feat(input): make input placeholder attr work

Closes #1279.

src/components/input/demoBasicUsage/index.html

@@ -22,7 +22,7 @@
       <div layout layout-sm="column">
         <md-input-container flex>
           <label>First Name</label>
-          <input ng-model="user.firstName">
+          <input ng-model="user.firstName" placeholder="Placeholder text">
         </md-input-container>
         <md-input-container flex>
           <label>Last Name</label>

src/components/input/input-theme.scss

@@ -6,7 +6,8 @@ md-input-container.md-THEME_NAME-theme {
     text-shadow: '{{foreground-shadow}}';
   }
 
-  label {
+  label,
+  .md-placeholder {
     text-shadow: '{{foreground-shadow}}';
     color: '{{foreground-3}}';
   }

src/components/input/input.js

@@ -12,7 +12,8 @@ angular.module('material.components.input', [
   .directive('label', labelDirective)
   .directive('input', inputTextareaDirective)
   .directive('textarea', inputTextareaDirective)
-  .directive('mdMaxlength', mdMaxlengthDirective);
+  .directive('mdMaxlength', mdMaxlengthDirective)
+  .directive('placeholder', placeholderDirective);
 
 /**
  * @ngdoc directive
@@ -42,7 +43,7 @@ angular.module('material.components.input', [
  *
  * </hljs>
  */
-function mdInputContainerDirective($mdTheming) {
+function mdInputContainerDirective($mdTheming, $animate, $mdUtil) {
   return {
     restrict: 'E',
     link: postLink,
@@ -52,18 +53,18 @@ function mdInputContainerDirective($mdTheming) {
   function postLink(scope, element, attr) {
     $mdTheming(element);
   }
-  function ContainerCtrl($scope, $element, $mdUtil) {
+  function ContainerCtrl($scope, $element) {
     var self = this;
 
     self.element = $element;
     self.setFocused = function(isFocused) {
-      $element.toggleClass('md-input-focused', !!isFocused);
+      $animate[isFocused ? 'addClass' : 'removeClass']($element, 'md-input-focused');
     };
     self.setHasValue = function(hasValue) {
-      $element.toggleClass('md-input-has-value', !!hasValue);
+      $animate[hasValue ? 'addClass' : 'removeClass']($element, 'md-input-has-value');
     };
     self.setInvalid = function(isInvalid) {
-      $element.toggleClass('md-input-invalid', !!isInvalid);
+      $animate[isInvalid ? 'addClass' : 'removeClass']($element, 'md-input-invalid');
     };
 
     $scope.$watch(function() {
@@ -207,11 +208,15 @@ function inputTextareaDirective($mdUtil, $window, $compile, $animate) {
     element
       .on('input', inputCheckValue)
       .on('focus', function(ev) {
-        containerCtrl.setFocused(true);
+        scope.$evalAsync(function() {
+          containerCtrl.setFocused(true);
+        });
       })
       .on('blur', function(ev) {
-        containerCtrl.setFocused(false);
-        inputCheckValue();
+        scope.$evalAsync(function() {
+          containerCtrl.setFocused(false);
+          inputCheckValue();
+        });
       });
 
     scope.$on('$destroy', function() {
@@ -313,4 +318,19 @@ function mdMaxlengthDirective($animate) {
   }
 }
 
+function placeholderDirective() {
+  return {
+    restrict: 'A',
+    require: '^mdInputContainer',
+    link: postLink
+  };
+
+  function postLink(scope, element, attr, inputContainer) {
+    var placeholderText = attr.placeholder;
+    element.removeAttr('placeholder');
+
+    inputContainer.element.append('<div class="md-placeholder">' + placeholderText + '</div>');
+  }
+}
+
 })();

src/components/input/input.scss

@@ -5,6 +5,8 @@ $input-label-default-scale: 1.0 !default;
 $input-label-float-offset: 4px !default;
 $input-label-float-scale: 0.75 !default;
 
+$input-placeholder-offset: $input-label-default-offset !default;
+
 $input-border-width-default: 1px !default;
 $input-border-width-focused: 2px !default;
 $input-line-height: 26px !default;
@@ -44,7 +46,8 @@ md-input-container {
     overflow: hidden;
   }
 
-  label {
+  label, 
+  .md-placeholder {
     order: 1;
     pointer-events: none;
     -webkit-font-smoothing: antialiased;
@@ -54,6 +57,24 @@ md-input-container {
     transform-origin: left top;
     transition: transform $swift-ease-out-timing-function 0.25s;
   }
+  .md-placeholder {
+    position: absolute;
+    top: 0;
+    opacity: 0;
+    transition-property: opacity, transform;
+    transform: translate3d(0, $input-placeholder-offset + $baseline-grid, 0);
+  }
+  &.md-input-focused:not(.md-input-has-value) {
+    .md-placeholder {
+      opacity: 1;
+      transform: translate3d(0, $input-placeholder-offset, 0);
+    }
+  }
+  &.md-input-has-value-remove-active,
+  &.md-input-focused {
+    transition: none;
+    transition-delay: none;
+  }
 
   /* 
    * The .md-input class is added to the input/textarea 
@@ -117,6 +138,9 @@ md-input-container {
       transform: translate3d(0,$input-label-float-offset,0) scale($input-label-float-scale);
     }
   }
+  &.md-input-has-value .md-placeholder {
+    transition: none;
+  }
 
   // Use wide border in error state or in focused state
   &.md-input-focused .md-input,