Platform: added AndroidApplication::framebufferSize() and dpiScaling().

Doesn't provide any new interesting values, just for compatibility with
other toolkits.

doc/changelog.dox

@@ -61,6 +61,13 @@ r<Player<T, K>>>)
     @ref Math::Color3 and @ref Math::Color4 literals with the new experimental
     @ref Corrade::Utility::Tweakable utility. See also @ref tweakableliterals.
 
+@subsubsection changelog-latest-new-platform Platform libraries
+
+-   Added @ref Platform::AndroidApplication::framebufferSize(),
+    @ref Platform::AndroidApplication::dpiScaling() and
+    @ref Platform::AndroidApplication::ViewportEvent::dpiScaling() for
+    compatibility with other application implementations
+
 @subsection changelog-latest-changes Changes and improvements
 
 @subsubsection changelog-latest-changes-gl GL library

src/Magnum/Platform/AbstractXApplication.h

@@ -212,7 +212,21 @@ class AbstractXApplication {
     #else
     private:
     #endif
-        /** @copydoc GlfwApplication::viewportEvent(ViewportEvent&) */
+        /**
+         * @brief Viewport event
+         *
+         * Called when window size changes. The default implementation does
+         * nothing. If you want to respond to size changes, you should pass the
+         * new size to @ref GL::DefaultFramebuffer::setViewport() (if using
+         * OpenGL) and possibly elsewhere (to
+         * @ref SceneGraph::Camera::setViewport(), other framebuffers...).
+         *
+         * Note that this function might not get called at all if the window
+         * size doesn't change. You should configure the initial state of your
+         * cameras, framebuffers etc. in application constructor rather than
+         * relying on this function to be called. Size of the window can be
+         * retrieved using @ref windowSize().
+         */
         virtual void viewportEvent(ViewportEvent& event);
 
         #ifdef MAGNUM_BUILD_DEPRECATED

src/Magnum/Platform/AndroidApplication.cpp

@@ -165,7 +165,7 @@ bool AndroidApplication::tryCreate(const Configuration& configuration, const GLC
     return _context->tryCreate();
 }
 
-Vector2i AndroidApplication::windowSize() const {
+Vector2i AndroidApplication::framebufferSize() const {
     return {ANativeWindow_getWidth(_state->window),
             ANativeWindow_getHeight(_state->window)};
 }

src/Magnum/Platform/AndroidApplication.h

@@ -306,8 +306,45 @@ class AndroidApplication {
          * @brief Window size
          *
          * Window size to which all input event coordinates can be related.
+         * Expects that a window is already created, equivalent to
+         * @ref framebufferSize().
+         *
+         * @attention The reported value will be incorrect in case you use
+         *      the [Screen Compatibility Mode](http://www.androiddocs.com/guide/practices/screen-compat-mode.html).
+         *      See @ref platforms-android-apps-manifest-screen-compatibility-mode
+         *      for details.
+         */
+        Vector2i windowSize() const { return framebufferSize(); }
+
+        /**
+         * @brief Framebuffer size
+         *
+         * Size of the default framebuffer, equivalent to @ref windowSize().
+         * Expects that a window is already created.
+         * @see @ref dpiScaling()
+         */
+        Vector2i framebufferSize() const;
+
+        /**
+         * @brief DPI scaling
+         *
+         * Provided only for compatibility with other toolkits. Returns always
+         * @cpp {1.0f, 1.0f} @ce.
+         * @see @ref framebufferSize()
          */
-        Vector2i windowSize() const;
+        Vector2 dpiScaling() const { return Vector2{1.0f}; }
+
+        /**
+         * @brief DPI scaling for given configuration
+         *
+         * Provided only for compatibility with other toolkits. Returns always
+         * @cpp {1.0f, 1.0f} @ce.
+         * @see @ref framebufferSize()
+         */
+        Vector2 dpiScaling(const Configuration& configuration) const {
+            static_cast<void>(configuration);
+            return Vector2{1.0f};
+        }
 
         /**
          * @brief Swap buffers
@@ -521,18 +558,26 @@ class AndroidApplication::ViewportEvent {
         /**
          * @brief Window size
          *
-         * @see @ref AndroidApplication::windowSize()
+         * The same as @ref framebufferSize(). See
+         * @ref AndroidApplication::windowSize() for possible caveats.
          */
         Vector2i windowSize() const { return _windowSize; }
 
         /**
          * @brief Framebuffer size
          *
-         * The same as @ref windowSize().
-         * @todo this might not be true, implement properly!
+         * The same as @ref windowSize(). See
+         * @ref AndroidApplication::framebufferSize() for possible caveats.
          */
         Vector2i framebufferSize() const { return _windowSize; }
 
+        /**
+         * @brief DPI scaling
+         *
+         * Always @cpp {1.0f, 1.0f} @ce.
+         */
+        Vector2 dpiScaling() const { return Vector2{1.0f}; }
+
     private:
         friend AndroidApplication;