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<concept id="GUID-C60DC070-572B-5960-B394-550426FDB909" xml:lang="en"><title> Advanced

Pointer Tutorial</title><shortdesc>This tutorial provides step-by-step instructions and sample code

to help you write applications using advanced pointers. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p> <b>Variant</b>: <xref href="GUID-D93978BE-11A3-5CE3-B110-1DEAA5AD566C.dita">ScreenPlay</xref>. <b>Target

audience</b>: Application developers. </p>

<section><title>Required background </title> <p>This topic builds on the material

in the following topics: </p> <ul>

<li id="GUID-C4209FBD-3860-5F4B-8458-87D22D483953"><p><xref href="GUID-9C269F45-F160-5A4B-ABF8-896D2A538E3B.dita">Advanced

Pointer Overview</xref>  </p> </li>

<li id="GUID-9D3C3B31-F43A-5201-A1EC-A1F2848CFF43"><p><xref href="GUID-9AD75103-CD56-5279-B639-5CA2BBF979B5.dita">Advanced

Pointer States and Event Communication</xref>  </p> </li>

</ul> </section>

<section><title>Using advanced pointers</title> <p>This topic covers the following: </p> <ul>

<li id="GUID-C3AD43AA-09C0-5BA2-8496-5B87D40C89F5"><p><xref href="GUID-C60DC070-572B-5960-B394-550426FDB909.dita#GUID-C60DC070-572B-5960-B394-550426FDB909/GUID-8CBE862B-0C1D-5088-89B7-9B3EC898E4FC">Enabling multi-touch for a window</xref>  </p> </li>

<li id="GUID-177323F2-55C6-56D9-B3D2-A8DDACF69E10"><p><xref href="GUID-C60DC070-572B-5960-B394-550426FDB909.dita#GUID-C60DC070-572B-5960-B394-550426FDB909/GUID-C026DAB9-C11C-5D29-A1EA-6730E914250F">Getting Z coordinates from TPointerEvent</xref>  </p> </li>

<li id="GUID-91CEA92C-A692-5853-96F0-625A76B7DC8D"><p><xref href="GUID-C60DC070-572B-5960-B394-550426FDB909.dita#GUID-C60DC070-572B-5960-B394-550426FDB909/GUID-B7057F69-191F-5AA4-8C61-EBECE66D92F6"> Pinch zooming</xref>  </p> </li>

</ul> </section>

<section id="GUID-8CBE862B-0C1D-5088-89B7-9B3EC898E4FC"><title>Enabling multi-touch

in a window</title> <ol id="GUID-210D17A8-4869-5F9B-B71C-672101AC591C">

<li id="GUID-81A2AC5C-7837-5216-8F47-FC5959C27522"><p> <xref href="GUID-637F82AF-0CF9-3C85-834D-7C1A0866DF87.dita"><apiname>RWindow</apiname></xref> provides

a handle to a standard window. Call <codeph>RWindow</codeph> to create an

instance of a window. </p> <codeblock id="GUID-0E31C3F6-3719-5F16-9F74-C405850604B8" xml:space="preserve">

RWindow window(ws);

User::LeaveIfError(window.Construct(wg, reinterpret_cast<TUint32>(&wg) + 1));

</codeblock> </li>

<li id="GUID-B67D3702-1A8F-5C6A-AB0F-FEA7C4D04A07"><p>Call <xref href="GUID-683603DD-F3D3-3193-BEB3-8236C7DE7F79.dita#GUID-683603DD-F3D3-3193-BEB3-8236C7DE7F79/GUID-05293539-F1B0-3C7D-BB14-3FD42F23D5C8"><apiname>RWindow::EnableAdvancedPointers()</apiname></xref> to

enable advanced pointers. Then call <xref href="GUID-1460DD8F-9AA1-3B99-8FFD-F309959CCA34.dita#GUID-1460DD8F-9AA1-3B99-8FFD-F309959CCA34/GUID-4E02165A-DFCC-3D18-BB18-18726B28E90A"><apiname>RWindowBase::Activate()</apiname></xref> to

display the window and enable the window to receive events. <xref href="GUID-683603DD-F3D3-3193-BEB3-8236C7DE7F79.dita"><apiname>RWindow</apiname></xref> inherits

from <xref href="GUID-1460DD8F-9AA1-3B99-8FFD-F309959CCA34.dita"><apiname>RWindowBase</apiname></xref>, so you can call the <codeph>Activate()</codeph> function

on <codeph>RWindow</codeph>. </p> <codeblock id="GUID-DB2FB570-2BB0-5C5F-9E4F-076D6A0E469E" xml:space="preserve">

window.EnableAdvancedPointers();

window.Activate();

</codeblock> <p>When an application needs to receive advanced pointer events

in a window, it must call <codeph>RWindowBase::EnableAdvancedPointers()</codeph> for

the window <i>before</i> it is activated. </p> <p>If advanced pointers are

not enabled for a window, it receives only standard <xref href="GUID-1FFA0073-3D83-388E-A824-08C31F90CC54.dita"><apiname>TPointerEvent</apiname></xref> information

from a single pointer with no pressure and proximity data. The single pointer

environment rules describe the way in which pointer events coming from many

pointers in the multi-pointer model are transformed into events of one pointer.

They are necessary to ensure that old single-pointer applications work in

a multi-touch environment intuitively and as expected by the user. </p> <p>However,

the new <codeph>TPointerEvent</codeph> types, <xref href="GUID-239D0A8B-2759-321D-AD48-976E80192239.dita"><apiname>EEnterCloseProximity</apiname></xref>, <xref href="GUID-8C6264B4-5E19-33A7-92B0-BB79C871BEC7.dita"><apiname>EExitCloseProximity</apiname></xref>, <xref href="GUID-F02DB96E-1541-3223-9B7B-79D45840DB7B.dita"><apiname>EEnterHighPressure</apiname></xref> and <xref href="GUID-15B5991C-B075-3110-B0A4-540EC282AA56.dita"><apiname>EExitHighPressure</apiname></xref>, are delivered to all windows,

even to those that do not enable advanced pointers. </p> </li>

</ol> </section>

<section id="GUID-C026DAB9-C11C-5D29-A1EA-6730E914250F"><title>Getting Z coordinates

from TPointerEvent</title> <ol id="GUID-4CC2271D-1798-51B3-9A9D-E7E0B9A33DAE">

<li id="GUID-184B5B63-4EFC-55CD-8D1F-E015EEBACBE2"><p>Call <xref href="GUID-1FFA0073-3D83-388E-A824-08C31F90CC54.dita#GUID-1FFA0073-3D83-388E-A824-08C31F90CC54/GUID-E961DA4D-AD38-31F0-88DD-A07D36346DCB"><apiname>TPointerEvent::AdvancedPointerEvent()</apiname></xref> on

a <codeph>TPointerEvent</codeph> to return a pointer to a <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita"><apiname>TAdvancedPointerEvent</apiname></xref>. </p> <codeblock id="GUID-6E81680A-3070-546B-B575-49EA9E34FAF9" xml:space="preserve">

TZType aZType;

TPointerEvent& aPointerEvent;

TInt* aZ; 

TInt* aPoint3D;

TAdvancedPointerEvent *advancedP = aPointerEvent.AdvancedPointerEvent();

</codeblock> <p> <codeph>TPointerEvent</codeph> is a struct that contains

details of a pointer event. <codeph>TZType</codeph> is a struct provided by

the programmer containing members to hold proximity, pressure, and "proximity

and pressure" data. </p> </li>

<li id="GUID-ABA8FA09-5F57-51BC-8CAE-43649B5ED6D3"><p>Now we need to test

whether the pointer event contains advanced pointer data. If it is not an

advanced pointer, the code leaves. </p> <p>If it is an advanced pointer, we

call functions to detect proximity, pressure, "proximity and pressure" data

and coordinates. </p> <codeblock id="GUID-DF109643-2564-51A0-B0F6-33BF4DA1F6E3" xml:space="preserve">

if(!advancedP)

    {

    // The TPointerEvent isn't an instance of TAdvancedPointerEvent

    User::Leave(KErrArgument);

    }

switch(aZType)

    {

    case EZTypeProximity:

        aZ = advancedP->Proximity();

        aPoint3D = advancedP->Proximity3D(); 

        break;

    case EZTypePressure:

        aZ = advancedP->Pressure();

        aPoint3D = advancedP->Pressure3D();

        break;

    case EZTypeProximityAndPressure:

        aZ = advancedP->ProximityAndPressure();

        aPoint3D = advancedP->ProximityAndPressure3D();

        break;

    default: 

        User::Leave(KErrArgument);

        break;

    }

</codeblock> <ul>

<li id="GUID-40C01884-AC86-5882-935D-2EC2E27C9004"><p> <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-0ED4B1CC-0655-3246-8645-AAC9E0C27298"><apiname>TAdvancedPointerEvent::Proximity()</apiname></xref> returns

the proximity. </p> </li>

<li id="GUID-16A9A86B-A837-5E43-BB3A-F5A04A7F4552"><p> <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-15DEBFBF-7B7D-3FCF-9929-C973824A5FD3"><apiname>TAdvancedPointerEvent::Pressure()</apiname></xref> returns

the pressure. </p> </li>

<li id="GUID-3E614890-C317-596E-A5B9-FD76426DBD12"><p> <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-114AE77E-D0BD-321E-BFCB-1388B35582EC"><apiname>TAdvancedPointerEvent::ProximityAndPressure()</apiname></xref> returns

the proximity and pressure combined. </p> </li>

<li id="GUID-6F62C0D1-FAE4-5F8F-B451-68ABA404A369"><p> <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-E5AA7737-D217-3FDE-9E4D-AAA7F5D2C300"><apiname>TAdvancedPointerEvent::

Position3D()</apiname></xref> returns the proximity and the X, Y and Z coordinates. </p> </li>

<li id="GUID-5AD1811D-BCBF-5A44-B6E7-EB71BF254BCA"><p> <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-2F30A8F5-75BA-3FE3-84B7-3C772ED75857"><apiname>TAdvancedPointerEvent::Pressure3D()</apiname></xref> returns

the pressure and the X and Y coordinates. </p> </li>

</ul> <p>Proximity is <i>always</i> negative and pressure is <i>always</i> positive.

Internally they are combined together as a Z coordinate. When Z > 0, the proximity

is 0 and the Z value represents the pressure. When Z < 0, the pressure

is 0 and the Z value represents the proximity. Some APIs use only a Z coordinate

(such as the threshold getters and setters and <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-114AE77E-D0BD-321E-BFCB-1388B35582EC"><apiname>TAdvancedPointerEvent::ProximityAndPressure()</apiname></xref>).

In these, the Z coordinate is interpreted in terms of pressure and proximity. </p> </li>

</ol> <fig id="GUID-7A49B143-5458-5916-B937-55D98B77BB2C">

<title> Relationships between the pointer proximity, pressure and Z      

       coordinate            </title>

<image href="GUID-1A0FB98B-8DB3-5067-9B71-FF838F6AE402_d0e170634_href.png" placement="inline"/>

</fig> </section>

<section id="GUID-B7057F69-191F-5AA4-8C61-EBECE66D92F6"><title>Pinch zooming</title> <p>This

example shows an easy way to pinch zoom an image when the screen receives

pointer events from two pointers. There are two functions in this code that

must be implemented by the programmer: <codeph>BitmapCoordinates()</codeph> and <codeph>MoveBitmap()</codeph>.

They are not included in the example because they involve complex calculations

that are not related to advanced pointers. </p> <p>The high-level steps to

perform pinch zooming are: </p> <ol id="GUID-AEF3917C-AAFE-5C25-9609-396D08478AC0">

<li id="GUID-7839E665-C4E1-59C8-BA89-22A62615EFA3"><p>Define the coordinates,

equivalent to the given on-screen coordinates. In the code example, this is

done using the function <codeph>BitmapCoordinates()</codeph>. </p> </li>

<li id="GUID-FC4B1BDA-8120-53C9-9C88-BEFEF1AD54B4"><p>Define the ID of the

pointer by using <xref href="GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023.dita#GUID-FADA3278-FF8B-308F-90AD-3DCF8911A023/GUID-67593D7E-CE40-303F-B847-81D6FC0578B1"><apiname>TAdvancedPointerEvent::PointerNumber()</apiname></xref>.

If the device can handle two pointers (two fingers) at the same time, their

numbers are 0 and 1. The pointer number enables you to distinguish a given

pointer from other pointers. </p> </li>

<li id="GUID-1E8F7D23-EEAD-5EA5-8863-276076D6B54E"><p>For each pointer assign

its coordinates to a local variable. We assume there are only two pointers

handled by the system here. </p> </li>

<li id="GUID-E44B3D9B-560A-5959-996D-A63CBD4C3786"><p>Use the <codeph>MoveBitmap()</codeph> function

to achieve the zoom effect. </p> <codeblock id="GUID-D85CCFDD-8F65-530A-ACD7-93DD1D435FC6" xml:space="preserve">

/**

Receives pointer events from two pointers to perform Pinch Zoom of the image.

Function will finish when EButton1Up is received for any of the pointers.

@param aPointer1    Coordinates of pointer number 1 when zoom is started

@param aPointer2    Coordinates of pointer number 2 when zoom is started

*/

void PinchZoom(TPoint aPointer1, TPoint aPointer2)

    {

    TPoint actualP1 = aPointer1;

    TPoint actualP2 = aPointer2;

    // translate on-screen pointer coordinates to coordinates of displayed bitmap

    TPoint bitmapCatching1 = BitmapCoordinates(aPointer1);

    TPoint bitmapCatching2 = BitmapCoordinates(aPointer2);

    TBool repaint = EFalse;

    while (ETrue)

        {

        TAdvancedPointerEvent event = GetNextPointerEvent();

        if (event.iType == TPointerEvent::EDrag)

            { 

            if (event.PointerNumber() == 1)

                { 

                actualP1 = event.iPosition;

                repaint = ETrue;

                }

            else if (event.PointerNumber() == 2)

                {

                actualP2 = event.iPosition;

                repaint = ETrue;

                }

            }

        else if (event.iType == TPointerEvent::EButton1Up)

            {

            break;

            }

        if (repaint)

            {

            // move bitmap on the screen in the way that

            // bitmapCatching1 point of the bitmap will be displayed at actualP1 screen coordinate,

            // bitmapCatching2 point of the bitmap will be displayed at actualP2 screen coordinate.

            MoveBitmap(bitmapCatching1, actualP1, bitmapCatching2, actualP2);

            repaint = EFalse;

            }

        }

    }

</codeblock> </li>

</ol> </section>

</conbody><related-links>

<link href="GUID-9C269F45-F160-5A4B-ABF8-896D2A538E3B.dita"><linktext>Advanced

Pointer                 Overview</linktext></link>

<link href="GUID-9AD75103-CD56-5279-B639-5CA2BBF979B5.dita"><linktext>Advanced

Pointer States and                 Event Communication</linktext></link>

</related-links></concept>