fix(select): support floating labels with slotted content

BREAKING.md

@@ -229,6 +229,39 @@ When using `interface="action-sheet"`, `ion-select` no longer assigns the `selec
 
 Previously, the `selected` role was assigned only to the option matching the select's current value. Because the dismiss role mirrors the tapped button, this surfaced in just one case: re-selecting the already-selected option dismissed the action sheet with `role: "selected"` in `ionActionSheetDidDismiss`. Tapping any other option changed the value and dismissed with `role: ""`. Now that the role is no longer assigned, both cases dismiss with `role: undefined`. Apps that inspected this role to detect that a value was chosen, such as reading `role` from the underlying action sheet's `onDidDismiss` result, should listen for `ion-select`'s `ionChange` event instead, which emits the selected value when the selection changes.
 
+**Floating Label Behavior**
+
+Floating labels no longer automatically float when the select contains slotted content. Labels float only when the select is focused or has a value. Additionally, when using a floating label, the placeholder is only visible when the select is focused.
+
+**Internal DOM Structure Changes**
+
+The internal DOM structure has been reorganized to support floating labels with slotted content. This changes the structure and location of several exposed shadow parts.
+
+Added:
+- `.select-start` — `part="start"`
+- `.select-control` — `part="control"`
+- `.select-end` — `part="end"`
+
+Removed:
+- `.select-wrapper-inner` — `part="inner"`
+
+Restructured:
+- `.label-text-wrapper` remains `part="label"` but moved from `.select-wrapper` into `.select-control`
+- `.native-wrapper` remains `part="container"` but moved from `.select-wrapper-inner` into `.select-control`
+- Start slot moved from `.select-wrapper-inner` into `.select-start` (`part="start"`)
+- End slot moved from `.select-wrapper-inner` into `.select-end` (`part="end"`)
+- `.select-icon` remains `part="icon"` but its location depends on the label state:
+    - With a start/end label, the icon is inside `.native-wrapper`
+    - With a floating/stacked label, the icon is inside `.select-end`
+
+Update selectors that target the exposed shadow parts to account for the new structure:
+
+If you currently target `part="inner"`, that part has been removed. Update those styles to target the new parts as appropriate.
+
+If you target `part="label"`, `part="container"`, or `part="icon"`, the part names remain unchanged, but their position in the shadow DOM has changed. This may affect styles that depend on the relationship or layout of these parts.
+
+Use the new `part="start"`, `part="control"`, and `part="end"` parts to target the new structural wrappers.
+
 <h2 id="version-9x-framework-specific">Framework Specific</h2>
 
 <h4 id="version-9x-angular">Angular</h4>

core/api.txt

@@ -1758,12 +1758,14 @@ ion-select,css-prop,--select-text-media-width,ios
 ion-select,css-prop,--select-text-media-width,md
 ion-select,part,bottom
 ion-select,part,container
+ion-select,part,control
+ion-select,part,end
 ion-select,part,error-text
 ion-select,part,helper-text
 ion-select,part,icon
-ion-select,part,inner
 ion-select,part,label
 ion-select,part,placeholder
+ion-select,part,start
 ion-select,part,supporting-text
 ion-select,part,text
 ion-select,part,wrapper

core/src/components/select/select.ios.scss

@@ -19,14 +19,6 @@
   color: #{$text-color-step-350};
 }
 
-// Select Inner Wrapper
-// ----------------------------------------------------------------
-
-:host(.select-label-placement-stacked) .select-wrapper-inner,
-:host(.select-label-placement-floating) .select-wrapper-inner {
-  width: calc(100% - $select-ios-icon-size - $select-icon-margin-start);
-}
-
 // Select: Disabled
 // ----------------------------------------------------------------
 // The select and label should use the

core/src/components/select/select.md.outline.scss

@@ -9,6 +9,15 @@
   --padding-start: 16px;
   --padding-end: 16px;
 
+  /**
+   * The measured width of the start container, as a negative offset
+   * in LTR and a positive one in RTL. Written to the host by the
+   * start container controller, so renaming it here requires renaming
+   * it there too. Declared with a default so the label is positioned
+   * correctly before the first measurement runs.
+   */
+  --internal-start-container-adjustment: 0px;
+
   min-height: 56px;
 }
 
@@ -82,10 +91,11 @@
   position: absolute;
 
   /**
-   * Label text should not extend
-   * beyond the bounds of the select.
+   * While resting this is the width of the select, which already
+   * excludes the start and end slots. Once the label floats the
+   * containing block becomes the wrapper and the rule below takes over.
    */
-  max-width: calc(100% - var(--padding-start) - var(--padding-end));
+  max-width: 100%;
 }
 
 /**
@@ -99,11 +109,20 @@
   z-index: 1;
 }
 
+/**
+ * The resting label is positioned relative to the control so it can size to
+ * the space between the start and end slots. When floating, the label needs
+ * to escape the control and position itself relative to the wrapper instead.
+ */
+:host(.select-fill-outline:not(.label-floating)) .select-control {
+  position: relative;
+}
+
 /**
  * This makes the label sit above the select.
  */
 :host(.label-floating.select-fill-outline) .label-text-wrapper {
-  @include transform(translateY(-32%), scale(#{$form-control-label-stacked-scale}));
+  @include transform(translate(var(--internal-start-container-adjustment, 0px), -32%), scale(#{$form-control-label-stacked-scale}));
   @include margin(0);
 
   /**
@@ -197,13 +216,8 @@
 
 :host(.select-fill-outline) .select-outline-start {
   @include border(null, null, null, var(--border-width) var(--border-style) var(--border-color));
-}
-
-:host(.select-fill-outline) .select-outline-start {
   @include border-radius(var(--border-radius), 0px, 0px, var(--border-radius));
-}
 
-:host(.select-fill-outline) .select-outline-start {
   /**
    * There should be spacing between the translated text
    * and .select-outline-start. However, we can't add this
@@ -217,13 +231,8 @@
 
 :host(.select-fill-outline) .select-outline-end {
   @include border(null, var(--border-width) var(--border-style) var(--border-color), null, null);
-}
-
-:host(.select-fill-outline) .select-outline-end {
   @include border-radius(0px, var(--border-radius), var(--border-radius), 0px);
-}
 
-:host(.select-fill-outline) .select-outline-end {
   /**
    * The ending outline fragment
    * should take up the remaining free space.

core/src/components/select/select.md.scss

@@ -118,14 +118,6 @@
   --border-radius: 16px;
 }
 
-// Select Inner Wrapper
-// ----------------------------------------------------------------
-
-:host(.select-label-placement-stacked) .select-wrapper-inner,
-:host(.select-label-placement-floating) .select-wrapper-inner {
-  width: calc(100% - $select-md-icon-size - $select-icon-margin-start);
-}
-
 // Select: Disabled
 // ----------------------------------------------------------------
 // The select and label should use the

core/src/components/select/select.scss

@@ -154,36 +154,6 @@ button {
   color: inherit;
 }
 
-/**
- * The select icon should be centered with
- * the entire container not just the control
- * with floating/stacked labels.
- */
-:host(.select-label-placement-stacked) .select-icon,
-:host(.select-label-placement-floating) .select-icon {
-  position: absolute;
-
-  height: 100%;
-}
-
-/**
- * This positions the icon at the correct
- * edge of the component with LTR and RTL
- * text directions. The position mixin cannot be
- * used here because the icon is in the Shadow DOM.
- */
-:host(.select-ltr.select-label-placement-stacked) .select-icon,
-:host(.select-ltr.select-label-placement-floating) .select-icon {
-  // stylelint-disable-next-line property-disallowed-list
-  right: var(--padding-end, 0);
-}
-
-:host(.select-rtl.select-label-placement-stacked) .select-icon,
-:host(.select-rtl.select-label-placement-floating) .select-icon {
-  // stylelint-disable-next-line property-disallowed-list
-  left: var(--padding-start, 0);
-}
-
 // Select Text
 // --------------------------------------------------
 .select-text {
@@ -237,7 +207,7 @@ button {
 
   flex-grow: 1;
 
-  align-items: center;
+  align-items: stretch;
   justify-content: space-between;
 
   height: inherit;
@@ -270,23 +240,28 @@ button {
   transition: opacity 150ms cubic-bezier(0.4, 0, 0.2, 1);
 }
 
-.select-wrapper-inner {
+/**
+ * The control must inherit specific flex properties
+ * so that it will be placed properly when justify
+ * or label-placement are set on the host.
+ */
+.select-control {
   display: flex;
 
-  align-items: center;
+  flex: 1;
 
-  overflow: hidden;
-}
+  flex-direction: inherit;
+
+  align-items: center;
+  justify-content: inherit;
 
-:host(.select-label-placement-stacked) .select-wrapper-inner,
-:host(.select-label-placement-floating) .select-wrapper-inner {
   /**
-   * When using a stacked/floating label, the inner wrapper is
-   * stacked vertically under the label container. This line
-   * ensures that the inner wrapper fills all the remaining height
-   * of the component.
+   * The min-width is set to 0 to allow flex items to shrink below
+   * their content size. This enables the select text to collapse
+   * in width. We avoid overflow: hidden here because it will clip
+   * the floating label.
    */
-  flex-grow: 1;
+  min-width: 0;
 }
 
 // Select Highlight
@@ -390,6 +365,13 @@ button {
 
   align-items: center;
 
+  /**
+   * Allows the label to shrink below its intrinsic content width.
+   * Without this the label keeps its full width and can push the
+   * select and end slot outside the wrapper.
+   */
+  min-width: 0;
+
   /**
    * Label text should not extend
    * beyond the bounds of the select.
@@ -410,6 +392,18 @@ button {
   pointer-events: none;
 }
 
+/**
+ * When start/end slots are added or removed, we temporarily
+ * disable the label transition to prevent the floating label
+ * from animating as its position is adjusted.
+ *
+ * This class is applied by the start container controller, so
+ * renaming it here requires renaming it there too.
+ */
+:host(.skip-label-transition) .label-text-wrapper {
+  transition: none;
+}
+
 /**
  * We need to use two elements instead of
  * one. The .label-text-wrapper is responsible
@@ -448,6 +442,14 @@ button {
 .native-wrapper {
   display: flex;
 
+  /**
+   * Give up space before the label does. Flexbox would otherwise take
+   * from both in proportion to their size and truncate the shorter
+   * label first. The factor is this large because the label truncates
+   * as soon as it loses any width at all, even a fraction of a pixel.
+   */
+  flex-shrink: 100000;
+
   align-items: center;
 
   /**
@@ -554,9 +556,18 @@ button {
  * down when the select is focused or has a value.
  *
  */
-:host(.select-label-placement-stacked) .select-wrapper,
-:host(.select-label-placement-floating) .select-wrapper {
+:host(.select-label-placement-stacked) .select-control,
+:host(.select-label-placement-floating) .select-control {
   flex-direction: column;
+
+  /**
+   * When using a stacked/floating label, the control is
+   * stacked vertically under the label container. This line
+   * ensures that the control fills all the remaining height
+   * of the component.
+   */
+  flex-grow: 1;
+
   align-items: start;
 }
 
@@ -583,15 +594,11 @@ button {
 }
 
 /**
- * Ensures the select does not
- * overlap the label.
- * Also ensure that the native wrapper
- * takes up the remaining available height and width.
+ * Ensures that the native wrapper takes up the
+ * remaining available height and width.
  */
 :host(.select-label-placement-stacked) .native-wrapper,
 :host(.select-label-placement-floating) .native-wrapper {
-  @include margin(1px, 0, 0, 0);
-
   flex-grow: 1;
 
   width: 100%;
@@ -616,27 +623,16 @@ button {
  * The placeholder should be hidden when the label
  * is on top of the select. This prevents the label
  * from overlapping any placeholder value.
- *
- * TODO(FW-5592): Remove :not(.label-floating) piece
  */
-:host(.select-label-placement-floating:not(.label-floating)) .native-wrapper .select-placeholder {
+:host(.select-label-placement-floating) .native-wrapper .select-placeholder {
   opacity: 0;
 }
 
 /**
- * We don't use .label-floating here because that would
- * also include the case where the label is floating due
- * to content in the start/end slot. We want the opacity
- * to remain at the default in this case, since the select
- * isn't being actively interacted with.
- *
- * TODO(FW-5592): Change entire selector to:
- * :host(.label-floating.select-label-placement-floating) .native-wrapper .select-placeholder
+ * Show the placeholder when the label is floating.
  */
-:host(.select-expanded.select-label-placement-floating) .native-wrapper .select-placeholder,
-:host(.has-focus.select-label-placement-floating) .native-wrapper .select-placeholder,
-:host(.has-value.select-label-placement-floating) .native-wrapper .select-placeholder {
-  opacity: 1;
+:host(.label-floating.select-label-placement-floating) .native-wrapper .select-placeholder {
+  opacity: var(--placeholder-opacity);
 }
 
 /**
@@ -655,6 +651,17 @@ button {
 // Start/End Slots
 // ----------------------------------------------------------------
 
+.select-start,
+.select-end {
+  display: flex;
+
+  position: relative;
+
+  flex-shrink: 0;
+
+  align-items: center;
+}
+
 ::slotted([slot="start"]), ::slotted([slot="end"]) {
   /**
    * Prevent the slots from shrinking when the label and/or