Simplify the converter utility plugin loading code.

Also have different return codes for different kinds of errors.

src/Magnum/Text/fontconverter.cpp

@@ -148,20 +148,18 @@ int FontConverter::exec() {
 
     /* Load font */
     PluginManager::Manager<Text::AbstractFont> fontManager(Utility::Directory::join(args.value("plugin-dir"), "fonts/"));
-    if(!(fontManager.load(args.value("font")) & PluginManager::LoadState::Loaded))
-        std::exit(1);
-    std::unique_ptr<Text::AbstractFont> font = fontManager.instance(args.value("font"));
+    std::unique_ptr<Text::AbstractFont> font = fontManager.loadAndInstantiate(args.value("font"));
+    if(!font) return 1;
 
     /* Load font converter */
     PluginManager::Manager<Text::AbstractFontConverter> converterManager(Utility::Directory::join(args.value("plugin-dir"), "fontconverters/"));
-    if(!(converterManager.load(args.value("converter")) & PluginManager::LoadState::Loaded))
-        std::exit(1);
-    std::unique_ptr<Text::AbstractFontConverter> converter = converterManager.instance(args.value("converter"));
+    std::unique_ptr<Text::AbstractFontConverter> converter = converterManager.loadAndInstantiate(args.value("converter"));
+    if(!converter) return 2;
 
     /* Open font */
     if(!font->openFile(args.value("input"), args.value<Float>("font-size"))) {
         Error() << "Cannot open font" << args.value("input");
-        std::exit(1);
+        return 3;
     }
 
     /* Create distance field glyph cache if radius is specified */

src/Magnum/TextureTools/distancefieldconverter.cpp

@@ -141,21 +141,19 @@ DistanceFieldConverter::DistanceFieldConverter(const Arguments& arguments): Plat
 int DistanceFieldConverter::exec() {
     /* Load importer plugin */
     PluginManager::Manager<Trade::AbstractImporter> importerManager(Utility::Directory::join(args.value("plugin-dir"), "importers/"));
-    if(!(importerManager.load(args.value("importer")) & PluginManager::LoadState::Loaded))
-        return 1;
-    std::unique_ptr<Trade::AbstractImporter> importer = importerManager.instance(args.value("importer"));
+    std::unique_ptr<Trade::AbstractImporter> importer = importerManager.loadAndInstantiate(args.value("importer"));
+    if(!importer) return 1;
 
     /* Load converter plugin */
     PluginManager::Manager<Trade::AbstractImageConverter> converterManager(Utility::Directory::join(args.value("plugin-dir"), "imageconverters/"));
-    if(!(converterManager.load(args.value("converter")) & PluginManager::LoadState::Loaded))
-        return 1;
-    std::unique_ptr<Trade::AbstractImageConverter> converter = converterManager.instance(args.value("converter"));
+    std::unique_ptr<Trade::AbstractImageConverter> converter = converterManager.loadAndInstantiate(args.value("converter"));
+    if(!converter) return 2;
 
     /* Open input file */
     Containers::Optional<Trade::ImageData2D> image;
     if(!importer->openFile(args.value("input")) || !(image = importer->image2D(0))) {
         Error() << "Cannot open file" << args.value("input");
-        return 1;
+        return 3;
     }
 
     /* Decide about internal format */
@@ -165,7 +163,7 @@ int DistanceFieldConverter::exec() {
     else if(image->format() == PixelFormat::RGBA) internalFormat = TextureFormat::RGBA8;
     else {
         Error() << "Unsupported image format" << image->format();
-        return 1;
+        return 4;
     }
 
     /* Input texture */
@@ -191,7 +189,7 @@ int DistanceFieldConverter::exec() {
     output.image(0, result);
     if(!converter->exportToFile(result, args.value("output"))) {
         Error() << "Cannot save file" << args.value("output");
-        return 1;
+        return 5;
     }
 
     return 0;

src/Magnum/Trade/imageconverter.cpp

@@ -86,21 +86,19 @@ int main(int argc, char** argv) {
 
     /* Load importer plugin */
     PluginManager::Manager<Trade::AbstractImporter> importerManager(Utility::Directory::join(args.value("plugin-dir"), "importers/"));
-    if(!(importerManager.load(args.value("importer")) & PluginManager::LoadState::Loaded))
-        return 1;
-    std::unique_ptr<Trade::AbstractImporter> importer = importerManager.instance(args.value("importer"));
+    std::unique_ptr<Trade::AbstractImporter> importer = importerManager.loadAndInstantiate(args.value("importer"));
+    if(!importer) return 1;
 
     /* Load converter plugin */
     PluginManager::Manager<Trade::AbstractImageConverter> converterManager(Utility::Directory::join(args.value("plugin-dir"), "imageconverters/"));
-    if(!(converterManager.load(args.value("converter")) & PluginManager::LoadState::Loaded))
-        return 1;
-    std::unique_ptr<Trade::AbstractImageConverter> converter = converterManager.instance(args.value("converter"));
+    std::unique_ptr<Trade::AbstractImageConverter> converter = converterManager.loadAndInstantiate(args.value("converter"));
+    if(!converter) return 2;
 
     /* Open input file */
     Containers::Optional<Trade::ImageData2D> image;
     if(!importer->openFile(args.value("input")) || !(image = importer->image2D(0))) {
         Error() << "Cannot open file" << args.value("input");
-        return 1;
+        return 3;
     }
 
     Debug() << "Converting image of size" << image->size() << Debug::nospace << ", format" << image->format() << "and type"  << image->type() << "to" << args.value("output");
@@ -108,6 +106,6 @@ int main(int argc, char** argv) {
     /* Save output file */
     if(!converter->exportToFile(*image, args.value("output"))) {
         Error() << "Cannot save file" << args.value("output");
-        return 1;
+        return 4;
     }
 }