TextureTools: add a NoCreate constructor to DistanceField.

Should have been there for ages already.

doc/changelog.dox

@@ -810,6 +810,11 @@ See also:
     needed in order to prevent aligning pixel-perfect fonts to fractional
     positions.
 
+@subsubsection changelog-latest-changes-texturetools TextureTools library
+
+-   Added a @ref TextureTools::DistanceField::DistanceField(NoCreateT)
+    constructor allowing to construct the object without a GL context present
+
 @subsubsection changelog-latest-changes-trade Trade library
 
 -   A changed signature of the @ref Trade::AbstractImporter::doOpenData(Containers::Array<char>&&, DataFlags)

src/Magnum/TextureTools/DistanceField.cpp

@@ -171,6 +171,8 @@ DistanceField::DistanceField(const UnsignedInt radius): _state{new State{radius}
     }
 }
 
+DistanceField::DistanceField(NoCreateT) noexcept {}
+
 DistanceField::DistanceField(DistanceField&&) noexcept = default;
 
 DistanceField::~DistanceField() = default;

src/Magnum/TextureTools/DistanceField.h

@@ -95,6 +95,22 @@ class MAGNUM_TEXTURETOOLS_EXPORT DistanceField {
          */
         explicit DistanceField(UnsignedInt radius);
 
+        /**
+         * @brief Construct without creating the internal OpenGL state
+         * @m_since_latest
+         *
+         * The constructed instance is equivalent to moved-from state, i.e. no
+         * APIs can be safely called on the object. Useful in cases where you
+         * will overwrite the instance later anyway. Move another object over
+         * it to make it useful.
+         *
+         * This function can be safely used for constructing (and later
+         * destructing) objects even without any OpenGL context being active.
+         * However note that this is a low-level and a potentially dangerous
+         * API, see the documentation of @ref NoCreate for alternatives.
+         */
+        explicit DistanceField(NoCreateT) noexcept;
+
         /** @brief Copying is not allowed */
         DistanceField(const DistanceField&) = delete;
 

src/Magnum/TextureTools/Test/CMakeLists.txt

@@ -87,42 +87,46 @@ else()
     endif()
 endif()
 
-if(MAGNUM_BUILD_GL_TESTS)
-    # Otherwise CMake complains that Corrade::PluginManager is not found, wtf
-    find_package(Corrade REQUIRED PluginManager)
+if(MAGNUM_TARGET_GL)
+    corrade_add_test(TextureToolsDistanceFieldTest DistanceFieldTest.cpp LIBRARIES MagnumTextureTools)
 
-    set(TextureToolsDistanceFieldGLTest_SRCS DistanceFieldGLTest.cpp)
-    if(CORRADE_TARGET_IOS)
-        # TODO: do this in a generic way in corrade_add_test()
-        set_source_files_properties(DistanceFieldGLTestFiles PROPERTIES
-            MACOSX_PACKAGE_LOCATION Resources)
-        list(APPEND TextureToolsDistanceFieldGLTest_SRCS DistanceFieldGLTestFiles)
-    endif()
-    corrade_add_test(TextureToolsDistanceFieldGLTest ${TextureToolsDistanceFieldGLTest_SRCS}
-        LIBRARIES
-            MagnumDebugTools
-            MagnumGL
-            MagnumOpenGLTester
-            MagnumTextureToolsTestLib
-            MagnumTrade
-        FILES
-            DistanceFieldGLTestFiles/input.tga
-            DistanceFieldGLTestFiles/output.tga)
-    target_include_directories(TextureToolsDistanceFieldGLTest PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/$<CONFIG>)
-    if(MAGNUM_BUILD_PLUGINS_STATIC)
-        if(MAGNUM_WITH_ANYIMAGEIMPORTER)
-            target_link_libraries(TextureToolsDistanceFieldGLTest PRIVATE AnyImageImporter)
-        endif()
-        if(MAGNUM_WITH_TGAIMPORTER)
-            target_link_libraries(TextureToolsDistanceFieldGLTest PRIVATE TgaImporter)
-        endif()
-    else()
-        # So the plugins get properly built when building the test
-        if(MAGNUM_WITH_ANYIMAGEIMPORTER)
-            add_dependencies(TextureToolsDistanceFieldGLTest AnyImageImporter)
+    if(MAGNUM_BUILD_GL_TESTS)
+        # Otherwise CMake complains that Corrade::PluginManager is not found, wtf
+        find_package(Corrade REQUIRED PluginManager)
+
+        set(TextureToolsDistanceFieldGLTest_SRCS DistanceFieldGLTest.cpp)
+        if(CORRADE_TARGET_IOS)
+            # TODO: do this in a generic way in corrade_add_test()
+            set_source_files_properties(DistanceFieldGLTestFiles PROPERTIES
+                MACOSX_PACKAGE_LOCATION Resources)
+            list(APPEND TextureToolsDistanceFieldGLTest_SRCS DistanceFieldGLTestFiles)
         endif()
-        if(MAGNUM_WITH_TGAIMPORTER)
-            add_dependencies(TextureToolsDistanceFieldGLTest TgaImporter)
+        corrade_add_test(TextureToolsDistanceFieldGLTest ${TextureToolsDistanceFieldGLTest_SRCS}
+            LIBRARIES
+                MagnumDebugTools
+                MagnumGL
+                MagnumOpenGLTester
+                MagnumTextureToolsTestLib
+                MagnumTrade
+            FILES
+                DistanceFieldGLTestFiles/input.tga
+                DistanceFieldGLTestFiles/output.tga)
+        target_include_directories(TextureToolsDistanceFieldGLTest PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/$<CONFIG>)
+        if(MAGNUM_BUILD_PLUGINS_STATIC)
+            if(MAGNUM_WITH_ANYIMAGEIMPORTER)
+                target_link_libraries(TextureToolsDistanceFieldGLTest PRIVATE AnyImageImporter)
+            endif()
+            if(MAGNUM_WITH_TGAIMPORTER)
+                target_link_libraries(TextureToolsDistanceFieldGLTest PRIVATE TgaImporter)
+            endif()
+        else()
+            # So the plugins get properly built when building the test
+            if(MAGNUM_WITH_ANYIMAGEIMPORTER)
+                add_dependencies(TextureToolsDistanceFieldGLTest AnyImageImporter)
+            endif()
+            if(MAGNUM_WITH_TGAIMPORTER)
+                add_dependencies(TextureToolsDistanceFieldGLTest TgaImporter)
+            endif()
         endif()
     endif()
 endif()

src/Magnum/TextureTools/Test/DistanceFieldTest.cpp

@@ -0,0 +1,54 @@
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
+                2020, 2021, 2022, 2023 Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include <Corrade/TestSuite/Tester.h>
+
+#include "Magnum/TextureTools/DistanceField.h"
+
+namespace Magnum { namespace TextureTools { namespace Test { namespace {
+
+struct DistanceFieldTest: TestSuite::Tester {
+    explicit DistanceFieldTest();
+
+    void constructNoCreate();
+};
+
+DistanceFieldTest::DistanceFieldTest() {
+    addTests({&DistanceFieldTest::constructNoCreate});
+}
+
+void DistanceFieldTest::constructNoCreate() {
+    DistanceField distanceField{NoCreate};
+
+    /* Shouldn't crash or try to acces GL */
+    CORRADE_VERIFY(true);
+
+    /* Implicit construction is not allowed */
+    CORRADE_VERIFY(!std::is_convertible<NoCreateT, DistanceField>::value);
+}
+
+}}}}
+
+CORRADE_TEST_MAIN(Magnum::TextureTools::Test::DistanceFieldTest)