From 9a715453036038acf40328af80cd02b68bb0e7a0 Mon Sep 17 00:00:00 2001
From: MaysWind <i@mayswind.net>
Date: Fri, 24 Jun 2016 23:25:11 +0800
Subject: [PATCH] improve piece map performance

---
 src/scripts/directives/pieceMap.js | 37 ++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/src/scripts/directives/pieceMap.js b/src/scripts/directives/pieceMap.js
index 52f9777..0505c2b 100644
--- a/src/scripts/directives/pieceMap.js
+++ b/src/scripts/directives/pieceMap.js
@@ -11,19 +11,46 @@
                 pieceCount: '='
             },
             link: function (scope, element) {
+                var pieces = [];
+                var currentPieceStatus = [];
+
                 var redraw = function () {
-                    var pieces = aria2TaskService.getPieceStatus(scope.bitField, scope.pieceCount);
+                    currentPieceStatus = aria2TaskService.getPieceStatus(scope.bitField, scope.pieceCount);
+                    pieces.length = 0;
                     element.empty();
 
-                    var pieceCount = Math.max(1, pieces.length);
-
+                    var pieceCount = Math.max(1, currentPieceStatus.length);
+                    
                     for (var i = 0; i < pieceCount; i++) {
-                        element.append('<div class="piece' + (pieces[i] ? ' piece-completed' : '') + '"></div>');
+                        var piece = angular.element('<div class="piece' + (currentPieceStatus[i] ? ' piece-completed' : '') + '"></div>');
+                        pieces.push(piece);
+                        element.append(piece);
                     }
                 };
 
+                var refresh = function () {
+                    var newPieceStatus = aria2TaskService.getPieceStatus(scope.bitField, scope.pieceCount);
+
+                    if (!currentPieceStatus || !newPieceStatus || currentPieceStatus.length != newPieceStatus.length || newPieceStatus.length != pieces.length) {
+                        redraw();
+                        return;
+                    }
+
+                    for (var i = 0; i < pieces.length; i++) {
+                        if (currentPieceStatus[i] != newPieceStatus[i]) {
+                            if (newPieceStatus[i]) {
+                                pieces[i].addClass('piece-completed');
+                            } else {
+                                pieces[i].removeClass('piece-completed');
+                            }
+                        }
+                    }
+
+                    currentPieceStatus = newPieceStatus;
+                };
+
                 scope.$watch('bitField', function () {
-                    redraw();
+                    refresh();
                 });
 
                 scope.$watch('pieceNumber', function () {