如何实现一个橡皮区矩形

时间： 2021-07-31 作者：daque

crecttracker是一个很有效的类，不妨经过挪用crecttracker::trackrubberband 相应wm_lbuttondown动静来创造一个橡皮区矩形。下例表白运用crecttracker挪动和重置视窗中的蓝色长圆的巨细是很简单的工作。开始，在文献档中证明一个crecttracker数据分子：class csampleview : public cview{…public :crecttracker m_tracker…}其次，在文书档案类的结构因变量中初始化crecttracker 东西：csampledoc:: csampledoc (){//initialize tracker position, size and style.m_tracker.m_rect.setrect (0, 0, 10, 10)m_tracker.m_nstyle=crecttracker:: resizeinside | crecttracker ::dottedline}而后，在ondraw因变量中画长圆和形迹矩形：void csampleview:: ondraw (cdc* pdc){csampledoc* pdoc=getdocument ()assert_valid (pdoc)//select blue brush into device context.cbrush brush (rgb (0, 0, 255))cbrush* poldbrush=pdc->selectobject (&brush)//draw ellipse in tracking rectangle.crect rcellipsepdoc->m_tracker.gettruerect (rcellipse)pdc->ellipse (rcellipse)//draw tracking rectangle.pdoc->m_tracker.draw (pdc)//select blue brush out of device context.pdc->selectobject (poldbrush)}结果，运用classwizard处置wm_lbuttondown动静，并减少下述代码。该段代码按照鼠标击键情景不妨拖放、挪动大概重置长圆的巨细。void csampleview::onlbuttondown (uint nflags, cpoint point){//get pointer to document.csampledoc* pdoc=getdocument ()assert_valid (pdoc)//if clicked on ellipse, drag or resize it.otherwise create a//rubber-band rectangle nd create a new ellipse.bool bresult=pdoc->m_tracker.hittest (point)!= crecttracker::hitnothing//tracker rectangle changed so update views.if (bresult){pdoc->m_tracker.track (this,point,true)pdoc->setmodifiedflag ()pdoc->updateallviews (null)}elsepdoc->m-tracker.trackrubberband(this,point,true)cview:: onlbuttondown (nflags,point)}

如何实现一个橡皮区矩形

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