flesh out gradient shaders

core/fpdfapi/fpdf_page/pageint.h

Index: core/fpdfapi/fpdf_page/pageint.h
diff --git a/core/fpdfapi/fpdf_page/pageint.h b/core/fpdfapi/fpdf_page/pageint.h
index e6496cfd20abbd6b56253e8d229a21287a0cd476..98a05d5495035c3a5b664108ac5f81deb5229c79 100644
--- a/core/fpdfapi/fpdf_page/pageint.h
+++ b/core/fpdfapi/fpdf_page/pageint.h
@@ -393,6 +393,7 @@ class CPDF_Function {
   uint32_t CountInputs() const { return m_nInputs; }
   uint32_t CountOutputs() const { return m_nOutputs; }
   FX_FLOAT GetDomain(int i) const { return m_pDomains[i]; }
+  FX_FLOAT GetRange(int i) const { return m_pRanges[i]; }
   Type GetType() const { return m_Type; }
 
  protected:
@@ -423,6 +424,33 @@ class CPDF_ExpIntFunc : public CPDF_Function {
   FX_FLOAT* m_pEndValues;
 };
 
+class CPDF_SampledFunc : public CPDF_Function {
+ public:
+  struct SampleEncodeInfo {
+    FX_FLOAT encode_max;
+    FX_FLOAT encode_min;
+    uint32_t sizes;
+  };
+
+  struct SampleDecodeInfo {
+    FX_FLOAT decode_max;
+    FX_FLOAT decode_min;
+  };
+
+  CPDF_SampledFunc();
+  ~CPDF_SampledFunc() override;
+
+  // CPDF_Function
+  FX_BOOL v_Init(CPDF_Object* pObj) override;
+  FX_BOOL v_Call(FX_FLOAT* inputs, FX_FLOAT* results) const override;
+
+  SampleEncodeInfo* m_pEncodeInfo;
+  SampleDecodeInfo* m_pDecodeInfo;
+  uint32_t m_nBitsPerSample;
+  uint32_t m_SampleMax;
+  CPDF_StreamAcc* m_pSampleStream;
+};
+
 class CPDF_StitchFunc : public CPDF_Function {
  public:
   CPDF_StitchFunc();