C#学习笔记TreeView ClassWord文件下载.docx

C#学习笔记TreeView ClassWord文件下载.docx

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Syntax:

publicclassTreeView:

Control

Remarks:

TheNodescollectionholdsalltheTreeNodeobjectsthatareassignedtotheTreeViewcontrol.Thetreenodesinthiscollectionarereferredtoastheroottreenodes.Anytreenodethatissubsequentlyaddedtoaroottreenodeisreferredtoasachildnode.BecauseeachTreeNodecancontainacollectionofotherTreeNodeobjects,youmightfinditdifficulttodetermineyourlocationinthetreestructurewhenyouiteratethroughthecollection.YoucanparsetheTreeNode.FullPathstringbyusingthePathSeparatorstringvaluetodeterminewhereaTreeNodelabelbeginsandends.

YoucandisplayimagesnexttothetreenodesbyassigninganImageListtotheImageListpropertyandreferencingtheindexvalueofanImageintheImageListtoassignthatImage.Usethefollowingpropertiestoassignimages:

·

SettheImageIndexpropertytotheindexvalueoftheImagethatyouwanttodisplaywhenatreenodeisnotselected.

SettheSelectedImageIndexpropertytotheindexvalueoftheImagethatyouwanttodisplaywhenatreenodeisselected.

TheimagesreferencedbytheImageIndexandSelectedImageIndexpropertyvaluesarethedefaultimagesdisplayedbyallthetreenodesthatareassignedtotheNodescollection.IndividualtreenodescanoverridethedefaultimagesbysettingtheTreeNode.ImageIndexandTreeNode.SelectedImageIndexproperties.

Treenodescanbeexpandedtodisplaythenextlevelofchildtreenodes.TheusercanexpandtheTreeNodebyclickingtheplus-sign（+）button,ifoneisdisplayednexttotheTreeNode,oryoucanexpandtheTreeNodebycallingtheTreeNode.Expandmethod.ToexpandallthechildtreenodelevelsintheNodescollection,calltheExpandAllmethod.YoucancollapsethechildTreeNodelevelbycallingtheTreeNode.Collapsemethod,ortheusercanpresstheminus-sign（-）button,ifoneisdisplayednexttotheTreeNode.YoucanalsocalltheTreeNode.Togglemethodtoalternatebetweentheexpandedandcollapsedstates.

Treenodescanoptionallydisplaycheckboxes.Todisplaythecheckboxes,settheCheckBoxespropertyoftheTreeViewtotrue.TheCheckedpropertyissettotruefortreenodesthatareinacheckedstate.

Note:

SettingtheTreeNode.CheckedpropertyfromwithintheBeforeCheckorAfterCheckeventcausestheeventtoberaisedmultipletimesandcanresultinunexpectedbehavior.Forexample,youmightsettheCheckedpropertyintheeventhandlerwhenyouarerecursivelyupdatingthechildnodessothattheuserdoesnothavetoexpandandcheckeachoneindividually.Topreventtheeventfrombeingraisedmultipletimes,addlogictoyoureventhandlerthatonlyexecutesyourrecursivecodeiftheActionpropertyoftheTreeViewEventArgsisnotsettoTreeViewAction.Unknown.Foranexampleofhowtodothis,seetheExamplesectionoftheAfterCheckorBeforeCheckevents.

YoucanchangetheappearanceoftheTreeViewcontrolbysettingsomeofitsdisplayandstyleproperties.SettingShowPlusMinustotruedisplaysaplus-signorminus-signbuttonnexttoeachTreeNodethatcanbeexpandedorcollapsed,respectively.SettingtheShowRootLinespropertytotruecausestheTreeViewtodisplaylinesthatjoinalltheroottreenodestogether.YoucandisplaylinesthatconnectchildtreenodestotheirrootnodebysettingtheShowLinespropertytotrue.SettingtheHotTrackingpropertytotruechangestheappearanceofthetreenodelabelsasthemousepointerpassesoverthem.Whenhot-tracked,thetreenodelabelstakeontheappearanceofahyperlink.YoucanalsocompletelycustomizetheappearanceoftheTreeViewcontrol.Todothis,settheDrawModepropertytoavalueotherthanTreeViewDrawMode.NormalandhandletheDrawNodeevent.

WhensettingtheCheckBoxes,Scrollable,ImageIndex,andSelectedImageIndexpropertiesatruntime,theTreeViewhandleisrecreated（seeControl.RecreateHandle）toupdatethecontrol'

sappearance.Thiscausesalltreenodestobecollapsed,exceptfortheselectedTreeNode.

Constructor:

publicTreeView（）:

InitializesanewinstanceoftheTreeViewclass.

Properties:

1、AllowDrop:

publicvirtualbool型,Getsorsetsavalueindicatingwhetherthecontrolcanacceptdatathattheuserdragsontoit.Thedefaultisfalse.

NotestoInheritors:

WhenoverridingtheAllowDroppropertyinaderivedclass,usethebaseclass'

sAllowDroppropertytoextendthebaseimplementation.Otherwise,youmustprovidealltheimplementation.YouarenotrequiredtooverrideboththegetandsetaccessorsoftheAllowDropproperty;

youcanoverrideonlyoneifneeded.

2、Anchor:

publicvirtualAnchorStyles型,Getsorsetstheedgesofthecontainertowhichacontrolisboundanddetermineshowacontrolisresizedwithitsparent.ThedefaultisTopandLeft.

UsetheAnchorpropertytodefinehowacontrolisautomaticallyresizedasitsparentcontrolisresized.Anchoringacontroltoitsparentcontrolensuresthattheanchorededgesremaininthesamepositionrelativetotheedgesoftheparentcontrolwhentheparentcontrolisresized.

Youcananchoracontroltooneormoreedgesofitscontainer.Forexample,ifyouhaveaFormwithaButtonwhoseAnchorpropertyvalueissettoTopandBottom,theButtonisstretchedtomaintaintheanchoreddistancetothetopandbottomedgesoftheFormastheHeightoftheFormisincreased.

TheAnchorandDockpropertiesaremutuallyexclusive.Onlyonecanbesetatatime,andthelastonesettakesprecedence.

WhenoverridingtheAnchorpropertyinaderivedclass,usethebaseclass'

sAnchorpropertytoextendthebaseimplementation.Otherwise,youmustprovidealltheimplementation.YouarenotrequiredtooverrideboththegetandsetaccessorsoftheAnchorproperty;

youcanoverrideonlyoneifneeded.

3、AutoScrollOffset:

publicvirtualPoint型,GetsorsetswherethiscontrolisscrolledtoinScrollControlIntoView.Thedefaultistheupper-leftcornerofthecontrol.

4、AutoSize:

publicvirtualbool型，ThisAPIsupportsthe.NETFrameworkinfrastructureandisnotintendedtobeuseddirectlyfromyourcode.Thispropertyisnotrelevantforthisclass.

5、BackColor:

publicoverrideColor型,Getsorsetsthebackgroundcolorforthecontrol.ThedefaultisthevalueoftheDefaultBackColorproperty.

6、Bottom:

publicint型,Getsthedistance,inpixels,betweenthebottomedgeofthecontrolandthetopedgeofitscontainer'

sclientarea.

ThevalueofthispropertyisequaltothesumoftheToppropertyvalue,andtheHeightpropertyvalue.

TheBottompropertyisaread-onlyproperty.YoucanmanipulatethispropertyvaluebychangingthevalueoftheToporHeightpropertiesorcallingtheSetBounds,SetBoundsCore,UpdateBounds,orSetClientSizeCoremethods.

7、BorderStyle:

public 

BorderStyle型，Getsorsetstheborderstyleofthetreeviewcontrol.

Whenthe 

BorderStyle 

propertyissetto 

Fixed3D,the 

TreeView 

hasasunken,three-dimensionalappearance.Todisplayaflat,thinborderaroundthe 

control,setthe 

propertyto 

FixedSingle.

8、CanFocus:

publicbool型,Getsavalueindicatingwhetherthecontrolcanreceivefocus.

Inorderforacontroltoreceiveinputfocus,thecontrolmusthaveahandleassignedtoit,andtheVisibleandEnabledpropertiesmustbothbesettotrueforboththecontrolandallitsparentcontrols,andthecontrolmustbeaformorthecontrol'

soutermostparentmustbeaform.

9、CanRaiseEvents：

protectedoverridebool型,Determinesifeventscanberaisedonthecontrol.

IfthiscontrolisbeinghostedasanActiveXcontrol,thispropertywillreturnfalseiftheActiveXcontrolhasitseventsfrozen.

10、CanSelect:

publicbool型,Getsavalueindicatingwhetherthecontrolcanbeselected.

ThispropertyreturnstrueiftheSelectablevalueofSystem.Windows.Forms.ControlStylesissettotrue,iscontainedinanothercontrol,thecontrolitselfisvisibleandenabled,andallitsparentcontrolsarevisibleandenabled.

TheWindowsFormscontrolsinthefollowinglistarenotselectableandwillreturnavalueoffalsefortheCanSelectproperty.Controlsderivedfromthesecontrolsarealsonotselectable.

Panel·

GroupBox·

PictureBox·

ProgressBar·

Splitter·

Label·

LinkLabel（whenthereisnolinkpresentinthecontrol）

11、Capture:

publicbool型，Getsorsetsavalueindicatingwhetherthecontrolhascapturedthemouse.

Whenacontrolhascapturedthemouse,itreceivesmouseinputwhetherornotthecursoriswithinitsborders.Themouseistypicallyonlycapturedduringdragoperations.

Onlytheforegroundwindowcancapturethemouse.Whenabackgroundwindowattemptstodoso,thewindowreceivesmessagesonlyformouseeventsthatoccurwhenthemousecursoriswithinthevisibleportionofthewindow.Also,eveniftheforegroundwindowhascapturedthemouse,theusercanstillclickanotherwindow,bringingittotheforeground.

Whenthemouseiscaptured,shortcutkeysshouldnotwork.

12、CheckBoxes：

publicbool型,Getsorsetsavalueindicatingwhethercheckboxesaredisplayednexttothetreenodesinthetreeviewcontrol.Thedefaultisfalse.

AcheckboxisdisplayedtotheleftofboththetreenodelabelandtreenodeImage,ifany.Checkboxesallowtheusertoselectmorethanonetreenodeatatime.

WhentheCheckBoxespropertyofaTreeViewissettotrue,andtheStateImageListpropertyisset,eachTreeNodethatiscontainedintheTreeViewdisplaysthefirstandsecondimagesfrom