Support "-" for input/output files as stdin/stdout.

Support dumping output file to stdout. Switch logger to stderr, make it multithreaded. Log input/output files. Closes #8, closes #10, closes #13.
author: Vasile Vilvoiu <vasi@vilvoiu.ro> 2021-07-15 22:53:30 +0300
committer: Vasile Vilvoiu <vasi@vilvoiu.ro> 2021-07-15 22:53:30 +0300
commit: 82c81858c65c80fb667e73ffdcc4ff69007cfa17 (patch)
tree: 455bdf7a85f99c770f97d05d53c8ce340c3f7fa0
parent: 3938ba31f633d48bb6f4471a3f49ab696a453aee (diff)
6 files changed, 123 insertions, 12 deletions
diff --git a/man/specgram.1 b/man/specgram.1
index 8df7812..971af9d 100644
--- a/man/specgram.1
+++ b/man/specgram.1
@@ -56,6 +56,8 @@ See \fBEXAMPLES\fR for common use cases.
 .BR \fIoutfile\fR
 Optional output image file. Check \fISFML\fR documentation for supported file types, but PNG files are recommended.
 
+If "\fB-\fR" is provided then the resulting image is written to stdout in PNG format.
+
 Either \fIoutfile\fR must be specified, \fB\-l, \-\-live\fR must be set, or both.
 
 .TP
@@ -75,7 +77,7 @@ Input file name.
 If option is provided, \fIINFILE\fR is handled as a raw dump of values (i.e. input file format is not considered).
 The program will stop when EOF is encountered.
 
-If option is not provided, data will be read indefinitely from stdin.
+If option is not provided or "\fB-\fR" is provided, data will be read indefinitely from stdin.
 
 .TP
 .BR \-r ", " \-\-rate =\fIRATE\fR
@@ -325,6 +327,12 @@ Render a crisp output with a transparent background, so it can be embedded in a
 .IP
 \fBspecgram\fR -qe --bg-color=00000000 -i \fIinfile\fR \fIoutfile.png\fR
 
+.LP
+Generating from a file to stdout and displaying the output with \fBimagemagick\fR:
+
+.IP
+\fBspecgram\fR -i \fIinfile\fR - | \fBdisplay\fR
+
 .SH BUGS
 
 Frequency bounds (\fB\-x, \-\-fmin\fR and \fB\-y, \-\-fmax\fR) may exceed FFT window frequency limits when resampling is enabled (i.e. default behaviour), but may not do so when resampling is disabled (\fB\-q, \-\-no_resampling\fR).
diff --git a/man/specgram.1.html b/man/specgram.1.html
index 1559b4c..41cce87 100644
--- a/man/specgram.1.html
+++ b/man/specgram.1.html
@@ -1,5 +1,5 @@
 <!-- Creator     : groff version 1.22.4 -->
-<!-- CreationDate: Thu Jul 15 15:26:09 2021 -->
+<!-- CreationDate: Thu Jul 15 19:45:50 2021 -->
 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
 "http://www.w3.org/TR/html4/loose.dtd">
 <html>
@@ -128,6 +128,10 @@ forcefully quit.</p>
 Check <i>SFML</i> documentation for supported file types,
 but PNG files are recommended.</p>
 
+<p style="margin-left:22%; margin-top: 1em">If
+&quot;<b>-</b>&quot; is provided then the resulting image is
+written to stdout in PNG format.</p>
+
 <p style="margin-left:22%; margin-top: 1em">Either
 <i>outfile</i> must be specified, <b>&minus;l,
 &minus;&minus;live</b> must be set, or both.</p>
@@ -151,7 +155,8 @@ provided, <i>INFILE</i> is handled as a raw dump of values
 stop when EOF is encountered.</p>
 
 <p style="margin-left:22%; margin-top: 1em">If option is
-not provided, data will be read indefinitely from stdin.</p>
+not provided or &quot;<b>-</b>&quot; is provided, data will
+be read indefinitely from stdin.</p>
 
 <p style="margin-left:11%;"><b>&minus;r</b>,
 <b>&minus;&minus;rate</b>=<i>RATE</i></p>
@@ -536,6 +541,14 @@ in a document:</p>
 <p style="margin-left:22%; margin-top: 1em"><b>specgram</b>
 -qe --bg-color=00000000 -i <i>infile outfile.png</i></p>
 
+<p style="margin-left:11%; margin-top: 1em">Generating from
+a file to stdout and displaying the output with
+<b>imagemagick</b>:</p>
+
+
+<p style="margin-left:22%; margin-top: 1em"><b>specgram</b>
+-i <i>infile</i> - | <b>display</b></p>
+
 <h2>BUGS
 <a name="BUGS"></a>
 </h2>
diff --git a/man/specgram.1.pdf b/man/specgram.1.pdf
index 7c6de03..4b9db2d 100644
--- a/man/specgram.1.pdf
+++ b/man/specgram.1.pdf
diff --git a/src/configuration.cpp b/src/configuration.cpp
index eeb4da4..abfecfa 100644
--- a/src/configuration.cpp
+++ b/src/configuration.cpp
@@ -18,6 +18,7 @@ Configuration::Configuration()
 {
     this->input_filename_ = {};
     this->output_filename_ = {};
+    this->dump_to_stdout_ = false;
 
     this->block_size_ = 256;
     this->rate_ = 44100;
@@ -207,14 +208,20 @@ Configuration::FromArgs(int argc, char **argv)
 
     /* check and store command line arguments */
     if (outfile) {
-        conf.output_filename_ = args::get(outfile);
+        if (args::get(outfile) != "-") { /* "-" denotes stdout */
+            conf.output_filename_ = args::get(outfile);
+        } else {
+            conf.dump_to_stdout_ = true;
+        }
     } else if (!live) {
-        std::cerr << "Either specify file or '--live', otherwise nothing to do." << std::endl;
+        std::cerr << "Either specify output file name or '--live', otherwise nothing to do." << std::endl;
         return std::make_tuple(conf, 1, true);
     }
 
     if (infile) {
-        conf.input_filename_ = args::get(infile);
+        if (args::get(infile) != "-") { /* "-" denotes stdin */
+            conf.input_filename_ = args::get(infile);
+        }
     }
     if (block_size) {
         if (args::get(block_size) <= 0) {
diff --git a/src/configuration.hpp b/src/configuration.hpp
index d7627ee..db3be73 100644
--- a/src/configuration.hpp
+++ b/src/configuration.hpp
@@ -21,6 +21,7 @@ class Configuration {
 private:
     std::optional<std::string> input_filename_;
     std::optional<std::string> output_filename_;
+    bool dump_to_stdout_;
 
     std::size_t block_size_;
     double rate_;
@@ -76,6 +77,7 @@ public:
     Configuration GetForLive() const;
     const auto & GetInputFilename() const { return input_filename_; }
     const auto & GetOutputFilename() const { return output_filename_; }
+    const auto MustDumpToStdout() const { return dump_to_stdout_; }
 
     /* input getters */
     auto GetBlockSize() const { return block_size_; }
diff --git a/src/specgram.cpp b/src/specgram.cpp
index f4a03e1..6e209af 100644
--- a/src/specgram.cpp
+++ b/src/specgram.cpp
@@ -14,15 +14,21 @@
 #include "live.hpp"
 
 #include <spdlog/spdlog.h>
+#include <spdlog/sinks/stdout_color_sinks.h>
 #include <iostream>
 #include <iomanip>
 #include <fstream>
 #include <csignal>
 #include <list>
+#include <random>
+#include <cstdio>
 
 /* main loop exit condition */
 volatile bool main_loop_running = true;
 
+/* temporary output file name */
+std::string temp_file_name = "";
+
 /*
  * SIGINT handler
  */
@@ -39,7 +45,8 @@ sigint_handler(int)
 /*
  * printing functions
  */
-void print_complex_window(const std::string& name, const ComplexWindow& window)
+void
+print_complex_window(const std::string& name, const ComplexWindow& window)
 {
     std::cout << name << ": [";
     for (const auto& v : window) {
@@ -49,7 +56,8 @@ void print_complex_window(const std::string& name, const ComplexWindow& window)
     std::cout << "]" << std::endl;
 }
 
-void print_real_window(const std::string& name, const RealWindow& window)
+void
+print_real_window(const std::string& name, const RealWindow& window)
 {
     std::cout << name << ": [";
     for (const auto& v : window) {
@@ -59,17 +67,77 @@ void print_real_window(const std::string& name, const RealWindow& window)
 }
 
 /*
+ * generate a random string (see https://stackoverflow.com/a/50556436)
+ */
+std::string
+generate_random_string(std::size_t length)
+{
+    std::mt19937 generator { std::random_device{}() };
+    std::uniform_int_distribution<int> distribution { 'a', 'z' };
+
+    std::string output(length, '\0');
+    for(auto& ch : output) {
+        ch = static_cast<char>(distribution(generator) & 0xff);
+    }
+
+    return output;
+}
+
+/*
+ * dump image to stdout (in PNG format). This writes a temp file in /dev/shm since SFML cannot save to memory.
+ */
+void
+dump_to_stdout(const sf::Image& image)
+{
+    static constexpr size_t TEMP_BUFFER_SIZE = 1024;
+    static constexpr size_t TEMP_FILENAME_LENGTH = 32;
+
+    /* save */
+    temp_file_name = "/dev/shm/" + generate_random_string(TEMP_FILENAME_LENGTH) + ".png";
+    spdlog::info("Temporary file: {}", temp_file_name);
+    image.saveToFile(temp_file_name);
+
+    /* from now on we have a leakable resource (the file); if using STDIN for input, we're here from a SIGINT,
+     * and we expect a SIGPIPE soon; install a handler that will clean up */
+    std::signal(SIGPIPE, [](int) { std::remove(temp_file_name.c_str()); /* no logger, no checks */ std::exit(0); });
+
+    /* dump */
+    std::ifstream file(temp_file_name, std::ios::in | std::ios::binary);
+    if (file.fail()) {
+        throw std::runtime_error("cannot read temp file " + temp_file_name);
+    }
+    while (!file.eof()) {
+        char buffer[TEMP_BUFFER_SIZE];
+        file.read(buffer, TEMP_BUFFER_SIZE);
+        std::size_t read_count = file.gcount();
+        std::cout.write(buffer, read_count);
+    }
+    file.close();
+
+    /* clean up */
+    if (std::remove(temp_file_name.c_str()) != 0) {
+        spdlog::warn("Failed to delete temp file {}", temp_file_name);
+    }
+}
+
+/*
  * entry point
  */
 int
 main(int argc, char** argv)
 {
+    /* set spdlog to STDERR and make it multithreaded */
+    spdlog::set_default_logger(spdlog::stderr_color_mt("stderr"));
+
     /* parse command line arguments into global settings */
     auto [conf, conf_rc, conf_must_exit] = Configuration::FromArgs(argc, argv);
     if (conf_must_exit) {
         return conf_rc;
     }
 
+    /* decide whether we have output or not */
+    bool have_output = conf.GetOutputFilename().has_value() || conf.MustDumpToStdout();
+
     /* create window function */
     auto win_function = WindowFunction::FromType(conf.GetWindowFunction(), conf.GetFFTWidth());
 
@@ -108,6 +176,7 @@ main(int argc, char** argv)
     std::istream *input_stream = nullptr;
     std::unique_ptr<InputReader> reader = nullptr;
     if (conf.GetInputFilename().has_value()) {
+        spdlog::info("Input: {}", *conf.GetInputFilename());
         input_stream = new std::ifstream(*conf.GetInputFilename(), std::ios::in | std::ios::binary);
         assert(input_stream != nullptr);
         if (!input_stream->good()) {
@@ -117,6 +186,7 @@ main(int argc, char** argv)
         reader = std::make_unique<SyncInputReader>(input_stream,
                                                    input->GetDataTypeSize() * conf.GetBlockSize());
     } else {
+        spdlog::info("Input: STDIN");
         input_stream = &std::cin;
         reader = std::make_unique<AsyncInputReader>(input_stream,
                                                     input->GetDataTypeSize() * conf.GetBlockSize());
@@ -229,7 +299,7 @@ main(int argc, char** argv)
         }
 
         /* add to history */
-        if (conf.GetOutputFilename().has_value()) {
+        if (have_output) {
             history.push_back(colorized);
         }
 
@@ -250,11 +320,12 @@ main(int argc, char** argv)
     }
 
     /* save file */
-    if (conf.GetOutputFilename().has_value()) {
+    if (have_output) {
         Renderer file_renderer(conf, *color_map, *value_map, history.size());
         file_renderer.RenderFFTArea(history);
         auto image = file_renderer.GetCanvas().copyToImage();
 
+        /* rotate, if needed */
         if (conf.IsHorizontal()) {
             std::size_t w = image.getSize().x;
             std::size_t h = image.getSize().y;
@@ -276,9 +347,19 @@ main(int argc, char** argv)
             sf::Image rimage;
             rimage.create(h, w, reinterpret_cast<const uint8_t *>(optr));
             delete[] optr;
-            rimage.saveToFile(*conf.GetOutputFilename());
-        } else {
+
+            image = rimage;
+        }
+
+        /* dump to file or stdout */
+        if (conf.GetOutputFilename().has_value()) {
+            spdlog::info("Output: {}", *conf.GetOutputFilename());
             image.saveToFile(*conf.GetOutputFilename());
+        } else if (conf.MustDumpToStdout()) {
+            spdlog::info("Output: STDOUT");
+            dump_to_stdout(image);
+        } else {
+            throw std::runtime_error("don't know what to do with output");
         }
     }
author	Vasile Vilvoiu <vasi@vilvoiu.ro>	2021-07-15 22:53:30 +0300
committer	Vasile Vilvoiu <vasi@vilvoiu.ro>	2021-07-15 22:53:30 +0300
commit	82c81858c65c80fb667e73ffdcc4ff69007cfa17 (patch)
tree	455bdf7a85f99c770f97d05d53c8ce340c3f7fa0
parent	3938ba31f633d48bb6f4471a3f49ab696a453aee (diff)