Extract XCUI text input controller to common layer

engine/CMakeLists.txt

@@ -517,7 +517,9 @@ add_library(XCEngine STATIC
     ${CMAKE_CURRENT_SOURCE_DIR}/src/UI/Input/UIShortcutRegistry.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/UI/Input/UIInputDispatcher.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/UI/Text/UITextEditing.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/UI/Text/UITextInputController.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/UI/Text/UITextEditing.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/UI/Text/UITextInputController.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/UI/Runtime/UIScreenTypes.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/UI/Runtime/UIScreenDocumentHost.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/UI/Runtime/UIScreenPlayer.h

engine/include/XCEngine/UI/Text/UITextInputController.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <XCEngine/UI/Types.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+
+namespace XCEngine {
+namespace UI {
+namespace Text {
+
+struct UITextInputState {
+    std::string value = {};
+    std::size_t caret = 0u;
+};
+
+struct UITextInputOptions {
+    bool multiline = false;
+    std::size_t tabWidth = 4u;
+};
+
+struct UITextInputEditResult {
+    bool handled = false;
+    bool valueChanged = false;
+    bool submitRequested = false;
+};
+
+void ClampCaret(UITextInputState& state);
+bool InsertCharacter(UITextInputState& state, std::uint32_t character);
+UITextInputEditResult HandleKeyDown(
+    UITextInputState& state,
+    std::int32_t keyCode,
+    const UIInputModifiers& modifiers,
+    const UITextInputOptions& options = {});
+
+} // namespace Text
+} // namespace UI
+} // namespace XCEngine

engine/src/UI/Text/UITextInputController.cpp

@@ -0,0 +1,156 @@
+#include <XCEngine/UI/Text/UITextInputController.h>
+
+#include <XCEngine/Input/InputTypes.h>
+#include <XCEngine/UI/Text/UITextEditing.h>
+
+#include <algorithm>
+
+namespace XCEngine {
+namespace UI {
+namespace Text {
+
+namespace {
+
+using XCEngine::Input::KeyCode;
+
+} // namespace
+
+void ClampCaret(UITextInputState& state) {
+    state.caret = (std::min)(state.caret, state.value.size());
+}
+
+bool InsertCharacter(UITextInputState& state, std::uint32_t character) {
+    if (character < 32u || character == 127u) {
+        return false;
+    }
+
+    std::string encoded = {};
+    AppendUtf8Codepoint(encoded, character);
+    if (encoded.empty()) {
+        return false;
+    }
+
+    ClampCaret(state);
+    state.value.insert(state.caret, encoded);
+    state.caret += encoded.size();
+    return true;
+}
+
+UITextInputEditResult HandleKeyDown(
+    UITextInputState& state,
+    std::int32_t keyCode,
+    const UIInputModifiers& modifiers,
+    const UITextInputOptions& options) {
+    ClampCaret(state);
+
+    UITextInputEditResult result = {};
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Backspace)) {
+        result.handled = true;
+        if (state.caret > 0u) {
+            const std::size_t previousCaret = RetreatUtf8Offset(state.value, state.caret);
+            state.value.erase(previousCaret, state.caret - previousCaret);
+            state.caret = previousCaret;
+            result.valueChanged = true;
+        }
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Delete)) {
+        result.handled = true;
+        if (state.caret < state.value.size()) {
+            const std::size_t nextCaret = AdvanceUtf8Offset(state.value, state.caret);
+            state.value.erase(state.caret, nextCaret - state.caret);
+            result.valueChanged = true;
+        }
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Left)) {
+        result.handled = true;
+        state.caret = RetreatUtf8Offset(state.value, state.caret);
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Right)) {
+        result.handled = true;
+        state.caret = AdvanceUtf8Offset(state.value, state.caret);
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Up) && options.multiline) {
+        result.handled = true;
+        state.caret = MoveCaretVertically(state.value, state.caret, -1);
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Down) && options.multiline) {
+        result.handled = true;
+        state.caret = MoveCaretVertically(state.value, state.caret, 1);
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Home)) {
+        result.handled = true;
+        state.caret = options.multiline
+            ? FindLineStartOffset(state.value, state.caret)
+            : 0u;
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::End)) {
+        result.handled = true;
+        state.caret = options.multiline
+            ? FindLineEndOffset(state.value, state.caret)
+            : state.value.size();
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Enter)) {
+        result.handled = true;
+        if (options.multiline) {
+            state.value.insert(state.caret, "\n");
+            ++state.caret;
+            result.valueChanged = true;
+        } else {
+            result.submitRequested = true;
+        }
+        return result;
+    }
+
+    if (keyCode == static_cast<std::int32_t>(KeyCode::Tab) &&
+        options.multiline &&
+        !modifiers.control &&
+        !modifiers.alt &&
+        !modifiers.super) {
+        result.handled = true;
+
+        if (modifiers.shift) {
+            const std::size_t lineStart = FindLineStartOffset(state.value, state.caret);
+            std::size_t removed = 0u;
+            while (removed < options.tabWidth &&
+                lineStart + removed < state.value.size() &&
+                state.value[lineStart + removed] == ' ') {
+                ++removed;
+            }
+
+            if (removed > 0u) {
+                state.value.erase(lineStart, removed);
+                state.caret = state.caret >= lineStart + removed ? state.caret - removed : lineStart;
+                result.valueChanged = true;
+            }
+        } else {
+            state.value.insert(state.caret, std::string(options.tabWidth, ' '));
+            state.caret += options.tabWidth;
+            result.valueChanged = true;
+        }
+
+        return result;
+    }
+
+    return result;
+}
+
+} // namespace Text
+} // namespace UI
+} // namespace XCEngine