Rectangle Functions

前言

在GDI绘图刷新无效区域时, 如果进行粗略的矩形计算, 要用到矩形操作的API.

为了减小图形的闪烁，可以一小块一小块的调用InvalidateRect.

验证代码

void fnTest() {    /**    <<Rectangle Functions>>    RECT操作API共11个    SetRectEmpty ///< 设置RECT为空    SetRect ///< 设置RECT值    CopyRect ///< RECT之间的拷贝    EqualRect ///< 矩形是否相等    IsRectEmpty ///< 矩形是否为空    OffsetRect ///< 将矩形整体移动(x,y)的偏移    PtInRect ///< 判断点pt是否在矩形内    InflateRect ///< 增加或减小矩形的宽度和高度, 左右均变化dx, 上下均变化dy    IntersectRect ///< 求2个矩形的交集, 如果没有交集, 返回空RECT        /// 矩形减法, 这个用起来有限制, 被减去的矩形2必须完全遮挡住矩形1的一边(左面，右面，上面 or 下面)    /// 而且必须有一个坐标必须和原坐标相同    /// 这API真挫, 可以自己封装一个SubtractRectEx, 先求交集, 然后再调用这个API    SubtractRect ///< 矩形减法    UnionRect ///< 求包含2个矩形的最小矩形    */    BOOL bRc = FALSE;    RECT rtSrc;    RECT rtSrc1;    RECT rtDst;    POINT pt;    SetRectEmpty(&rtDst);    SetRect(&rtSrc, 100, 101, 200, 201);    bRc = CopyRect(&rtDst, &rtSrc);    assert(bRc);    bRc = EqualRect(&rtDst, &rtSrc);    assert(bRc);    SetRectEmpty(&rtDst);    bRc = EqualRect(&rtDst, &rtSrc);    assert(!bRc);    SetRectEmpty(&rtDst);    bRc = IsRectEmpty(&rtDst);    assert(bRc);    bRc = IsRectEmpty(&rtSrc);    assert(!bRc);    CopyRect(&rtDst, &rtSrc);    OffsetRect(&rtSrc, 10, 10);    pt.x = 100;    pt.y = 100;    bRc = PtInRect(&rtSrc, pt);    assert(!bRc);    bRc = SetRect(&rtSrc, 100, 101, 200, 201);    assert(bRc);    bRc = InflateRect(&rtSrc, -1, -1);    assert(bRc);    SetRect(&rtSrc, 100, 100, 200, 200);    SetRect(&rtSrc1, 101, 101, 201, 201);    bRc = IntersectRect(&rtDst, &rtSrc, &rtSrc1);    if (!bRc) {        OutputDebugStringA("没有交集");    }    /*    The function only subtracts the rectangle specified by lprcSrc2     from the rectangle specified by lprcSrc1 when the rectangles intersect     completely in either the x- or y-direction.         For example,     if *lprcSrc1 has the coordinates (10,10,100,100) and *lprcSrc2 has the coordinates (50,50,150,150),     the function sets the coordinates of the rectangle pointed to by lprcDst to (10,10,100,100).         If *lprcSrc1 has the coordinates (10,10,100,100) and *lprcSrc2 has the coordinates (50,10,150,150),     however, the function sets the coordinates of the rectangle pointed to by lprcDst to (10,10,50,100).     */    SetRect(&rtSrc, 10, 10, 100, 100);    SetRect(&rtSrc1, 50, 50, 150, 150);    bRc = SubtractRect(&rtDst, &rtSrc, &rtSrc1);    SetRect(&rtSrc, 10, 10, 100, 100);    SetRect(&rtSrc1, 50, 10, 150, 150);    bRc = SubtractRect(&rtDst, &rtSrc, &rtSrc1);    SetRect(&rtSrc, 10, 10, 100, 100);    SetRect(&rtSrc1, 10, 20, 150, 150);    SetRectEmpty(&rtDst);    bRc = SubtractRect(&rtDst, &rtSrc, &rtSrc1);    SetRect(&rtSrc, 10, 10, 50, 50);    SetRect(&rtSrc1, 52, 52, 100, 100);    SetRectEmpty(&rtDst);    bRc = UnionRect(&rtDst, &rtSrc, &rtSrc1);}