Memory safety and output format

include/mtx2img/mtx2img.hpp

@@ -22,7 +22,7 @@ enum class Object
 enum class Format
 {
     Coordinate,     // <== supported (sparse representation)
-    Array           // <== unsupported, planned (dense representation)
+    Array           // <== supported (dense representation)
 }; // enum class Format
 
 
@@ -47,9 +47,17 @@ enum class Structure
 } // namespace format
 
 
+enum class Aggregation
+{
+    Count,      // <== count the number of nonzeros referencing each pixel
+    Sum         // <== sum the values of each entry referencing a pixel
+}; // enum class Aggregation
+
+
 std::vector<unsigned char> convert(std::istream& r_stream,
                                    std::size_t& r_imageWidth,
                                    std::size_t& r_imageHeight,
+                                   const Aggregation aggregation,
                                    const std::string& r_colormapName);
 
 

src/main.cpp

@@ -23,6 +23,7 @@
  */
 const std::map<std::string,std::string> defaultArguments {
     {"-r", "1080"},
+    {"-a", "count"},
     {"-c", "binary"}
 };
 
@@ -32,6 +33,7 @@ struct Arguments
     std::filesystem::path inputPath;
     std::filesystem::path outputPath;
     std::size_t resolution;
+    mtx2img::Aggregation aggregation;
     std::string colormap;
 }; // struct Arguments
 
@@ -43,7 +45,10 @@ void printHelp()
         << "Usage: mtx2img <path-to-source> <path-to-output> [OPTION ARGUMENT] ...\n"
         << "Options:\n"
         << "    -r <resolution>  : highest resolution of the output image in pixels (default: " << defaultArguments.at("-r") << ").\n"
-        << "    -c <colormap>    : colormap to use for per pixel nonzero density. Options: [binary, kindlmann, viridis] (default: "  << defaultArguments.at("-c") << ").\n"
+        << "    -a <aggregation> : controls how sparse entries are aggregated to pixels. Options: [count, sum]\n"
+        << "                       \"count\" ignores values and counts the number of entries referencing each pixel.\n"
+        << "                       \"sum\" reads values and sums them up for each pixel.\n"
+        << "    -c <colormap>    : colormap to use for aggregated pixel values. Options: [binary, kindlmann, viridis] (default: "  << defaultArguments.at("-c") << ").\n"
         << "\n"
         << "The input path must point to an existing MatrixMarket file (or pass '-' to read the same format from stdin).\n"
         << "The parent directory of the output path must exist, and the output path is assumed to either not exist, or\n"
@@ -66,8 +71,8 @@ std::optional<Arguments> parseArguments(int argc, char const* const* argv)
             if (it_argument == argMap.end()) {
                 if ((it_argument = argMap.find(arg)) == argMap.end()) {
                     // The provided key does not exist in the argument map
-                    // Special case: "--help"
-                    if (arg == "--help") {
+                    // Special case: "--help" or "-h"
+                    if (arg == "--help" || arg == "-h") {
                         return {};
                     }
 
@@ -178,6 +183,18 @@ std::optional<Arguments> parseArguments(int argc, char const* const* argv)
         } // if !writePermission
     } // if arguments.outputPath != "-"
 
+    // Validate aggregation method
+    if (argMap["-a"] == "count") {
+        arguments.aggregation = mtx2img::Aggregation::Count;
+    } else if (argMap["-a"] == "sum") {
+        arguments.aggregation = mtx2img::Aggregation::Sum;
+    } else {
+        throw std::invalid_argument(std::format(
+            "Error: invalid aggregation method: {}\n",
+            argMap["a"]
+        ));
+    }
+
     // Validate colormap
     arguments.colormap = argMap["-c"];
     {
@@ -295,6 +312,7 @@ int main(int argc, char const* const* argv)
     image = mtx2img::convert(*p_inputStream,
                              imageSize.first,
                              imageSize.second,
+                             arguments.aggregation,
                              arguments.colormap);
 
     #ifdef NDEBUG