Add conversion from any input file via ImageMagick

src/conversion.cpp

@@ -0,0 +1,50 @@
+#include <stdexcept>
+#include <string>
+#include <sstream>
+#include <unistd.h>
+#include <libscerror.hpp>
+#include <libscterm.hpp>
+#include "pixels.hpp"
+
+static std::string resize_str() {
+    sc::term t {STDERR_FILENO};
+    int cols = t.cols() - 1;
+    int rows = t.rows() * 2 - 4;
+    std::ostringstream oss;
+    oss << cols << "x" << rows;
+    return oss.str();
+}
+
+void convert(const std::string& path) { // try to convert to ppm using ImageMagick
+    int pfd[2];
+    throw_if_min1_msg(pipe(pfd), "could not create pipe");
+
+    switch (fork()) {
+        case -1:
+            throw std::runtime_error {"could not fork"};
+
+        case 0: { // child
+            throw_if_min1(dup2(pfd[1], STDOUT_FILENO));
+            throw_if_min1(close(pfd[0]));
+            throw_if_min1(close(pfd[1]));
+
+            std::string resize {resize_str()};
+            int res = execlp("magick", "magick", path.c_str(), "-resize", resize.c_str(), "ppm:-", nullptr);
+            if (res == -1) { // probably "magick" not found, try "convert"
+                res = execlp("convert", "convert", path.c_str(), "-resize", resize.c_str(), "ppm:-", nullptr);
+                if (res == -1) { // no ImageMagick, abort
+                    throw std::runtime_error {"no ImageMagick installed, abort"};
+                }
+            }
+            break;
+        }
+
+        default: // parent
+            throw_if_min1(dup2(pfd[0], STDIN_FILENO));
+            throw_if_min1(close(pfd[0]));
+            throw_if_min1(close(pfd[1]));
+
+            write_image(std::cout, stdin);
+            break;
+    }
+}

src/conversion.hpp

@@ -0,0 +1,8 @@
+#ifndef CONVERSION_H_
+#define CONVERSION_H_
+
+#include <string>
+
+void convert(const std::string& path);
+
+#endif // CONVERSION_H_

src/main.cpp

@@ -4,8 +4,10 @@
 #include <stdexcept>
 #include <getopt.h>
 #include <netpbm/pam.h>
+#include <libscstring.hpp>
 #include "commit.inc"
 #include "pixels.hpp"
+#include "conversion.hpp"
 
 void print_help() {
     std::cout << "usage: termage [-h|--version] <imagefile>\n";
@@ -55,7 +57,13 @@ int main(int argc, char* argv[]) {
         }
         for (int i = optind; i < argc; ++i) {
             try {
-                write_image(std::cout, argv[i]);
+                std::string path {argv[i]};
+                std::string ext {sc::filename_extension(path)};
+                if (ext != "ppm") {
+                    convert(path);
+                } else {
+                    write_image(std::cout, path);
+                }
             } catch (const std::runtime_error& ex) {
                 std::cerr << "termage: " << ex.what() << '\n';
             }

src/pixels.cpp

@@ -3,7 +3,7 @@
 #include <netpbm/pam.h>
 #include "pixels.hpp"
 
-static void write(std::ostream& os, FILE* in) {
+void write_image(std::ostream& os, FILE* in) {
     struct pam info;
     pnm_readpaminit(in, &info, PAM_STRUCT_SIZE(tuple_type));
     std::unique_ptr<tuple, void(*)(void*)> row1 {pnm_allocpamrow(&info), pm_freerow};
@@ -32,10 +32,10 @@ static void write(std::ostream& os, FILE* in) {
 }
 
 void write_image(std::ostream& os) {
-    write(os, stdin);
+    write_image(os, stdin);
 }
 
 void write_image(std::ostream& os, const std::string& path) {
     std::unique_ptr<FILE, void(*)(FILE*)> infile {pm_openr(path.c_str()), pm_close};
-    write(os, infile.get());
+    write_image(os, infile.get());
 }

src/pixels.hpp

@@ -4,6 +4,7 @@
 #include <iostream>
 
 void write_image(std::ostream& os);
+void write_image(std::ostream& os, FILE*);
 void write_image(std::ostream& os, const std::string& path);
 
 #endif // PIXELS_H_