一、基本思路
1.匀速运动:物体在每一个时刻的速度是相同的,即Vx和Vy保持不变;
2.关于下次的贴图坐标:
下次X的坐标=当前X的坐标 + Vx;
下次Y的坐标=当前Y的坐标 + Vy;
3.设小球匀速运动,碰到窗口边缘则反弹;
二、效果
三、代码如下
#include "stdafx.h"
#include <stdio.h>
HINSTANCE hInst;
HBITMAP bg,ball;
HDC hdc,mdc,bufdc;
HWND hWnd;
DWORD tPre,tNow,tCheck;
RECT rect;//用来存储内部窗口区域的矩形结构
int x=50,y=50,vx=20,vy=20;//小球的贴图坐标及速度分量
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
void MyPaint(HDC hdc);
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
MSG msg;
MyRegisterClass(hInstance);
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
while( msg.message!=WM_QUIT )
{
if( PeekMessage( &msg, NULL, 0,0 ,PM_REMOVE) )
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
else
{
tNow = GetTickCount();
if(tNow-tPre >= 40)
MyPaint(hdc);
}
}
return msg.wParam;
}
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEX wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = (WNDPROC)WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = NULL;
wcex.hCursor = NULL;
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = NULL;
wcex.lpszClassName = "canvas";
wcex.hIconSm = NULL;
return RegisterClassEx(&wcex);
}
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HBITMAP bmp;
hInst = hInstance;
hWnd = CreateWindow("canvas", "绘图窗口" , WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
if (!hWnd)
{
return FALSE;
}
MoveWindow(hWnd,10,10,600,450,true);
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
hdc = GetDC(hWnd);
mdc = CreateCompatibleDC(hdc);
bufdc = CreateCompatibleDC(hdc);
bmp = CreateCompatibleBitmap(hdc,640,480);
SelectObject(mdc,bmp);
bg = (HBITMAP)LoadImage(NULL,"bg.bmp",IMAGE_BITMAP,640,480,LR_LOADFROMFILE);
ball = (HBITMAP)LoadImage(NULL,"ball.bmp",IMAGE_BITMAP,52,26,LR_LOADFROMFILE);
GetClientRect(hWnd,&rect);//取得内部窗口区域的大小;利用rect中的内容判断判断小球移动是否碰到窗口边缘
MyPaint(hdc);
return TRUE;
}
//1.窗口贴图
//2.计算小球贴图坐标并判断小球是否碰到窗口边缘
void MyPaint(HDC hdc)
{
SelectObject(bufdc,bg);
BitBlt(mdc,0,0,640,480,bufdc,0,0,SRCCOPY);
SelectObject(bufdc,ball);
BitBlt(mdc,x,y,26,26,bufdc,26,0,SRCAND);
BitBlt(mdc,x,y,26,26,bufdc,0,0,SRCPAINT);
BitBlt(hdc,0,0,640,480,mdc,0,0,SRCCOPY);
x += vx;
if(x <= 0)
{
x = 0;
vx = -vx;
}
else if(x >= rect.right-26)
{
x = rect.right - 26;//rect.right:矩形右下角x点的坐标
vx = -vx;
}
y += vy;
if(y<=0)
{
y = 0;
vy = -vy;
}
else if(y >= rect.bottom-26)
{
y = rect.bottom - 26;
vy = -vy;
}
tPre = GetTickCount();
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_KEYDOWN:
if(wParam==VK_ESCAPE)
PostQuitMessage(0);
break;
case WM_DESTROY:
DeleteDC(mdc);
DeleteDC(bufdc);
DeleteObject(bg);
DeleteObject(ball);
ReleaseDC(hWnd,hdc);
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}