Add a visual bell to TerminalWidget. Also backspace.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/fb4ae12bc24

Widgets/Color.h

@@ -4,7 +4,16 @@
 
 class Color {
 public:
+    enum NamedColor {
+        Black,
+        White,
+        Red,
+        Green,
+        Blue,
+    };
+
     Color() { }
+    Color(NamedColor);
     Color(byte r, byte g, byte b);
 
     dword value() const { return m_value; }

Widgets/ColorSDL.cpp

@@ -5,3 +5,24 @@ Color::Color(byte r, byte g, byte b)
 {
     m_value = SDL_MapRGB(FrameBufferSDL::the().surface()->format, r, g, b);
 }
+
+Color::Color(NamedColor named)
+{
+    struct {
+        byte r;
+        byte g;
+        byte b;
+    } rgb;
+
+    switch (named) {
+    case Black: rgb = { 0, 0, 0 }; break;
+    case White: rgb = { 255, 255, 255 }; break;
+    case Red: rgb = { 255, 0, 0}; break;
+    case Green: rgb = { 0, 255, 0}; break;
+    case Blue: rgb = { 0, 0, 255}; break;
+    default: ASSERT_NOT_REACHED(); break;
+    }
+
+    m_value = SDL_MapRGB(FrameBufferSDL::the().surface()->format, rgb.r, rgb.g, rgb.g);
+
+}

Widgets/TerminalWidget.cpp

@@ -63,7 +63,7 @@ CharacterWithAttributes& TerminalWidget::at(unsigned row, unsigned column)
 void TerminalWidget::onPaint(PaintEvent&)
 {
     Painter painter(*this);
-    painter.fillRect({ 0, 0, width(), height() }, Color(0, 0, 0));
+    painter.fillRect(rect(), Color(0, 0, 0));
 
     auto& font = Font::defaultFont();
 
@@ -76,6 +76,9 @@ void TerminalWidget::onPaint(PaintEvent&)
             painter.drawText({ x + 2, y + 2, width(), font.glyphHeight() }, buf, Painter::TextAlignment::TopLeft, Color(0xa0, 0xa0, 0xa0));
         }
     }
+
+    if (m_belling)
+        painter.drawRect(rect(), Color::Red);
 }
 
 void TerminalWidget::onReceive(const ByteBuffer& buffer)
@@ -105,20 +108,35 @@ void TerminalWidget::onReceive(byte ch)
         }
     };
 
-    if (ch == '\n') {
-        if (m_cursorRow < (m_rows - 1)) {
-            ++m_cursorRow;
-        } else {
-            scrollScreen();
+    switch (ch) {
+        case '\n':
+            if (m_cursorRow < (m_rows - 1)) {
+                ++m_cursorRow;
+            } else {
+                scrollScreen();
+            }
+            break;
+        case '\r':
+            m_cursorColumn = 0;
+            break;
+        case '\t':
+            // FIXME: Respect terminal tab stops.
+            while ((m_cursorColumn % 8) != 0 && m_cursorColumn < m_columns) {
+                addChar(' ');
+            break;
+        case '\a':
+            bell();
+            break;
+        case 8:
+            if (m_cursorColumn > 0) {
+                --m_cursorColumn;
+                at(m_cursorRow, m_cursorColumn).character = ' ';
+            }
+            break;
+        default:
+            addChar(ch);
+            break;
         }
-    } else if (ch == '\r') {
-        m_cursorColumn = 0;
-    } else if (ch == '\t') {
-        while ((m_cursorColumn % 8) != 0 && m_cursorColumn < m_columns) {
-            addChar(' ');
-        }
-    } else {
-        addChar(ch);
     }
     update();
 }
@@ -136,3 +154,18 @@ void TerminalWidget::onKeyUp(KeyEvent& event)
     return Widget::onKeyUp(event);
 }
 
+void TerminalWidget::bell()
+{
+    if (m_belling)
+        stopTimer();
+    startTimer(250);
+    m_belling = true;
+    update();
+}
+
+void TerminalWidget::onTimer(TimerEvent&)
+{
+    m_belling = false;
+    stopTimer();
+    update();
+}

Widgets/TerminalWidget.h

@@ -25,6 +25,9 @@ private:
     virtual void onPaint(PaintEvent&) override;
     virtual void onKeyDown(KeyEvent&) override;
     virtual void onKeyUp(KeyEvent&) override;
+    virtual void onTimer(TimerEvent&) override;
+
+    void bell();
 
     unsigned m_columns { 80 };
     unsigned m_rows { 25 };
@@ -33,4 +36,6 @@ private:
     unsigned m_cursorColumn { 0 };
 
     CharacterWithAttributes* m_screen { nullptr };
+
+    bool m_belling { false };
 };