Support editing utf-8 text in TextBox

aka "Flüxbøx"

βµγ, pardon,
BUG: 720

src/FbTk/App.cc

@@ -45,6 +45,9 @@ App::App(const char *displayname):m_done(false), m_display(0) {
     if (s_app != 0)
         throw std::string("Can't create more than one instance of FbTk::App");
     s_app = this;
+    // with recent versions of X11 one needs to specify XSetLocaleModifiers,
+    // otherwise no extra events won't be generated.
+    const bool setmodifiers = XSetLocaleModifiers("@im=none");
     // this allows the use of std::string.c_str(), which returns 
     // a blank string, rather than a null string, so we make them equivalent
     if (displayname != 0 && displayname[0] == '\0')
@@ -59,6 +62,11 @@ App::App(const char *displayname):m_done(false), m_display(0) {
     }
 
     FbStringUtil::init();
+
+    m_xim = 0;
+    if (setmodifiers && FbStringUtil::haveUTF8()) {
+        m_xim = XOpenIM(m_display, NULL, NULL, NULL);
+    }
 }
 
 App::~App() {

src/FbTk/App.hh

@@ -53,6 +53,7 @@ public:
     /// forces an end to event loop
     void end();
     bool done() const { return m_done; }
+    const XIM &inputModule() const { return m_xim; }
 
     // the setenv()-routine is not everywhere available and
     // putenv() doesnt manage the strings in the environment
@@ -62,6 +63,7 @@ private:
     static App *s_app;
     bool m_done;
     Display *m_display;
+    XIM m_xim;
 };
 
 } // end namespace FbTk

src/FbTk/EventManager.cc

@@ -161,7 +161,8 @@ void EventManager::dispatch(Window win, XEvent &ev, bool parent) {
 
     switch (ev.type) {
     case KeyPress:
-        evhand->keyPressEvent(ev.xkey);
+        if (!XFilterEvent(&ev, win))
+            evhand->keyPressEvent(ev.xkey);
     break;
     case KeyRelease:
         evhand->keyReleaseEvent(ev.xkey);

src/FbTk/TextBox.cc

@@ -43,18 +43,22 @@
 #include <X11/keysym.h>
 #include <X11/Xutil.h>
 
+#include <iostream>
+
 namespace FbTk {
 
+
 TextBox::TextBox(int screen_num,
                  const Font &font, const std::string &text):
-    FbWindow(screen_num, 0, 0, 1, 1, ExposureMask | KeyPressMask | ButtonPressMask),
+    FbWindow(screen_num, 0, 0, 1, 1, ExposureMask | KeyPressMask | ButtonPressMask | FocusChangeMask | KeymapStateMask),
     m_font(&font),
     m_text(text),
     m_gc(0),
     m_cursor_pos(0),
     m_start_pos(0),
     m_end_pos(0),
-    m_select_pos(std::string::npos) {
+    m_select_pos(std::string::npos),
+    m_xic(0) {
 
     FbTk::EventManager::instance()->add(*this, *this);
 }
@@ -68,7 +72,8 @@ TextBox::TextBox(const FbWindow &parent,
     m_cursor_pos(0),
     m_start_pos(0),
     m_end_pos(0),
-    m_select_pos(std::string::npos) {
+    m_select_pos(std::string::npos),
+    m_xic(0) {
 
     FbTk::EventManager::instance()->add(*this, *this);
 }
@@ -111,36 +116,43 @@ void TextBox::cursorEnd() {
 }
 
 void TextBox::cursorForward() {
-    if (m_start_pos + cursorPosition() < m_end_pos)
-        m_cursor_pos++;
+    StringRange r = charRange(m_start_pos + cursorPosition());
+    const std::string::size_type s = r.end - r.begin + 1;
+    if (r.end < m_end_pos)
+        m_cursor_pos = r.end + 1 - m_start_pos;
     else if (m_end_pos < text().size()) {
-        m_cursor_pos++;
-        m_end_pos++;
+        m_cursor_pos = r.end + 1 - m_start_pos;
+        m_end_pos += s;
         adjustStartPos();
     }
 }
 
 void TextBox::cursorBackward() {
-    if (cursorPosition())
-        m_cursor_pos--;
-    else if (m_start_pos) {
-        m_start_pos--;
-        adjustEndPos();
+    if (m_start_pos || cursorPosition()) {
+        StringRange r = charRange(m_start_pos + cursorPosition() - 1);
+        const std::string::size_type s = r.end - r.begin + 1;
+        if (cursorPosition())
+            m_cursor_pos = r.begin - m_start_pos;
+        else if (m_start_pos) {
+            m_start_pos -= s;
+            adjustEndPos();
+        }
     }
 }
 
 void TextBox::backspace() {
     if (hasSelection())
         return deleteForward();
-
     if (m_start_pos || cursorPosition()) {
         FbString t = text();
-        t.erase(m_start_pos + cursorPosition() - 1, 1);
+        StringRange r = charRange(m_start_pos + cursorPosition() - 1);
+        const std::string::size_type s = r.end - r.begin + 1;
+        t.erase(r.begin, s);
         m_text.setLogical(t);
         if (cursorPosition())
-            setCursorPosition(cursorPosition() - 1);
+            setCursorPosition(r.begin - m_start_pos);
         else
-            m_start_pos--;
+            m_start_pos -= s;
         adjustEndPos();
     }
 }
@@ -148,10 +160,15 @@ void TextBox::backspace() {
 void TextBox::deleteForward() {
     std::string::size_type pos = m_start_pos + m_cursor_pos;
     int length = 1;
-    if (hasSelection()) {
+    bool selected = false;
+    if (selected = hasSelection()) {
         pos = std::min(m_start_pos + m_cursor_pos, m_select_pos);
         length = std::max(m_start_pos + m_cursor_pos, m_select_pos) - pos;
         m_cursor_pos = pos - m_start_pos;
+    } else {
+        StringRange r = charRange(pos);
+        pos = r.begin;
+        length = r.end - r.begin + 1;
     }
     if (pos < m_end_pos) {
         FbString t = text();
@@ -159,7 +176,7 @@ void TextBox::deleteForward() {
         m_text.setLogical(t);
         adjustEndPos();
     }
-    if (length > 1)
+    if (selected && length > 1)
         adjustStartPos();
 }
 
@@ -168,7 +185,8 @@ void TextBox::insertText(const std::string &val) {
         deleteForward();
 
     FbString t = text();
-    t.insert(m_start_pos + cursorPosition(), val);
+    std::string::size_type pos = m_start_pos + m_cursor_pos;
+    t.insert(pos ? charRange(pos - 1).end + 1 : pos, val);
     m_text.setLogical(t);
     m_cursor_pos += val.size();
     m_end_pos += val.size();
@@ -267,12 +285,17 @@ void TextBox::buttonPressEvent(XButtonEvent &event) {
 }
 
 void TextBox::keyPressEvent(XKeyEvent &event) {
-    
+
     event.state = KeyUtil::instance().cleanMods(event.state);
 
     KeySym ks;
-    char keychar[1];
-    XLookupString(&event, keychar, 1, &ks, 0);
+    char keychar[20];
+    int count = 1;
+    if (m_xic)
+        count = Xutf8LookupString(m_xic, &event, keychar, 20, &ks, 0);
+    else
+        XLookupString(&event, keychar, 1, &ks, 0);
+
     // a modifier key by itself doesn't do anything
     if (IsModifierKey(ks)) return;
 
@@ -401,6 +424,17 @@ void TextBox::keyPressEvent(XKeyEvent &event) {
             break;
         }
     }
+    if (count > 1 && count < 20) {
+        wchar_t wc;
+        count = mbrtowc(&wc, keychar, count, 0);
+        if (count > 0 && iswprint(wc)) {
+            keychar[count] = '\0';
+            std::string val;
+            val += (char*)keychar;
+            insertText(val);
+            m_select_pos = std::string::npos;
+        }
+    }
     if (isprint(keychar[0])) {
         std::string val;
         val += keychar[0];
@@ -412,6 +446,23 @@ void TextBox::keyPressEvent(XKeyEvent &event) {
     clear();
 }
 
+void TextBox::handleEvent(XEvent &event) {
+    if (event.type == KeymapNotify) {
+        XRefreshKeyboardMapping(&event.xmapping);
+    } else if (event.type == FocusIn) {
+        if (!m_xic && App::instance()->inputModule())
+            m_xic = XCreateIC(App::instance()->inputModule(), XNInputStyle, XIMPreeditNothing | XIMStatusNothing, XNClientWindow, window(), NULL);
+        if (m_xic)
+            XSetICFocus(m_xic);
+    } else if (event.type == FocusIn) {
+        if (m_xic) {
+            XUnsetICFocus(m_xic);
+            XFree(m_xic);
+            m_xic = 0;
+        }
+    }
+}
+
 void TextBox::setCursorPosition(int pos) {
     m_cursor_pos = pos < 0 ? 0 : pos;
     if (m_cursor_pos > text().size())
@@ -527,4 +578,27 @@ void TextBox::selectAll() {
     select(0, m_text.visual().size());
 }
 
+TextBox::StringRange TextBox::charRange(std::string::size_type pos) const {
+    auto isUtf8Head = [](char c) {
+        const char indicator = (1<<7)|(1<<6); // first byte starts 11, following 10
+        return (c & indicator) == indicator;
+    };
+
+    StringRange range = {pos, pos};
+    FbString t = text();
+
+    if (pos < 0 || pos >= t.size() || t.at(pos) > 0) // invalid pos or ASCII
+        return range;
+
+    while (range.begin > 0 && t.at(range.begin) < 0 && !isUtf8Head(t.at(range.begin)))
+        --range.begin;
+
+    if (isUtf8Head(t.at(range.end))) // if pos is a utf-8 head, move into the range
+        ++range.end;
+    while (range.end < t.size() - 1 && t.at(range.end + 1) < 0 && !isUtf8Head(t.at(range.end + 1)))
+        ++range.end;
+
+    return range;
+}
+
 } // end namespace FbTk

src/FbTk/TextBox.hh

@@ -58,6 +58,7 @@ public:
     void exposeEvent(XExposeEvent &event);
     void buttonPressEvent(XButtonEvent &event);
     void keyPressEvent(XKeyEvent &event);
+    void handleEvent(XEvent &event);
 
     const FbString &text() const { return m_text.logical(); }
     const Font &font() const { return *m_font; }
@@ -79,10 +80,14 @@ private:
 
     void adjustPos();
 
+    typedef struct { std::string::size_type begin, end; } StringRange;
+    StringRange charRange(std::string::size_type pos) const;
+
     const FbTk::Font *m_font;
     BiDiString m_text;
     GC m_gc;
     std::string::size_type m_cursor_pos, m_start_pos, m_end_pos, m_select_pos;
+    XIC m_xic;
 };
 
 } // end namespace FbTk