svg_loader: append text to the SvgTextNode

Text can be added in parts due to the presence
of the <tspan> tag. This requires that each
subsequent piece of text is appended rather than
overwriting the previous one.

src/common/tvgStr.cpp

@@ -219,6 +219,14 @@ char* strDuplicate(const char *str, size_t n)
     return (char *) memcpy(ret, str, n);
 }
 
+char* strAppend(char* lhs, const char* rhs, size_t n)
+{
+    if (!rhs) return lhs;
+    if (!lhs) return strDuplicate(rhs, n);
+    lhs = (char*)realloc(lhs, strlen(lhs) + n + 1);
+    return strncat(lhs, rhs, n);
+}
+
 char* strDirname(const char* path)
 {
     const char *ptr = strrchr(path, '/');

src/common/tvgStr.h

@@ -30,6 +30,7 @@ namespace tvg
 
 float strToFloat(const char *nPtr, char **endPtr);  //convert to float
 char* strDuplicate(const char *str, size_t n);      //copy the string
+char* strAppend(char* lhs, const char* rhs, size_t n);  //append the rhs to the lhs
 char* strDirname(const char* path);                 //return the full directory name
 
 }

src/loaders/svg/tvgSvgLoader.cpp

@@ -2183,6 +2183,7 @@ static SvgNode* _createTextNode(SvgLoaderData* loader, SvgNode* parent, const ch
     //TODO: support the def font and size as used in a system?
     loader->svgParse->node->node.text.fontSize = 10.0f;
     loader->svgParse->node->node.text.fontFamily = nullptr;
+    loader->svgParse->node->node.text.text = nullptr;
 
     func(buf, bufLength, _attrParseTextNode, loader);
 
@@ -3400,8 +3401,7 @@ static void _svgLoaderParserXmlOpen(SvgLoaderData* loader, const char* content,
 static void _svgLoaderParserText(SvgLoaderData* loader, const char* content, unsigned int length)
 {
     auto text = &loader->svgParse->node->node.text;
-    if (text->text) free(text->text);
-    text->text = strDuplicate(content, length);
+    text->text = strAppend(text->text, content, length);
 }