diff --git a/src/kiwano/render/Brush.cpp b/src/kiwano/render/Brush.cpp
index a2cc08c6..9b09d60c 100644
--- a/src/kiwano/render/Brush.cpp
+++ b/src/kiwano/render/Brush.cpp
@@ -40,6 +40,11 @@ GradientStop::GradientStop(float offset, Color color)
 {
 }
 
+LinearGradientStyle::LinearGradientStyle()
+    : extend_mode(GradientExtendMode::Clamp)
+{
+}
+
 LinearGradientStyle::LinearGradientStyle(const Point& begin, const Point& end, const Vector<GradientStop>& stops,
                                          GradientExtendMode extend_mode)
     : begin(begin)
@@ -49,6 +54,11 @@ LinearGradientStyle::LinearGradientStyle(const Point& begin, const Point& end, c
 {
 }
 
+RadialGradientStyle::RadialGradientStyle() 
+    : extend_mode(GradientExtendMode::Clamp)
+{
+}
+
 RadialGradientStyle::RadialGradientStyle(const Point& center, const Vec2& offset, const Vec2& radius,
                                          const Vector<GradientStop>& stops, GradientExtendMode extend_mode)
     : center(center)
diff --git a/src/kiwano/render/Brush.h b/src/kiwano/render/Brush.h
index d840c85b..c4545b2a 100644
--- a/src/kiwano/render/Brush.h
+++ b/src/kiwano/render/Brush.h
@@ -64,6 +64,8 @@ struct LinearGradientStyle
     Vector<GradientStop> stops;        ///< 渐变转换点集合
     GradientExtendMode   extend_mode;  ///< 渐变扩充模式
 
+    LinearGradientStyle();
+
     LinearGradientStyle(const Point& begin, const Point& end, const Vector<GradientStop>& stops,
                         GradientExtendMode extend_mode = GradientExtendMode::Clamp);
 };
@@ -78,6 +80,8 @@ struct RadialGradientStyle
     Vector<GradientStop> stops;        ///< 渐变转换点集合
     GradientExtendMode   extend_mode;  ///< 渐变扩充模式
 
+    RadialGradientStyle();
+
     RadialGradientStyle(const Point& center, const Vec2& offset, const Vec2& radius, const Vector<GradientStop>& stops,
                         GradientExtendMode extend_mode = GradientExtendMode::Clamp);
 };