Qt 4.8: HighScoreModel.qml Example File (demos/declarative/snake/qml/snake/content/HighScoreModel.qml)

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# HighScoreModel.qml Example File

demos/declarative/snake/qml/snake/content/HighScoreModel.qml

     /****************************************************************************
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     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
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     ** This file is part of the QtDeclarative module of the Qt Toolkit.
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     import QtQuick 1.0

     // Models a high score table.
     //
     // Use this component like this:
     //
     //  HighScoreModel {
     //      id: highScores
     //      game: "MyCoolGame"
     //  }
     //
     // Then use either use the top-score properties:
     //
     //  Text { text: "HI: " + highScores.topScore }
     //
     // or, use the model in a view:
     //
     //  ListView {
     //      model: highScore
     //      delegate: Component {
     //                    ... player ... score ...
     //                }
     //  }
     //
     // Add new scores via:
     //
     //  saveScore(newScore)
     //
     // or:
     //
     //  savePlayerScore(playerName,newScore)
     //
     // The best maxScore scores added by this method will be retained in an SQL database,
     // and presented in the model and in the topScore/topPlayer properties.
     //

     ListModel {
         id: model
         property string game: ""
         property int topScore: 0
         property string topPlayer: ""
         property int maxScores: 10

         function __db()
         {
             return openDatabaseSync("HighScoreModel", "1.0", "Generic High Score Functionality for QML", 1000000);
         }
         function __ensureTables(tx)
         {
             tx.executeSql('CREATE TABLE IF NOT EXISTS HighScores(game TEXT, score INT, player TEXT)', []);
         }

         function fillModel() {
             __db().transaction(
                 function(tx) {
                     __ensureTables(tx);
                     var rs = tx.executeSql("SELECT score,player FROM HighScores WHERE game=? ORDER BY score DESC", [game]);
                     model.clear();
                     if (rs.rows.length > 0) {
                         topScore = rs.rows.item(0).score
                         topPlayer = rs.rows.item(0).player
                         for (var i=0; i<rs.rows.length; ++i) {
                             if (i < maxScores)
                                 model.append(rs.rows.item(i))
                         }
                         if (rs.rows.length > maxScores)
                             tx.executeSql("DELETE FROM HighScores WHERE game=? AND score <= ?",
                                                 [game, rs.rows.item(maxScores).score]);
                     }
                 }
             )
         }

         function savePlayerScore(player,score) {
             __db().transaction(
                 function(tx) {
                     __ensureTables(tx);
                     tx.executeSql("INSERT INTO HighScores VALUES(?,?,?)", [game,score,player]);
                     fillModel();
                 }
             )
         }

         function saveScore(score) {
             savePlayerScore("player",score);
         }

         function clearScores() {
             __db().transaction(
                 function(tx) {
                     tx.executeSql("DELETE FROM HighScores WHERE game=?", [game]);
                     fillModel();
                 }
             )
         }

         Component.onCompleted: { fillModel() }
     }