More window management work.

- Fix inverted mouse event hit test z-ordering.
- Let the RootWidget backing store simply be the display framebuffer.

Widgets/GraphicsBitmap.cpp

@@ -6,15 +6,30 @@ RetainPtr<GraphicsBitmap> GraphicsBitmap::create(const Size& size)
     return adopt(*new GraphicsBitmap(size));
 }
 
+RetainPtr<GraphicsBitmap> GraphicsBitmap::create_wrapper(const Size& size, byte* data)
+{
+    return adopt(*new GraphicsBitmap(size, data));
+}
+
 GraphicsBitmap::GraphicsBitmap(const Size& size)
     : m_size(size)
 {
     m_data = (byte*)kmalloc(size.width() * size.height() * 4);
+    m_owned = true;
+}
+
+GraphicsBitmap::GraphicsBitmap(const Size& size, byte* data)
+    : m_size(size)
+{
+    m_data = data;
+    m_owned = false;
 }
 
 GraphicsBitmap::~GraphicsBitmap()
 {
-    kfree(m_data);
+    if (m_owned)
+        kfree(m_data);
+    m_data = nullptr;
 }
 
 dword* GraphicsBitmap::scanline(int y)

Widgets/GraphicsBitmap.h

@@ -7,6 +7,7 @@
 class GraphicsBitmap : public Retainable<GraphicsBitmap> {
 public:
     static RetainPtr<GraphicsBitmap> create(const Size&);
+    static RetainPtr<GraphicsBitmap> create_wrapper(const Size&, byte*);
     ~GraphicsBitmap();
 
     dword* scanline(int y);
@@ -17,7 +18,9 @@ public:
 
 private:
     explicit GraphicsBitmap(const Size&);
+    GraphicsBitmap(const Size&, byte*);
 
     Size m_size;
     byte* m_data { nullptr };
+    bool m_owned { false };
 };

Widgets/RootWidget.cpp

@@ -3,11 +3,12 @@
 #include "RootWidget.h"
 #include "Painter.h"
 #include "WindowManager.h"
+#include "FrameBufferSDL.h"
 #include <cstdio>
 
 RootWidget::RootWidget()
 {
-    m_backing = GraphicsBitmap::create(AbstractScreen::the().size());
+    m_backing = GraphicsBitmap::create_wrapper(FrameBufferSDL::the().size(), (byte*)FrameBufferSDL::the().scanline(0));
 }
 
 RootWidget::~RootWidget()

Widgets/WindowManager.cpp

@@ -58,12 +58,6 @@ WindowManager::~WindowManager()
 {
 }
 
-void WindowManager::paintWindowFrames()
-{
-    for (auto* window = m_windows_in_order.head(); window; window = window->next())
-        paintWindowFrame(*window);
-}
-
 void WindowManager::paintWindowFrame(Window& window)
 {
     Painter p(*m_rootWidget);
@@ -139,15 +133,17 @@ void WindowManager::repaint()
     handlePaintEvent(*make<PaintEvent>());
 }
 
-void WindowManager::did_paint(Window&)
+void WindowManager::did_paint(Window& window)
 {
     auto& framebuffer = FrameBufferSDL::the();
-    framebuffer.blit({ 0, 0 }, *m_rootWidget->backing());
+    if (m_windows_in_order.head() == &window) {
-    for (auto* window = m_windows_in_order.head(); window; window = window->next()) {
+        ASSERT(window.backing());
-        ASSERT(window->backing());
+        framebuffer.blit(window.position(), *window.backing());
-        framebuffer.blit(window->position(), *window->backing());
+        return;
     }
-    framebuffer.flush();
+
+    // FIXME: Check if anything overlaps this window, otherwise just blit.
+    recompose();
 }
 
 void WindowManager::removeWindow(Window& window)
@@ -237,11 +233,12 @@ void WindowManager::processMouseEvent(MouseEvent& event)
             pos.moveBy(event.x() - m_dragOrigin.x(), event.y() - m_dragOrigin.y());
             m_dragWindow->setPositionWithoutRepaint(pos);
             paintWindowFrame(*m_dragWindow);
+            FrameBufferSDL::the().flush();
             return;
         }
     }
 
-    for (auto* window = m_windows_in_order.head(); window; window = window->next()) {
+    for (auto* window = m_windows_in_order.tail(); window; window = window->prev()) {
         if (titleBarRectForWindow(*window).contains(event.position())) {
             if (event.type() == Event::MouseDown) {
                 move_to_front(*window);
@@ -273,14 +270,21 @@ void WindowManager::handlePaintEvent(PaintEvent& event)
     }
 
     m_rootWidget->event(event);
-    paintWindowFrames();
 
     for (auto* window = m_windows_in_order.head(); window; window = window->next())
         window->event(event);
 
+    recompose();
+}
+
+void WindowManager::recompose()
+{
     auto& framebuffer = FrameBufferSDL::the();
-    framebuffer.blit({ 0, 0 }, *m_rootWidget->backing());
+    m_rootWidget->repaint(m_rootWidget->rect());
     for (auto* window = m_windows_in_order.head(); window; window = window->next()) {
+        paintWindowFrame(*window);
+        if (m_dragWindow.ptr() == window)
+            continue;
         ASSERT(window->backing());
         framebuffer.blit(window->position(), *window->backing());
     }

Widgets/WindowManager.h

@@ -17,7 +17,6 @@ public:
     static WindowManager& the(); 
     void addWindow(Window&);
     void removeWindow(Window&);
-    void paintWindowFrames();
 
     void notifyTitleChanged(Window&);
     void notifyRectChanged(Window&, const Rect& oldRect, const Rect& newRect);
@@ -52,6 +51,7 @@ private:
     Color m_inactiveWindowBorderColor;
     Color m_inactiveWindowTitleColor;
 
+    void recompose();
     void paintWindowFrame(Window&);
     HashTable<Window*> m_windows;
     InlineLinkedList<Window> m_windows_in_order;