fix(mdInput): Support multiple ng-messages simultaneously.

Previously, multiple `ng-message`s would render on top of each
other. Fix by altering CSS position and altering transition to
support multiple messages (i.e. potentially varying height).

Also some other small fixes to inputs/errors:

 * Fix number input widths in Firefox
 * Update errors demo messages to be more dynamic and show multiple errors
 * Update SCSS to allow `ng-message-exp` and associated `data-` and `x-` attributes
 * Add demo using `ng-message-exp` to show new SCSS styles being applied

Fixes #2648. Fixes #1957. Fixes #1793.

Should also close PRs #4472 and #4008. Thanks to @bopm and @iksose for the
initial PRs!

src/components/input/demoErrors/index.html

@@ -25,13 +25,42 @@ <h1 class="md-toolbar-tools">
         </div>
       </md-input-container>
 
+      <md-input-container>
+        <label>Client Email</label>
+        <input required type="email" name="clientEmail" ng-model="project.clientEmail"
+               minlength="10" maxlength="100" ng-pattern="/^.+@.+\..+$/" />
+
+        <div ng-messages="projectForm.clientEmail.$error" role="alert">
+          <div ng-message-exp="['minlength', 'maxlength', 'pattern']">
+            Your email must be between 10 and 100 characters long and look like an e-mail address.
+          </div>
+        </div>
+      </md-input-container>
+
       <md-input-container>
         <label>Hourly Rate (USD)</label>
-        <input required type="number" step="any" name="rate" ng-model="project.rate" min="800" max="4999">
-        <div ng-messages="projectForm.rate.$error">
-          <div ng-message="required">You've got to charge something! You can't just <b>give away</b> a Missile Defense System.</div>
-          <div ng-message="min">You should charge at least $800 an hour. This job is a big deal... if you mess up, everyone dies!</div>
-          <div ng-message="max">$5,000 an hour? That's a little ridiculous. I doubt event Bill Clinton could afford that.</div>
+        <input required type="number" step="any" name="rate" ng-model="project.rate" min="800"
+               max="4999" ng-pattern="/^1234$/">
+
+        <div ng-messages="projectForm.rate.$error" multiple>
+          <div ng-message="required">
+            You've got to charge something! You can't just <b>give away</b> a Missile Defense
+            System.
+          </div>
+
+          <div ng-message="min">
+            You should charge at least $800 an hour. This job is a big deal... if you mess up,
+            everyone dies!
+          </div>
+
+          <div ng-message="pattern">
+            You should charge exactly $1,234.
+          </div>
+
+          <div ng-message="max">
+            {{projectForm.rate.$viewValue | currency:"$":0}} an hour? That's a little ridiculous. I
+            doubt event Bill Clinton could afford that.
+          </div>
         </div>
       </md-input-container>
     </form>

src/components/input/input-theme.scss

@@ -16,12 +16,13 @@ md-input-container.md-THEME_NAME-theme {
     color: '{{foreground-3}}';
   }
 
-  ng-messages,
-  [ng-message], [data-ng-message], [x-ng-message] {
-    color: '{{warn-500}}'
+  ng-messages, [ng-messages],
+  ng-message, data-ng-message, x-ng-message,
+  [ng-message], [data-ng-message], [x-ng-message],
+  [ng-message-exp], [data-ng-message-exp], [x-ng-message-exp] {
+    color: '{{warn-500}}';
   }
 
-
   &:not(.md-input-invalid) {
     &.md-input-has-value {
       label {
@@ -65,6 +66,7 @@ md-input-container.md-THEME_NAME-theme {
     }
     ng-message, data-ng-message, x-ng-message,
     [ng-message], [data-ng-message], [x-ng-message],
+    [ng-message-exp], [data-ng-message-exp], [x-ng-message-exp],
     .md-char-counter {
       color: '{{warn-500}}';
     }

src/components/input/input.js

@@ -11,7 +11,8 @@ angular.module('material.components.input', [
   .directive('input', inputTextareaDirective)
   .directive('textarea', inputTextareaDirective)
   .directive('mdMaxlength', mdMaxlengthDirective)
-  .directive('placeholder', placeholderDirective);
+  .directive('placeholder', placeholderDirective)
+  .directive('ngMessages', ngMessagesDirective);
 
 /**
  * @ngdoc directive
@@ -69,6 +70,9 @@ function mdInputContainerDirective($mdTheming, $parse) {
     self.setHasValue = function(hasValue) {
       $element.toggleClass('md-input-has-value', !!hasValue);
     };
+    self.setHasMessages = function(hasMessages) {
+      $element.toggleClass('md-input-has-messages', !!hasMessages);
+    };
     self.setInvalid = function(isInvalid) {
       $element.toggleClass('md-input-invalid', !!isInvalid);
     };
@@ -341,11 +345,12 @@ function mdMaxlengthDirective($animate) {
     var ngModelCtrl = ctrls[0];
     var containerCtrl = ctrls[1];
     var charCountEl = angular.element('<div class="md-char-counter">');
+    var input = angular.element(containerCtrl.element[0].querySelector('[md-maxlength]'));
 
     // Stop model from trimming. This makes it so whitespace
     // over the maxlength still counts as invalid.
     attr.$set('ngTrim', 'false');
-    containerCtrl.element.append(charCountEl);
+    input.after(charCountEl);
 
     ngModelCtrl.$formatters.push(renderCharCount);
     ngModelCtrl.$viewChangeListeners.push(renderCharCount);
@@ -357,8 +362,7 @@ function mdMaxlengthDirective($animate) {
       maxlength = value;
       if (angular.isNumber(value) && value > 0) {
         if (!charCountEl.parent().length) {
-          $animate.enter(charCountEl, containerCtrl.element,
-                         angular.element(containerCtrl.element[0].lastElementChild));
+          $animate.enter(charCountEl, containerCtrl.element, input);
         }
         renderCharCount();
       } else {
@@ -408,3 +412,27 @@ function placeholderDirective($log) {
 
   }
 }
+
+function ngMessagesDirective() {
+  return {
+    restrict: 'EA',
+    link: postLink,
+
+    // This is optional because we don't want target *all* ngMessage instances, just those inside of
+    // mdInputContainer.
+    require: '^^?mdInputContainer'
+  };
+
+  function postLink(scope, element, attr, inputContainer) {
+    // If we are not a child of an input container, don't do anything
+    if (!inputContainer) return;
+
+    // Tell our parent input container we have messages so we can set the proper classes
+    inputContainer.setHasMessages(true);
+
+    // When destroyed, inform our input container
+    scope.$on('$destroy', function() {
+      inputContainer.setHasMessages(false);
+    });
+  }
+}

src/components/input/input.scss

@@ -28,6 +28,12 @@ md-input-container {
   padding: $input-container-padding;
   padding-bottom: $input-container-padding + $input-error-height;
 
+  // When we have ng-messages, remove the input error height from our bottom padding, since the
+  // ng-messages wrapper has a min-height of 1 error (so we don't adjust height as often; see below)
+  &.md-input-has-messages {
+    padding-bottom: $input-container-padding;
+  }
+
   > md-icon {
     position: absolute;
     top: 5px;
@@ -143,6 +149,9 @@ md-input-container {
     -ms-flex-preferred-size: $input-line-height; //IE fix
     border-radius: 0;
 
+    // Fix number inputs in Firefox to be full-width
+    width: auto;
+
     &:focus {
       outline: none;
     }
@@ -156,45 +165,66 @@ md-input-container {
     }
   }
 
+  .md-char-counter {
+    position: absolute;
+    right: 0;
+    order: 3;
+  }
+
   ng-messages, data-ng-messages, x-ng-messages,
   [ng-messages], [data-ng-messages], [x-ng-messages] {
-    order: 3;
     position: relative;
+    order: 4;
+    min-height: $input-error-height;
   }
+
   ng-message, data-ng-message, x-ng-message,
   [ng-message], [data-ng-message], [x-ng-message],
+  [ng-message-exp], [data-ng-message-exp], [x-ng-message-exp],
   .md-char-counter {
+    $input-error-line-height: $input-error-font-size + 2px;
     //-webkit-font-smoothing: antialiased;
-    position: absolute;
     font-size: $input-error-font-size;
-    line-height: $input-error-height;
+    line-height: $input-error-line-height;
+    overflow: hidden;
+
+    // Add some top padding which is equal to half the difference between the expected height
+    // and the actual height
+    $error-padding-top: ($input-error-height - $input-error-line-height) / 2;
+    padding-top: $error-padding-top;
 
     &:not(.md-char-counter) {
-      padding-right: rem(3);
+      padding-right: rem(5);
     }
 
     &.ng-enter {
-      transition: $swift-ease-out;
-      transition-delay: 0.2s;
+      transition: $swift-ease-in;
+
+      // Delay the enter transition so it happens after the leave
+      transition-delay: $swift-ease-in-duration / 1.5;
+
+      // Since we're delaying the transition, we speed up the duration a little bit to compensate
+      transition-duration: $swift-ease-in-duration / 1.5;
     }
     &.ng-leave {
-      transition: $swift-ease-in;
+      transition: $swift-ease-out;
+
+      // Speed up the duration (see enter comment above)
+      transition-duration: $swift-ease-out-duration / 1.5;
     }
     &.ng-enter,
     &.ng-leave.ng-leave-active {
+      // Move the error upwards off the screen and fade it out
+      margin-top: -$input-error-line-height - $error-padding-top;
       opacity: 0;
-      transform: translate3d(0, -20%, 0);
     }
     &.ng-leave,
     &.ng-enter.ng-enter-active {
+      // Move the error down into position and fade it in
+      margin-top: 0;
       opacity: 1;
-      transform: translate3d(0, 0, 0);
     }
   }
-  .md-char-counter {
-    bottom: $input-container-padding;
-    right: $input-container-padding;
-  }
 
   &.md-input-focused,
   &.md-input-has-value {