feat(textarea): textarea shrinking and resizing

* Changes the textarea behavior to consider the "rows" attribute as the minimum, instead of the maximum, when auto-expanding the element.
* Adds a handle for vertically resizing the textarea element.
* Simplifies the logic for determining the textarea height.
* Makes the textarea sizing more accurate by using scrollHeight directly, instead of depending on the line height and amount of rows.
* Avoids potential issues where the textarea wouldn't resize when adding a newline.
* Adds the option to specify a maximum number of rows for a textarea via the `max-rows` attribute.

Closes #7649.

BREAKING CHANGE
This changes the behavior from considering the "rows" attribute as the maximum to considering it as the minimum.

src/components/input/input-theme.scss

@@ -35,10 +35,14 @@ md-input-container.md-THEME_NAME-theme {
  color: '{{foreground-2}}';
  }
  }
- &.md-input-focused {
+ &.md-input-focused,
+ &.md-input-resized {
  .md-input {
  border-color: '{{primary-color}}';
  }
+ }
+
+ &.md-input-focused {
  label {
  color: '{{primary-color}}';
  }

src/components/input/input.js

@@ -169,7 +169,9 @@ function labelDirective() {
  * @param {string=} placeholder An alternative approach to using aria-label when the label is not
  * PRESENT. The placeholder text is copied to the aria-label attribute.
  * @param md-no-autogrow {boolean=} When present, textareas will not grow automatically.
+ * @param md-no-resize {boolean=} Disables the textarea resize handle.
  * @param md-no-asterisk {boolean=} When present, asterisk will not be appended to required inputs label
+ * @param {number=} max-rows The maximum amount of rows for a textarea.
  * @param md-detect-hidden {boolean=} When present, textareas will be sized properly when they are
  * revealed after being hidden. This is off by default for performance reasons because it
  * guarantees a reflow every digest cycle.
@@ -255,9 +257,21 @@ function labelDirective() {
  * error animation effects. Therefore, it is *not* advised to use the Layout system inside of the
  * `<md-input-container>` tags. Instead, use relative or absolute positioning.
  *
+ *
+ * <h3>Textarea directive</h3>
+ * The `textarea` element within a `md-input-container` has the following specific behavior:
+ * - By default the `textarea` grows as the user types. This can be disabled via the `md-no-autogrow`
+ * attribute.
+ * - If a `textarea` has the `rows` attribute, it will treat the `rows` as the minimum height and will
+ * continue growing as the user types. For example a textarea with `rows="3"` will be 3 lines of text
+ * high initially. If no rows are specified, the directive defaults to 1.
+ * - If you wan't a `textarea` to stop growing at a certain point, you can specify the `max-rows` attribute.
+ * - The textarea's bottom border acts as a handle which users can drag, in order to resize the element vertically.
+ * Once the user has resized a `textarea`, the autogrowing functionality becomes disabled. If you don't want a
+ * `textarea` to be resizeable by the user, you can add the `md-no-resize` attribute.
  */
 
-function inputTextareaDirective($mdUtil, $window, $mdAria, $timeout) {
+function inputTextareaDirective($mdUtil, $window, $mdAria, $timeout, $mdGesture) {
  return {
  restrict: 'E',
  require: ['^?mdInputContainer', '?ngModel'],
@@ -375,13 +389,16 @@ function inputTextareaDirective($mdUtil, $window, $mdAria, $timeout) {
  }
 
  function setupTextarea() {
- if (attr.hasOwnProperty('mdNoAutogrow')) {
- return;
- }
+ var isAutogrowing = !attr.hasOwnProperty('mdNoAutogrow');
+
+ attachResizeHandle();
+
+ if (!isAutogrowing) return;
 
  // Can't check if height was or not explicity set,
  // so rows attribute will take precedence if present
  var minRows = attr.hasOwnProperty('rows') ? parseInt(attr.rows) : NaN;
+ var maxRows = attr.hasOwnProperty('maxRows') ? parseInt(attr.maxRows) : NaN;
  var lineHeight = null;
  var node = element[0];
 
@@ -391,78 +408,151 @@ function inputTextareaDirective($mdUtil, $window, $mdAria, $timeout) {
  $mdUtil.nextTick(growTextarea);
  }, 10, false);
 
- // We can hook into Angular's pipeline, instead of registering a new listener.
- // Note that we should use `$parsers`, as opposed to `$viewChangeListeners` which
- // was used before, because `$viewChangeListeners` don't fire if the input is
- // invalid.
+ // We could leverage ngModel's $parsers here, however it
+ // isn't reliable, because Angular trims the input by default,
+ // which means that growTextarea won't fire when newlines and
+ // spaces are added.
+ element.on('input', growTextarea);
+
+ // We should still use the $formatters, because they fire when
+ // the value was changed from outside the textarea.
  if (hasNgModel) {
- ngModelCtrl.$formatters.unshift(pipelineListener);
- ngModelCtrl.$parsers.unshift(pipelineListener);
- } else {
- // Note that it's safe to use the `input` event since we're not supporting IE9 and below.
- element.on('input', growTextarea);
+ ngModelCtrl.$formatters.push(formattersListener);
  }
 
  if (!minRows) {
- element
- .attr('rows', 1)
- .on('scroll', onScroll);
+ element.attr('rows', 1);
  }
 
  angular.element($window).on('resize', growTextarea);
-
- scope.$on('$destroy', function() {
- angular.element($window).off('resize', growTextarea);
- });
+ scope.$on('$destroy', disableAutogrow);
 
  function growTextarea() {
  // temporarily disables element's flex so its height 'runs free'
  element
- .addClass('md-no-flex')
- .attr('rows', 1);
-
- if (minRows) {
- if (!lineHeight) {
- node.style.minHeight = 0;
- lineHeight = element.prop('clientHeight');
- node.style.minHeight = null;
- }
+ .attr('rows', 1)
+ .css('height', 'auto')
+ .addClass('md-no-flex');
 
- var newRows = Math.round( Math.round(getHeight() / lineHeight) );
- var rowsToSet = Math.min(newRows, minRows);
+ var height = getHeight();
 
- element
- .css('height', lineHeight * rowsToSet + 'px')
- .attr('rows', rowsToSet)
- .toggleClass('_md-textarea-scrollable', newRows >= minRows);
+ if (!lineHeight) {
+ // offsetHeight includes padding which can throw off our value
+ lineHeight = element.css('padding', 0).prop('offsetHeight');
+ element.css('padding', null);
+ }
 
- } else {
- element.css('height', 'auto');
- node.scrollTop = 0;
- var height = getHeight();
- if (height) element.css('height', height + 'px');
+ if (minRows && lineHeight) {
+ height = Math.max(height, lineHeight * minRows);
+ }
+
+ if (maxRows && lineHeight) {
+ var maxHeight = lineHeight * maxRows;
+
+ if (maxHeight < height) {
+ element.attr('md-no-autogrow', '');
+ height = maxHeight;
+ } else {
+ element.removeAttr('md-no-autogrow');
+ }
+ }
+
+ if (lineHeight) {
+ element.attr('rows', Math.round(height / lineHeight));
  }
 
- element.removeClass('md-no-flex');
+ element
+ .css('height', height + 'px')
+ .removeClass('md-no-flex');
  }
 
  function getHeight() {
  var offsetHeight = node.offsetHeight;
  var line = node.scrollHeight - offsetHeight;
- return offsetHeight + (line > 0 ? line : 0);
+ return offsetHeight + Math.max(line, 0);
  }
 
- function onScroll(e) {
- node.scrollTop = 0;
- // for smooth new line adding
- var line = node.scrollHeight - node.offsetHeight;
- var height = node.offsetHeight + line;
- node.style.height = height + 'px';
+ function formattersListener(value) {
+ $mdUtil.nextTick(growTextarea);
+ return value;
  }
 
- function pipelineListener(value) {
- growTextarea();
- return value;
+ function disableAutogrow() {
+ if (!isAutogrowing) return;
+
+ isAutogrowing = false;
+ angular.element($window).off('resize', growTextarea);
+ element
+ .attr('md-no-autogrow', '')
+ .off('input', growTextarea);
+
+ if (hasNgModel) {
+ var listenerIndex = ngModelCtrl.$formatters.indexOf(formattersListener);
+
+ if (listenerIndex > -1) {
+ ngModelCtrl.$formatters.splice(listenerIndex, 1);
+ }
+ }
+ }
+
+ function attachResizeHandle() {
+ if (attr.hasOwnProperty('mdNoResize')) return;
+
+ var handle = angular.element('<div class="md-resize-handle"></div>');
+ var isDragging = false;
+ var dragStart = null;
+ var startHeight = 0;
+ var container = containerCtrl.element;
+ var dragGestureHandler = $mdGesture.register(handle, 'drag', { horizontal: false });
+
+ element.after(handle);
+ handle.on('mousedown', onMouseDown);
+
+ container
+ .on('$md.dragstart', onDragStart)
+ .on('$md.drag', onDrag)
+ .on('$md.dragend', onDragEnd);
+
+ scope.$on('$destroy', function() {
+ handle
+ .off('mousedown', onMouseDown)
+ .remove();
+
+ container
+ .off('$md.dragstart', onDragStart)
+ .off('$md.drag', onDrag)
+ .off('$md.dragend', onDragEnd);
+
+ dragGestureHandler();
+ handle = null;
+ container = null;
+ dragGestureHandler = null;
+ });
+
+ function onMouseDown(ev) {
+ ev.preventDefault();
+ isDragging = true;
+ dragStart = ev.clientY;
+ startHeight = parseFloat(element.css('height')) || element.prop('offsetHeight');
+ }
+
+ function onDragStart(ev) {
+ if (!isDragging) return;
+ ev.preventDefault();
+ disableAutogrow();
+ container.addClass('md-input-resized');
+ }
+
+ function onDrag(ev) {
+ if (!isDragging) return;
+ element.css('height', startHeight + (ev.pointer.y - dragStart) + 'px');
+ }
+
+ function onDragEnd(ev) {
+ if (!isDragging) return;
+ isDragging = false;
+ container.removeClass('md-input-resized');
+ }
  }
 
  // Attach a watcher to detect when the textarea gets shown.

src/components/input/input.scss

@@ -24,6 +24,8 @@ $icon-top-offset: ($icon-offset - $input-padding-top - $input-border-width-focus
 
 $icon-float-focused-top: -8px !default;
 
+$input-resize-handle-height: 10px !default;
+
 md-input-container {
  @include pie-clearfix();
  display: inline-block;
@@ -46,6 +48,16 @@ md-input-container {
  min-width: 1px;
  }
 
+ .md-resize-handle {
+ position: absolute;
+ bottom: $input-error-height - $input-border-width-default * 2;
+ left: 0;
+ height: $input-resize-handle-height;
+ background: transparent;
+ width: 100%;
+ cursor: ns-resize;
+ }
+
  > md-icon {
  position: absolute;
  top: $icon-top-offset;
@@ -88,14 +100,10 @@ md-input-container {
  -ms-flex-preferred-size: auto; //IE fix
  }
 
- &._md-textarea-scrollable,
- &[md-no-autogrow] {
- overflow: auto;
- }
-
  // The height usually gets set to 1 line by `.md-input`.
  &[md-no-autogrow] {
  height: auto;
+ overflow: auto;
  }
  }
 
@@ -299,7 +307,8 @@ md-input-container {
 
  // Use wide border in error state or in focused state
  &.md-input-focused .md-input,
- .md-input.ng-invalid.ng-dirty {
+ .md-input.ng-invalid.ng-dirty,
+ &.md-input-resized .md-input {
  padding-bottom: 0; // Increase border width by 1px, decrease padding by 1
  border-width: 0 0 $input-border-width-focused 0;
  }