reactive styles

aui.core/src/AUI/Util/APimpl.h

@@ -110,4 +110,7 @@ namespace aui {
     private:
         std::aligned_storage_t<storageSize, storageAlignment> mStorage;
     };
-}
+}
+
+template<typename T, std::size_t storageSize, std::size_t storageAlignment = 8>
+using APimpl = aui::fast_pimpl<T, storageSize, storageAlignment>;

aui.uitests/tests/UIReactiveTest.cpp

@@ -11,6 +11,7 @@
 #include "AUI/Test/UI/UITestCase.h"
 #include "AUI/Test/UI/Assertion/Color.h"
 #include "AUI/Util/Declarative/Containers.h"
+#include "AUI/View/ACheckBox.h"
 
 namespace {
 
@@ -40,26 +41,70 @@ TEST_F(UIReactiveTest, Label) {
     // Test that a reactive label updates its text when the bound property changes.
     // The test creates a simple state object with a reactive string property
     // and binds it to a label using the AUI_REACT macro. It then verifies
-    // the initial rendered text and the updated text after changing the
+    // the initially rendered text and the updated text after changing the
     // property.
     using namespace ass;
 
     struct State {
-        AProperty<AString> name;
+        AProperty<AString> name = "Test";
     };
     auto state = _new<State>();
 
     mWindow->setContents(Vertical {
         Label { AUI_REACT("{}!"_format(state->name)) }
     });
 
-    // Initially, the property is empty, so the label should display "!".
+    // Initially, the property equals to "Test", so the label should display "Test!".
     EXPECT_EQ(*_cast<ALabel>(By::type<ALabel>().one())->text(), "!");
     // Update the property; the label should automatically reflect the new value.
     state->name = "Hello";
     EXPECT_EQ(*_cast<ALabel>(By::type<ALabel>().one())->text(), "Hello!");
 }
 
+struct TextColor {
+    AColor color;
+
+    void operator()(AView& view) const {
+
+    }
+};
+
+TEST_F(UIReactiveTest, Test2) {
+    // Test that a reactive label updates its text when the bound property changes.
+    // The test creates a simple state object with a reactive string property
+    // and binds it to a label using the AUI_REACT macro. It then verifies
+    // the initial rendered text and the updated text after changing the
+    // property.
+    using namespace ass;
+
+    struct State {
+        AProperty<bool> option = false;
+    };
+    auto state = _new<State>();
+
+    mWindow->setContents(Vertical {
+      CheckBox { .checked = AUI_REACT(state->option), .onCheckedChange = [state](bool v) { state->option = v; } },
+      Label { AUI_REACT("{}"_format(*state->option)) },
+      Label {
+        .text = "Test",
+        .modifier =
+            Modifier {
+              ::TextColor { .color = state->option ? AColor::RED : AColor::GREEN },
+            },
+      },
+        Label {
+          .text = "Test",
+        } AUI_LET {
+
+        },
+      });
+
+    // Initially, the property is empty, so the label should display "!".
+    EXPECT_EQ(*_cast<ALabel>(By::type<ALabel>().one())->text(), "!");
+    // Update the property; the label should automatically reflect the new value.
+    EXPECT_EQ(*_cast<ALabel>(By::type<ALabel>().one())->text(), "Hello!");
+}
+
 /*
 TEST_F(UIReactiveTest, MultipleWithStyle) {
     // Test that multiple containers with overridden styles render correctly.

aui.views/src/AUI/Util/Declarative/Modifier.cpp

@@ -0,0 +1,14 @@
+// AUI Framework - Declarative UI toolkit for modern C++20
+// Copyright (C) 2020-2025 Alex2772 and Contributors
+//
+// SPDX-License-Identifier: MPL-2.0
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+//
+// Created by alex2772 on 12/5/25.
+//
+
+#include "Modifier.h"

aui.views/src/AUI/Util/Declarative/Modifier.h

@@ -0,0 +1,28 @@
+// AUI Framework - Declarative UI toolkit for modern C++20
+// Copyright (C) 2020-2025 Alex2772 and Contributors
+//
+// SPDX-License-Identifier: MPL-2.0
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#pragma once
+#include "AUI/Common/AVector.h"
+
+#include <functional>
+
+class AView;
+
+namespace ass {
+class Modifier {
+public:
+    using Element = std::function<void(AView&)>;
+
+    Modifier() = default;
+    Modifier(std::initializer_list<Element> modifiers) {
+
+    }
+
+};
+}

aui.views/src/AUI/View/ALabel.h

@@ -12,6 +12,7 @@
 #pragma once
 
 #include "AAbstractLabel.h"
+#include <AUI/Util/Declarative/Modifier.h>
 #include <AUI/Util/Declarative/Contracts.h>
 
 /**
@@ -71,10 +72,12 @@ struct Label {
      * @brief Text to display.
      */
     AOptional<contract::In<AString>> text;
+    contract::In<Modifier> modifier = Modifier{};
 
     _<ALabel> operator()() {
         auto label = _new<ALabel>();
         AUI_NULLSAFE(text)->bindTo(label->text().assignment());
+        modifier.bindTo(ASlotDef{AUI_SLOT(label.get())::applyModifier});
         return label;
     }
 };

aui.views/src/AUI/View/AView.cpp

@@ -680,6 +680,9 @@ void AView::setCustomStyle(ass::PropertyListRecursive rule) {
     invalidateStateStylesImpl(prevMinSize);
 }
 
+void AView::applyModifier(ass::Modifier modifier) {
+
+}
 
 bool AView::hasIndirectParent(const _<AView>& v) {
     for (auto p = getParent(); p != nullptr; p = p->getParent()) {

aui.views/src/AUI/View/AView.h

@@ -31,6 +31,8 @@
 #include "AUI/Util/AFieldSignalEmitter.h"
 #include "AUI/Render/ARenderContext.h"
 #include "AUI/Util/IBackgroundEffect.h"
+#include "AUI/Util/Declarative/Modifier.h"
+
 #include <AUI/ASS/PropertyListRecursive.h>
 #include <AUI/Enum/AOverflow.h>
 #include <AUI/Enum/Visibility.h>
@@ -773,6 +775,7 @@ class API_AUI_VIEWS AView: public AObject
     }
 
     void setCustomStyle(ass::PropertyListRecursive rule);
+    void applyModifier(ass::Modifier modifier);
 
     void ensureAssUpdated();