Multitouch WMTouch with MFCNative.docx

Multitouch WMTouch with MFCNative.docx

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MultitouchWMTouchwithMFCNative

Hands-OnLab

MultitouchWMTouchwithMFC-Native

Labversion:

1.0.0

Lastupdated:

9/25/2018

CONTENTS

Overview3

Exercise1:

BuildaMultitouchApplication5

Task1–PreparetheApplication5

Task2–AddTouchSupporttotheapplication8

Task3–AddtheStrokeSourceandHeaderFilestotheProject,andDrawLineswithyourFingers11

Summary16

Overview

Windows7givesuserstheabilitytomanageapplicationswiththetouchoftheirfingers,usingnointermediatedevice.Thisexpandsthestylus-basedcapabilitiesoftabletPCs.Unlikeotherpointingdevices,thisnewcapabilityallowsmultipleinputeventsatthesametimefromdifferentpointinglocations,anditenablescomplexscenarios,suchasmanagingapplicationswithtenfingersorwithmultiplesimultaneoususers.However,topullthisoff,wehavetoadaptourapplication'suserinterfaceandbehaviortosupportthisnewinputmodel.

MFCinVisualStudio2010hasaddedsupportforcheckingMultitouchhardwarereadinessandsimplifiedtheprocessofreceivingtouchevents.

Objectives

InthisHands-OnLab,youwilllearnhowtomanageMultitouchevents,including:

ProcessinginputfromWindowsTouch

Understandingtheimplicationsofmanipulatingmultipletoucheventssimultaneously

CheckingforMultitouchhardwareexistenceandreadiness

SystemRequirements

Youmusthavethefollowingitemstocompletethislab:

Windows7

MicrosoftVisualStudio2010Beta2（orlater）

AMultitouchhardwaredevice

Introduction

TocreateaMultitouchdrivenapplicationyoucanchooseoneofthreeapproaches:

Good,Better,andBest.

The“Good”approachistheeasiestofthethree.Youshoulddesignyourapplicationuserinterfacewithtouchabilityinmind.UselargeandcleanWin32basedcontrolsthatmakeanaturalinterfaceforbetteruserexperience.TouchabilitiessuchasscrollingcomefromtheWin32controls.Thereisnoneedforextrawork.Forexample,trytoscrollthedocumentthatyouarereadingnowwithyourfingers!

Thisisthe“Good”approach.

The"Better"approachletsthesystemreceivevariouslow-leveltoucheventsandpassestheresultoftheheuristicsthatthesystemperformswiththeseeventstoyourapplicationas“gestures”.Forexample,iftheusermakesarotationmovementonthescreen,thesystemwillissuearotationgestureeventwiththerotationangle.Althoughthe"Better"approachiseasytouse,ithasitslimitations.UsinggesturesonecannotgetRotate,Translate,andScalesimultaneously.Alsoyoucannothandlemanydifferenttouch-basedactionsatthesametime.ForexampletwousersthatoperatedifferentareasoftheWindow.

The“Best”approachistoreadthelow-leveltoucheventsastheinputtotheapplication.Applicationslike“Piano”orcomplexcontrolslikemultipleslidersthatcanbeoperatedsimultaneouslyaregoodexamples.Forexample,runMSPaint,selectadrawingtoolfromthegalleryanddrawwithfourofyourfingers.

InthisHands-OnLabyouwillmimicthenewMSPaintMultitouchpaintingfeatureusingthe“Best”approach.Wewillreadandusetherawtouchevents.

AbouttheMultitouchScratchpadApplication

TheMultitouchScratchpadapplicationpresentsasimplewindowthatallowssimultaneouslydrawingofcontinuouslineswithyourfingers.WhilethefolderSource\MFC_WMTouchSource\Startercontainsfilesneededfortheexercise,Source\MFC_WMTouchSource\Finalcontainsthecompletedsolution.

Exercise1:

BuildaMultitouchApplication

Task1–PreparetheApplication

1.StartVisualStudio2010

2.CreateanewMFCapplicationprojectandgiveitthenameScratchPad:

3.IntheApplicationType,selectSingleDocument.Tokeeptheapplicationsimple,unselecttheotheroptionsinthedialogsimilartothescreen-shotsbelow:

4.ContinueclickingNextuntilyoufinallyhitFinish:

Task2–AddTouchSupporttotheapplication

5.Theapplicationthatwearebuildingrequirestouch-enabledhardware,soweneedtomakethischeckintheapplication.

6.InScratchpad.cpp,addthefollowingcheckattheendofCScratchPadApp:

:

InitInstance（）:

C++

BYTEdigitizerStatus=（BYTE）GetSystemMetrics（SM_DIGITIZER）;

if（（digitizerStatus&（0x80+0x40））==0）//StackReady+MultiTouch

{

AfxMessageBox（L"Notouchinputiscurrentlyavailable."）;

returnFALSE;

}

BYTEnInputs=（BYTE）GetSystemMetrics（SM_MAXIMUMTOUCHES）;

CStringstr;

str.Format（L"Touchinputavailablewith%dtouchpoints.",nInputs）;

AfxMessageBox（str）;

returnTRUE;

7.Youcanseethatbesidescheckingfortouchavailabilityandreadinesswealsofindoutthenumberoftouchinputsthatthehardwaresupports.

8.Compileandrun.

9.Dependingonthenumberoftouchinputsyouhaveonyourmachine,youshouldseeoutputsimilartothis:

10.InordertoregistertheapplicationclientviewwindowtoreceiveTouchmessages,weneedtocalltheMFCfunctionCWnd:

:

RegisterTouchWindow（）.We’lldosoaftertheviewhasbeencreated;i.e.intheOnCreate（）eventhandler.

SwitchtotheClassViewandSelecttheCChildViewclass.

InthePropertiespage,gototheMessagepropertysheetandnavigatetoWM_CREATE,thenaddtheOnCreate（）messagehandlerfromthedropdownbox:

11.InsidetheCChildView:

:

OnCreate（）handlerappendthefollowingcodetoregistertouchinputfortheviewwindow:

C++

if（!

RegisterTouchWindow（））

{

ASSERT（FALSE）;

}

Note:

CallingCWnd:

:

RegisterTouchWindow（）registers（andunregisters）awindowastouchcapable,allowingittoreceivelow-levelWM_TOUCHmessages.

12.Sincewe’veregisteredtheviewtoreceivetouchinput,wemustoverridethehandlerreceivingeachofthetouchmessages:

CWnd:

:

OnTouchInput（）.

ThishandlerreceivesasingleinputfromWindowsTouchandshouldreturnTRUEiftheapplicationprocessesthismessage;otherwiseFALSE.

13.InChildView.h,addthismethoddeclaration:

C++

//Overrides

protected:

virtualBOOLOnTouchInput（CPointpt,intnInputNumber,intnInputsCount,PTOUCHINPUTpInput）;

14.AndinChildView.cpp,providethecorrespondingimplementation:

C++

BOOLCChildView:

:

OnTouchInput（CPointpt,intnInputNumber,intnInputsCount,PTOUCHINPUTpInput）

{

//TODO:

HandleTocuhinputmessageshere

returnFALSE;

}

Task3–AddtheStrokeSourceandHeaderFilestotheProject,andDrawLineswithyourFingers

Wewouldliketouseourfingersasmultipleinputdevices.Wewanttodrawalineforeachfingerthattouchesthescreen.Todothatwearegoingtousetwostrokecollections.Onecollectionholdsthefinishedstrokes（lines）andanothercollectionholdstheongoing,currentlypaintinglines.Eachfingerthattouchesthescreenaddspointstoastrokeinthem_StrkColDrawingcollection.Whenweraisethefingerfromthescreen,wemovethefinger'sstrokefromthem_StrkColDrawingtothem_StrkColFinishedcollection.Inadditionwewantstrokestohavedifferentcolorsifauserisusingtwoormorefingersonamultitouchmonitor.

15.IntheStarterfolderyouwillfindtwofiles:

Stroke.handStroke.cpp.Copythemtotheprojectfolderanduse“AddExistingitem…”toaddthemtotheproject.

16.Similarly,addStrokeCollection.handStrokeCollection.cpptotheproject.

17.Include"Stroke.h"and"StrokeCollection.h"attheendofStdAfx.hheaderfile.

C++

#include"Stroke.h"

#include"StrokeCollection.h"

18.AddtheseprivatemembervariabledefinitionstoChildView.h:

C++

private:

intm_iCurrColor;//Thecurrentstrokecolor

CStrokeCollectionm_StrkColFinished;//Theuserfinishedenteringstrokes

//afteruserliftedhisorherfinger.

CStrokeCollectionm_StrkColDrawing;//TheStrokescollectiontheuseris

//currentlydrawing.

19.Important:

wehavetoinitializethecurrentcolor.We’lldosointheCChildViewconstructorinChildView.cpp:

C++

CChildView:

:

CChildView（）:

m_iCurrColor（0）

{

}

20.Todrawthefinishedcollection,weaddthefollowingcalltotheendoftheCChildView:

:

OnPaint（）handler.Itwilldrawallfinishedstrokes.

C++

m_StrkColFinished.Draw（&dc）;

21.WeneedtoprocesseachTouchinputmessagereceived,sowehandleeachoftheeventswe’reinterestedin:

touchinputdown,moveandup.

22.InCChildView.h,declarethefollowingmethods,whichwe’llusetohandledifferenttouchinputevents:

C++

protected:

//Handlersfordifferenttouchinputevents

BOOLOnTouchInputDown（CPointpt,PTOUCHINPUTpInput）;

BOOLOnTouchInputMove（CPointpt,PTOUCHINPUTpInput）;

BOOLOnTouchInputUp（CPointpt,PTOUCHINPUTpInput）;

23.InCChildView.cpp,addtheimplementationofeachofthetouchinputhandlers:

C++

BOOLCChildView:

:

OnTouchInputDown（CPointpt,PTOUCHINPUTpInput）

{

//Createnewstrokeandaddpointtoit.

COLORREFstrokeColor=GetTouchColor（（pInput->dwFlags&TOUCHEVENTF_PRIMARY）!

=0）;

CStroke*pStrkNew=newCStroke（pInput->dwID,strokeColor）;

pStrkNew->Add（pt）;

//Addnewstroketothecollectionofstrokesindrawing.

m_StrkColDrawing.Add（pStrkNew）;

returnTRUE;

}

BOOLCChildView:

:

OnTouchInputMove（CPointpt,PTOUCHINPUTpInput）

{

//Findthestrokeinthecollectionofthestrokesindrawing.

intstrokeIndex=m_StrkColDrawing.FindStrokeById（pInput->dwID）;

if（strokeIndex>=0）

{

CStroke*pStrk=m_StrkColDrawing[strokeIndex];

//Addcontactpointtothestroke

pStrk->Add（pt）;

//Drawthelaststroke

pStrk->Draw（GetDC（））;

}

returnTRUE;

}

BOOLCChildView:

:

OnTouchInputUp（CPointpt,PTOUCHINPUTpInput）

{

//Findthestrokeinthecollectionofthestrokesindrawing.

intstrokeIndex=m_StrkColDrawing.FindStrokeById（pInput->dwID）;

if（strokeIndex>=0）

{

CStroke*pStrkCopy=m_StrkColDrawing[strokeIndex];

//Removethisstrokefromthecollectionofstrokesindrawing.

m_StrkColDrawing.RemoveAt