圖形旋轉90度計算

1原地旋轉90度

    double cx = (bBox.top + bBox.bottom) * 0.5;;
    double cy = bBox.left + fabs(bBox.bottom - bBox.top) * 0.5;;
    double dRotateRadian = -90.0 / 360.0 * TWO_PI;
    double dCos = cos(dRotateRadian);
    double dSin = sin(dRotateRadian);
    double dtx = -dCos * cx + dSin * cy + cx;
    double dty = -dSin * cx - dCos * cy + cy;
    CBTransformer rotato(dCos, -dSin, dtx, dSin, dCos, dty);

2中心旋轉90度

    double cx = (bBox.left + bBox.right) * 0.5;
    double cy = (bBox.top + bBox.bottom) * 0.5;
    double dRotateRadian = -90.0 / 360.0 * TWO_PI;
    double dCos = cos(dRotateRadian);
    double dSin = sin(dRotateRadian);
    double dtx = -dCos * cx + dSin * cy + cx;
    double dty = -dSin * cx - dCos * cy + cy;
    CBTransformer rotato(dCos, -dSin, dtx, dSin, dCos, dty);
    emptyTransformer.transformedBy(&rotato);

3中心旋轉180度

CBTransformer rotateTranf(-1, 0, boxRect.left + boxRect.right, 0, -1, boxRect.top + boxRect.bottom);

4中心旋轉其他角度

    CBRect bbox = pDoc->getSelectionBBox();
    double cx = (bbox.left + bbox.right) * 0.5;
    double cy = (bbox.top + bbox.bottom) * 0.5;
    double dRotateRadian = m_dAngle / 360.0 * TWO_PI;
    double dCos = cos(dRotateRadian);
    double dSin = sin(dRotateRadian);
    double dtx = -dCos * cx + dSin * cy + cx;
    double dty = -dSin * cx - dCos * cy + cy;
    CBTransformer rotateTranf(dCos, -dSin, dtx, dSin, dCos, dty);