centerW copyFrom cxWnd cyWnd dpiX dpiY GiTransformImpl matD2M matD2W matM2D matM2W matW2D matW2M maxViewScale minViewScale rectLimitsW tmpCenterW tmpViewScale updateTransforms viewScale w2dx w2dy ydown zoomChanged zoomEnabled zoomNoAdjust zoomPanAdjust zoomTimes

viewScale float GiTransformImpl::viewScale 显示比例，默认100%