python: exposed basics of trade.AbstractImageConverter.

doc/python/magnum.trade.rst

@@ -166,3 +166,31 @@
     :raise RuntimeError: If image import fails
     :raise IndexError: If :p:`id` is negative or not less than
         :ref:`image3d_count`
+
+.. py:class:: magnum.trade.ImageConverterManager
+    :summary: Manager for :ref:`AbstractImageConverter` plugin instances
+
+    Each plugin returned by :ref:`instantiate()` or :ref:`load_and_instantiate()`
+    references its owning :ref:`ImageConverterManager` through
+    :ref:`AbstractImageConverter.manager`, ensuring the manager is not deleted
+    before the plugin instances are.
+
+.. py:class:: magnum.trade.AbstractImageConverter
+
+    Similarly to C++, image converter plugins are loaded through
+    :ref:`ImageConverterManager`:
+
+    ..
+        >>> from magnum import trade
+
+    .. code:: py
+
+        >>> manager = trade.ImageConverterManager()
+        >>> converter = manager.load_and_instantiate('PngImageConverter')
+
+    Unlike C++, errors in both API usage and file parsing are reported by
+    raising an exception. See particular function documentation for detailed
+    behavior.
+
+.. py:function:: magnum.trade.AbstractImageConverter.convert_to_file
+    :raise RuntimeError: If image conversion fails

doc/python/pages/changelog.rst

@@ -90,6 +90,7 @@ Changelog
     :ref:`platform.glfw.Application.exit_event`
 -   Exposed :ref:`platform.glfw.Application.swap_interval` and
     :ref:`platform.glfw.Application.main_loop_iteration`
+-   Exposed a basic interface of :ref:`trade.AbstractImageConverter`
 -   Exposed :ref:`Color3.red()` and other convenience constructors (see
     :gh:`mosra/magnum-bindings#12`)
 -   Fixed issues with an in-source build (see :gh:`mosra/magnum-bindings#13`)

package/ci/appveyor-desktop-gles.bat

@@ -75,6 +75,7 @@ cmake .. ^
     -DCMAKE_INSTALL_PREFIX=%APPVEYOR_BUILD_FOLDER%/deps ^
     -DBUILD_STATIC=%BUILD_STATIC% ^
     -DWITH_DDSIMPORTER=ON ^
+    -DWITH_STBIMAGECONVERTER=ON ^
     -DWITH_STBIMAGEIMPORTER=ON ^
     -DWITH_CGLTFIMPORTER=ON ^
     -G Ninja || exit /b

package/ci/appveyor-desktop.bat

@@ -82,6 +82,7 @@ cmake .. ^
     -DCMAKE_INSTALL_PREFIX=%APPVEYOR_BUILD_FOLDER%/deps ^
     -DBUILD_STATIC=%BUILD_STATIC% ^
     -DWITH_DDSIMPORTER=ON ^
+    -DWITH_STBIMAGECONVERTER=ON ^
     -DWITH_STBIMAGEIMPORTER=ON ^
     -DWITH_CGLTFIMPORTER=ON ^
     %COMPILER_EXTRA% -G Ninja || exit /b

package/ci/unix-desktop-gles.sh

@@ -58,6 +58,7 @@ cmake .. \
     -DCMAKE_BUILD_TYPE=Release \
     -DBUILD_STATIC=$BUILD_STATIC \
     -DWITH_DDSIMPORTER=ON \
+    -DWITH_STBIMAGECONVERTER=ON \
     -DWITH_STBIMAGEIMPORTER=ON \
     -DWITH_CGLTFIMPORTER=ON \
     -G Ninja

package/ci/unix-desktop.sh

@@ -66,6 +66,7 @@ cmake .. \
     -DCMAKE_BUILD_TYPE=Release \
     -DBUILD_STATIC=$BUILD_STATIC \
     -DWITH_DDSIMPORTER=ON \
+    -DWITH_STBIMAGECONVERTER=ON \
     -DWITH_STBIMAGEIMPORTER=ON \
     -DWITH_CGLTFIMPORTER=ON \
     -G Ninja

src/python/magnum/test/test_trade.py

@@ -25,6 +25,7 @@
 
 import os
 import sys
+import tempfile
 import unittest
 
 from corrade import pluginmanager
@@ -265,3 +266,26 @@ class Importer(unittest.TestCase):
 
         with self.assertRaisesRegex(RuntimeError, "import failed"):
             importer.image2d(0)
+
+class ImageConverter(unittest.TestCase):
+    def test_image2d(self):
+        importer = trade.ImporterManager().load_and_instantiate('StbImageImporter')
+        importer.open_file(os.path.join(os.path.dirname(__file__), 'rgb.png'))
+        image = importer.image2d(0)
+
+        converter = trade.ImageConverterManager().load_and_instantiate('StbImageConverter')
+
+        with tempfile.TemporaryDirectory() as tmp:
+            converter.convert_to_file(image, os.path.join(tmp, "image.png"))
+            self.assertTrue(os.path.exists(os.path.join(tmp, "image.png")))
+
+    def test_image2d_failed(self):
+        importer = trade.ImporterManager().load_and_instantiate('StbImageImporter')
+        importer.open_file(os.path.join(os.path.dirname(__file__), 'rgb.png'))
+        image = importer.image2d(0)
+
+        converter = trade.ImageConverterManager().load_and_instantiate('StbImageConverter')
+
+        with tempfile.TemporaryDirectory() as tmp:
+            with self.assertRaisesRegex(RuntimeError, "conversion failed"):
+                converter.convert_to_file(image, os.path.join(tmp, "image.hdr"))

src/python/magnum/trade.cpp

@@ -29,6 +29,7 @@
 #include <Corrade/Containers/StringStl.h> /** @todo drop once we have our string casters */
 #include <Magnum/ImageView.h>
 #include <Magnum/Trade/AbstractImporter.h>
+#include <Magnum/Trade/AbstractImageConverter.h>
 #include <Magnum/Trade/ImageData.h>
 #include <Magnum/Trade/MeshData.h>
 
@@ -241,6 +242,17 @@ template<class R, Containers::Optional<R>(Trade::AbstractImporter::*f)(UnsignedI
     return *std::move(out);
 }
 
+/** @todo drop std::string in favor of our own string caster */
+template<class T, bool(Trade::AbstractImageConverter::*f)(const T&, Containers::StringView)> void checkResult(Trade::AbstractImageConverter& self, const T& image, const std::string& filename) {
+    /** @todo log redirection -- but we'd need assertions to not be part of
+        that so when it dies, the user can still see why */
+    bool out = (self.*f)(image, filename);
+    if(!out) {
+        PyErr_SetString(PyExc_RuntimeError, "conversion failed");
+        throw py::error_already_set{};
+    }
+}
+
 }
 
 void trade(py::module_& m) {
@@ -318,6 +330,17 @@ void trade(py::module_& m) {
 
     py::class_<PluginManager::Manager<Trade::AbstractImporter>, PluginManager::AbstractManager> importerManager{m, "ImporterManager", "Manager for importer plugins"};
     corrade::manager(importerManager);
+
+    /* Image converter */
+    py::class_<Trade::AbstractImageConverter, PluginManager::PyPluginHolder<Trade::AbstractImageConverter>> abstractImageConverter{m, "AbstractImageConverter", "Interface for image converter plugins"};
+    abstractImageConverter
+        .def("convert_to_file", checkResult<ImageView1D, &Trade::AbstractImageConverter::convertToFile>, "Convert a 1D image to a file", py::arg("image"), py::arg("filename"))
+        .def("convert_to_file", checkResult<ImageView2D, &Trade::AbstractImageConverter::convertToFile>, "Convert a 2D image to a file", py::arg("image"), py::arg("filename"))
+        .def("convert_to_file", checkResult<ImageView3D, &Trade::AbstractImageConverter::convertToFile>, "Convert a 3D image to a file", py::arg("image"), py::arg("filename"));
+    corrade::plugin(abstractImageConverter);
+
+    py::class_<PluginManager::Manager<Trade::AbstractImageConverter>, PluginManager::AbstractManager> imageConverterManager{m, "ImageConverterManager", "Manager for image converter plugins"};
+    corrade::manager(imageConverterManager);
 }
 
 }