From a931275d0940c8cce77e2c6eb7f4b38dfcdbf0eb Mon Sep 17 00:00:00 2001
From: Denis Lugowski <denis.lugowski@gmail.com>
Date: Sun, 15 Feb 2026 12:23:30 +0100
Subject: [PATCH] feat(frontend): Add animations for form elements

---
 legalconsenthub/app/assets/css/main.css       |  41 +++-
 legalconsenthub/app/components/FormEngine.vue | 186 +++++++++---------
 .../components/FormStepperWithNavigation.vue  |  73 +++----
 3 files changed, 177 insertions(+), 123 deletions(-)

diff --git a/legalconsenthub/app/assets/css/main.css b/legalconsenthub/app/assets/css/main.css
index b18fbeb..227e577 100644
--- a/legalconsenthub/app/assets/css/main.css
+++ b/legalconsenthub/app/assets/css/main.css
@@ -49,7 +49,11 @@
 /* Global focus styles for elements without built-in focus styling.
    Nuxt UI components (inputs, buttons, selects, etc.) have their own
    focus ring styling, so we exclude them to avoid double borders. */
-:focus-visible:not(input):not(textarea):not(select):not(button):not([role="combobox"]):not([role="listbox"]):not([role="option"]):not([role="checkbox"]):not([role="radio"]):not([role="switch"]):not([role="slider"]):not([role="tab"]):not([role="menuitem"]) {
+:focus-visible:not(input):not(textarea):not(select):not(button):not([role='combobox']):not([role='listbox']):not(
+    [role='option']
+  ):not([role='checkbox']):not([role='radio']):not([role='switch']):not([role='slider']):not([role='tab']):not(
+    [role='menuitem']
+  ) {
   outline: 2px solid var(--color-teal-500);
   outline-offset: 2px;
 }
@@ -95,3 +99,38 @@
 .dark .nav-separator {
   background: linear-gradient(90deg, transparent, var(--color-gray-700), transparent);
 }
+
+/* ============================================
+   FORM ELEMENT VISIBILITY TRANSITIONS
+   ============================================ */
+
+/* Subtle fade + slide animation for form elements appearing/disappearing */
+.form-element-enter-active {
+  transition:
+    opacity 200ms ease-out,
+    transform 200ms ease-out;
+}
+
+.form-element-leave-active {
+  transition:
+    opacity 200ms ease-out,
+    transform 200ms ease-out;
+  /* Take leaving elements out of flow so remaining elements reposition smoothly */
+  position: absolute;
+  width: 100%;
+}
+
+.form-element-enter-from {
+  opacity: 0;
+  transform: translateY(-8px);
+}
+
+.form-element-leave-to {
+  opacity: 0;
+  transform: translateY(8px);
+}
+
+/* Smooth repositioning when elements are added/removed */
+.form-element-move {
+  transition: transform 200ms ease-out;
+}
diff --git a/legalconsenthub/app/components/FormEngine.vue b/legalconsenthub/app/components/FormEngine.vue
index a6340c0..0c93294 100644
--- a/legalconsenthub/app/components/FormEngine.vue
+++ b/legalconsenthub/app/components/FormEngine.vue
@@ -1,102 +1,107 @@
 <template>
-  <template
-    v-for="(formElementItem, visibleIndex) in visibleFormElements"
-    :key="getElementKey(formElementItem.formElement, formElementItem.indexInSubsection)"
-  >
-    <div class="group flex py-3 lg:py-4">
-      <div class="flex-auto min-w-0">
-        <p
-          v-if="formElementItem.formElement.title"
-          :class="['font-semibold', formElementItem.formElement.description ? '' : 'pb-3']"
-        >
-          {{ formElementItem.formElement.title }}
-        </p>
-        <p v-if="formElementItem.formElement.description" class="text-dimmed pb-3">
-          {{ formElementItem.formElement.description }}
-        </p>
-        <component
-          :is="getResolvedComponent(formElementItem.formElement)"
-          :form-options="formElementItem.formElement.options"
-          :disabled="props.disabled"
-          :all-form-elements="props.allFormElements"
-          :table-row-preset="formElementItem.formElement.tableRowPreset"
-          :application-form-id="props.applicationFormId"
-          :form-element-reference="formElementItem.formElement.reference"
-          @update:form-options="updateFormOptions($event, formElementItem)"
-        />
-        <div v-if="formElementItem.formElement.isClonable && !props.disabled" class="mt-3">
-          <UButton
-            variant="outline"
-            size="sm"
-            leading-icon="i-lucide-copy-plus"
-            @click="handleCloneElement(formElementItem.formElement, formElementItem.indexInSubsection)"
+  <TransitionGroup name="form-element" tag="div" class="relative" @before-enter="applyCascadingEntryDelay">
+    <div
+      v-for="(formElementItem, visibleIndex) in visibleFormElements"
+      :key="getElementKey(formElementItem.formElement, formElementItem.indexInSubsection)"
+      :data-index="visibleIndex"
+    >
+      <div class="group flex py-3 lg:py-4">
+        <div class="flex-auto min-w-0">
+          <p
+            v-if="formElementItem.formElement.title"
+            :class="['font-semibold', formElementItem.formElement.description ? '' : 'pb-3']"
           >
-            {{ $t('applicationForms.formElements.addAnother') }}
-          </UButton>
-        </div>
-        <TheComment
-          v-if="
-            applicationFormId && formElementItem.formElement.id && activeFormElement === formElementItem.formElement.id
-          "
-          :form-element-id="formElementItem.formElement.id"
-          :application-form-id="applicationFormId"
-          :comments="comments?.[formElementItem.formElement.id]"
-          :total-count="
-            commentCounts?.[formElementItem.formElement.id] ?? comments?.[formElementItem.formElement.id]?.length ?? 0
-          "
-          @close="activeFormElement = ''"
-        />
-      </div>
-      <div class="flex items-start gap-1">
-        <div class="min-w-9">
-          <UButton
+            {{ formElementItem.formElement.title }}
+          </p>
+          <p v-if="formElementItem.formElement.description" class="text-dimmed pb-3">
+            {{ formElementItem.formElement.description }}
+          </p>
+          <component
+            :is="getResolvedComponent(formElementItem.formElement)"
+            :form-options="formElementItem.formElement.options"
+            :disabled="props.disabled"
+            :all-form-elements="props.allFormElements"
+            :table-row-preset="formElementItem.formElement.tableRowPreset"
+            :application-form-id="props.applicationFormId"
+            :form-element-reference="formElementItem.formElement.reference"
+            @update:form-options="updateFormOptions($event, formElementItem)"
+          />
+          <div v-if="formElementItem.formElement.isClonable && !props.disabled" class="mt-3">
+            <UButton
+              variant="outline"
+              size="sm"
+              leading-icon="i-lucide-copy-plus"
+              @click="handleCloneElement(formElementItem.formElement, formElementItem.indexInSubsection)"
+            >
+              {{ $t('applicationForms.formElements.addAnother') }}
+            </UButton>
+          </div>
+          <TheComment
             v-if="
               applicationFormId &&
               formElementItem.formElement.id &&
-              (commentCounts?.[formElementItem.formElement.id] ?? 0) > 0
+              activeFormElement === formElementItem.formElement.id
             "
-            color="neutral"
-            variant="soft"
-            size="xs"
-            icon="i-lucide-message-square"
-            class="w-full justify-center"
-            @click="toggleComments(formElementItem.formElement.id)"
-          >
-            {{ commentCounts?.[formElementItem.formElement.id] ?? 0 }}
-          </UButton>
+            :form-element-id="formElementItem.formElement.id"
+            :application-form-id="applicationFormId"
+            :comments="comments?.[formElementItem.formElement.id]"
+            :total-count="
+              commentCounts?.[formElementItem.formElement.id] ?? comments?.[formElementItem.formElement.id]?.length ?? 0
+            "
+            @close="activeFormElement = ''"
+          />
         </div>
-        <div
-          :class="[
-            'transition-opacity duration-200',
-            openDropdownId === getElementKey(formElementItem.formElement, formElementItem.indexInSubsection)
-              ? 'opacity-100'
-              : 'opacity-100 lg:opacity-0 lg:group-hover:opacity-100 lg:focus-within:opacity-100'
-          ]"
-        >
-          <UDropdownMenu
-            :items="
-              getDropdownItems(
-                formElementItem.formElement,
-                getElementKey(formElementItem.formElement, formElementItem.indexInSubsection),
-                formElementItem.indexInSubsection
-              )
-            "
-            :content="{ align: 'end' }"
-            @update:open="
-              (isOpen: boolean) =>
-                handleDropdownToggle(
-                  getElementKey(formElementItem.formElement, formElementItem.indexInSubsection),
-                  isOpen
-                )
-            "
+        <div class="flex items-start gap-1">
+          <div class="min-w-9">
+            <UButton
+              v-if="
+                applicationFormId &&
+                formElementItem.formElement.id &&
+                (commentCounts?.[formElementItem.formElement.id] ?? 0) > 0
+              "
+              color="neutral"
+              variant="soft"
+              size="xs"
+              icon="i-lucide-message-square"
+              class="w-full justify-center"
+              @click="toggleComments(formElementItem.formElement.id)"
+            >
+              {{ commentCounts?.[formElementItem.formElement.id] ?? 0 }}
+            </UButton>
+          </div>
+          <div
+            :class="[
+              'transition-opacity duration-200',
+              openDropdownId === getElementKey(formElementItem.formElement, formElementItem.indexInSubsection)
+                ? 'opacity-100'
+                : 'opacity-100 lg:opacity-0 lg:group-hover:opacity-100 lg:focus-within:opacity-100'
+            ]"
           >
-            <UButton icon="i-lucide-ellipsis-vertical" color="neutral" variant="ghost" />
-          </UDropdownMenu>
+            <UDropdownMenu
+              :items="
+                getDropdownItems(
+                  formElementItem.formElement,
+                  getElementKey(formElementItem.formElement, formElementItem.indexInSubsection),
+                  formElementItem.indexInSubsection
+                )
+              "
+              :content="{ align: 'end' }"
+              @update:open="
+                (isOpen: boolean) =>
+                  handleDropdownToggle(
+                    getElementKey(formElementItem.formElement, formElementItem.indexInSubsection),
+                    isOpen
+                  )
+              "
+            >
+              <UButton icon="i-lucide-ellipsis-vertical" color="neutral" variant="ghost" />
+            </UDropdownMenu>
+          </div>
         </div>
       </div>
+      <USeparator v-if="visibleIndex < visibleFormElements.length - 1" />
     </div>
-    <USeparator v-if="visibleIndex < visibleFormElements.length - 1" />
-  </template>
+  </TransitionGroup>
 </template>
 
 <script setup lang="ts">
@@ -245,4 +250,9 @@ async function toggleComments(formElementId: string) {
 function handleCloneElement(formElement: FormElementDto, position: number) {
   emit('clone:element', formElement, position)
 }
+
+function applyCascadingEntryDelay(el: Element) {
+  const index = parseInt((el as HTMLElement).dataset.index ?? '0', 10)
+  ;(el as HTMLElement).style.transitionDelay = `${index * 30}ms`
+}
 </script>
diff --git a/legalconsenthub/app/components/FormStepperWithNavigation.vue b/legalconsenthub/app/components/FormStepperWithNavigation.vue
index 2cd1213..260bc80 100644
--- a/legalconsenthub/app/components/FormStepperWithNavigation.vue
+++ b/legalconsenthub/app/components/FormStepperWithNavigation.vue
@@ -57,40 +57,45 @@
           {{ currentFormElementSection.title }}
         </h1>
 
-        <UCard
-          v-for="{ subsection, sectionIndex } in visibleSubsections"
-          :key="getSubsectionKey(currentFormElementSection, sectionIndex, subsection)"
-          variant="subtle"
-          class="mb-6"
-        >
-          <div class="mb-4">
-            <h2 class="text-lg font-semibold text-highlighted">{{ subsection.title }}</h2>
-            <p v-if="subsection.subtitle" class="text-sm text-dimmed">{{ subsection.subtitle }}</p>
-          </div>
-          <FormEngine
-            :model-value="subsection.formElements"
-            :visibility-map="visibilityMap"
-            :application-form-id="applicationFormId"
-            :disabled="disabled"
-            :all-form-elements="allFormElements"
-            @update:model-value="
-              (elements) =>
-                handleFormElementUpdate(elements, getSubsectionKey(currentFormElementSection, sectionIndex, subsection))
-            "
-            @add:input-form="
-              (position) =>
-                handleAddInputForm(position, getSubsectionKey(currentFormElementSection, sectionIndex, subsection))
-            "
-            @clone:element="
-              (element, position) =>
-                handleCloneElement(
-                  element,
-                  position,
-                  getSubsectionKey(currentFormElementSection, sectionIndex, subsection)
-                )
-            "
-          />
-        </UCard>
+        <TransitionGroup name="form-element" tag="div" class="relative">
+          <UCard
+            v-for="{ subsection, sectionIndex } in visibleSubsections"
+            :key="getSubsectionKey(currentFormElementSection, sectionIndex, subsection)"
+            variant="subtle"
+            class="mb-6"
+          >
+            <div class="mb-4">
+              <h2 class="text-lg font-semibold text-highlighted">{{ subsection.title }}</h2>
+              <p v-if="subsection.subtitle" class="text-sm text-dimmed">{{ subsection.subtitle }}</p>
+            </div>
+            <FormEngine
+              :model-value="subsection.formElements"
+              :visibility-map="visibilityMap"
+              :application-form-id="applicationFormId"
+              :disabled="disabled"
+              :all-form-elements="allFormElements"
+              @update:model-value="
+                (elements) =>
+                  handleFormElementUpdate(
+                    elements,
+                    getSubsectionKey(currentFormElementSection, sectionIndex, subsection)
+                  )
+              "
+              @add:input-form="
+                (position) =>
+                  handleAddInputForm(position, getSubsectionKey(currentFormElementSection, sectionIndex, subsection))
+              "
+              @clone:element="
+                (element, position) =>
+                  handleCloneElement(
+                    element,
+                    position,
+                    getSubsectionKey(currentFormElementSection, sectionIndex, subsection)
+                  )
+              "
+            />
+          </UCard>
+        </TransitionGroup>
 
         <UCard v-if="visibleSubsections.length === 0" variant="subtle" class="mb-6">
           <div class="text-center py-8 text-dimmed">