LibGUI: Share code for widget rendering styles in a GStyle class.

Since GScrollBar wants its internal buttons to look like GButtons,
let's share the painting code between them.

LibGUI/GButton.cpp

@@ -1,5 +1,6 @@
 #include "GButton.h"
 #include <SharedGraphics/Painter.h>
+#include <LibGUI/GStyle.h>
 
 //#define GBUTTON_DEBUG
 
@@ -23,37 +24,9 @@ void GButton::set_caption(String&& caption)
 
 void GButton::paint_event(GPaintEvent&)
 {
-    Color button_color = Color::LightGray;
-    Color highlight_color = Color::White;
-    Color shadow_color = Color(96, 96, 96);
-
     Painter painter(*this);
-    painter.draw_rect(rect(), Color::Black, true);
 
-    if (m_being_pressed) {
-        // Base
-        painter.fill_rect(rect().shrunken(2, 2), button_color);
-
-        // Sunken shadow
-        painter.draw_line({ 1, 1 }, { width() - 2, 1 }, shadow_color);
-        painter.draw_line({ 1, 2 }, {1, height() - 2 }, shadow_color);
-    } else {
-        // Base
-        painter.fill_rect({ 3, 3, width() - 5, height() - 5 }, button_color);
-        painter.fill_rect_with_gradient({ 3, 3, width() - 5, height() - 5 }, button_color, Color::White);
-
-        // White highlight
-        painter.draw_line({ 1, 1 }, { width() - 2, 1 }, highlight_color);
-        painter.draw_line({ 1, 2 }, { width() - 3, 2 }, highlight_color);
-        painter.draw_line({ 1, 3 }, { 1, height() - 2 }, highlight_color);
-        painter.draw_line({ 2, 3 }, { 2, height() - 3 }, highlight_color);
-
-        // Gray shadow 
-        painter.draw_line({ width() - 2, 1 }, { width() - 2, height() - 4 }, shadow_color);
-        painter.draw_line({ width() - 3, 2 }, { width() - 3, height() - 4 }, shadow_color);
-        painter.draw_line({ 1, height() - 2 }, { width() - 2, height() - 2 }, shadow_color);
-        painter.draw_line({ 2, height() - 3 }, { width() - 2, height() - 3 }, shadow_color);
-    }
+    GStyle::the().paint_button(painter, rect(), m_being_pressed);
 
     if (!caption().is_empty() || m_icon) {
         auto content_rect = rect();

LibGUI/GScrollBar.cpp

@@ -1,4 +1,5 @@
 #include <LibGUI/GScrollBar.h>
+#include <LibGUI/GStyle.h>
 #include <SharedGraphics/GraphicsBitmap.h>
 #include <SharedGraphics/Painter.h>
 
@@ -71,6 +72,11 @@ int GScrollBar::scrubbable_range_in_pixels() const
     return height() - button_size() * 3;
 }
 
+bool GScrollBar::has_scrubber() const
+{
+    return m_max != m_min;
+}
+
 Rect GScrollBar::scrubber_rect() const
 {
     int range_size = m_max - m_min;
@@ -122,16 +128,14 @@ void GScrollBar::paint_event(GPaintEvent&)
 
     painter.fill_rect(rect(), Color(164, 164, 164));
 
-    painter.draw_rect(up_button_rect(), Color::DarkGray, true);
-    painter.fill_rect_with_gradient(up_button_rect().shrunken(2, 2), Color::LightGray, Color::White);
+    GStyle::the().paint_button(painter, up_button_rect(), false);
     painter.draw_bitmap(up_button_rect().location().translated(3, 3), *s_up_arrow_bitmap, Color::Black);
 
-    painter.draw_rect(down_button_rect(), Color::DarkGray, true);
-    painter.fill_rect_with_gradient(down_button_rect().shrunken(2, 2), Color::LightGray, Color::White);
+    GStyle::the().paint_button(painter, down_button_rect(), false);
     painter.draw_bitmap(down_button_rect().location().translated(3, 3), *s_down_arrow_bitmap, Color::Black);
 
-    painter.draw_rect(scrubber_rect(), Color::White, true);
-    painter.fill_rect_with_gradient(scrubber_rect().shrunken(2, 2), Color::LightGray, Color::White);
+    if (has_scrubber())
+        GStyle::the().paint_button(painter, scrubber_rect(), m_scrubbing);
 }
 
 void GScrollBar::mousedown_event(GMouseEvent& event)
@@ -154,11 +158,12 @@ void GScrollBar::mousedown_event(GMouseEvent& event)
         set_value(value() + m_big_step);
         return;
     }
-    if (scrubber_rect().contains(event.position())) {
+    if (has_scrubber() && scrubber_rect().contains(event.position())) {
         m_scrubbing = true;
         m_scrub_start_value = value();
         m_scrub_origin = event.position();
         set_global_cursor_tracking(true);
+        update();
         return;
     }
 }
@@ -171,6 +176,7 @@ void GScrollBar::mouseup_event(GMouseEvent& event)
         return;
     m_scrubbing = false;
     set_global_cursor_tracking(false);
+    update();
 }
 
 void GScrollBar::mousemove_event(GMouseEvent& event)

LibGUI/GScrollBar.h

@@ -18,6 +18,7 @@ public:
     void set_value(int value);
     void set_step(int step) { m_step = step; }
     void set_big_step(int big_step) { m_big_step = big_step; }
+    bool has_scrubber() const;
 
     Function<void(int)> on_change;
 

LibGUI/GStyle.cpp

@@ -0,0 +1,52 @@
+#include <LibGUI/GStyle.h>
+#include <SharedGraphics/Painter.h>
+
+GStyle* s_the;
+
+GStyle& GStyle::the()
+{
+    if (!s_the)
+        s_the = new GStyle;
+    return *s_the;
+}
+
+GStyle::GStyle()
+{
+}
+
+void GStyle::paint_button(Painter& painter, const Rect& rect, bool pressed)
+{
+    Color button_color = Color::LightGray;
+    Color highlight_color = Color::White;
+    Color shadow_color = Color(96, 96, 96);
+    painter.draw_rect(rect, Color::Black, true);
+
+    painter.translate(rect.location());
+
+    if (pressed) {
+        // Base
+        painter.fill_rect({ 1, 1, rect.width() - 2, rect.height() - 2 }, button_color);
+
+        // Sunken shadow
+        painter.draw_line({ 1, 1 }, { rect.width() - 2, 1 }, shadow_color);
+        painter.draw_line({ 1, 2 }, {1, rect.height() - 2 }, shadow_color);
+    } else {
+        // Base
+        painter.fill_rect({ 3, 3, rect.width() - 5, rect.height() - 5 }, button_color);
+        painter.fill_rect_with_gradient({ 3, 3, rect.width() - 5, rect.height() - 5 }, button_color, Color::White);
+
+        // White highlight
+        painter.draw_line({ 1, 1 }, { rect.width() - 2, 1 }, highlight_color);
+        painter.draw_line({ 1, 2 }, { rect.width() - 3, 2 }, highlight_color);
+        painter.draw_line({ 1, 3 }, { 1, rect.height() - 2 }, highlight_color);
+        painter.draw_line({ 2, 3 }, { 2, rect.height() - 3 }, highlight_color);
+
+        // Gray shadow
+        painter.draw_line({ rect.width() - 2, 1 }, { rect.width() - 2, rect.height() - 4 }, shadow_color);
+        painter.draw_line({ rect.width() - 3, 2 }, { rect.width() - 3, rect.height() - 4 }, shadow_color);
+        painter.draw_line({ 1, rect.height() - 2 }, { rect.width() - 2, rect.height() - 2 }, shadow_color);
+        painter.draw_line({ 2, rect.height() - 3 }, { rect.width() - 2, rect.height() - 3 }, shadow_color);
+    }
+
+    painter.translate(-rect.location().x(), -rect.location().y());
+}

LibGUI/GStyle.h

@@ -0,0 +1,14 @@
+#pragma once
+
+class Painter;
+class Rect;
+
+class GStyle {
+public:
+    static GStyle& the();
+
+    void paint_button(Painter& painter, const Rect& rect, bool pressed);
+
+private:
+    GStyle();
+};

LibGUI/Makefile

@@ -16,6 +16,7 @@ LIBGUI_OBJS = \
     GTextBox.o \
     GScrollBar.o \
     GWidget.o \
+    GStyle.o \
     GWindow.o
 
 OBJS = $(SHAREDGRAPHICS_OBJS) $(LIBGUI_OBJS)

SharedGraphics/Painter.h

@@ -50,6 +50,7 @@ public:
     Rect clip_rect() const { return m_clip_rect; }
 
     void translate(int dx, int dy) { m_translation.move_by(dx, dy); }
+    void translate(const Point& delta) { m_translation.move_by(delta); }
 
 private:
     void set_pixel_with_draw_op(dword& pixel, const Color&);

SharedGraphics/Point.h

@@ -28,7 +28,7 @@ public:
         move_by(delta.x(), delta.y());
     }
 
-    Point translated(int dx, int dy)
+    Point translated(int dx, int dy) const
     {
         Point point = *this;
         point.move_by(dx, dy);

SharedGraphics/Rect.h

@@ -68,21 +68,21 @@ public:
         set_height(height() - h);
     }
 
-    Rect shrunken(int w, int h)
+    Rect shrunken(int w, int h) const
     {
         Rect rect = *this;
         rect.shrink(w, h);
         return rect;
     }
 
-    Rect inflated(int w, int h)
+    Rect inflated(int w, int h) const
     {
         Rect rect = *this;
         rect.inflate(w, h);
         return rect;
     }
 
-    Rect translated(int dx, int dy)
+    Rect translated(int dx, int dy) const
     {
         Rect rect = *this;
         rect.move_by(dx, dy);