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# snake.js Example File

demos/declarative/snake/qml/snake/content/snake.js

     var snake = new Array;
     var board = new Array;
     var links = new Array;
     var scheduledDirections = new Array;
     var numRows = 1;
     var numColumns = 1;
     var linkComponent = Qt.createComponent("content/Link.qml"); // XXX should resolve relative to script, not component
     var cookieComponent = Qt.createComponent("content/Cookie.qml");
     var cookie;
     var linksToGrow = 0;
     var linksToDie = 0;
     var waitForCookie = 0;
     var growType = 0;
     var skullMovementsBeforeDirectionChange = 0;

     function rand(n)
     {
       return (Math.floor(Math.random() * n));
     }

     function scheduleDirection(dir)
     {
         if (state == "starting") {
             direction = dir;
             headDirection = direction;
             head.rotation = headDirection;
         } else if (state == "running"){
             direction = dir;
             if(scheduledDirections[scheduledDirections.length-1]!=direction)
                 scheduledDirections.push(direction);
         }
     }

     function startNewGame()
     {
         if (state == "starting") {
             return;
         }

         if (activeGame) {
             endGame();
             startNewGameTimer.running = true;
             return;
         }

         state = "starting";

         numRows = numRowsAvailable;
         numColumns = numColumnsAvailable;
         board = new Array(numRows * numColumns);
         snake = new Array;
         scheduledDirections = new Array;
         growType = 0;

         skull.z = numRows * numColumns + 1;

         for (var i = 0; i < numRows * numColumns; ++i) {
             if (i < links.length) {
                 var link = links[i];
                 link.spawned = false;
                 link.dying = false;
             } else {
                 if(linkComponent.status != Component.Ready) {
                     if(linkComponent.status == Component.Error)
                         console.log(linkComponent.errorString());
                     else
                         console.log("Still loading linkComponent");
                     continue;//TODO: Better error handling?
                 }
                 var link = linkComponent.createObject(playfield);
                 link.z = numRows * numColumns + 1 - i;
                 link.type = i == 0 ? 2 : 0;
                 link.spawned = false;
                 link.dying = false;
                 links.push(link);
             }
         }

         head = links[0];
         snake.push(head);
         head.row = numRows/2 -1;
         head.column = numColumns/2 -1;
         head.spawned = true;

         linksToGrow = 5;
         linksToDie = 0;
         waitForCookie = 5;
         score = 0;
         startHeartbeatTimer.running = true;
     }

     function endGame()
     {
         activeGame = false;
         for(var i in snake)
             snake[i].dying = true;
         if (cookie) {
             cookie.dying = true;
             cookie = 0;
         }
         lastScore = score;
         highScores.saveScore(lastScore);
         state = "";
     }

     function move() {

         if (!head)
             return;

         var dir = direction;

         if (scheduledDirections.length) {
             dir = scheduledDirections.shift();
         }

         if (state == "starting") {
             var turn = (dir - headDirection);
             head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
             headDirection = dir;
             return;
         }

         var row = head.row;
         var column = head.column;

         if (dir == 0) {
             row = row - 1;
         } else if (dir == 1) {
             column = column + 1
         } else if (dir == 2) {
             row = row + 1;
         } else if (dir == 3) {
             column = column - 1;
         }

         //validate the new position
         if (row < 0 || row >= numRows
             || column < 0 || column >= numColumns
             || (row == skull.row && column == skull.column)
             || !isFree(row, column)) {
             var turn = (dir - headDirection);
             head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
             headDirection = dir;
             endGame();
             return;
         }

         var newLink;
         if (linksToGrow > 0) {
             --linksToGrow;
             newLink = links[snake.length];
             newLink.spawned = false;
             newLink.rotation = snake[snake.length-1].rotation;
             newLink.type = growType;
             newLink.dying = false;
             snake.push(newLink);
         } else {
             var lastLink = snake[snake.length-1];
             board[lastLink.row * numColumns + lastLink.column] = undefined;
         }

         if (waitForCookie > 0) {
             if (--waitForCookie == 0)
                 createCookie(cookie? (cookie.value+1) : 1);
         }

         for (var i = snake.length-1; i > 0; --i) {
             snake[i].row = snake[i-1].row;
             snake[i].column = snake[i-1].column;
             snake[i].rotation = snake[i-1].rotation;
         }

         if (newLink) {
             newLink.spawned = true;
         }

         // move the head
         head.row = row;
         head.column = column;
         board[row * numColumns + column] = head;

         var turn = (dir - headDirection);
         head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );
         headDirection = dir;

         var value = testCookie(row, column);
         if (value > 0) {
             linksToGrow += value;
             score += value;
         }
     }

     function isFree(row, column)
     {
         return board[row * numColumns + column] == undefined;
     }

     function isHead(row, column)
     {
         return head.column == column && head.row == row;
     }

     function testCookie(row, column)
     {
         if (cookie && !cookie.dying && cookie.row == row && cookie.column == column) {
             var value = cookie.value;
             waitForCookie = value;
             growType = snake[snake.length-1].type == 1 ? 0 : 1;
             cookie.dying = true;
             cookie.z = numRows * numColumns + 2;
             return value;
         }
         return 0;
     }

     function moveSkull()
     {

         if (linksToDie > 0) {
             --linksToDie;
             var link = snake.pop();
             link.dying = true;
             board[link.row * numColumns + link.column] = undefined;
             if (score > 0)
                 --score;
             if (snake.length == 0) {
                 endGame();
                 return;
             }
         }

         var row = skull.row;
         var column = skull.column;
         if (isHead(row, column)) {
             endGame();
             return;
         }
         row +=  skull.verticalMovement;
         column += skull.horizontalMovement;

         var attempts = 4;

         while (skullMovementsBeforeDirectionChange == 0 || row < 0 || row >= numRows
             || column < 0 || column >= numColumns
             || (!isFree(row, column) && !isHead(row, column))) {
             var d = rand(8);
             skull.verticalMovement = 0;
             skull.horizontalMovement = 0;
             skullMovementsBeforeDirectionChange = rand(20)+1;
             if (d == 0) {
                 skull.verticalMovement = -1
             } else if (d == 1) {
                 skull.horizontalMovement = -1;
             } else if (d == 2) {
                 skull.verticalMovement = 1
             } else if (d == 3){
                 skull.horizontalMovement = 1;
             } else if (cookie) {
                 var rd = cookie.row - skull.row;
                 var rc = cookie.column - skull.column;
                 if (Math.abs(rd) > Math.abs(rc)) {
                     skull.verticalMovement = rd > 0 ? 1 : -1;
                     skullMovementsBeforeDirectionChange = Math.abs(rd);
                 } else {
                     skull.horizontalMovement= rc > 0 ? 1 : -1;
                     skullMovementsBeforeDirectionChange = Math.abs(rc);
                 }
             }
             row = skull.row + skull.verticalMovement;
             column = skull.column + skull.horizontalMovement;
             if (--attempts == 0)
                 return;
         }

         skull.row = row;
         skull.column = column;
         --skullMovementsBeforeDirectionChange;
         var value = testCookie(row, column);
         if (value > 0)
             linksToDie += value/2;

         if (isHead(row, column))
             endGame();
     }

     function createCookie(value) {
         if (numRows * numColumns - snake.length < 10)
             return;

         var column = rand(numColumns);
         var row = rand(numRows);
         while (!isFree(row, column)) {
             column++;
             if (column == numColumns) {
                 column = 0;
                 row++;
                 if (row == numRows)
                     row = 0;
             }
         }

         if(cookieComponent.status != Component.Ready) {
             if(cookieComponent.status == Component.Error)
                 console.log(cookieComponent.errorString());
             else
                 console.log("Still loading cookieComponent");
             return;//TODO: Better error handling?
         }
         cookie = cookieComponent.createObject(head.parent);
         cookie.value = value;
         cookie.row = row;
         cookie.column = column;
     }