feat: add render context blend mode

src/kiwano/render/DirectX/RenderContextImpl.cpp

@@ -429,6 +429,12 @@ void RenderContextImpl::SetTransform(const Matrix3x2& matrix)
     }
 }
 
+void RenderContextImpl::SetBlendMode(BlendMode blend)
+{
+    KGE_ASSERT(render_ctx_ && "Render target has not been initialized!");
+    render_ctx_->SetPrimitiveBlend(D2D1_PRIMITIVE_BLEND(blend));
+}
+
 void RenderContextImpl::SetAntialiasMode(bool enabled)
 {
     KGE_ASSERT(render_ctx_ && "Render target has not been initialized!");

src/kiwano/render/DirectX/RenderContextImpl.h

@@ -87,6 +87,8 @@ public:
 
     void SetTransform(const Matrix3x2& matrix) override;
 
+    void SetBlendMode(BlendMode blend) override;
+
     void SetAntialiasMode(bool enabled) override;
 
     void SetTextAntialiasMode(TextAntialiasMode mode) override;

src/kiwano/render/RenderContext.h

@@ -46,6 +46,17 @@ enum class TextAntialiasMode
     None        ///< 不启用抗锯齿
 };
 
+/// \~chinese
+/// @brief »ìºÏģʽ
+enum class BlendMode
+{
+    SourceOver = 0,
+    Copy       = 1,
+    Min        = 2,
+    Add        = 3,
+    Max        = 4,
+};
+
 /// \~chinese
 /// @brief 渲染上下文
 /// @details 渲染上下文将完成基础图元的绘制，并将绘制结果输出到特定的平面中
@@ -204,6 +215,10 @@ public:
     /// @brief 设置当前使用的线条样式
     virtual void SetCurrentStrokeStyle(StrokeStylePtr stroke);
 
+    /// \~chinese
+    /// @brief ÉèÖûìºÏģʽ
+    virtual void SetBlendMode(BlendMode blend) = 0;
+
     /// \~chinese
     /// @brief 设置抗锯齿模式
     virtual void SetAntialiasMode(bool enabled) = 0;