diff --git a/fxbarcode/oned/BC_OneDimWriter.cpp b/fxbarcode/oned/BC_OneDimWriter.cpp
index 8630b36..a282765 100644
--- a/fxbarcode/oned/BC_OneDimWriter.cpp
+++ b/fxbarcode/oned/BC_OneDimWriter.cpp
@@ -90,20 +90,15 @@
                                         int32_t pos,
                                         const int8_t* pattern,
                                         int32_t patternLength,
-                                        int32_t startColor,
-                                        int32_t& e) {
-  if (startColor != 0 && startColor != 1) {
-    e = BCExceptionValueMustBeEither0or1;
-    return 0;
-  }
-  uint8_t color = (uint8_t)startColor;
+                                        bool startColor) {
+  bool color = startColor;
   int32_t numAdded = 0;
   for (int32_t i = 0; i < patternLength; i++) {
     for (int32_t j = 0; j < pattern[i]; j++) {
-      target[pos++] = color;
+      target[pos++] = color ? 1 : 0;
       numAdded += 1;
     }
-    color ^= 1;
+    color = !color;
   }
   return numAdded;
 }
diff --git a/fxbarcode/oned/BC_OneDimWriter.h b/fxbarcode/oned/BC_OneDimWriter.h
index 34048bc..35d3ca0 100644
--- a/fxbarcode/oned/BC_OneDimWriter.h
+++ b/fxbarcode/oned/BC_OneDimWriter.h
@@ -53,31 +53,30 @@
                                   int32_t hints);
   virtual uint8_t* EncodeImpl(const ByteString& contents,
                               int32_t& outLength) = 0;
-  virtual void CalcTextInfo(const ByteString& text,
-                            FXTEXT_CHARPOS* charPos,
-                            CFX_Font* cFont,
-                            float geWidth,
-                            int32_t fontSize,
-                            float& charsLen);
   virtual bool ShowChars(const WideStringView& contents,
                          CFX_RenderDevice* device,
                          const CFX_Matrix* matrix,
                          int32_t barWidth,
                          int32_t multiple);
-  virtual void ShowDeviceChars(CFX_RenderDevice* device,
-                               const CFX_Matrix* matrix,
-                               const ByteString str,
-                               float geWidth,
-                               FXTEXT_CHARPOS* pCharPos,
-                               float locX,
-                               float locY,
-                               int32_t barWidth);
-  virtual int32_t AppendPattern(uint8_t* target,
-                                int32_t pos,
-                                const int8_t* pattern,
-                                int32_t patternLength,
-                                int32_t startColor,
-                                int32_t& e);
+  void ShowDeviceChars(CFX_RenderDevice* device,
+                       const CFX_Matrix* matrix,
+                       const ByteString str,
+                       float geWidth,
+                       FXTEXT_CHARPOS* pCharPos,
+                       float locX,
+                       float locY,
+                       int32_t barWidth);
+  void CalcTextInfo(const ByteString& text,
+                    FXTEXT_CHARPOS* charPos,
+                    CFX_Font* cFont,
+                    float geWidth,
+                    int32_t fontSize,
+                    float& charsLen);
+  int32_t AppendPattern(uint8_t* target,
+                        int32_t pos,
+                        const int8_t* pattern,
+                        int32_t patternLength,
+                        bool startColor);
 
   void RenderVerticalBars(int32_t outputX, int32_t width, int32_t height);
 
diff --git a/fxbarcode/oned/BC_OnedCode128Writer.cpp b/fxbarcode/oned/BC_OnedCode128Writer.cpp
index 7a16280..c8d1128 100644
--- a/fxbarcode/oned/BC_OnedCode128Writer.cpp
+++ b/fxbarcode/oned/BC_OnedCode128Writer.cpp
@@ -157,10 +157,7 @@
   int32_t pos = 0;
   for (size_t i = 0; i < patterns.size(); ++i) {
     const int8_t* pattern = CODE_PATTERNS[patterns[i]];
-    int32_t e = BCExceptionNO;
-    pos += AppendPattern(result.get(), pos, pattern, kPatternSize, 1, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, pattern, kPatternSize, true);
   }
   return result.release();
 }
diff --git a/fxbarcode/oned/BC_OnedCode39Writer.cpp b/fxbarcode/oned/BC_OnedCode39Writer.cpp
index 50862c9..4fa2fb5 100644
--- a/fxbarcode/oned/BC_OnedCode39Writer.cpp
+++ b/fxbarcode/oned/BC_OnedCode39Writer.cpp
@@ -187,15 +187,10 @@
   outlength = codeWidth;
   std::unique_ptr<uint8_t, FxFreeDeleter> result(FX_Alloc(uint8_t, codeWidth));
   ToIntArray(kOnedCode39CharacterEncoding[39], widths);
-  int32_t e = BCExceptionNO;
-  int32_t pos = AppendPattern(result.get(), 0, widths, 9, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  int32_t pos = AppendPattern(result.get(), 0, widths, 9, true);
 
   int8_t narrowWhite[] = {1};
-  pos += AppendPattern(result.get(), pos, narrowWhite, 1, 0, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, narrowWhite, 1, false);
 
   for (int32_t l = m_iContentLen - 1; l >= 0; l--) {
     for (size_t i = 0; i < kOnedCode39AlphabetLen; i++) {
@@ -203,18 +198,12 @@
         continue;
 
       ToIntArray(kOnedCode39CharacterEncoding[i], widths);
-      pos += AppendPattern(result.get(), pos, widths, 9, 1, e);
-      if (e != BCExceptionNO)
-        return nullptr;
+      pos += AppendPattern(result.get(), pos, widths, 9, true);
     }
-    pos += AppendPattern(result.get(), pos, narrowWhite, 1, 0, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, narrowWhite, 1, false);
   }
   ToIntArray(kOnedCode39CharacterEncoding[39], widths);
-  pos += AppendPattern(result.get(), pos, widths, 9, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, widths, 9, true);
 
   auto* result_ptr = result.get();
   for (int32_t i = 0; i < codeWidth / 2; i++) {
diff --git a/fxbarcode/oned/BC_OnedEAN13Writer.cpp b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
index 8d4f864..d35a281 100644
--- a/fxbarcode/oned/BC_OnedEAN13Writer.cpp
+++ b/fxbarcode/oned/BC_OnedEAN13Writer.cpp
@@ -103,10 +103,7 @@
   std::unique_ptr<uint8_t, FxFreeDeleter> result(
       FX_Alloc(uint8_t, m_codeWidth));
   int32_t pos = 0;
-  int32_t e = BCExceptionNO;
-  pos += AppendPattern(result.get(), pos, kOnedEAN13StartPattern, 3, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN13StartPattern, 3, true);
 
   int32_t i = 0;
   for (i = 1; i <= 6; i++) {
@@ -114,23 +111,15 @@
     if ((parities >> (6 - i) & 1) == 1) {
       digit += 10;
     }
-    pos += AppendPattern(result.get(), pos, L_AND_G_PATTERNS[digit], 4, 0, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, L_AND_G_PATTERNS[digit], 4, false);
   }
-  pos += AppendPattern(result.get(), pos, kOnedEAN13MiddlePattern, 5, 0, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN13MiddlePattern, 5, false);
 
   for (i = 7; i <= 12; i++) {
     int32_t digit = FXSYS_DecimalCharToInt(contents[i]);
-    pos += AppendPattern(result.get(), pos, kOnedEAN13LPattern[digit], 4, 1, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, kOnedEAN13LPattern[digit], 4, true);
   }
-  pos += AppendPattern(result.get(), pos, kOnedEAN13StartPattern, 3, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN13StartPattern, 3, true);
   return result.release();
 }
 
diff --git a/fxbarcode/oned/BC_OnedEAN8Writer.cpp b/fxbarcode/oned/BC_OnedEAN8Writer.cpp
index 71c93df..741a3e7 100644
--- a/fxbarcode/oned/BC_OnedEAN8Writer.cpp
+++ b/fxbarcode/oned/BC_OnedEAN8Writer.cpp
@@ -106,31 +106,20 @@
   std::unique_ptr<uint8_t, FxFreeDeleter> result(
       FX_Alloc(uint8_t, m_codeWidth));
   int32_t pos = 0;
-  int32_t e = BCExceptionNO;
-  pos += AppendPattern(result.get(), pos, kOnedEAN8StartPattern, 3, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN8StartPattern, 3, true);
 
   int32_t i = 0;
   for (i = 0; i <= 3; i++) {
     int32_t digit = FXSYS_DecimalCharToInt(contents[i]);
-    pos += AppendPattern(result.get(), pos, kOnedEAN8LPattern[digit], 4, 0, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, kOnedEAN8LPattern[digit], 4, false);
   }
-  pos += AppendPattern(result.get(), pos, kOnedEAN8MiddlePattern, 5, 0, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN8MiddlePattern, 5, false);
 
   for (i = 4; i <= 7; i++) {
     int32_t digit = FXSYS_DecimalCharToInt(contents[i]);
-    pos += AppendPattern(result.get(), pos, kOnedEAN8LPattern[digit], 4, 1, e);
-    if (e != BCExceptionNO)
-      return nullptr;
+    pos += AppendPattern(result.get(), pos, kOnedEAN8LPattern[digit], 4, true);
   }
-  pos += AppendPattern(result.get(), pos, kOnedEAN8StartPattern, 3, 1, e);
-  if (e != BCExceptionNO)
-    return nullptr;
+  pos += AppendPattern(result.get(), pos, kOnedEAN8StartPattern, 3, true);
   return result.release();
 }
 
diff --git a/fxbarcode/qrcode/BC_QRCoder.cpp b/fxbarcode/qrcode/BC_QRCoder.cpp
index b0a24fa..fe96c5f 100644
--- a/fxbarcode/qrcode/BC_QRCoder.cpp
+++ b/fxbarcode/qrcode/BC_QRCoder.cpp
@@ -77,20 +77,11 @@
   return m_numRSBlocks;
 }
 
-CBC_CommonByteMatrix* CBC_QRCoder::GetMatrix() const {
+const CBC_CommonByteMatrix* CBC_QRCoder::GetMatrix() const {
   return m_matrix.get();
 }
 
-int32_t CBC_QRCoder::At(int32_t x, int32_t y, int32_t& e) {
-  int32_t value = m_matrix->Get(x, y);
-  if (!(value == 0 || value == 1)) {
-    e = BCExceptionValueMustBeEither0or1;
-    return 0;
-  }
-  return value;
-}
-
-bool CBC_QRCoder::IsValid() {
+bool CBC_QRCoder::IsValid() const {
   return m_mode && m_ecLevel && m_version != -1 && m_matrixWidth != -1 &&
          m_maskPattern != -1 && m_numTotalBytes != -1 && m_numDataBytes != -1 &&
          m_numECBytes != -1 && m_numRSBlocks != -1 &&
diff --git a/fxbarcode/qrcode/BC_QRCoder.h b/fxbarcode/qrcode/BC_QRCoder.h
index af53ded..7b7e680 100644
--- a/fxbarcode/qrcode/BC_QRCoder.h
+++ b/fxbarcode/qrcode/BC_QRCoder.h
@@ -33,10 +33,9 @@
   int32_t GetNumDataBytes() const;
   int32_t GetNumECBytes() const;
   int32_t GetNumRSBlocks() const;
-  CBC_CommonByteMatrix* GetMatrix() const;
+  const CBC_CommonByteMatrix* GetMatrix() const;
 
-  int32_t At(int32_t x, int32_t y, int32_t& e);
-  bool IsValid();
+  bool IsValid() const;
 
   void SetMode(CBC_QRCoderMode* value);
   void SetECLevel(const CBC_QRCoderErrorCorrectionLevel* ecLevel);
diff --git a/fxbarcode/utils.h b/fxbarcode/utils.h
index bb3bc1c..bd2688e 100644
--- a/fxbarcode/utils.h
+++ b/fxbarcode/utils.h
@@ -24,7 +24,6 @@
 
 #define BCExceptionNO 0
 #define BCExceptionIllegalArgument 16
-#define BCExceptionValueMustBeEither0or1 50
 #define BCExceptionGeneric 107
 
 #endif  // FXBARCODE_UTILS_H_