Modularize virtual keyboard and add an extension interface

With the extension interface it is possible to add new input
method and/or languages without recompiling the Qt Virtual
Keyboard plugin itself.

The existing input methods are now isolated into plugins.
So installing a new input method is a matter of copying the
corresponding extension plugin to the plugins/virtualkeyboard
directory (and any collateral required by the extension plugin
itself).

This change also renames the HunspellInputMethod to
DefaultInputMethod. This change is necessary because some other
extension plugin may want to provide the default input method
instead.

Implementation plan
===================
[x] Create virtualkeyboard-private module
[x] Create plugin library
[x] Define interface for input method plugin
[x] Define interface for keyboard layouts
[x] Move existing input methods and layouts to plugins
    [x] HangulInputMethod
    [x] HunspellInputMethod
        [x] Maybe create a private library for sharing
            between HunspellInputMethod and LipiInputMethod
    [x] LipiInputMethod
    [x] OpenWnnInputMethod
    [x] PinyinInputMethod
    [x] T9WriteInputMethod
    [x] TCInputMethod
[o] Rename some C++ classes (too generic name?)
[x] Think again replacing the QtVirtualKeyboard namespace
[x] Update documentation
    [x] General instructions for creating a plugin
    [x] For the C++ interfaces too (previously removed)

[ChangeLog][Important Behavior Changes] Introduce an extension
interface for the virtual keyboard. All the current input methods and
some special keyboard layouts (e.g. Hunspell, OpenWnn, etc.) have been
moved to extensions. The extension interface allows third party to
create a new input method without having to modify or rebuild the
virtual keyboard. In addition, this change makes it possible to add
features and languages independently by copying the desired extension
to the system.

[ChangeLog][Important Behavior Changes] Introduce a virtualkeyboard
module, which can be linked against an extension plugin. This module
provides the C++ API necessary for creating an input method.

[ChangeLog][Important Behavior Changes] Wrap the entire virtual
keyboard API into Qt namespace (e.g. QT_BEGIN_NAMESPACE/QT_END_NAMESPACE).

Task-number: QTBUG-57602
Change-Id: I449f4429109f596a7a1df7517c81f97d4aada27c
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 35 insertions, 282 deletions

diff --git a/src/virtualkeyboard/virtualkeyboard.pro b/src/virtualkeyboard/virtualkeyboard.pro
index 4990c44c..91497ee2 100644
--- a/src/virtualkeyboard/virtualkeyboard.pro
+++ b/src/virtualkeyboard/virtualkeyboard.pro
@@ -1,5 +1,6 @@
-TARGET  = qtvirtualkeyboardplugin
-DATAPATH = $$[QT_INSTALL_DATA]/qtvirtualkeyboard
+TARGET  = QtVirtualKeyboard
+MODULE = virtualkeyboard
+MODULE_PLUGIN_TYPES = virtualkeyboard
 
 QMAKE_DOCS = $$PWD/doc/qtvirtualkeyboard.qdocconf
 include(doc/doc.pri)
@@ -7,28 +8,23 @@ include(doc/doc.pri)
 QT += qml quick gui gui-private core-private
 CONFIG += qtquickcompiler
 
-win32 {
-    CONFIG += no-pkg-config
-    QMAKE_TARGET_PRODUCT = "Qt Virtual Keyboard (Qt $$QT_VERSION)"
-    QMAKE_TARGET_DESCRIPTION = "Virtual Keyboard for Qt."
-}
-
-!no-pkg-config: CONFIG += link_pkgconfig
+DEFINES += QVIRTUALKEYBOARD_LIBRARY
 
 include(../config.pri)
 
-SOURCES += platforminputcontext.cpp \
+SOURCES += \
+    platforminputcontext.cpp \
     inputcontext.cpp \
     abstractinputmethod.cpp \
     plaininputmethod.cpp \
     inputengine.cpp \
     shifthandler.cpp \
-    plugin.cpp \
     inputmethod.cpp \
     inputselectionhandle.cpp \
     selectionlistmodel.cpp \
-    defaultinputmethod.cpp \
+    fallbackinputmethod.cpp \
     abstractinputpanel.cpp \
+    appinputpanel.cpp \
     enterkeyaction.cpp \
     enterkeyactionattachedtype.cpp \
     settings.cpp \
@@ -37,30 +33,35 @@ SOURCES += platforminputcontext.cpp \
     desktopinputselectioncontrol.cpp \
     shadowinputcontext.cpp \
     gesturerecognizer.cpp \
-    handwritinggesturerecognizer.cpp
+    handwritinggesturerecognizer.cpp \
+    qvirtualkeyboardextensionplugin.cpp
 
-HEADERS += platforminputcontext.h \
+HEADERS += \
+    platforminputcontext_p.h \
     inputcontext.h \
     abstractinputmethod.h \
-    plaininputmethod.h \
+    plaininputmethod_p.h \
     inputengine.h \
-    shifthandler.h \
-    inputmethod.h \
-    inputselectionhandle.h \
+    shifthandler_p.h \
+    inputmethod_p.h \
+    inputselectionhandle_p.h \
     selectionlistmodel.h \
-    defaultinputmethod.h \
-    abstractinputpanel.h \
-    virtualkeyboarddebug.h \
-    enterkeyaction.h \
-    enterkeyactionattachedtype.h \
-    settings.h \
-    virtualkeyboardsettings.h \
-    plugin.h \
+    fallbackinputmethod_p.h \
+    abstractinputpanel_p.h \
+    appinputpanel_p.h \
+    appinputpanel_p_p.h \
+    virtualkeyboarddebug_p.h \
+    enterkeyaction_p.h \
+    enterkeyactionattachedtype_p.h \
+    settings_p.h \
+    virtualkeyboardsettings_p.h \
     trace.h \
-    desktopinputselectioncontrol.h \
-    shadowinputcontext.h \
-    gesturerecognizer.h \
-    handwritinggesturerecognizer.h
+    desktopinputselectioncontrol_p.h \
+    shadowinputcontext_p.h \
+    gesturerecognizer_p.h \
+    handwritinggesturerecognizer_p.h \
+    qvirtualkeyboard_global.h \
+    qvirtualkeyboardextensionplugin.h
 
 !no-builtin-style: RESOURCES += \
     content/styles/default/default_style.qrc \
@@ -78,8 +79,6 @@ contains(CONFIG, lang-en.*) {
     LAYOUT_FILES += \
         content/layouts/en_GB/main.qml \
         content/layouts/en_GB/symbols.qml
-t9write-alphabetic|lipi-toolkit: LAYOUT_FILES += \
-        content/layouts/en_GB/handwriting.qml
 }
 contains(CONFIG, lang-ar.*) {
     LAYOUT_FILES += \
@@ -87,57 +86,41 @@ contains(CONFIG, lang-ar.*) {
         content/layouts/ar_AR/main.qml \
         content/layouts/ar_AR/numbers.qml \
         content/layouts/ar_AR/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/ar_AR/handwriting.qml
 }
 contains(CONFIG, lang-bg.*) {
     LAYOUT_FILES += \
         content/layouts/bg_BG/main.qml \
         content/layouts/bg_BG/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/bg_BG/handwriting.qml
 }
 contains(CONFIG, lang-cs.*) {
     LAYOUT_FILES += \
         content/layouts/cs_CZ/main.qml \
         content/layouts/cs_CZ/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/cs_CZ/handwriting.qml
 }
 contains(CONFIG, lang-da.*) {
     LAYOUT_FILES += \
         content/layouts/da_DK/main.qml \
         content/layouts/da_DK/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/da_DK/handwriting.qml
 }
 contains(CONFIG, lang-de.*) {
     LAYOUT_FILES += \
         content/layouts/de_DE/main.qml \
         content/layouts/de_DE/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/de_DE/handwriting.qml
 }
 contains(CONFIG, lang-el.*) {
     LAYOUT_FILES += \
         content/layouts/el_GR/main.qml \
         content/layouts/el_GR/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/el_GR/handwriting.qml
 }
 contains(CONFIG, lang-es.*) {
     LAYOUT_FILES += \
         content/layouts/es_ES/main.qml \
         content/layouts/es_ES/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/es_ES/handwriting.qml
 }
 contains(CONFIG, lang-et.*) {
     LAYOUT_FILES += \
         content/layouts/et_EE/main.qml \
         content/layouts/et_EE/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/et_EE/handwriting.qml
 }
 contains(CONFIG, lang-fa.*) {
     LAYOUT_FILES += \
@@ -145,29 +128,21 @@ contains(CONFIG, lang-fa.*) {
         content/layouts/fa_FA/main.qml \
         content/layouts/fa_FA/numbers.qml \
         content/layouts/fa_FA/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/fa_FA/handwriting.qml
 }
 contains(CONFIG, lang-fi.*) {
     LAYOUT_FILES += \
         content/layouts/fi_FI/main.qml \
         content/layouts/fi_FI/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/fi_FI/handwriting.qml
 }
 contains(CONFIG, lang-fr.*) {
     LAYOUT_FILES += \
         content/layouts/fr_FR/main.qml \
         content/layouts/fr_FR/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/fr_FR/handwriting.qml
 }
 contains(CONFIG, lang-he.*) {
     LAYOUT_FILES += \
         content/layouts/he_IL/main.qml \
         content/layouts/he_IL/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/he_IL/handwriting.qml
 }
 contains(CONFIG, lang-hi.*) {
     LAYOUT_FILES += \
@@ -178,113 +153,61 @@ contains(CONFIG, lang-hr.*) {
     LAYOUT_FILES += \
         content/layouts/hr_HR/main.qml \
         content/layouts/hr_HR/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/hr_HR/handwriting.qml
 }
 contains(CONFIG, lang-hu.*) {
     LAYOUT_FILES += \
         content/layouts/hu_HU/main.qml \
         content/layouts/hu_HU/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/hu_HU/handwriting.qml
 }
 contains(CONFIG, lang-it.*) {
     LAYOUT_FILES += \
         content/layouts/it_IT/main.qml \
         content/layouts/it_IT/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/it_IT/handwriting.qml
-}
-contains(CONFIG, lang-ja.*) {
-    LAYOUT_FILES += \
-        content/layouts/ja_JP/main.qml \
-        content/layouts/ja_JP/symbols.qml
-t9write-cjk: LAYOUT_FILES += \
-        content/layouts/ja_JP/handwriting.qml
-}
-contains(CONFIG, lang-ko.*) {
-    LAYOUT_FILES += \
-        content/layouts/ko_KR/main.qml \
-        content/layouts/ko_KR/symbols.qml
-t9write-cjk: LAYOUT_FILES += \
-        content/layouts/ko_KR/handwriting.qml
 }
 contains(CONFIG, lang-nb.*) {
     LAYOUT_FILES += \
         content/layouts/nb_NO/main.qml \
         content/layouts/nb_NO/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/nb_NO/handwriting.qml
 }
 contains(CONFIG, lang-nl.*) {
     LAYOUT_FILES += \
         content/layouts/nl_NL/main.qml \
         content/layouts/nl_NL/symbols.qml
-t9write-alphabetic|lipi-toolkit: LAYOUT_FILES += \
-        content/layouts/nl_NL/handwriting.qml
 }
 contains(CONFIG, lang-pl.*) {
     LAYOUT_FILES += \
         content/layouts/pl_PL/main.qml \
         content/layouts/pl_PL/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/pl_PL/handwriting.qml
 }
 contains(CONFIG, lang-pt.*) {
     LAYOUT_FILES += \
         content/layouts/pt_PT/main.qml \
         content/layouts/pt_PT/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/pt_PT/handwriting.qml
 }
 contains(CONFIG, lang-ro.*) {
     LAYOUT_FILES += \
         content/layouts/ro_RO/main.qml \
         content/layouts/ro_RO/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/ro_RO/handwriting.qml
 }
 contains(CONFIG, lang-ru.*) {
     LAYOUT_FILES += \
         content/layouts/ru_RU/main.qml \
         content/layouts/ru_RU/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/ru_RU/handwriting.qml
 }
 contains(CONFIG, lang-sr.*) {
     LAYOUT_FILES += \
         content/layouts/sr_SP/main.qml \
         content/layouts/sr_SP/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/sr_SP/handwriting.qml
 }
 contains(CONFIG, lang-sv.*) {
     LAYOUT_FILES += \
         content/layouts/sv_SE/main.qml \
         content/layouts/sv_SE/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/sv_SE/handwriting.qml
 }
 contains(CONFIG, lang-vi.*) {
     LAYOUT_FILES += \
         content/layouts/vi_VN/main.qml \
         content/layouts/vi_VN/symbols.qml
-t9write-alphabetic: LAYOUT_FILES += \
-        content/layouts/vi_VN/handwriting.qml
-}
-contains(CONFIG, lang-zh(_CN)?) {
-    LAYOUT_FILES += \
-        content/layouts/zh_CN/main.qml \
-        content/layouts/zh_CN/symbols.qml
-t9write-cjk: LAYOUT_FILES += \
-        content/layouts/zh_CN/handwriting.qml
-}
-contains(CONFIG, lang-zh(_TW)?) {
-    LAYOUT_FILES += \
-        content/layouts/zh_TW/main.qml \
-        content/layouts/zh_TW/symbols.qml
-t9write-cjk: LAYOUT_FILES += \
-        content/layouts/zh_TW/handwriting.qml
 }
 
 no-builtin-style {
@@ -306,184 +229,17 @@ OTHER_FILES += \
 
 !disable-desktop:isEmpty(CROSS_COMPILE):!android-embedded:!qnx {
     SOURCES += desktopinputpanel.cpp inputview.cpp
-    HEADERS += desktopinputpanel.h inputview.h
+    HEADERS += desktopinputpanel_p.h inputview_p.h
     DEFINES += QT_VIRTUALKEYBOARD_DESKTOP
     !no-pkg-config:packagesExist(xcb) {
         PKGCONFIG += xcb xcb-xfixes
         DEFINES += QT_VIRTUALKEYBOARD_HAVE_XCB
     }
 }
-SOURCES += appinputpanel.cpp
-HEADERS += appinputpanel.h
-
-!disable-hunspell {
-    exists(3rdparty/hunspell/src/hunspell/hunspell.h) {
-        SOURCES += hunspellinputmethod.cpp hunspellinputmethod_p.cpp hunspellworker.cpp
-        HEADERS += hunspellinputmethod.h hunspellinputmethod_p.h hunspellworker.h
-        DEFINES += HAVE_HUNSPELL
-        QMAKE_USE += hunspell
-        exists(3rdparty/hunspell/data) {
-            hunspell_data.files = 3rdparty/hunspell/data/*.dic 3rdparty/hunspell/data/*.aff
-            hunspell_data.path = $$DATAPATH/hunspell
-            INSTALLS += hunspell_data
-            !prefix_build: COPIES += hunspell_data
-        } else {
-            error("Hunspell dictionaries are missing! Please copy .dic and .aff" \
-                  "files to src/virtualkeyboard/3rdparty/hunspell/data directory.")
-        }
-    } else:!no-pkg-config:packagesExist(hunspell) {
-        SOURCES += hunspellinputmethod.cpp hunspellinputmethod_p.cpp hunspellworker.cpp
-        HEADERS += hunspellinputmethod.h hunspellinputmethod_p.h hunspellworker.h
-        DEFINES += HAVE_HUNSPELL
-        PKGCONFIG += hunspell
-    } else {
-        message("Hunspell not found! Spell correction will not be available.")
-    }
-}
-
-pinyin {
-    SOURCES += \
-        pinyininputmethod.cpp \
-        pinyindecoderservice.cpp
-    HEADERS += \
-        pinyininputmethod.h \
-        pinyindecoderservice.h
-    DEFINES += HAVE_PINYIN
-    QMAKE_USE += pinyin
-    !no-bundle-pinyin {
-        PINYIN_FILES += 3rdparty/pinyin/data/dict_pinyin.dat
-        pinyin.files = $$PINYIN_FILES
-        pinyin.prefix = /QtQuick/VirtualKeyboard
-        RESOURCES += pinyin
-    } else {
-        pinyin_data.files = $$PWD/3rdparty/pinyin/data/dict_pinyin.dat
-        pinyin_data.path = $$DATAPATH/pinyin
-        INSTALLS += pinyin_data
-        !prefix_build: COPIES += pinyin_data
-    }
-}
-
-tcime {
-    SOURCES += \
-        tcinputmethod.cpp
-    HEADERS += \
-        tcinputmethod.h
-    DEFINES += HAVE_TCIME
-    cangjie: DEFINES += HAVE_TCIME_CANGJIE
-    zhuyin: DEFINES += HAVE_TCIME_ZHUYIN
-    QMAKE_USE += tcime
-    !no-bundle-tcime {
-        TCIME_FILES += 3rdparty/tcime/data/qt/dict_phrases.dat
-        cangjie: TCIME_FILES += \
-            3rdparty/tcime/data/qt/dict_cangjie.dat
-        zhuyin: TCIME_FILES += \
-            3rdparty/tcime/data/qt/dict_zhuyin.dat
-        tcime.files = $$TCIME_FILES
-        tcime.prefix = /QtQuick/VirtualKeyboard
-        RESOURCES += tcime
-    } else {
-        tcime_data.files = \
-            $$PWD/3rdparty/tcime/data/qt/dict_phrases.dat
-        cangjie: tcime_data.files += \
-            $$PWD/3rdparty/tcime/data/qt/dict_cangjie.dat
-        zhuyin: tcime_data.files += \
-            $$PWD/3rdparty/tcime/data/qt/dict_zhuyin.dat
-        tcime_data.path = $$DATAPATH/tcime
-        INSTALLS += tcime_data
-        !prefix_build: COPIES += tcime_data
-    }
-}
-
-hangul {
-    SOURCES += \
-        hangulinputmethod.cpp \
-        hangul.cpp
-    HEADERS += \
-        hangulinputmethod.h \
-        hangul.h
-    DEFINES += HAVE_HANGUL
-}
-
-openwnn {
-    SOURCES += openwnninputmethod.cpp
-    HEADERS += openwnninputmethod.h
-    DEFINES += HAVE_OPENWNN
-    QMAKE_USE += openwnn
-}
-
-lipi-toolkit:t9write: \
-    error("Conflicting configuration flags: lipi-toolkit and t9write." \
-          "Please use either one, but not both at the same time.")
-
-lipi-toolkit {
-    CONFIG += exceptions
-    SOURCES += \
-        lipiinputmethod.cpp \
-        lipisharedrecognizer.cpp \
-        lipiworker.cpp
-    HEADERS += \
-        lipiinputmethod.h \
-        lipisharedrecognizer.h \
-        lipiworker.h
-    DEFINES += HAVE_LIPI_TOOLKIT
-    INCLUDEPATH += \
-        3rdparty/lipi-toolkit/src/include \
-        3rdparty/lipi-toolkit/src/util/lib
-    LIBS += -L$$OUT_PWD/../../lib \
-        -lshaperecommon$$qtPlatformTargetSuffix() \
-        -lltkcommon$$qtPlatformTargetSuffix() \
-        -lltkutil$$qtPlatformTargetSuffix()
-    win32: LIBS += Advapi32.lib
-    else: QMAKE_USE += libdl
-    ltk_projects.files = $$PWD/3rdparty/lipi-toolkit/projects
-    ltk_projects.path = $$[QT_INSTALL_DATA]/qtvirtualkeyboard/lipi_toolkit
-    INSTALLS += ltk_projects
-    !prefix_build: COPIES += ltk_projects
-}
-
-t9write {
-    include(3rdparty/t9write/t9write-build.pri)
-    equals(T9WRITE_FOUND, 0): \
-        error("T9Write SDK could not be found. For more information, see" \
-              "the documentation in Building Qt Virtual Keyboard")
-    SOURCES += \
-        t9writeinputmethod.cpp \
-        t9writeworker.cpp \
-        t9writedictionary.cpp
-    HEADERS += \
-        t9writeinputmethod.h \
-        t9writeworker.h \
-        t9writedictionary.h \
-        t9write.h
-    DEFINES += HAVE_T9WRITE
-    QMAKE_USE += t9write_db
-    INCLUDEPATH += $$T9WRITE_INCLUDE_DIRS
-    t9write-alphabetic {
-        LIBS += $$T9WRITE_ALPHABETIC_LIBS
-        DEFINES += HAVE_T9WRITE_ALPHABETIC
-        !isEmpty(T9WRITE_ALPHABETIC_BINS) {
-            t9write_alphabetic_bins.files = $$T9WRITE_ALPHABETIC_BINS
-            t9write_alphabetic_bins.path = $$[QT_INSTALL_BINS]
-            INSTALLS += t9write_alphabetic_bins
-            !prefix_build: COPIES += t9write_alphabetic_bins
-        }
-    }
-    t9write-cjk {
-        LIBS += $$T9WRITE_CJK_LIBS
-        DEFINES += HAVE_T9WRITE_CJK
-        !isEmpty(T9WRITE_CJK_BINS) {
-            t9write_cjk_bins.files = $$T9WRITE_CJK_BINS
-            t9write_cjk_bins.path = $$[QT_INSTALL_BINS]
-            INSTALLS += t9write_cjk_bins
-            !prefix_build: COPIES += t9write_cjk_bins
-        }
-    }
-    DEFINES += QT_VIRTUALKEYBOARD_DEBUG
-}
 
 record-trace-input {
     SOURCES += unipentrace.cpp
-    HEADERS += unipentrace.h
+    HEADERS += unipentrace_p.h
     DEFINES += QT_VIRTUALKEYBOARD_RECORD_TRACE_INPUT
 }
 
@@ -491,12 +247,9 @@ arrow-key-navigation: DEFINES += QT_VIRTUALKEYBOARD_ARROW_KEY_NAVIGATION
 
 !disable-layouts {
     layouts.files = $$LAYOUT_FILES
-    layouts.prefix = /QtQuick/VirtualKeyboard
+    layouts.prefix = $$LAYOUTS_PREFIX
     RESOURCES += layouts
     DEFINES += HAVE_LAYOUTS
 }
 
-PLUGIN_TYPE = platforminputcontexts
-PLUGIN_EXTENDS = -
-PLUGIN_CLASS_NAME = QVirtualKeyboardPlugin
-load(qt_plugin)
+load(qt_module)