Symbian3/Examples/guid-6013a680-57f9-415b-8851-c4fa63356636/_declaring_descriptors_8cpp_source.html
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<h1>examples/ForumNokia/DescriptorExample/src/DeclaringDescriptors.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*</span>
<a name="l00002"></a>00002 <span class="comment"> * Copyright © 2008 Nokia Corporation.</span>
<a name="l00003"></a>00003 <span class="comment"> */</span>
<a name="l00004"></a>00004
<a name="l00005"></a>00005 <span class="preprocessor">#include <e32std.h></span>
<a name="l00006"></a>00006 <span class="preprocessor">#include <e32base.h></span>
<a name="l00007"></a>00007 <span class="preprocessor">#include "DescriptorExamples.h"</span>
<a name="l00008"></a>00008 <span class="preprocessor">#include "StringRenderer.h"</span>
<a name="l00009"></a>00009
<a name="l00010"></a>00010 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00011"></a>00011 <span class="comment">// This example method is documented in header file "DescriptorExamples.h"</span>
<a name="l00012"></a>00012 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00013"></a><a class="code" href="class_c_descriptor_examples.html#a7f529caf8413e46dbb90c73f9b8839da">00013</a> <span class="keywordtype">void</span> <a class="code" href="class_c_descriptor_examples.html#a7f529caf8413e46dbb90c73f9b8839da">CDescriptorExamples::ToStack</a>()
<a name="l00014"></a>00014 {
<a name="l00015"></a>00015 TPtr output( iViewer-><a class="code" href="class_m_result_viewer.html#a30d7e86bbb78ba769648736a9ee9e62d">GetViewBuffer</a>() );
<a name="l00016"></a>00016
<a name="l00017"></a>00017 <span class="comment">//Note, You should use the _LIT macro instead of _L</span>
<a name="l00018"></a>00018 RenderHeader( _L( <span class="stringliteral">"ToStack"</span> ), output );
<a name="l00019"></a>00019
<a name="l00020"></a>00020 <span class="comment">// --------------------</span>
<a name="l00021"></a>00021 <span class="comment">// declare constant buffers to stack as automatic variable:</span>
<a name="l00022"></a>00022 <span class="comment">// length=0, maxsize=20, data="".</span>
<a name="l00023"></a>00023 <span class="comment">// Note that these automatic variables consumes stack until the</span>
<a name="l00024"></a>00024 <span class="comment">// method ends...</span>
<a name="l00025"></a>00025 TBufC<20> tbufc20( _L(<span class="stringliteral">"Hey!"</span>) );
<a name="l00026"></a>00026 RenderVariableFormatted( tbufc20.Des(), output, KRenderCharacteristics );
<a name="l00027"></a>00027
<a name="l00028"></a>00028 <span class="comment">// --------------------</span>
<a name="l00029"></a>00029 <span class="comment">// declare modifiable buffers to stack as automatic variable:</span>
<a name="l00030"></a>00030 <span class="comment">// length=0, maxsize=20, data=""</span>
<a name="l00031"></a>00031 TBuf<20> tbuf20;
<a name="l00032"></a>00032 RenderVariableFormatted( tbuf20, output, KRenderCharacteristics );
<a name="l00033"></a>00033
<a name="l00034"></a>00034 <span class="comment">// --------------------</span>
<a name="l00035"></a>00035 <span class="comment">// declare a non modifying descriptor pointer that points to array in</span>
<a name="l00036"></a>00036 <span class="comment">// the middle of a temporary buffer: length=3, data="loWo"</span>
<a name="l00037"></a>00037 <span class="comment">// Example is declared to own code block so automatic variables are</span>
<a name="l00038"></a>00038 <span class="comment">// deleted when block ends.</span>
<a name="l00039"></a>00039 {
<a name="l00040"></a>00040 TBuf<20> tmpBuf(_L(<span class="stringliteral">"HelloWorld"</span>));
<a name="l00041"></a>00041 <span class="keyword">const</span> TText* arrayInBuf = tmpBuf.Ptr(); <span class="comment">// point to first char in buffer</span>
<a name="l00042"></a>00042 TPtrC partOfBuffer( arrayInBuf + 3, 4 );
<a name="l00043"></a>00043 RenderVariableFormatted( tmpBuf, output,
<a name="l00044"></a>00044 KRenderCharacteristics );
<a name="l00045"></a>00045 RenderVariableFormatted( partOfBuffer, output,
<a name="l00046"></a>00046 KRenderCharacteristics );
<a name="l00047"></a>00047 } <span class="comment">// tmpBuf, arrayInBuf and partOfBuffer do no more exist in stack</span>
<a name="l00048"></a>00048
<a name="l00049"></a>00049 <span class="comment">// --------------------</span>
<a name="l00050"></a>00050 <span class="comment">// declare modifying buffer pointer pointing to memory</span>
<a name="l00051"></a>00051 <span class="comment">// in another buffer: length=4, maxSize=5, data=loWo</span>
<a name="l00052"></a>00052 {
<a name="l00053"></a>00053 <span class="comment">// tmpBuf below can't be edited with its methods but we can alter data</span>
<a name="l00054"></a>00054 <span class="comment">// through modifiable buffer pointer created few lines later</span>
<a name="l00055"></a>00055 TBufC<20> tmpBuf(_L(<span class="stringliteral">"HelloWorld"</span>));
<a name="l00056"></a>00056 <span class="comment">// Set arrayInBuf to point to first character in buffer. Has to be</span>
<a name="l00057"></a>00057 <span class="comment">// cast to non const pointer since TPtr expects such (of course)</span>
<a name="l00058"></a>00058 TText* arrayInBuf = (TText*)tmpBuf.Ptr();
<a name="l00059"></a>00059 TPtr modifyingPointer( arrayInBuf + 3, 4, 5 );
<a name="l00060"></a>00060 RenderVariableFormatted( modifyingPointer, output,
<a name="l00061"></a>00061 KRenderCharacteristics );
<a name="l00062"></a>00062 }
<a name="l00063"></a>00063
<a name="l00064"></a>00064 <span class="comment">// --------------------</span>
<a name="l00065"></a>00065 <span class="comment">// declare modifying buffer pointing to a buffer descriptor - instead of</span>
<a name="l00066"></a>00066 <span class="comment">// of its buffer directrly. The only way to do a such is to call method</span>
<a name="l00067"></a>00067 <span class="comment">// Des() of non modifiable descriptors buffers TBufC and HBuf.</span>
<a name="l00068"></a>00068 <span class="comment">// contents of tmpBuf after modification: length=6, maxlength=20,</span>
<a name="l00069"></a>00069 <span class="comment">// data="HWorld"</span>
<a name="l00070"></a>00070 {
<a name="l00071"></a>00071 TBufC<20> originalBuf( _L(<span class="stringliteral">"HelloWorld"</span>) );
<a name="l00072"></a>00072 TPtr tmpBufPtr = originalBuf.Des();
<a name="l00073"></a>00073 <span class="comment">// modify the original buffer. Length in both descriptors</span>
<a name="l00074"></a>00074 <span class="comment">// is updated!</span>
<a name="l00075"></a>00075 tmpBufPtr.Delete(1, 4);
<a name="l00076"></a>00076 RenderVariableFormatted( originalBuf.Des(), output,
<a name="l00077"></a>00077 KRenderCharacteristics );
<a name="l00078"></a>00078 }
<a name="l00079"></a>00079 iViewer-><a class="code" href="class_m_result_viewer.html#a8e10673e2504a4af6382f26794bb8004">UpdateView</a>();
<a name="l00080"></a>00080 }
<a name="l00081"></a>00081
<a name="l00082"></a>00082 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00083"></a>00083 <span class="comment">// This example method is documented in header file "DescriptorExamples.h"</span>
<a name="l00084"></a>00084 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00085"></a><a class="code" href="class_c_descriptor_examples.html#abfb8e980e2e7e89daa2b46de2cb98d4a">00085</a> <span class="keywordtype">void</span> <a class="code" href="class_c_descriptor_examples.html#abfb8e980e2e7e89daa2b46de2cb98d4a">CDescriptorExamples::ToHeapL</a>()
<a name="l00086"></a>00086 {
<a name="l00087"></a>00087 TPtr output( iViewer-><a class="code" href="class_m_result_viewer.html#a30d7e86bbb78ba769648736a9ee9e62d">GetViewBuffer</a>() );
<a name="l00088"></a>00088 RenderHeader( _L( <span class="stringliteral">"ToHeap"</span> ), output );
<a name="l00089"></a>00089
<a name="l00090"></a>00090 <span class="comment">// --------------------</span>
<a name="l00091"></a>00091 <span class="comment">// Allocate heap buffer with buffer size of 512. Factory</span>
<a name="l00092"></a>00092 <span class="comment">// method LC allocates the object, pushes cleanup item to</span>
<a name="l00093"></a>00093 <span class="comment">// cleanup stack and returns pointer to allocated object.</span>
<a name="l00094"></a>00094 <span class="comment">//</span>
<a name="l00095"></a>00095 HBufC *hbufc = HBufC::NewLC( 512 );
<a name="l00096"></a>00096 RenderVariableFormatted( hbufc->Des(), output, KRenderCharacteristics );
<a name="l00097"></a>00097
<a name="l00098"></a>00098 <span class="comment">// --------------------</span>
<a name="l00099"></a>00099 <span class="comment">// Allocate TBuf descriptor with the same characteristics</span>
<a name="l00100"></a>00100 <span class="comment">// like example above. Let also the constructor to initialize</span>
<a name="l00101"></a>00101 <span class="comment">// the buffer with text.</span>
<a name="l00102"></a>00102 TBuf<512> *tbuf = <span class="keyword">new</span> (ELeave) TBuf<512>( _L(<span class="stringliteral">"Hello World!"</span>) );
<a name="l00103"></a>00103 <span class="comment">// Objects allocated from heap have to be deleted explicitly. Quite good</span>
<a name="l00104"></a>00104 <span class="comment">// practise is to push every item allocated from heap to cleanup stack and</span>
<a name="l00105"></a>00105 <span class="comment">// let the last line in method delete all allocated objects with one method</span>
<a name="l00106"></a>00106 <span class="comment">// call (CleanupStack::PopAndDestroy(count)). If method leaves at the middle</span>
<a name="l00107"></a>00107 <span class="comment">// of execution, the trap harness deletes automatically all objects pushed</span>
<a name="l00108"></a>00108 <span class="comment">// to cleanup stack and no memory leaks occur.</span>
<a name="l00109"></a>00109 CleanupStack::PushL( tbuf );
<a name="l00110"></a>00110 RenderVariableFormatted( *tbuf, output, KRenderCharacteristics );
<a name="l00111"></a>00111
<a name="l00112"></a>00112 <span class="comment">// we do no more need allocated objects, so lets remove them from cleanup</span>
<a name="l00113"></a>00113 <span class="comment">// stack with one method call.</span>
<a name="l00114"></a>00114 CleanupStack::PopAndDestroy(2); <span class="comment">// hbufc & tbuf</span>
<a name="l00115"></a>00115 iViewer-><a class="code" href="class_m_result_viewer.html#a8e10673e2504a4af6382f26794bb8004">UpdateView</a>();
<a name="l00116"></a>00116 }
<a name="l00117"></a>00117
<a name="l00118"></a>00118 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00119"></a>00119 <span class="comment">// This example method is documented in header file "DescriptorExamples.h"</span>
<a name="l00120"></a>00120 <span class="comment">// -----------------------------------------------------------------------------</span>
<a name="l00121"></a><a class="code" href="class_c_descriptor_examples.html#ac09dcbba3fcb7b55391e50c3692052d5">00121</a> <span class="keywordtype">void</span> <a class="code" href="class_c_descriptor_examples.html#ac09dcbba3fcb7b55391e50c3692052d5">CDescriptorExamples::Literals</a>()
<a name="l00122"></a>00122 {
<a name="l00123"></a>00123 TPtr output( iViewer-><a class="code" href="class_m_result_viewer.html#a30d7e86bbb78ba769648736a9ee9e62d">GetViewBuffer</a>() );
<a name="l00124"></a>00124 RenderHeader( _L( <span class="stringliteral">"Literals"</span> ), output );
<a name="l00125"></a>00125
<a name="l00126"></a>00126 <span class="comment">// --------------------</span>
<a name="l00127"></a>00127 <span class="comment">// Declare variable KLit1 and assing some text to it. _LIT macro</span>
<a name="l00128"></a>00128 <span class="comment">// evaluates so that static constant variable is declared and</span>
<a name="l00129"></a>00129 <span class="comment">// initialized with given string data. Since static and constant,</span>
<a name="l00130"></a>00130 <span class="comment">// it is compiled as part of program binary.</span>
<a name="l00131"></a>00131 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>( KLit1, <span class="stringliteral">"String declared with macro _LIT"</span> );
<a name="l00132"></a>00132 RenderVariableFormatted( KLit1, output, KRenderCharacteristics );
<a name="l00133"></a>00133
<a name="l00134"></a>00134 <span class="comment">// --------------------</span>
<a name="l00135"></a>00135 <span class="comment">// Literals can be also created with macro _L. However, it isn't</span>
<a name="l00136"></a>00136 <span class="comment">// so efficient (refer book "Symbian OS C++ for Mobile Phones"</span>
<a name="l00137"></a>00137 <span class="comment">// for details). Using it in test code is acceptable.</span>
<a name="l00138"></a>00138 TPtrC L1 = _L( <span class="stringliteral">"String declared with macro _L"</span> );
<a name="l00139"></a>00139 RenderVariableFormatted( L1, output, KRenderCharacteristics );
<a name="l00140"></a>00140
<a name="l00141"></a>00141 <span class="comment">// --------------------</span>
<a name="l00142"></a>00142 <span class="comment">// Let's declare a literal that contains euro sign (0x20AC).Since it</span>
<a name="l00143"></a>00143 <span class="comment">// doesn't exist in many 8 bit encodings , we declare it as 'e' when</span>
<a name="l00144"></a>00144 <span class="comment">// building non-unicode build</span>
<a name="l00145"></a>00145 <span class="preprocessor">#ifdef _UNICODE</span>
<a name="l00146"></a>00146 <span class="preprocessor"></span> <span class="comment">// note that in unicode literal the unicode chars can be declared</span>
<a name="l00147"></a>00147 <span class="comment">// by passing the unicode number of the character as hexadecimal number</span>
<a name="l00148"></a>00148 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>( KLitEuro, <span class="stringliteral">"I won 166\x20AC from lottery!"</span> );
<a name="l00149"></a>00149 <span class="preprocessor">#else</span>
<a name="l00150"></a>00150 <span class="preprocessor"></span> <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>( KLitEuro, <span class="stringliteral">"I won 166e from lottery!"</span> );
<a name="l00151"></a>00151 <span class="preprocessor">#endif</span>
<a name="l00152"></a>00152 <span class="preprocessor"></span> RenderVariableFormatted( KLitEuro, output, KRenderCharacteristics );
<a name="l00153"></a>00153 iViewer-><a class="code" href="class_m_result_viewer.html#a8e10673e2504a4af6382f26794bb8004">UpdateView</a>();
<a name="l00154"></a>00154 }
</pre></div></div>
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