[escher/text_field] Fix removing of \n in insertTextAtLocation

Scenario: Copy a text with \n (for instance from a script), then paste
it in a script name -> if \n are replaed with \0 instead of just being
removed, there are problems with the extension

escher/src/text_field.cpp

@@ -131,6 +131,7 @@ bool TextField::ContentView::insertTextAtLocation(const char * text, char * loca
   *overridenByteLocation = overridenByte;
   m_currentDraftTextLength += textLength;
 
+  // Remove the \n code points
   UTF8Decoder decoder(s_draftTextBuffer);
   const char * codePointPointer = decoder.stringPosition();
   CodePoint codePoint = decoder.nextCodePoint();
@@ -139,11 +140,12 @@ bool TextField::ContentView::insertTextAtLocation(const char * text, char * loca
     assert(codePointPointer < s_draftTextBuffer + m_draftTextBufferSize);
     if (codePoint == '\n') {
       assert(UTF8Decoder::CharSizeOfCodePoint('\n') == 1);
-      *(const_cast<char *>(codePointPointer)) = 0;
-      m_currentDraftTextLength = codePointPointer - s_draftTextBuffer;
-      break;
+      strlcpy(const_cast<char *>(codePointPointer), codePointPointer + 1, (s_draftTextBuffer + m_draftTextBufferSize) - codePointPointer);
+      // Put the decoder to the code point replacing \n
+      decoder.setPosition(codePointPointer);
+    } else  {
+      codePointPointer = decoder.stringPosition();
     }
-    codePointPointer = decoder.stringPosition();
     codePoint = decoder.nextCodePoint();
   }
 

ion/include/ion/unicode/utf8_decoder.h

@@ -41,9 +41,11 @@ public:
   const char * nextGlyphPosition();
   const char * previousGlyphPosition();
   const char * stringPosition() const { return m_stringPosition; }
+  void setPosition(const char * position);
   static size_t CharSizeOfCodePoint(CodePoint c);
   static size_t CodePointToChars(CodePoint c, char * buffer, size_t bufferSize); // No null-terminating char
 private:
+  static bool IsInTheMiddleOfACodePoint(uint8_t value);
   const char * const m_string;
   const char * m_stringPosition;
 };

ion/src/shared/unicode/utf8_decoder.cpp

@@ -1,4 +1,5 @@
 #include <ion/unicode/utf8_decoder.h>
+#include <string.h>
 #include <assert.h>
 
 static inline int leading_ones(uint8_t value) {
@@ -87,6 +88,12 @@ const char * UTF8Decoder::previousGlyphPosition() {
   return resultGlyphPosition;
 }
 
+void UTF8Decoder::setPosition(const char * position) {
+  assert(m_stringPosition >= m_string && m_stringPosition <= m_string + strlen(m_string));
+  assert(!IsInTheMiddleOfACodePoint(*position));
+  m_stringPosition = position;
+}
+
 size_t UTF8Decoder::CharSizeOfCodePoint(CodePoint c) {
   if (c <= 0x7F) {
     return 1;
@@ -131,3 +138,7 @@ size_t UTF8Decoder::CodePointToChars(CodePoint c, char * buffer, size_t bufferSi
   assert(i == charCount);
   return charCount;
 }
+
+bool UTF8Decoder::IsInTheMiddleOfACodePoint(uint8_t value) {
+  return value >= 0b10000000 && value < 0b11000000;
+}