Platform: text input support for Sdl2Application.

src/Magnum/Platform/Sdl2Application.cpp

@@ -33,6 +33,7 @@
 #endif
 
 #include "Magnum/Version.h"
+#include "Magnum/Math/Range.h"
 #include "Magnum/Platform/Context.h"
 #include "Magnum/Platform/ScreenedApplication.hpp"
 
@@ -383,6 +384,18 @@ void Sdl2Application::mainLoop() {
                 break;
             }
 
+            #ifndef CORRADE_TARGET_EMSCRIPTEN
+            case SDL_TEXTINPUT: {
+                TextInputEvent e{event.text.text};
+                textInputEvent(e);
+            } break;
+
+            case SDL_TEXTEDITING: {
+                TextEditingEvent e{event.edit.text, event.edit.start, event.edit.length};
+                textEditingEvent(e);
+            } break;
+            #endif
+
             case SDL_QUIT:
                 #ifndef CORRADE_TARGET_EMSCRIPTEN
                 _flags |= Flag::Exit;
@@ -438,6 +451,20 @@ void Sdl2Application::setMouseLocked(bool enabled) {
     #endif
 }
 
+#ifndef CORRADE_TARGET_EMSCRIPTEN
+void Sdl2Application::startTextInput(const Range2Di& rect) {
+    SDL_StartTextInput();
+    if(!rect.size().isZero()) {
+        SDL_Rect r{rect.min().x(), rect.min().y(), rect.sizeX(), rect.sizeY()};
+        SDL_SetTextInputRect(&r);
+    }
+}
+
+void Sdl2Application::startTextInput() {
+    startTextInput({});
+}
+#endif
+
 void Sdl2Application::tickEvent() {
     /* If this got called, the tick event is not implemented by user and thus
        we don't need to call it ever again */
@@ -451,6 +478,11 @@ void Sdl2Application::mousePressEvent(MouseEvent&) {}
 void Sdl2Application::mouseReleaseEvent(MouseEvent&) {}
 void Sdl2Application::mouseMoveEvent(MouseMoveEvent&) {}
 
+#ifndef CORRADE_TARGET_EMSCRIPTEN
+void Sdl2Application::textInputEvent(TextInputEvent&) {}
+void Sdl2Application::textEditingEvent(TextEditingEvent&) {}
+#endif
+
 Sdl2Application::Configuration::Configuration():
     #if !defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(CORRADE_TARGET_IOS)
     _title("Magnum SDL2 Application"),

src/Magnum/Platform/Sdl2Application.h

@@ -330,6 +330,10 @@ class Sdl2Application {
         class KeyEvent;
         class MouseEvent;
         class MouseMoveEvent;
+        #ifndef CORRADE_TARGET_EMSCRIPTEN
+        class TextInputEvent;
+        class TextEditingEvent;
+        #endif
 
         /**
          * @brief Default constructor
@@ -571,6 +575,69 @@ class Sdl2Application {
 
         /*@}*/
 
+        #ifndef CORRADE_TARGET_EMSCRIPTEN
+        /** @{ @name Text input handling */
+    public:
+        /**
+         * @brief Whether text input is active
+         *
+         * If text input is active, text input events go to @ref textInputEvent()
+         * and @ref textEditingEvent().
+         * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref startTextInput(), @ref stopTextInput()
+         */
+        bool isTextInputActive() { return SDL_IsTextInputActive(); }
+
+        /**
+         * @brief Start text input
+         *
+         * Starts text input that will go to @ref textInputEvent() and
+         * @ref textEditingEvent(). The @p rect defines an area where the text
+         * is being displayed, for example to hint the system where to place
+         * on-screen keyboard. Ignored if empty.
+         * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref stopTextInput(), @ref isTextInputActive(),
+         */
+        #ifdef DOXYGEN_GENERATING_OUTPUT
+        void startTextInput(const Range2Di& rect = {});
+        #else
+        /* To avoid including the type in header */
+        void startTextInput(const Range2Di& rect);
+        void startTextInput();
+        #endif
+
+        /**
+         * @brief Stop text input
+         *
+         * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref startTextInput(), @ref isTextInputActive(), @ref textInputEvent()
+         *      @ref textEditingEvent()
+         */
+        void stopTextInput() { SDL_StopTextInput(); }
+
+    #ifdef DOXYGEN_GENERATING_OUTPUT
+    protected:
+    #else
+    private:
+    #endif
+        /**
+         * @brief Text input event
+         *
+         * Called when text input is active and the text is being input.
+         * @see @ref isTextInputActive()
+         */
+        virtual void textInputEvent(TextInputEvent& event);
+
+        /**
+         * @brief Text editing event
+         *
+         * Called when text input is active and the text is being edited.
+         */
+        virtual void textEditingEvent(TextEditingEvent& event);
+
+        /*@}*/
+        #endif
+
     private:
         enum class Flag: UnsignedByte {
             Redraw = 1 << 0,
@@ -1123,6 +1190,105 @@ class Sdl2Application::MouseMoveEvent: public Sdl2Application::InputEvent {
         Modifiers _modifiers;
 };
 
+#ifndef CORRADE_TARGET_EMSCRIPTEN
+/**
+@brief Text input event
+
+@note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+@see @ref TextEditingEvent, @ref textInputEvent()
+*/
+class Sdl2Application::TextInputEvent {
+    friend Sdl2Application;
+
+    public:
+        /** @brief Copying is not allowed */
+        TextInputEvent(const TextInputEvent&) = delete;
+
+        /** @brief Moving is not allowed */
+        TextInputEvent(TextInputEvent&&) = delete;
+
+        /** @brief Copying is not allowed */
+        TextInputEvent& operator=(const TextInputEvent&) = delete;
+
+        /** @brief Moving is not allowed */
+        TextInputEvent& operator=(TextInputEvent&&) = delete;
+
+        /** @brief Whether the event is accepted */
+        constexpr bool isAccepted() const { return _accepted; }
+
+        /**
+         * @brief Set event as accepted
+         *
+         * If the event is ignored (i.e., not set as accepted), it might be
+         * propagated elsewhere, for example to another screen when using
+         * @ref BasicScreenedApplication "ScreenedApplication". By default is
+         * each event ignored and thus propagated.
+         */
+        void setAccepted(bool accepted = true) { _accepted = accepted; }
+
+        /** @brief Input text in UTF-8 */
+        constexpr Containers::ArrayView<const char> text() const { return _text; }
+
+    private:
+        constexpr TextInputEvent(Containers::ArrayView<const char> text): _text{text} {}
+
+        Containers::ArrayView<const char> _text;
+        bool _accepted;
+};
+
+/**
+@brief Text editing event
+
+@note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+@see @ref textEditingEvent()
+*/
+class Sdl2Application::TextEditingEvent {
+    friend Sdl2Application;
+
+    public:
+        /** @brief Copying is not allowed */
+        TextEditingEvent(const TextEditingEvent&) = delete;
+
+        /** @brief Moving is not allowed */
+        TextEditingEvent(TextEditingEvent&&) = delete;
+
+        /** @brief Copying is not allowed */
+        TextEditingEvent& operator=(const TextEditingEvent&) = delete;
+
+        /** @brief Moving is not allowed */
+        TextEditingEvent& operator=(TextEditingEvent&&) = delete;
+
+        /** @brief Whether the event is accepted */
+        constexpr bool isAccepted() const { return _accepted; }
+
+        /**
+         * @brief Set event as accepted
+         *
+         * If the event is ignored (i.e., not set as accepted), it might be
+         * propagated elsewhere, for example to another screen when using
+         * @ref BasicScreenedApplication "ScreenedApplication". By default is
+         * each event ignored and thus propagated.
+         */
+        void setAccepted(bool accepted = true) { _accepted = accepted; }
+
+        /** @brief Input text in UTF-8 */
+        constexpr Containers::ArrayView<const char> text() const { return _text; }
+
+        /** @brief Location to begin editing from */
+        constexpr Int start() const { return _start; }
+
+        /** @brief Number of characters to edit from the start point */
+        constexpr Int length() const { return _length; }
+
+    private:
+        constexpr TextEditingEvent(Containers::ArrayView<const char> text, Int start, Int length): _text{text}, _start{start}, _length{length} {}
+
+        Containers::ArrayView<const char> _text;
+        Int _start, _length;
+        bool _accepted;
+};
+#endif
+
 /** @hideinitializer
 @brief Entry point for SDL2-based applications
 @param className Class name