在一個項目中需要一個用來輸入分鐘數和秒數的控件，然而調查了一些開源項目後並未發現合適的控件。在Angular Bootstrap UI中有一個類似的控件TimePicker，但是它並沒有深入到分鐘和秒的精度。
因此，決定參考它的源碼然後自己進行實現。
最終的效果如下：
首先是該directive的定義：
app.directive('minuteSecondPicker', function() { return { restrict: 'EA', require: ['minuteSecondPicker', '?^ngModel'], controller: 'minuteSecondPickerController', replace: true, scope: { validity: '=' }, templateUrl: 'partials/directives/minuteSecondPicker.html', link: function(scope, element, attrs, ctrls) { var minuteSecondPickerCtrl = ctrls[0], ngModelCtrl = ctrls[1]; if(ngModelCtrl) { minuteSecondPickerCtrl.init(ngModelCtrl, element.find('input')); } } };});在以上的link函數中，ctrls是一個數組： ctrls[0]是定義在本directive上的controller實例，ctrls[1]是ngModelCtrl，即ng-model對應的controller實例。這個順序實際上是通過require: ['minuteSecondPicker', '?^ngModel']定義的。
注意到第一個依賴就是directive本身的名字，此時會將該directive中controller聲明的對應實例傳入。第二個依賴的寫法有些奇怪："?^ngModel"，?的含義是即使沒有找到該依賴，也不要拋出異常，即該依賴是一個可選項。 ^的含義是查找父元素的controller。
然後，定義該directive中用到的一些默認設置，通過constant directive實現：
app.constant('minuteSecondPickerConfig', { minuteStep: 1, secondStep: 1, readonlyInput: false, mousewheel: true});緊接著是directive對應的controller，它的聲明如下：
app.controller('minuteSecondPickerController', ['$scope', '$attrs', '$parse', 'minuteSecondPickerConfig', function($scope, $attrs, $parse, minuteSecondPickerConfig) { ...}]);在directive的link函數中，調用了此controller的init方法：
this.init = function(ngModelCtrl_, inputs) { ngModelCtrl = ngModelCtrl_; ngModelCtrl.$render = this.render; var minutesInputEl = inputs.eq(0), secondsInputEl = inputs.eq(1); var mousewheel = angular.isDefined($attrs.mousewheel) ? $scope.$parent.$eval($attrs.mousewheel) : minuteSecondPickerConfig.mousewheel; if(mousewheel) { this.setupMousewheelEvents(minutesInputEl, secondsInputEl); } $scope.readonlyInput = angular.isDefined($attrs.readonlyInput) ? $scope.$parent.$eval($attrs.readonlyInput) : minuteSecondPickerConfig.readonlyInput; this.setupInputEvents(minutesInputEl, secondsInputEl); };init方法接受的第二個參數是inputs，在link函數中傳入的是：element.find('input')。 所以第一個輸入框用來輸入分鐘，第二個輸入框用來輸入秒。
然後，檢查是否覆蓋了mousewheel屬性，如果沒有覆蓋則使用在constant中設置的默認mousewheel，並進行相關設置如下：
// respond on mousewheel spin this.setupMousewheelEvents = function(minutesInputEl, secondsInputEl) { var isScrollingUp = function(e) { if(e.originalEvent) { e = e.originalEvent; } // pick correct delta variable depending on event var delta = (e.wheelData) ? e.wheelData : -e.deltaY; return (e.detail || delta > 0); }; minutesInputEl.bind('mousewheel wheel', function(e) { $scope.$apply((isScrollingUp(e)) ? $scope.incrementMinutes() : $scope.decrementMinutes()); e.preventDefault(); }); secondsInputEl.bind('mousewheel wheel', function(e) { $scope.$apply((isScrollingUp(e)) ? $scope.incrementSeconds() : $scope.decrementSeconds()); e.preventDefault(); }); };init方法最後會對inputs本身進行一些設置：
// respond on direct input this.setupInputEvents = function(minutesInputEl, secondsInputEl) { if($scope.readonlyInput) { $scope.updateMinutes = angular.noop; $scope.updateSeconds = angular.noop; return; } var invalidate = function(invalidMinutes, invalidSeconds) { ngModelCtrl.$setViewValue(null); ngModelCtrl.$setValidity('time', false); $scope.validity = false; if(angular.isDefined(invalidMinutes)) { $scope.invalidMinutes = invalidMinutes; } if(angular.isDefined(invalidSeconds)) { $scope.invalidSeconds = invalidSeconds; } }; $scope.updateMinutes = function() { var minutes = getMinutesFromTemplate(); if(angular.isDefined(minutes)) { selected.minutes = minutes; refresh('m'); } else { invalidate(true); } }; minutesInputEl.bind('blur', function(e) { if(!$scope.invalidMinutes && $scope.minutes < 10) { $scope.$apply(function() { $scope.minutes = pad($scope.minutes); }); } }); $scope.updateSeconds = function() { var seconds = getSecondsFromTemplate(); if(angular.isDefined(seconds)) { selected.seconds = seconds; refresh('s'); } else { invalidate(undefined, true); } }; secondsInputEl.bind('blur', function(e) { if(!$scope.invalidSeconds && $scope.seconds < 10) { $scope.$apply(function() { $scope.seconds = pad($scope.seconds); }); } }); };此方法中，聲明了用於設置輸入非法的invalidate函數，它會在scope中暴露一個validity = false屬性讓頁面有機會做出合適的反應。
如果用戶使用了一個變量來表示minuteStep或者secondStep，那麼還需要設置相應的watchers：
var minuteStep = minuteSecondPickerConfig.minuteStep; if($attrs.minuteStep) { $scope.parent.$watch($parse($attrs.minuteStep), function(value) { minuteStep = parseInt(value, 10); }); } var secondStep = minuteSecondPickerConfig.secondStep; if($attrs.secondStep) { $scope.parent.$watch($parse($attrs.secondStep), function(value) { secondStep = parseInt(value, 10); }); }完整的directive實現代碼如下：
var app = angular.module("minuteSecondPickerDemo");app.directive('minuteSecondPicker', function() { return { restrict: 'EA', require: ['minuteSecondPicker', '?^ngModel'], controller: 'minuteSecondPickerController', replace: true, scope: { validity: '=' }, templateUrl: 'partials/directives/minuteSecondPicker.html', link: function(scope, element, attrs, ctrls) { var minuteSecondPickerCtrl = ctrls[0], ngModelCtrl = ctrls[1]; if(ngModelCtrl) { minuteSecondPickerCtrl.init(ngModelCtrl, element.find('input')); } } };});app.constant('minuteSecondPickerConfig', { minuteStep: 1, secondStep: 1, readonlyInput: false, mousewheel: true});app.controller('minuteSecondPickerController', ['$scope', '$attrs', '$parse', 'minuteSecondPickerConfig', function($scope, $attrs, $parse, minuteSecondPickerConfig) { var selected = { minutes: 0, seconds: 0 }, ngModelCtrl = { $setViewValue: angular.noop }; this.init = function(ngModelCtrl_, inputs) { ngModelCtrl = ngModelCtrl_; ngModelCtrl.$render = this.render; var minutesInputEl = inputs.eq(0), secondsInputEl = inputs.eq(1); var mousewheel = angular.isDefined($attrs.mousewheel) ? $scope.$parent.$eval($attrs.mousewheel) : minuteSecondPickerConfig.mousewheel; if(mousewheel) { this.setupMousewheelEvents(minutesInputEl, secondsInputEl); } $scope.readonlyInput = angular.isDefined($attrs.readonlyInput) ? $scope.$parent.$eval($attrs.readonlyInput) : minuteSecondPickerConfig.readonlyInput; this.setupInputEvents(minutesInputEl, secondsInputEl); }; var minuteStep = minuteSecondPickerConfig.minuteStep; if($attrs.minuteStep) { $scope.parent.$watch($parse($attrs.minuteStep), function(value) { minuteStep = parseInt(value, 10); }); } var secondStep = minuteSecondPickerConfig.secondStep; if($attrs.secondStep) { $scope.parent.$watch($parse($attrs.secondStep), function(value) { secondStep = parseInt(value, 10); }); } // respond on mousewheel spin this.setupMousewheelEvents = function(minutesInputEl, secondsInputEl) { var isScrollingUp = function(e) { if(e.originalEvent) { e = e.originalEvent; } // pick correct delta variable depending on event var delta = (e.wheelData) ? e.wheelData : -e.deltaY; return (e.detail || delta > 0); }; minutesInputEl.bind('mousewheel wheel', function(e) { $scope.$apply((isScrollingUp(e)) ? $scope.incrementMinutes() : $scope.decrementMinutes()); e.preventDefault(); }); secondsInputEl.bind('mousewheel wheel', function(e) { $scope.$apply((isScrollingUp(e)) ? $scope.incrementSeconds() : $scope.decrementSeconds()); e.preventDefault(); }); }; // respond on direct input this.setupInputEvents = function(minutesInputEl, secondsInputEl) { if($scope.readonlyInput) { $scope.updateMinutes = angular.noop; $scope.updateSeconds = angular.noop; return; } var invalidate = function(invalidMinutes, invalidSeconds) { ngModelCtrl.$setViewValue(null); ngModelCtrl.$setValidity('time', false); $scope.validity = false; if(angular.isDefined(invalidMinutes)) { $scope.invalidMinutes = invalidMinutes; } if(angular.isDefined(invalidSeconds)) { $scope.invalidSeconds = invalidSeconds; } }; $scope.updateMinutes = function() { var minutes = getMinutesFromTemplate(); if(angular.isDefined(minutes)) { selected.minutes = minutes; refresh('m'); } else { invalidate(true); } }; minutesInputEl.bind('blur', function(e) { if(!$scope.invalidMinutes && $scope.minutes < 10) { $scope.$apply(function() { $scope.minutes = pad($scope.minutes); }); } }); $scope.updateSeconds = function() { var seconds = getSecondsFromTemplate(); if(angular.isDefined(seconds)) { selected.seconds = seconds; refresh('s'); } else { invalidate(undefined, true); } }; secondsInputEl.bind('blur', function(e) { if(!$scope.invalidSeconds && $scope.seconds < 10) { $scope.$apply(function() { $scope.seconds = pad($scope.seconds); }); } }); }; this.render = function() { var time = ngModelCtrl.$modelValue ? { minutes: ngModelCtrl.$modelValue.minutes, seconds: ngModelCtrl.$modelValue.seconds } : null; // adjust the time for invalid value at first time if(time.minutes < 0) { time.minutes = 0; } if(time.seconds < 0) { time.seconds = 0; } var totalSeconds = time.minutes * 60 + time.seconds; time = { minutes: Math.floor(totalSeconds / 60), seconds: totalSeconds % 60 }; if(time) { selected = time; makeValid(); updateTemplate(); } }; // call internally when the model is valid function refresh(keyboardChange) { makeValid(); ngModelCtrl.$setViewValue({ minutes: selected.minutes, seconds: selected.seconds }); updateTemplate(keyboardChange); } function makeValid() { ngModelCtrl.$setValidity('time', true); $scope.validity = true; $scope.invalidMinutes = false; $scope.invalidSeconds = false; } function updateTemplate(keyboardChange) { var minutes = selected.minutes, seconds = selected.seconds; $scope.minutes = keyboardChange === 'm' ? minutes : pad(minutes); $scope.seconds = keyboardChange === 's' ? seconds : pad(seconds); } function pad(value) { return ( angular.isDefined(value) && value.toString().length < 2 ) ? '0' + value : value; } function getMinutesFromTemplate() { var minutes = parseInt($scope.minutes, 10); return (minutes >= 0) ? minutes : undefined; } function getSecondsFromTemplate() { var seconds = parseInt($scope.seconds, 10); if(seconds >= 60) { seconds = 59; } return (seconds >= 0) ? seconds : undefined; } $scope.incrementMinutes = function() { addSeconds(minuteStep * 60); }; $scope.decrementMinutes = function() { addSeconds(-minuteStep * 60); }; $scope.incrementSeconds = function() { addSeconds(secondStep); }; $scope.decrementSeconds = function() { addSeconds(-secondStep); }; function addSeconds(seconds) { var newSeconds = selected.minutes * 60 + selected.seconds + seconds; if(newSeconds < 0) { newSeconds = 0; } selected = { minutes: Math.floor(newSeconds / 60), seconds: newSeconds % 60 }; refresh(); } $scope.previewTime = function(minutes, seconds) { var totalSeconds = parseInt(minutes, 10) * 60 + parseInt(seconds, 10), hh = pad(Math.floor(totalSeconds / 3600)), mm = pad(minutes % 60), ss = pad(seconds); return hh + ':' + mm + ':' + ss; };}]);對應的Template實現：
<table> <tbody> <tr> <td> <a ng-click="incrementMinutes()"> <span></span> </a> </td> <td></td> <td> <a ng-click="incrementSeconds()"> <span></span> </a> </td> <td></td> </tr> <tr> <td ng-class="{'has-error': invalidMinutes}"> <input type="text" ng-model="minutes" ng-change="updateMinutes()" ng-mousewheel="incrementMinutes()" ng-readonly="readonlyInput" maxlength="3"> </td> <td>:</td> <td ng-class="{'has-error': invalidSeconds}"> <input type="text" ng-model="seconds" ng-change="updateSeconds()" ng-mousewheel="incrementSeconds()" ng-readonly="readonlyInput" maxlength="2"> <td> <!-- preview column --> <td> <span ng-show="validity"> {{ previewTime(minutes, seconds) }} </span> </td> </tr> <tr> <td> <a ng-click="decrementMinutes()"> <span></span> </a> </td> <td></td> <td> <a ng-click="decrementSeconds()"> <span></span> </a> </td> <td></td> </tr> </tbody></table>測試代碼(即前面截圖dialog的源代碼)：
<div> <h3>Highlight on <span>{{ movieName }}</span></h3></div><div> <div> <div id="highlight-start"> <h4>Start Time:</h4> <minute-second-picker ng-model="startTime" validity="startTimeValidity"></minute-second-picker> </div> <div id="highlight-end"> <h4>End Time:</h4> <minute-second-picker ng-model="endTime" validity="endTimeValidity"></minute-second-picker> </div> </div> <div> <div> Tags: </div> <div> <tags model="tags" src="s as s.name for s in sourceTags" options="{ addable: 'true' }"></tags> </div> </div></div><div> <button ng-click="ok()" ng-disabled="!startTimeValidity || !endTimeValidity || durationIncorrect(endTime, startTime)">OK</button> <button ng-click="cancel()">Cancel</button></div>如果大家還想深入學習，可以點擊這裡進行學習，再為大家附3個精彩的專題：
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