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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-1A26BD9E-5B8E-4E6D-904E-B8354B14E111" xml:lang="en"><title>Constructing |
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13 views in the view architecture</title><prolog><metadata><keywords/></metadata></prolog><conbody> |
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14 <p>The call on the first phase constructor method of the view occurs in <xref href="GUID-FD2CDEB8-0784-4BE5-A775-170F57D71BBC.dita">UI controller</xref>. The |
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15 view serves as the top-level window under the UI controller.</p> |
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16 <p>The methods you need to implement for your <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html" format="application/java-archive"><parmname>CCoeControl</parmname></xref>-derived |
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17 view are as follows:</p> |
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18 <ul> |
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19 <li><p>C++ default constructor, which cannot contain code that leaves. |
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20 A common implementation is:</p> |
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21 <itemgroup> |
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22 <codeblock id="GUID-7A108F7C-AD2E-4CDA-9758-5FD6ED477917" xml:space="preserve"> |
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23 CMyAppView* CMyAppView::NewL( const TRect& aRect ) |
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24 { |
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25 CMyAppView* self = CMyAppView::NewLC( aRect ); |
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26 CleanupStack::Pop( self ); |
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27 return self; |
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28 } |
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29 |
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30 CMyAppView* CMyAppView::NewLC( const TRect& aRect ) |
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31 { |
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32 CMyAppView* self = new ( ELeave ) CMyAppView; |
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33 CleanupStack::PushL( self ); |
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34 self->ConstructL( aRect ); |
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35 return self; |
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36 } |
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37 |
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38 CMyAppView::CMyAppView() |
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39 { |
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40 // No implementation required |
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41 }</codeblock> |
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42 <p>The declarations for <parmname>CMyAppView::NewL</parmname> and <parmname>CMyAppView::NewLC</parmname> in |
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43 the class header file needs to be public to support the construction method |
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44 required.</p> |
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45 <p>In this approach, <parmname>CMyAppView::NewL</parmname> is called from |
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46 the UI controller. It creates a view object by calling <parmname>CMyAppView::NewLC</parmname>. <parmname>CMyAppView::NewLC</parmname> calls |
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47 new (ELeave) on the C++ default constructor <parmname>CMyAppView</parmname> to |
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48 create the object (and leave if it cannot), <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Kernel_Architecture_2/CCleanupClass.html#%3a%3aCCleanup%3a%3aPushL%28CBase%20%2a%29" format="application/java-archive">pushes</xref> a pointer to the clean-up stack in case the second phase construction method |
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49 leaves, and then calls the second phase construction method of the object. |
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50 When it returns to <parmname>CMyAppView::NewL</parmname>, the pointer pushed |
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51 to the cleanup stack is <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Kernel_Architecture_2/CCleanupClass.html#%3a%3aCCleanup%3a%3aPop%28%29" format="application/java-archive">removed</xref>.</p> |
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52 </itemgroup> |
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53 </li> |
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54 <li><p>Symbian 2nd phase constructor with code that might leave. |
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55 A common implementation is:</p> |
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56 <itemgroup> |
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57 <codeblock id="GUID-32125111-6ACB-4539-8CD0-39ED5629789F" xml:space="preserve"> |
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58 void CMyAppView::ConstructL( const TRect& aRect ) |
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59 { |
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60 // Create a window for this application view |
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61 CreateWindowL(); |
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62 |
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63 //add construction for other controls if required |
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64 |
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65 // Set the windows size |
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66 SetRect( aRect ); |
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67 |
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68 // Activate the window, which makes it ready to be drawn |
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69 ActivateL(); |
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70 }</codeblock> |
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71 <p><parmname>CMyAppView::ConstructL</parmname> is a private class providing |
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72 the second phase construction that accepts the rectangle the view is drawn |
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73 to.</p> |
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74 <p><xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aCreateWindowL%28%29" format="application/java-archive"><parmname>CCoeControl::CreateWindowL</parmname></xref> creates a window |
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75 for the control. Note that this window is a child of the UI controller. This |
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76 method makes the control a <xref href="GUID-352850A9-227F-45DB-8DCD-C6268954B4ED.dita">window-owning |
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77 control</xref>. While, the use of window-owning controls is discouraged to |
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78 prevent the taxing of run-time resources, this is the top-level window for |
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79 the UI controller.</p> |
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80 <p>While this is a simple control that does not contain other controls, |
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81 other controls could be added to the control between <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aCreateWindowL%28%29" format="application/java-archive"><parmname>CCoeControl::CreateWindowL</parmname></xref> and <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aSetRect%28const%20TRect%20%26amp%3b%29" format="application/java-archive"><parmname>CCoeControl::SetRect(aRect)</parmname></xref>. For more information, |
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82 see <xref href="GUID-57CA8A13-05C6-4AFE-9804-E2EA2453143A.dita">Compound |
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83 controls in the view architecture</xref>.</p> |
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84 <p><xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aSetRect%28const%20TRect%20%26amp%3b%29" format="application/java-archive"><parmname>CCoeControl::SetRect(aRect)</parmname></xref> sets the window |
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85 size according to the requirements of the mobile device. The top-level control |
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86 rectangle is set to the area that the framework provides for the application. |
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87 Calling <parmname>SetRect</parmname> calls the <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aSizeChanged%28%29" format="application/java-archive"><parmname>CCoeControl::SizeChanged</parmname></xref> method, where the control should set the position and size |
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88 for any child controls and thus adjust the control layout to the UI.</p> |
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89 <p><xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aActivateL%28%29" format="application/java-archive"><parmname>CCoeControl::ActivateL</parmname></xref> sets the control |
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90 as ready to be drawn.</p> |
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91 </itemgroup> |
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92 </li> |
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93 </ul> |
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94 <p>If required for your application, you may need to implement other methods |
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95 for your control. For top-level windows, you would need to implement <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aSizeChanged%28%29" format="application/java-archive"><parmname>CCoeControl::SizeChanged</parmname></xref> to respond to |
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96 changes to the size and position of the contents of this control. This is |
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97 called by the Symbian platform when a change occurs. A typical implementation |
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98 for a compound control is:</p> |
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99 <codeblock id="GUID-6F100E69-F0BB-4637-A1AA-57024AF20CF4" xml:space="preserve">void CMyAppView::SizeChanged() |
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100 { |
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101 // Control resize code |
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102 iControl->SetExtent( const TPoint &aPosition, const TSize &aSize); |
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103 }</codeblock> |
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104 </conbody></concept> |