C++实现鼠标选中框功能代码

bool m_IsMouseScelect;
CSprite m_RectImage;
RECT m_MouseRect;
void init()
{
m_IsMouseScelect = false;

m_RectImage.LoadImage(".\\cards\\temp\\RGB.bmp");
m_RectImage.SetAlpha(176);
m_RectImage.SetRGB(176,176,176);
}
void render()
{
if (m_IsMouseScelect &&
m_MouseRect.bottom>0 && m_MouseRect.left>0 && m_MouseRect.right>0 && m_MouseRect.top>0)
{
m_RectImage.SetViewPort(m_MouseRect);
m_RectImage.SetPosition(m_MouseRect.left,m_MouseRect.top);
m_RectImage.Render();
}
}
void HandleMessage(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_LBUTTONDOWN:
{
if (!m_IsMouseScelect)
{
m_IsMouseScelect=true;
m_MouseRect.left=LOWORD(lParam);
m_MouseRect.top=HIWORD(lParam);
}
}
break;
case WM_LBUTTONUP:
{
int swap=0;
if (m_MouseRect.left>m_MouseRect.right)
{
swap=m_MouseRect.left;
m_MouseRect.left=m_MouseRect.right;
m_MouseRect.right=swap;

}
if (m_MouseRect.top>m_MouseRect.bottom)
{
swap=m_MouseRect.top;
m_MouseRect.top=m_MouseRect.bottom;
m_MouseRect.bottom=swap;
}

m_IsMouseScelect=false;
m_MouseRect.bottom=0;
m_MouseRect.left=0;
m_MouseRect.right=0;
m_MouseRect.top=0;
}
break;
case WM_MOUSEMOVE:
{
if (m_IsMouseScelect)
{
m_MouseRect.right=LOWORD(lParam);
m_MouseRect.bottom=HIWORD(lParam);
}
}
break;
}