Add PlatformDynamicRangeLimit::ValueType to abstract the value&storage type

https://bugs.webkit.org/show_bug.cgi?id=291621
rdar://149364934

Reviewed by Mike Wyrzykowski.

Use PlatformDynamicRangeLimit::ValueType instead of naked float.
This will make future changes simpler and clearer.

Exception: The private 3-float constructor still takes floats, because
that won't change even if/when ValueType changes.

* Source/WebCore/platform/graphics/PlatformDynamicRangeLimit.cpp:
(WebCore::PlatformDynamicRangeLimit::normalizedAverage):
* Source/WebCore/platform/graphics/PlatformDynamicRangeLimit.h:
(WebCore::PlatformDynamicRangeLimit::value const):
(WebCore::PlatformDynamicRangeLimit::PlatformDynamicRangeLimit):
* Tools/TestWebKitAPI/Tests/WebCore/PlatformDynamicRangeLimitTests.cpp:

Canonical link: https://commits.webkit.org/293945@main

Author: squelart

Source/WebCore/platform/graphics/PlatformDynamicRangeLimit.cpp

@@ -30,7 +30,7 @@
 
 namespace WebCore {
 
-float PlatformDynamicRangeLimit::normalizedAverage(float standardPercent, float constrainedHighPercent, float noLimitPercent)
+PlatformDynamicRangeLimit::ValueType PlatformDynamicRangeLimit::normalizedAverage(float standardPercent, float constrainedHighPercent, float noLimitPercent)
 {
     if (!std::isfinite(standardPercent) || standardPercent < 0 || standardPercent > 100 || !std::isfinite(constrainedHighPercent) || constrainedHighPercent < 0 || constrainedHighPercent > 100 || !std::isfinite(noLimitPercent) || noLimitPercent < 0 || noLimitPercent > 100) {
         ASSERT(std::isfinite(standardPercent));

Source/WebCore/platform/graphics/PlatformDynamicRangeLimit.h

@@ -40,6 +40,8 @@ struct DynamicRangeLimit;
 
 class PlatformDynamicRangeLimit {
 public:
+    using ValueType = float;
+
     static constexpr PlatformDynamicRangeLimit standard() { return PlatformDynamicRangeLimit(standardValue); }
     static constexpr PlatformDynamicRangeLimit constrainedHigh() { return PlatformDynamicRangeLimit(constrainedHighValue); }
     static constexpr PlatformDynamicRangeLimit noLimit() { return PlatformDynamicRangeLimit(noLimitValue); }
@@ -53,26 +55,26 @@ class PlatformDynamicRangeLimit {
     // `dynamic-range-limit` mapped to PlatformDynamicRangeLimit.value():
     // ["standard", "constrainedHigh"] -> [standard().value(), constrainedHigh().value()],
     // ["constrainedHigh", "noLimit"] -> [constrainedHigh().value(), noLimit().value()]
-    constexpr float value() const { return m_value; }
+    constexpr ValueType value() const { return m_value; }
 
     constexpr auto operator<=>(const PlatformDynamicRangeLimit&) const = default;
 
 private:
     friend struct IPC::ArgumentCoder<WebCore::PlatformDynamicRangeLimit, void>;
     friend Style::DynamicRangeLimit;
 
-    constexpr PlatformDynamicRangeLimit(float value) : m_value(std::clamp(value, 0.0f, 1.0f)) { }
+    constexpr PlatformDynamicRangeLimit(ValueType value) : m_value(std::clamp(value, 0.0f, 1.0f)) { }
 
     PlatformDynamicRangeLimit(float standardPercent, float constrainedHighPercent, float noLimitPercent)
         : m_value(normalizedAverage(standardPercent, constrainedHighPercent, noLimitPercent)) { }
 
-    static float normalizedAverage(float standardPercent, float constrainedHighPercent, float noLimitPercent);
+    static ValueType normalizedAverage(float standardPercent, float constrainedHighPercent, float noLimitPercent);
 
-    static constexpr float standardValue = 0;
-    static constexpr float constrainedHighValue = 0.5;
-    static constexpr float noLimitValue = 1;
+    static constexpr ValueType standardValue = 0;
+    static constexpr ValueType constrainedHighValue = 0.5;
+    static constexpr ValueType noLimitValue = 1;
 
-    float m_value { constrainedHighValue };
+    ValueType m_value { constrainedHighValue };
 };
 
 WEBCORE_EXPORT WTF::TextStream& operator<<(WTF::TextStream&, PlatformDynamicRangeLimit);

Tools/TestWebKitAPI/Tests/WebCore/PlatformDynamicRangeLimitTests.cpp

@@ -33,6 +33,8 @@
 namespace TestWebKitAPI {
 
 // Tests rely on these assumptions:
+static_assert(std::is_same_v<WebCore::PlatformDynamicRangeLimit::ValueType, float>);
+static_assert(std::is_same_v<decltype(WebCore::PlatformDynamicRangeLimit::standard().value()), float>);
 static_assert(WebCore::PlatformDynamicRangeLimit::standard().value() == 0.0f);
 static_assert(WebCore::PlatformDynamicRangeLimit::constrainedHigh().value() == 0.5f);
 static_assert(WebCore::PlatformDynamicRangeLimit::noLimit().value() == 1.0f);