WINDOWS /c

#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <tchar.h>

// Global variables

// The main window class name.
static TCHAR szWindowClass[] = _T("DesktopApp");

// The string that appears in the application's title bar.
static TCHAR szTitle[] = _T("Test Title");

HINSTANCE hInst;

// Forward declarations of functions included in this code module:
LRESULT CALLBACK WndProc(HWND,UINT,WParaM,LParaM);

int CALLBACK WinMain(
    _In_ HINSTANCE hInstance,_In_opt_ HINSTANCE hPrevInstance,_In_ LPSTR     lpCmdLine,_In_ int       nCmdshow
)
{
    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 = LoadIcon(hInstance,IDI_APPLICATION);
    wcex.hCursor = LoadCursor(NULL,IDC_ARROW);
    wcex.hbrBackground = (HBrush)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance,IDI_APPLICATION);

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(NULL,_T("Call to RegisterClassEx Failed!"),_T("Test Program 00"),NULL);

        return 1;
    }

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

    // The parameters to CreateWindow explained:
    // szWindowClass: the name of the application
    // szTitle: the text that appears in the title bar
    // WS_OVERLAPPEDWINDOW: the type of window to create
    // CW_USEDEFAULT,CW_USEDEFAULT: initial position (x,y)
    // 500,100: initial size (width,length)
    // NULL: the parent of this window
    // NULL: this application does not have a menu bar
    // hInstance: the first parameter from WinMain
    // NULL: not used in this application
    HWND hWnd = CreateWindow(
        szWindowClass,szTitle,WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,500,100,NULL,hInstance,NULL
    );

    if (!hWnd)
    {
        MessageBox(NULL,_T("Call to CreateWindow Failed!"),_T("Test Program 01"),NULL);

        return 1;
    }

    // The parameters to ShowWindow explained:
    // hWnd: the value returned from CreateWindow
    // nCmdshow: the fourth parameter from WinMain
    ShowWindow(hWnd,nCmdshow);
    UpdateWindow(hWnd);

    // Main message loop:
    MSG msg;
    while (GetMessage(&msg,0))
    {
        TranslateMessage(&msg);
        dispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

//  FUNCTION: WndProc(HWND,LParaM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  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)
{
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR greeting[] = _T("Test. 1,3.");
    PAINTSTRUCT ps1;
    HDC hdc1;
    TCHAR greeting1[] = _T("Test. 3,1.");

    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint(hWnd,&ps);
        

        // Here your application is laid out.
        // For this introduction,we just print out "Hello,Windows desktop!" <-----------------------------------------------
        // in the top left corner.
        textout(hdc,5,greeting,_tcslen(greeting));
        EndPaint(hWnd,&ps);


        // CAN ONLY PAINT ONE???
        hdc1 = BeginPaint(hWnd,&ps1);
        textout(hdc1,6,greeting1,_tcslen(greeting1));

        // End application-specific layout section.
        EndPaint(hWnd,&ps1);


        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd,message,wParam,lParam);
        break;
    }

    return 0;
}

解决方法

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