Added release() function to Image and Trade::ImageData.

Allows the image to release ownership of the data.

src/Image.h

@@ -96,7 +96,11 @@ template<UnsignedInt dimensions> class Image: public AbstractImage {
         /** @brief %Image size */
         typename DimensionTraits<Dimensions, Int>::VectorType size() const { return _size; }
 
-        /** @brief Pointer to raw data */
+        /**
+         * @brief Pointer to raw data
+         *
+         * @see @ref release()
+         */
         unsigned char* data() { return _data; }
         const unsigned char* data() const { return _data; } /**< @overload */
 
@@ -109,9 +113,19 @@ template<UnsignedInt dimensions> class Image: public AbstractImage {
          *
          * Deletes previous data and replaces them with new. Note that the
          * data are not copied, but they are deleted on destruction.
+         * @see @ref release()
          */
         void setData(ColorFormat format, ColorType type, const typename DimensionTraits<Dimensions, Int>::VectorType& size, void* data);
 
+        /**
+         * @brief Release data storage
+         *
+         * Returns the data pointer and resets internal state to default.
+         * Deleting the returned array is user responsibility.
+         * @see @ref setData()
+         */
+        unsigned char* release();
+
     private:
         Math::Vector<Dimensions, Int> _size;
         unsigned char* _data;
@@ -148,6 +162,14 @@ const
     return ImageReference<dimensions>(AbstractImage::format(), AbstractImage::type(), _size, _data);
 }
 
+template<UnsignedInt dimensions> inline unsigned char* Image<dimensions>::release() {
+    /** @todo I need `std::exchange` NOW. */
+    unsigned char* const data = _data;
+    _size = {};
+    _data = nullptr;
+    return data;
+}
+
 }
 
 #endif

src/Test/ImageTest.cpp

@@ -36,12 +36,14 @@ class ImageTest: public TestSuite::Tester {
         void moveConstructor();
         void moveAssignment();
         void toReference();
+        void release();
 };
 
 ImageTest::ImageTest() {
     addTests({&ImageTest::moveConstructor,
               &ImageTest::moveAssignment,
-              &ImageTest::toReference});
+              &ImageTest::toReference,
+              &ImageTest::release});
 }
 
 void ImageTest::moveConstructor() {
@@ -89,6 +91,15 @@ void ImageTest::toReference() {
     }
 }
 
+void ImageTest::release() {
+    unsigned char data[] = {'c', 'a', 'f', 'e'};
+    Image2D a(ColorFormat::Red, ColorType::UnsignedByte, {1, 4}, data);
+    const unsigned char* const pointer = a.release();
+    CORRADE_COMPARE(pointer, data);
+    CORRADE_VERIFY(!a.data());
+    CORRADE_VERIFY(a.size().isZero());
+}
+
 }}
 
 CORRADE_TEST_MAIN(Magnum::Test::ImageTest)

src/Trade/ImageData.h

@@ -86,10 +86,23 @@ template<UnsignedInt dimensions> class ImageData: public AbstractImage {
         /** @brief %Image size */
         typename DimensionTraits<Dimensions, Int>::VectorType size() const { return _size; }
 
-        /** @brief Pointer to raw data */
+        /**
+         * @brief Pointer to raw data
+         *
+         * @see @ref release()
+         */
         unsigned char* data() { return _data; }
         const unsigned char* data() const { return _data; } /**< @overload */
 
+        /**
+         * @brief Release data storage
+         *
+         * Returns the data pointer and resets internal state to default.
+         * Deleting the returned array is user responsibility.
+         * @see @ref data()
+         */
+        unsigned char* release();
+
     private:
         Math::Vector<Dimensions, Int> _size;
         unsigned char* _data;
@@ -126,6 +139,14 @@ const
     return ImageReference<dimensions>(AbstractImage::format(), AbstractImage::type(), _size, _data);
 }
 
+template<UnsignedInt dimensions> inline unsigned char* ImageData<dimensions>::release() {
+    /** @todo I need `std::exchange` NOW. */
+    unsigned char* const data = _data;
+    _size = {};
+    _data = nullptr;
+    return data;
+}
+
 }}
 
 #endif

src/Trade/Test/ImageDataTest.cpp

@@ -36,12 +36,14 @@ class ImageDataTest: public TestSuite::Tester {
         void moveConstructor();
         void moveAssignment();
         void toReference();
+        void release();
 };
 
 ImageDataTest::ImageDataTest() {
     addTests({&ImageDataTest::moveConstructor,
               &ImageDataTest::moveAssignment,
-              &ImageDataTest::toReference});
+              &ImageDataTest::toReference,
+              &ImageDataTest::release});
 }
 
 void ImageDataTest::moveConstructor() {
@@ -89,6 +91,15 @@ void ImageDataTest::toReference() {
     }
 }
 
+void ImageDataTest::release() {
+    unsigned char data[] = {'b', 'e', 'e', 'r'};
+    ImageData2D a(ColorFormat::Red, ColorType::UnsignedByte, {1, 4}, data);
+    const unsigned char* const pointer = a.release();
+    CORRADE_COMPARE(pointer, data);
+    CORRADE_VERIFY(!a.data());
+    CORRADE_VERIFY(a.size().isZero());
+}
+
 }}}
 
 CORRADE_TEST_MAIN(Magnum::Trade::Test::ImageDataTest)