VC MFC 屏幕画图桌面下雪效果源码圣诞礼物

最新推荐文章于 2021-05-24 01:02:13 发布

原创最新推荐文章于 2021-05-24 01:02:13 发布 · 2.3k 阅读

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CC 4.0 BY-SA版权

文章标签：

#mfc #dll #thread #delete #null #struct

本文介绍了一段使用MFC编写的DLL代码，实现了屏幕下雪的视觉效果。通过创建雪花结构体，定义了雪花的位置、颜色和移动方向。在DLL的主函数中，使用GetDC获取屏幕设备上下文，不断更新雪花位置并绘制，最终达到动态下雪的效果。用户可以通过按CTRL+F12组合键结束程序。

///.h
#pragma once

class HSnow
{
public:
    HSnow(void);
    ~HSnow(void);
    void Snow();

public:
    struct    HSnw{
        int    prex;
        int    prey;
        int    x;
        int y;
        COLORREF    clr;
        COLORREF    preclr;
        int    stepx;
        int    stepy;
    };

    void    Init(void) ;
private:
    int        nMaxSnow;
    HSnw*    snow;
    int        maxW;    //screen width
    int        maxH;    //screen height
};

//// dllmain

#include "stdafx.h"

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD ul_reason_for_call,
                       LPVOID lpReserved
                    )
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
        srand( UINT(0) ); break;
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

//////.cpp

#include "StdAfx.h"
#include "HSnow.h"

HSnow::HSnow(void)
{
snow = NULL;
nMaxSnow = 500;
}

HSnow::~HSnow(void)
{
    if( snow ){
        delete [] snow;
    }
}

void HSnow::Init()
{
    if( nMaxSnow <= 0 )    { return ;}
    if( snow )            { delete [] snow; snow = NULL;}
    snow = new HSnw[nMaxSnow];
    HDC    dc = GetDC(0);
    maxW    = ::GetSystemMetrics( SM_CXSCREEN );
    maxH    = ::GetSystemMetrics( SM_CYSCREEN );
    for( int i = 0; i < nMaxSnow; i++ ){
        snow[i].x = snow[i].prex = rand() % maxW;
        snow[i].y = snow[i].prey = rand() % maxH;
        snow[i].preclr = snow[i].clr = ::GetPixel( dc,snow[i].x,snow[i].y );
        snow[i].stepx = (rand()%2==1)?1:-1;
        snow[i].stepy = (rand() % 5)+1;
    }
    ::ReleaseDC(0,dc);
}

void HSnow::Snow(void)
{
    if( nMaxSnow <= 0 ){ return; }
    HDC    dc = GetDC(0);
    while( true )
    {
        if(GetAsyncKeyState(VK_CONTROL) && GetAsyncKeyState(VK_F12 ))
        {
            break;    ////按CTRL+F12 结束
        }
        for( int i = 0; i<nMaxSnow; i++ )
        {

            SetPixel( dc, snow[i].prex,snow[i].prey, snow[i].preclr );

            snow[i].prex = snow[i].x ;
            snow[i].prey = snow[i].y ;
            snow[i].preclr = snow[i].clr ;

            snow[i].x += snow[i].stepx ;
            snow[i].y += snow[i].stepy ;
            if( snow[i].x < 0 ) { snow[i].x = maxW ; }
            if( snow[i].x >maxW){ snow[i].x = 0    ;    }
            if( snow[i].y < 0 )    { snow[i].y = maxH ; }
            if( snow[i].y >maxH){ snow[i].y = 0    ;    }

snow[i].clr = GetPixel( dc, snow[i].x, snow[i].y ) ;

if( 0xffffff - snow[i].clr < 5000 ){ continue; } ///和白色相近就忽略

SetPixel( dc, snow[i].x, snow[i].y , 0xffffff ); ////设置雪点

if( rand()%4 != 1 ){ continue; }

            ////设置积雪点
            int    sx = snow[i].x + rand()%3;
            int    sy = snow[i].y + rand()%3;
            if( sx>maxW || sx<0 || sy>maxH || sy<0 ){ continue;    }
            COLORREF    sClr = GetPixel(dc,sx,sy);
            if( abs(0xffffff-sClr)<5000 || abs( snow[i].clr - sClr ) > 600000 )    //如果颜色相差太大就设置积雪点
            {
                SetPixel(dc,sx,sy,0xffffff);
            }
        }

Sleep(1);
}

::ReleaseDC(0,dc);
::InvalidateRect(0,0,1);
}

void DRun(void)
{
    HSnow    snow;
    snow.Init();
    snow.Snow();
}

///.def
EXPORTS
DRun

弄好了，这是写的DLL，不是可执行，要用RUNDLL32来运行
Rundll32 HSnow.dll,DRun
呵呵，终于看出来这样的效果，激动啊