terminal: Avoid doing too many redraws + support non-canonical mode

terminal/TerminalWidget.cpp

@@ -90,17 +90,23 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
 {
     // Avoid handling "key released" events
     if (!request.pressed) return ui::EventResult::DidNotHandle;
+
     // Non-printable key or key that has no special character (unlike Tab or Enter). We exit early to avoid inserting an
     // invalid zero byte into the terminal input (this would also happen on Shift or Ctrl keypresses).
     if (request.letter == '\0') return ui::EventResult::DidNotHandle;
 
+    return handle_input(request.letter);
+}
+
+Result<ui::EventResult> TerminalWidget::handle_input(char key)
+{
     query_termios();
 
     bool is_special_character { false };
 
-    if (/*is_canonical()*/ true)
+    if (is_canonical())
     {
-        if (request.letter == m_settings.c_cc[VERASE])
+        if (key == m_settings.c_cc[VERASE])
         {
             auto maybe_char = m_line_buffer.try_pop();
             if (maybe_char.has_value() && maybe_char.value())
@@ -114,17 +120,17 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
                         put_code_point(L'\b');
                         put_code_point(L'\b');
                     }
+                    return ui::EventResult::DidHandle;
                 }
-                ui::App::the().main_window()->draw();
+                return ui::EventResult::DidNotHandle;
-                return ui::EventResult::DidHandle;
             }
 
-            if ((m_settings.c_lflag & ECHOE)) return ui::EventResult::DidHandle;
+            if ((m_settings.c_lflag & ECHOE)) return ui::EventResult::DidNotHandle;
             else
                 is_special_character = true;
         }
 
-        if (request.letter == m_settings.c_cc[VEOF])
+        if (key == m_settings.c_cc[VEOF])
         {
             write(m_pty, m_line_buffer.data(), m_line_buffer.size());
             m_line_buffer.clear();
@@ -135,7 +141,7 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
 
         if (m_settings.c_lflag & ISIG)
         {
-            if (request.letter == m_settings.c_cc[VINTR])
+            if (key == m_settings.c_cc[VINTR])
             {
                 if (!(m_settings.c_lflag & NOFLSH)) m_line_buffer.clear();
 
@@ -145,7 +151,7 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
                 is_special_character = true;
             }
 
-            if (request.letter == m_settings.c_cc[VQUIT])
+            if (key == m_settings.c_cc[VQUIT])
             {
                 if (!(m_settings.c_lflag & NOFLSH)) m_line_buffer.clear();
 
@@ -159,48 +165,44 @@ Result<ui::EventResult> TerminalWidget::handle_key_event(const ui::KeyEventReque
 
     if (!is_special_character)
     {
-        if (/*is_canonical()*/ true)
+        if (is_canonical())
         {
-            m_line_buffer.try_append((u8)request.letter);
+            m_line_buffer.try_append((u8)key);
 
-            if (request.letter == '\n')
+            if (key == '\n')
             {
                 write(m_pty, m_line_buffer.data(), m_line_buffer.size());
                 m_line_buffer.clear();
             }
         }
         else
-            write(m_pty, &request.letter, 1);
+            write(m_pty, &key, 1);
     }
 
-    if (!(m_settings.c_lflag & ECHO)) return ui::EventResult::DidHandle;
+    if (!(m_settings.c_lflag & ECHO)) return ui::EventResult::DidNotHandle;
 
-    if (_iscntrl(request.letter))
+    if (_iscntrl(key))
     {
         if (m_settings.c_lflag & ECHOCTL)
         {
             bool should_echo = true;
-            if (request.letter == '\n' || request.letter == '\t' || request.letter == '\0' ||
+            if (key == '\n' || key == '\t' || key == '\0' || key == m_settings.c_cc[VEOF]) should_echo = false;
-                request.letter == m_settings.c_cc[VEOF])
-                should_echo = false;
 
             if (should_echo)
             {
                 char caret_notation[3] = { '^', '\0', '\0' };
-                if (request.letter == 0x7f) caret_notation[1] = '?';
+                if (key == 0x7f) caret_notation[1] = '?';
                 else
-                    caret_notation[1] = request.letter + 0x40;
+                    caret_notation[1] = key + 0x40;
 
                 for (int i = 0; i < 2; i++) { putchar(caret_notation[i]); }
             }
             else
-                putchar(request.letter);
+                putchar(key);
         }
     }
     else
-        putchar(request.letter);
+        putchar(key);
-
-    ui::App::the().main_window()->draw();
 
     return ui::EventResult::DidHandle;
 }
@@ -225,9 +227,15 @@ Result<bool> TerminalWidget::process()
 
     bool should_update_cursor = tick_cursor();
 
-    for (ssize_t i = 0; i < nread; i++) TRY(putchar(buffer[i]));
+    ssize_t drawn = 0;
 
-    if (should_update_cursor || nread > 0) ui::App::the().main_window()->draw();
+    for (ssize_t i = 0; i < nread; i++)
+    {
+        bool did_draw = TRY(putchar(buffer[i]));
+        if (did_draw) drawn++;
+    }
+
+    if (should_update_cursor || drawn > 0) ui::App::the().main_window()->draw();
 
     return nread == 0;
 }
@@ -260,6 +268,11 @@ void TerminalWidget::query_termios()
     tcgetattr(m_pty, &m_settings);
 }
 
+bool TerminalWidget::is_canonical()
+{
+    return m_settings.c_lflag & ICANON;
+}
+
 void TerminalWidget::draw_glyph(wchar_t c, int x, int y)
 {
     auto subcanvas = m_terminal_canvas.subcanvas({ x, y, m_font->width(), m_font->height() });
@@ -516,26 +529,28 @@ bool TerminalWidget::handle_escape_sequence(wchar_t c)
     return true;
 }
 
-Result<void> TerminalWidget::putchar(char c)
+Result<bool> TerminalWidget::putchar(char c)
 {
     auto guard = make_scope_guard([this] { m_decoder.reset(); });
 
     bool is_ready = TRY(m_decoder.feed(c));
 
-    if (is_ready) put_code_point(TRY(m_decoder.extract()));
+    bool result = false;
+
+    if (is_ready) result = put_code_point(TRY(m_decoder.extract()));
 
     guard.deactivate();
 
-    return {};
+    return result;
 }
 
-void TerminalWidget::put_code_point(wchar_t c)
+bool TerminalWidget::put_code_point(wchar_t c)
 {
     if (c > (wchar_t)255) c = (wchar_t)256;
 
     if (m_escape_parser.has_value())
     {
-        if (handle_escape_sequence(c)) return;
+        if (handle_escape_sequence(c)) return false;
     }
 
     // Erase the current cursor.
@@ -543,6 +558,8 @@ void TerminalWidget::put_code_point(wchar_t c)
 
     bool should_draw_cursor = m_cursor_enabled;
 
+    bool did_draw = false;
+
     switch (c)
     {
     case L'\n': {
@@ -552,6 +569,7 @@ void TerminalWidget::put_code_point(wchar_t c)
     }
     case L'\t': {
         for (int i = 0; i < 4; i++) { put_code_point(L' '); }
+        did_draw = true;
         break;
     }
     case L'\r': m_x_position = 0; break;
@@ -560,6 +578,7 @@ void TerminalWidget::put_code_point(wchar_t c)
         {
             prev_char();
             erase_current_char();
+            did_draw = true;
         }
         break;
     case L'\x1b':
@@ -568,9 +587,10 @@ void TerminalWidget::put_code_point(wchar_t c)
     case L'\x9d':
         m_escape_parser = EscapeSequenceParser { (u8)c };
         should_draw_cursor = false;
+        did_draw = true;
         break;
     default: {
-        if (iscntrl(c)) return;
+        if (iscntrl(c)) return false;
         draw_glyph(c, m_x_position, m_y_position);
         next_char();
         if (at_end_of_screen())
@@ -588,6 +608,8 @@ void TerminalWidget::put_code_point(wchar_t c)
         m_cursor_activated = true;
         draw_cursor();
     }
+
+    return did_draw;
 }
 
 void TerminalWidget::quit()

terminal/TerminalWidget.h

@@ -54,6 +54,9 @@ class TerminalWidget : public ui::Widget
     Utf8StateDecoder m_decoder;
     Option<EscapeSequenceParser> m_escape_parser;
 
+    Result<ui::EventResult> handle_input(char key);
+
+    bool is_canonical();
     void draw_glyph(wchar_t c, int x, int y);
     void erase_current_line();
     void scroll();
@@ -65,6 +68,6 @@ class TerminalWidget : public ui::Widget
     void draw_cursor();
     bool at_end_of_screen();
     bool handle_escape_sequence(wchar_t c);
-    Result<void> putchar(char c);
+    Result<bool> putchar(char c);
-    void put_code_point(wchar_t c);
+    bool put_code_point(wchar_t c);
 };