new_editor: unify shared UI text measurement semantics

new_editor/include/XCEditor/Foundation/UIEditorTextLayout.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <XCEditor/Foundation/UIEditorTextMeasurement.h>
+
+#include <algorithm>
+#include <string_view>
+
+namespace XCEngine::UI::Editor {
+
+inline float ClampUIEditorNonNegative(float value) {
+    return (std::max)(value, 0.0f);
+}
+
+inline float EstimateUIEditorSimpleTextWidth(
+    std::string_view text,
+    float estimatedGlyphWidth) {
+    return static_cast<float>(text.size()) * ClampUIEditorNonNegative(estimatedGlyphWidth);
+}
+
+inline float ResolveUIEditorMeasuredTextWidth(
+    std::string_view text,
+    float measuredWidth,
+    float fontSize,
+    float estimatedGlyphWidth,
+    const UIEditorTextMeasurer* textMeasurer = nullptr) {
+    if (measuredWidth > 0.0f) {
+        return measuredWidth;
+    }
+
+    if (textMeasurer != nullptr &&
+        !text.empty() &&
+        fontSize > 0.0f) {
+        return textMeasurer->MeasureTextWidth(UIEditorTextMeasureRequest { text, fontSize });
+    }
+
+    return EstimateUIEditorSimpleTextWidth(text, estimatedGlyphWidth);
+}
+
+} // namespace XCEngine::UI::Editor