Paint Button in a very Windows 3-ish style.

Widgets/Button.cpp

@@ -21,8 +21,36 @@ void Button::setCaption(String&& caption)
 
 void Button::onPaint(PaintEvent&)
 {
+    Color buttonColor(192, 192, 192);
+    Color shadowColor(96, 96, 96);
+
     Painter painter(*this);
-    painter.fillRect(rect(), backgroundColor());
+    painter.fillRect(rect(), Color(255, 0, 255));
+
+    painter.drawPixel({ 0, 0 }, backgroundColor());
+    painter.drawPixel({ width() - 1, 0 }, backgroundColor());
+    painter.drawPixel({ 0, height() - 1 }, backgroundColor());
+    painter.drawPixel({ width() - 1, height() - 1 }, backgroundColor());
+
+    painter.drawLine({ 1, 0 }, { width() - 2, 0 }, Color(0, 0, 0));
+    painter.drawLine({ 1, height() - 1 }, { width() - 2, height() - 1}, Color(0, 0, 0));
+    painter.drawLine({ 0, 1 }, { 0, height() - 2 }, Color(0, 0, 0));
+    painter.drawLine({ width() - 1, 1 }, { width() - 1, height() - 2 }, Color(0, 0, 0));
+
+    // White highlight
+    painter.drawLine({ 1, 1 }, { width() - 2, 1 }, Color(255, 255, 255));
+    painter.drawLine({ 1, 2 }, { width() - 3, 2 }, Color(255, 255, 255));
+    painter.drawLine({ 1, 3 }, { 1, height() - 2 }, Color(255, 255, 255));
+    painter.drawLine({ 2, 3 }, { 2, height() - 3 }, Color(255, 255, 255));
+
+    // Gray shadow 
+    painter.drawLine({ width() - 2, 1 }, { width() - 2, height() - 4 }, shadowColor);
+    painter.drawLine({ width() - 3, 2 }, { width() - 3, height() - 4 }, shadowColor);
+    painter.drawLine({ 1, height() - 2 }, { width() - 2, height() - 2 }, shadowColor);
+    painter.drawLine({ 2, height() - 3 }, { width() - 2, height() - 3 }, shadowColor);
+
+    painter.fillRect({ 3, 3, width() - 6, height() - 6 }, buttonColor);
+
     if (!caption().isEmpty()) {
         painter.drawText(rect(), caption(), Painter::TextAlignment::Center, Color(0, 0, 0));
     }

Widgets/Painter.cpp

@@ -125,3 +125,56 @@ void Painter::drawText(const Rect& rect, const String& text, TextAlignment align
     }
 }
 
+void Painter::drawPixel(const Point& p, Color color)
+{
+    auto point = p;
+    point.moveBy(m_translation);
+    scanline(point.y())[point.x()] = color.value();
+}
+
+void Painter::drawLine(const Point& p1, const Point& p2, Color color)
+{
+    auto point1 = p1;
+    point1.moveBy(m_translation);
+
+    auto point2 = p2;
+    point2.moveBy(m_translation);
+
+    // Special case: vertical line.
+    if (point1.x() == point2.x()) {
+        if (point1.y() > point2.y())
+            std::swap(point1, point2);
+        for (int y = point1.y(); y <= point2.y(); ++y)
+            scanline(y)[point1.x()] = color.value();
+        return;
+    }
+
+    if (point1.x() > point2.x())
+        std::swap(point1, point2);
+
+    // Special case: horizontal line.
+    if (point1.y() == point2.y()) {
+        if (point1.y() > point2.y())
+            std::swap(point1, point2);
+        auto* pixels = scanline(point1.y());
+        for (int x = point1.x(); x <= point2.x(); ++x)
+            pixels[x] = color.value();
+        return;
+    }
+
+    const double dx = point2.x() - point1.x();
+    const double dy = point2.y() - point1.y();
+    const double deltaError = fabs(dy / dx);
+    double error = 0;
+    const double yStep = dy == 0 ? 0 : (dy > 0 ? 1 : -1);
+
+    int y = point1.y();
+    for (int x = point1.x(); x <= point2.x(); ++x) {
+        scanline(y)[x] = color.value();
+        error += deltaError;
+        if (error >= 0.5) {
+            y = (double)y + yStep;
+            error -= 1.0;
+        }
+    }
+}

Widgets/Painter.h

@@ -19,6 +19,8 @@ public:
     void drawRect(const Rect&, Color);
     void drawText(const Rect&, const String&, TextAlignment = TextAlignment::TopLeft, Color = Color());
     void drawBitmap(const Point&, const CBitmap&, Color = Color());
+    void drawPixel(const Point&, Color);
+    void drawLine(const Point& p1, const Point& p2, Color);
 
     void xorRect(const Rect&, Color);