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Diffstat (limited to 'dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp')
-rw-r--r--dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp33
1 files changed, 32 insertions, 1 deletions
diff --git a/dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp b/dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp
index b2af27d636..1f331659f0 100644
--- a/dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp
+++ b/dviware/dvisvgm/src/DvisvgmSpecialHandler.cpp
@@ -21,6 +21,7 @@
#include <array>
#include <cstring>
#include <utility>
+#include "Calculator.hpp"
#include "DvisvgmSpecialHandler.hpp"
#include "InputBuffer.hpp"
#include "InputReader.hpp"
@@ -190,6 +191,35 @@ static void expand_constants (string &str, SpecialActions &actions) {
}
+/** Evaluates substrings of the form {?(expr)} where 'expr' is a math expression,
+ * and replaces the substring by the computed value.
+ * @param[in,out] str string to scan for expressions */
+static void evaluate_expressions (string &str, SpecialActions &actions) {
+ size_t left = str.find("{?("); // start position of expression macro
+ while (left != string::npos) {
+ size_t right = str.find(")}", left+2); // end position of expression macro
+ if (right == string::npos)
+ break;
+ Calculator calc;
+ calc.setVariable("x", actions.getX());
+ calc.setVariable("y", actions.getY());
+ string expr = str.substr(left+3, right-left-3); // math expression to evaluate
+ if (util::normalize_space(expr).empty()) // no expression given, e.g. {?( )}
+ str.erase(left, right-left+2); // => replace with empty string
+ else {
+ try {
+ double val = calc.eval(expr);
+ str.replace(left, right-left+2, XMLString(val));
+ }
+ catch (CalculatorException &e) {
+ throw SpecialException(string(e.what())+" in '{?("+expr+")}'");
+ }
+ }
+ left = str.find("{?(", right+1); // find next expression macro
+ }
+}
+
+
/** Processes raw SVG fragments from the input stream. The SVG data must represent
* a single or multiple syntactically complete XML parts, like opening/closing tags,
* comments, or CDATA blocks. These must not be split and distributed over several
@@ -199,6 +229,7 @@ void DvisvgmSpecialHandler::processRaw (InputReader &ir, SpecialActions &actions
if (_nestingLevel == 0) {
string xml = ir.getLine();
if (!xml.empty()) {
+ evaluate_expressions(xml, actions);
expand_constants(xml, actions);
_pageParser.parse(xml, actions);
}
@@ -536,4 +567,4 @@ void DvisvgmSpecialHandler::XMLParser::flush (SpecialActions &actions) {
tags.resize(tags.length()-2);
throw SpecialException("missing closing tags: "+tags);
}
-} \ No newline at end of file
+}