Less verbose and annoyingly useless debug output.

src/Magnum/DebugOutput.cpp

@@ -47,18 +47,59 @@ callbackWrapper(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei
 #endif
 
 void defaultCallback(const DebugOutput::Source source, const DebugOutput::Type type, const UnsignedInt id, const DebugOutput::Severity severity, const std::string& string, const void*) {
+    Debug output;
+    output << "Debug output:";
+
     switch(severity) {
         case DebugOutput::Severity::High:
-            Error() << source << type << id << severity << "\n   " << string;
+            output << "high severity"; break;
-            break;
 
         case DebugOutput::Severity::Medium:
+            output << "medium severity"; break;
+
         case DebugOutput::Severity::Low:
-            Warning() << source << type << id << severity << "\n   " << string;
+            output << "low severity"; break;
-            break;
+
+        case DebugOutput::Severity::Notification: ;
+    }
 
-        default: Debug() << source << type << id << severity << "\n   " << string;
+    switch(source) {
+        case DebugOutput::Source::Api:
+            output << "API"; break;
+        case DebugOutput::Source::WindowSystem:
+            output << "window system"; break;
+        case DebugOutput::Source::ShaderCompiler:
+            output << "shader compiler"; break;
+        case DebugOutput::Source::ThirdParty:
+            output << "third party"; break;
+        case DebugOutput::Source::Application:
+            output << "application"; break;
+
+        case DebugOutput::Source::Other: ;
     }
+
+    switch(type) {
+        case DebugOutput::Type::Error:
+            output << "error"; break;
+        case DebugOutput::Type::DeprecatedBehavior:
+            output << "deprecated behavior note"; break;
+        case DebugOutput::Type::UndefinedBehavior:
+            output << "undefined behavior note"; break;
+        case DebugOutput::Type::Portability:
+            output << "portability note"; break;
+        case DebugOutput::Type::Performance:
+            output << "performance note"; break;
+        case DebugOutput::Type::Marker:
+            output << "marker"; break;
+        case DebugOutput::Type::PushGroup:
+            output << "debug group enter"; break;
+        case DebugOutput::Type::PopGroup:
+            output << "debug group leave"; break;
+
+        case DebugOutput::Type::Other: ;
+    }
+
+    output << '(' + std::to_string(id) + "):" << string;
 }
 
 }

src/Magnum/DebugOutput.h

@@ -95,13 +95,10 @@ DebugOutput::setEnabled(DebugOutput::Source::Api, DebugOutput::Type::Other, {131
 With default callback the group entering/leaving and the inserted message (and
 possibly also other messages) will be printed on standard output:
 
-> DebugOutput::Source::Application DebugOutput::Type::PushGroup 42 DebugOutput::Severity::Notification\n
+> Debug output: application debug group enter (42): Scene rendering\n
->     Scene rendering\n
+> Debug output: application marker (1337): Rendering transparent mesh\n
-> DebugOutput::Source::Application DebugOutput::Type::Marker 1337 DebugOutput::Severity::Notification\n
->     Rendering transparent mesh\n
 > ...\n
-> DebugOutput::Source::Application DebugOutput::Type::PopGroup 42 DebugOutput::Severity::Notification\n
+> Debug output: application debug group leave (42): Scene rendering
->     Scene rendering
 
 If only @extension2{EXT,debug_marker} or @extension{GREMEDY,string_marker} are
 supported, only user-inserted messages and debug groups are supported and they
@@ -383,15 +380,14 @@ class MAGNUM_EXPORT DebugOutput {
          * @brief Set default debug message callback
          *
          * See @ref setCallback() for more information. The message is printed
-         * to either @ref Corrade::Utility::Error "Error", @ref Corrade::Utility::Warning "Warning"
+         * to @ref Corrade::Utility::Debug "Debug" output in the following
-         * or @ref Corrade::Utility::Debug "Debug" in the following format:
+         * format:
          * @code
          * DebugMessage::insert(DebugMessage::Source::Application,
          *      DebugMessage::Type::Marker, 1337, DebugOutput::Severity::Notification, "Hello from OpenGL command stream!");
          * @endcode
          *
-         * > DebugOutput::Source::Application DebugOutput::Type::Marker 1337 DebugOutput::Severity::Notification\n
+         * > Debug output: application marker (1337): Hello from OpenGL command stream!
-         * >     Hello from OpenGL command stream!
          */
         static void setDefaultCallback();
 
@@ -437,8 +433,7 @@ DebugMessage::insert(DebugMessage::Source::Application, DebugMessage::Type::Mark
     1337, DebugOutput::Severity::Notification, "Hello from OpenGL command stream!");
 @endcode
 
-> DebugOutput::Source::Application DebugOutput::Type::Marker 1337 DebugOutput::Severity::Notification\n
+> Debug output: application marker (1337): Hello from OpenGL command stream!
->     Hello from OpenGL command stream!
 
 If only @extension2{EXT,debug_marker} or @extension{GREMEDY,string_marker} are
 available, the message can be seen only through graphics debugger.
@@ -728,10 +723,8 @@ available and the default debug output callback is enabled for these kinds of
 messages, the group entering and leaving will be printed on standard output in
 the following form:
 
-> DebugOutput::Source::Application DebugOutput::Type::PushGroup 42 DebugOutput::Severity::Notification\n
+> Debug output: application debug group enter (42): Scene rendering\n
->     Scene rendering\n
+> Debug output: application debug group leave (42): Scene rendering
-> DebugOutput::Source::Application DebugOutput::Type::PopGroup 42 DebugOutput::Severity::Notification\n
->     Scene rendering
 
 If only @extension2{EXT,debug_marker} is available, the group can be seen only
 through graphics debugger.

src/Magnum/Test/DebugOutputGLTest.cpp

@@ -118,12 +118,11 @@ void DebugOutputGLTest::message() {
     std::ostringstream out;
     Debug::setOutput(&out);
     DebugMessage::insert(DebugMessage::Source::Application, DebugMessage::Type::Marker,
-        1337, DebugOutput::Severity::Notification, "Hello from OpenGL command stream!");
+        1337, DebugOutput::Severity::High, "Hello from OpenGL command stream!");
 
     MAGNUM_VERIFY_NO_ERROR();
     CORRADE_COMPARE(out.str(),
-        "DebugOutput::Source::Application DebugOutput::Type::Marker 1337 DebugOutput::Severity::Notification \n"
+        "Debug output: high severity application marker (1337): Hello from OpenGL command stream!\n");
-        "    Hello from OpenGL command stream!\n");
 }
 
 void DebugOutputGLTest::messageFallback() {
@@ -163,20 +162,16 @@ void DebugOutputGLTest::group() {
     {
         DebugGroup g1{DebugGroup::Source::Application, 42, "Automatic debug group"};
         DebugGroup g2;
-        g2.push(DebugGroup::Source::Application, 1337, "Manual debug group");
+        g2.push(DebugGroup::Source::ThirdParty, 1337, "Manual debug group");
         g2.pop();
     }
 
     MAGNUM_VERIFY_NO_ERROR();
     CORRADE_COMPARE(out.str(),
-        "DebugOutput::Source::Application DebugOutput::Type::PushGroup 42 DebugOutput::Severity::Notification \n"
+        "Debug output: application debug group enter (42): Automatic debug group\n"
-        "    Automatic debug group\n"
+        "Debug output: third party debug group enter (1337): Manual debug group\n"
-        "DebugOutput::Source::Application DebugOutput::Type::PushGroup 1337 DebugOutput::Severity::Notification \n"
+        "Debug output: third party debug group leave (1337): Manual debug group\n"
-        "    Manual debug group\n"
+        "Debug output: application debug group leave (42): Automatic debug group\n");
-        "DebugOutput::Source::Application DebugOutput::Type::PopGroup 1337 DebugOutput::Severity::Notification \n"
-        "    Manual debug group\n"
-        "DebugOutput::Source::Application DebugOutput::Type::PopGroup 42 DebugOutput::Severity::Notification \n"
-        "    Automatic debug group\n");
 }
 
 void DebugOutputGLTest::groupFallback() {