DebugTools: empty FrameProfiler shouldn't be implicitly enabled.

That just makes no sense, as one then has to explicitly call disable()
to not have printStatistics() produce a useless line in the output.

Also have the same behavior also if it's constructed or set up from an
empty list of measurements, since that should be equivalent.

src/Magnum/DebugTools/FrameProfiler.cpp

@@ -122,17 +122,18 @@ void FrameProfiler::setup(Containers::Array<Measurement>&& measurements, const U
     }
     #endif
 
-    /* Reset to have a clean slate in case we did some other measurements
+    /* Reset to a clean slate in case we did some other measurements before,
-       before */
+       then either disable or enable based on whether we have anything to
-    enable();
+       measure */
+    reset();
+    _measurements.isEmpty() ? disable() : enable();
 }
 
 void FrameProfiler::setup(const std::initializer_list<Measurement> measurements, const UnsignedInt maxFrameCount) {
     setup(Containers::array(measurements), maxFrameCount);
 }
 
-void FrameProfiler::enable() {
+void FrameProfiler::reset() {
-    _enabled = true;
     #ifndef CORRADE_NO_ASSERT
     _beginFrameCalled = false;
     #endif
@@ -148,6 +149,11 @@ void FrameProfiler::enable() {
     }
 }
 
+void FrameProfiler::enable() {
+    reset();
+    _enabled = true;
+}
+
 void FrameProfiler::disable() {
     _enabled = false;
 }

src/Magnum/DebugTools/FrameProfiler.h

@@ -176,7 +176,9 @@ class MAGNUM_DEBUGTOOLS_EXPORT FrameProfiler {
         /**
          * @brief Default constructor
          *
-         * Call @ref setup() to populate the profiler with measurements.
+         * Call @ref setup() to populate the profiler with measurements. A
+         * default-constructed instance has profiling implicitly disabled.
+         * @see @ref isEnabled()
          */
         explicit FrameProfiler() noexcept;
 
@@ -184,7 +186,9 @@ class MAGNUM_DEBUGTOOLS_EXPORT FrameProfiler {
          * @brief Constructor
          *
          * Equivalent to default-constructing an instance and calling
-         * @ref setup() afterwards.
+         * @ref setup() afterwards. If @p measurements are not empty, profiling
+         * is implicitly enabled after, otherwise it's implicitly disabled.
+         * @see @ref isEnabled()
          */
         explicit FrameProfiler(Containers::Array<Measurement>&& measurements, UnsignedInt maxFrameCount) noexcept;
 
@@ -211,23 +215,38 @@ class MAGNUM_DEBUGTOOLS_EXPORT FrameProfiler {
          *
          * Calling @ref setup() on an already set up profiler will replace
          * existing measurements with @p measurements and reset
-         * @ref measuredFrameCount() back to @cpp 0 @ce.
+         * @ref measuredFrameCount() back to @cpp 0 @ce. If @p measurements
+         * are not empty, profiling is implicitly enabled after, otherwise it's
+         * implicitly disabled.
+         * @see @ref isEnabled()
          */
         void setup(Containers::Array<Measurement>&& measurements, UnsignedInt maxFrameCount);
 
         /** @overload */
         void setup(std::initializer_list<Measurement> measurements, UnsignedInt maxFrameCount);
 
-        /** @brief Whether the profiling is enabled */
+        /**
+         * @brief Whether the profiling is enabled
+         *
+         * @see @ref enable(), @ref disable(), @ref setup()
+         */
         bool isEnabled() const { return _enabled; }
 
         /**
          * @brief Enable the profiler
          *
-         * The profiler is enabled implicitly after construction. When this
+         * When this function is called, it discards all measured data,
-         * function is called, it discards all measured data, effectively
+         * effectively making @ref measuredFrameCount() zero. If you want to
-         * making @ref measuredFrameCount() zero. If you want to reset the
+         * reset the profiler to measure different values as well, call
-         * profiler to measure different values as well, call @ref setup().
+         * @ref setup() instead.
+         *
+         * A default-constructed profiler is implicitly disabled as it has
+         * nothing to measure. Constructing it with a non-empty set of
+         * measurements or calling @ref setup() with a non-empty set of
+         * measurements makes it implicitly enabled. It's allowed to call this
+         * function even if the profiler has no measurements, although it'll
+         * result in @ref statistics() / @ref printStatistics() producing
+         * useless output.
          */
         void enable();
 
@@ -381,8 +400,8 @@ class MAGNUM_DEBUGTOOLS_EXPORT FrameProfiler {
          * but in addition, if the output is a TTY, it's colored and overwrites
          * itself instead of filling up the terminal history. If profiling is
          * disabled, does nothing.
-         * @see @ref isMeasurementAvailable(), @ref isEnabled()
+         * @see @ref isMeasurementAvailable(), @ref isEnabled(),
-         *      @ref Corrade::Utility::Debug::isTty()
+         *      @relativeref{Corrade,Utility::Debug::isTty()}
          */
         void printStatistics(UnsignedInt frequency) const;
 
@@ -404,11 +423,12 @@ class MAGNUM_DEBUGTOOLS_EXPORT FrameProfiler {
         }
 
     private:
+        void reset();
         UnsignedInt delayedCurrentData(UnsignedInt delay) const;
         Double measurementMeanInternal(const Measurement& measurement) const;
         void printStatisticsInternal(Debug& out) const;
 
-        bool _enabled = true;
+        bool _enabled = false;
         #ifndef CORRADE_NO_ASSERT
         /* Here it shouldn't cause the class to have a different size when
            asserts get disabled */

src/Magnum/DebugTools/Test/FrameProfilerGLTest.cpp

@@ -122,6 +122,7 @@ void FrameProfilerGLTest::test() {
     Shaders::FlatGL3D shader;
 
     FrameProfilerGL profiler{data.values, 4};
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.maxFrameCount(), 4);
 
     /* MSVC 2015 needs the {} */

src/Magnum/DebugTools/Test/FrameProfilerTest.cpp

@@ -158,11 +158,20 @@ FrameProfilerTest::FrameProfilerTest() {
 
 void FrameProfilerTest::defaultConstructed() {
     FrameProfiler profiler;
+    CORRADE_VERIFY(!profiler.isEnabled());
     CORRADE_COMPARE(profiler.maxFrameCount(), 1);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
     CORRADE_COMPARE(profiler.measurementCount(), 0);
     CORRADE_COMPARE(profiler.statistics(), "Last 0 frames:");
 
+    /* Nothing happens by default as it's not enabled */
+    profiler.beginFrame();
+    profiler.endFrame();
+    CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
+
+    profiler.enable();
+    CORRADE_VERIFY(profiler.isEnabled());
+
     profiler.beginFrame();
     profiler.endFrame();
     CORRADE_COMPARE(profiler.measuredFrameCount(), 1);
@@ -176,11 +185,20 @@ void FrameProfilerTest::defaultConstructed() {
 
 void FrameProfilerTest::noMeasurements() {
     FrameProfiler profiler{{}, 3};
+    CORRADE_VERIFY(!profiler.isEnabled());
     CORRADE_COMPARE(profiler.maxFrameCount(), 3);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
     CORRADE_COMPARE(profiler.measurementCount(), 0);
     CORRADE_COMPARE(profiler.statistics(), "Last 0 frames:");
 
+    /* Nothing happens by default as it's not enabled */
+    profiler.beginFrame();
+    profiler.endFrame();
+    CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
+
+    profiler.enable();
+    CORRADE_VERIFY(profiler.isEnabled());
+
     profiler.beginFrame();
     profiler.endFrame();
     CORRADE_COMPARE(profiler.measuredFrameCount(), 1);
@@ -213,6 +231,8 @@ void FrameProfilerTest::singleFrame() {
 
     UnsignedLong time = 0, memory = 50;
     FrameProfiler profiler;
+    CORRADE_VERIFY(!profiler.isEnabled());
+
     if(!data.delayed) {
         profiler.setup({
             FrameProfiler::Measurement{
@@ -279,6 +299,7 @@ void FrameProfilerTest::singleFrame() {
                 }, nullptr}
         }, 1);
     }
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.maxFrameCount(), 1);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
     CORRADE_COMPARE(profiler.measurementCount(), 3);
@@ -367,6 +388,8 @@ void FrameProfilerTest::multipleFrames() {
         UnsignedInt delay;
     } state {0, 50, {0, 0, 0}, {50, 0, 0}, data.delay};
     FrameProfiler profiler;
+    CORRADE_VERIFY(!profiler.isEnabled());
+
     if(!data.delayed) {
         profiler.setup({
             FrameProfiler::Measurement{
@@ -441,6 +464,7 @@ void FrameProfilerTest::multipleFrames() {
                 }, nullptr}
         }, 3);
     }
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.maxFrameCount(), 3);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
     CORRADE_COMPARE(profiler.measurementDelay(0), data.delay);
@@ -580,6 +604,7 @@ void FrameProfilerTest::enableDisable() {
     profiler.endFrame();
     profiler.beginFrame();
     profiler.endFrame();
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.measurementCount(), 1);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 3);
     CORRADE_COMPARE(profiler.measurementDelay(0), 2);
@@ -588,6 +613,7 @@ void FrameProfilerTest::enableDisable() {
 
     /* It should only freeze everything, not wipe out any data */
     profiler.disable();
+    CORRADE_VERIFY(!profiler.isEnabled());
     CORRADE_COMPARE(profiler.measurementCount(), 1);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 3);
     CORRADE_COMPARE(profiler.measurementDelay(0), 2);
@@ -607,6 +633,7 @@ void FrameProfilerTest::enableDisable() {
     /* Enabling should reset the data to have a clean slate, but not the
        measurements */
     profiler.enable();
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.measurementCount(), 1);
     CORRADE_COMPARE(profiler.maxFrameCount(), 5);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
@@ -638,10 +665,13 @@ void FrameProfilerTest::reSetup() {
             [](void*, UnsignedInt) {},
             [](void*, UnsignedInt, UnsignedInt) { return UnsignedLong{}; }, nullptr},
     }, 5};
+    CORRADE_VERIFY(profiler.isEnabled());
 
     profiler.beginFrame();
     profiler.endFrame();
     profiler.beginFrame();
+    CORRADE_COMPARE(profiler.measurementCount(), 1);
+    CORRADE_COMPARE(profiler.measuredFrameCount(), 1);
 
     /* Setup should replace everything */
     profiler.setup({
@@ -656,6 +686,7 @@ void FrameProfilerTest::reSetup() {
             [](void*) { return UnsignedLong{}; },
             nullptr},
     }, 10);
+    CORRADE_VERIFY(profiler.isEnabled());
     CORRADE_COMPARE(profiler.measurementCount(), 2);
     CORRADE_COMPARE(profiler.maxFrameCount(), 10);
     CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
@@ -668,6 +699,14 @@ void FrameProfilerTest::reSetup() {
        beginFrame() expected again */
     profiler.beginFrame();
     profiler.endFrame();
+    CORRADE_COMPARE(profiler.measuredFrameCount(), 1);
+
+    /* Empty setup clears everything and makes it disabled */
+    profiler.setup({}, 17);
+    CORRADE_VERIFY(!profiler.isEnabled());
+    CORRADE_COMPARE(profiler.measurementCount(), 0);
+    CORRADE_COMPARE(profiler.maxFrameCount(), 17);
+    CORRADE_COMPARE(profiler.measuredFrameCount(), 0);
 }
 
 void FrameProfilerTest::copy() {
@@ -811,7 +850,11 @@ void FrameProfilerTest::delayTooLittleFrames() {
 void FrameProfilerTest::startStopFrameUnexpected() {
     CORRADE_SKIP_IF_NO_ASSERT();
 
+    /* Empty profiler is disabled by default, enable it to not have
+       beginFrame() and endFrame() no-op */
     FrameProfiler profiler;
+    profiler.enable();
+    CORRADE_VERIFY(profiler.isEnabled());
 
     Containers::String out;
     {
@@ -1101,6 +1144,7 @@ void FrameProfilerTest::gl() {
     Containers::Pointer<FrameProfilerGL> profiler_{InPlaceInit, data.values, 4u};
     FrameProfilerGL profiler = Utility::move(*profiler_);
     profiler_ = nullptr;
+    CORRADE_COMPARE(profiler.isEnabled(), !!data.values);
     CORRADE_COMPARE(profiler.values(), data.values);
     CORRADE_COMPARE(profiler.maxFrameCount(), 4);
     CORRADE_COMPARE(profiler.measurementCount(), data.measurementCount);