asp.net barcode generator free THE MODEL-VIEW FRAMEWORK in Font

Drawer Data Matrix 2d barcode in Font THE MODEL-VIEW FRAMEWORK

CHAPTER 5 THE MODEL-VIEW FRAMEWORK
Data Matrix Creator In None
Using Barcode creation for Font Control to generate, create Data Matrix 2d barcode image in Font applications.
www.OnBarcode.com
PDF-417 2d Barcode Drawer In None
Using Barcode printer for Font Control to generate, create PDF 417 image in Font applications.
www.OnBarcode.com
Listing 5-44. The source model is assigned to the proxy model that is then used by the view instead of using the source model directly. int main( int argc, char **argv ) { QApplication app( argc, argv ); QStringListModel model; QStringList list; list << "Totte" << "Alfons" << "Laban" << "Bamse" << "Skalman"; model.setStringList( list ); SortOnSecondModel sorter; sorter.setSourceModel( &model ); QTableView table; table.setModel( &sorter ); table.setSortingEnabled( true ); table.show(); return app.exec(); } If you want to provide custom sorting through a class inheriting QSortFilterProxyModel, you need to override the lessThan(const QModelIndex&, const QModelIndex&) method. The proxy class itself is very simple all it takes is a constructor and the overriding method. The example sorter proxy model ignores the first letter of strings before sorting them alphabetically. The class is called SortOnSecondModel, and the declaration is shown in Listing 5-45. Listing 5-45. The class declaration of the custom sorting proxy model class SortOnSecondModel : public QSortFilterProxyModel { public: SortOnSecondModel( QObject *parent = 0 ); protected: bool lessThan( const QModelIndex &left, const QModelIndex &right ) const; }; The constructor of SortOnSecondModel is simple; it just passes the parent object onto the constructor of the base class. The code of the class is contained in the lessThan method shown in Listing 5-46.
GS1 - 12 Creation In None
Using Barcode encoder for Font Control to generate, create UPCA image in Font applications.
www.OnBarcode.com
Making Quick Response Code In None
Using Barcode maker for Font Control to generate, create QR Code 2d barcode image in Font applications.
www.OnBarcode.com
CHAPTER 5 THE MODEL-VIEW FRAMEWORK
Paint Code39 In None
Using Barcode printer for Font Control to generate, create Code-39 image in Font applications.
www.OnBarcode.com
Barcode Generator In None
Using Barcode encoder for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Listing 5-46. The lessThan method ignores the first character of strings before comparing them. bool SortOnSecondModel::lessThan( const QModelIndex &left, const QModelIndex &right ) const { QString leftString = sourceModel()->data( left ).toString(); QString rightString = sourceModel()->data( right ).toString();
Generating EAN 128 In None
Using Barcode generation for Font Control to generate, create EAN / UCC - 14 image in Font applications.
www.OnBarcode.com
Generating UPCE In None
Using Barcode encoder for Font Control to generate, create UPC-E Supplement 5 image in Font applications.
www.OnBarcode.com
if( !leftString.isEmpty() ) leftString = leftString.mid( 1 );
Scan ECC200 In VS .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Decoding Data Matrix ECC200 In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
if( !rightString.isEmpty() ) rightString = rightstring.mid( 1 ); return leftString < rightString; } In the method, you use the sourceModel() method to get a reference to the source model and you get the actual data to compare from it. Before comparing the strings, the first letter, if any, is truncated from the left and right strings. Figure 5-12 shows the application running with the source model sorted according to the proxy model s sort order.
Printing EAN / UCC - 14 In None
Using Barcode printer for Excel Control to generate, create USS-128 image in Microsoft Excel applications.
www.OnBarcode.com
Recognize Code-128 In Visual C#
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Figure 5-12. The custom sorting proxy model in action When a model s data changes, the sorting is not automatically updated, but it can be changed by setting the dynamicSortFilter property of the proxy model to true. Before using this method, make sure that your model is small enough to actually have the time to get sorted before it changes again. The previous application used only the sorting capabilities of QSortFilterProxyModel. If you need to filter a model to leave out a few rows, you can reimplement the filterAcceptsRow method. Use the filterAcceptsColumn to filter on columns. The methods take a source index and row (or column) and return a Boolean value that is true if the row (or column) is to be shown.
Draw ECC200 In None
Using Barcode maker for Office Word Control to generate, create DataMatrix image in Office Word applications.
www.OnBarcode.com
Linear 1D Barcode Generator In C#.NET
Using Barcode drawer for .NET Control to generate, create Linear image in .NET framework applications.
www.OnBarcode.com
CHAPTER 5 THE MODEL-VIEW FRAMEWORK
1D Barcode Drawer In Java
Using Barcode maker for Java Control to generate, create Linear image in Java applications.
www.OnBarcode.com
Data Matrix 2d Barcode Decoder In VB.NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Summary
Decoding UPC-A Supplement 2 In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Drawing EAN / UCC - 13 In VS .NET
Using Barcode creator for Reporting Service Control to generate, create GTIN - 13 image in Reporting Service applications.
www.OnBarcode.com
Using models and views can seem like an overly complex way of doing things, but the resulting software is built with a structure that has been proven to be flexible and powerful. You should consider using the model-view approach when you are dealing with situations in which you need to show the same data in several ways; deal with common selections; or just show lists, trees, or tables of data. Using a standard view with custom delegates and models is often a better solution than providing a completely custom widget.
Reading USS Code 128 In Visual Basic .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Decode UCC-128 In Visual Basic .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
CHAPTER
Creating Widgets
he term widgets is the name collectively applied to the various visual elements that comprise an application: buttons, title bars, text boxes, checkboxes, and so on. There are two schools of thought on using widgets to create user interfaces: either stick to the standard widgets or go out on a limb to create your own. Qt supports both. Unless you have esoteric needs, you should stick to the established widgets as much as possible. This makes your life really easy when you are using Qt because the standard widget looks native on most platforms. However, if you want to walk on the wild side, you can take advantage of Qt s excellent styling capabilities, inherit widgets and override their painting; or simply create your own widgets. In some situations you are required to do this because your application handles data that can t be shown otherwise. This chapter shows you how to tweak and create widgets to suit your own needs.
Copyright © OnBarcode.com . All rights reserved.