UI|Client|Oculus Rift: Draw a custom mouse cursor in Oculus Rift mode

The cursor is simply a LabelWidget that shows the old mouse cursor
image. It is moved to the coordinates of the real mouse cursor.

doomsday/client/data/defaultstyle.pack/images.dei

@@ -4,6 +4,7 @@ group window {
     image background { path = "graphics/background.jpg" }
     image borderglow { path = "graphics/borderglow.png" }
     image icon       { path = "graphics/window.png" }
+    image cursor     { path = "graphics/mouse.png" }
 }
 
 group logo {

doomsday/client/include/ui/windowsystem.h

@@ -25,6 +25,7 @@
 
 #include <de/System>
 #include <de/String>
+#include <de/Vector>
 #include "SettingsRegister"
 
 class ClientWindow;
@@ -105,6 +106,8 @@ class WindowSystem : public de::System
      */
     void dispatchLatestMousePosition();
 
+    de::Vector2i latestMousePosition() const;
+
     // System.
     bool processEvent(de::Event const &);
     void timeChanged(de::Clock const &);

doomsday/client/src/ui/clientwindow.cpp

@@ -28,6 +28,7 @@
 #include "clientapp.h"
 #include <de/DisplayMode>
 #include <de/NumberValue>
+#include <de/ConstantRule>
 #include <QGLFormat>
 #include <de/GLState>
 #include <de/GLFramebuffer>
@@ -82,6 +83,10 @@ DENG2_OBSERVES(App,              StartupComplete)
     GameSelectionWidget *gameSelMenu;
     BusyWidget *busy;
     GuiWidget *sidebar;
+    LabelWidget *cursor;
+    ConstantRule *cursorX;
+    ConstantRule *cursorY;
+    bool cursorHasBeenHidden;
 
     // FPS notifications.
     LabelWidget *fpsCounter;
@@ -91,24 +96,28 @@ DENG2_OBSERVES(App,              StartupComplete)
     VRWindowTransform contentXf;
 
     Instance(Public *i)
-        : Base(i),
-          needMainInit(true),
-          needRecreateCanvas(false),
-          needRootSizeUpdate(false),
-          mode(Normal),
-          root(thisPublic),
-          compositor(0),
-          game(0),
-          gameUI(0),
-          taskBar(0),
-          notifications(0),
-          colorAdjust(0),
-          background(0),
-          gameSelMenu(0),
-          sidebar(0),
-          fpsCounter(0),
-          oldFps(0),
-          contentXf(*i)
+        : Base(i)
+        , needMainInit(true)
+        , needRecreateCanvas(false)
+        , needRootSizeUpdate(false)
+        , mode(Normal)
+        , root(thisPublic)
+        , compositor(0)
+        , game(0)
+        , gameUI(0)
+        , taskBar(0)
+        , notifications(0)
+        , colorAdjust(0)
+        , background(0)
+        , gameSelMenu(0)
+        , sidebar(0)
+        , cursor(0)
+        , cursorX(new ConstantRule(0))
+        , cursorY(new ConstantRule(0))
+        , cursorHasBeenHidden(false)
+        , fpsCounter(0)
+        , oldFps(0)
+        , contentXf(*i)
     {
         /// @todo The decision whether to receive input notifications from the
         /// canvas is really a concern for the input drivers.
@@ -130,6 +139,9 @@ DENG2_OBSERVES(App,              StartupComplete)
         self.canvas().audienceForFocusChange -= this;
         self.canvas().audienceForMouseStateChange -= this;
         self.canvas().audienceForKeyEvent -= this;
+
+        releaseRef(cursorX);
+        releaseRef(cursorY);
     }
 
     Widget &container()
@@ -215,6 +227,17 @@ DENG2_OBSERVES(App,              StartupComplete)
         root.add(colorAdjust);
 
         taskBar->hide();
+
+        // Mouse cursor is used with transformed content.
+        cursor = new LabelWidget;
+        cursor->margins().set(""); // no margins
+        cursor->setImage(style.images().image("window.cursor"));
+        cursor->setAlignment(ui::AlignTopLeft);
+        cursor->rule()
+                .setSize(Const(48), Const(48))
+                .setLeftTop(*cursorX, *cursorY);
+        cursor->hide();
+        container().add(cursor);
     }
 
     void appStartupCompleted()
@@ -515,6 +538,7 @@ DENG2_OBSERVES(App,              StartupComplete)
         if(sidebar) container().remove(*sidebar);
         container().remove(*notifications);
         container().remove(*taskBar);
+        container().remove(*cursor);
 
         if(enable && !compositor)
         {
@@ -540,6 +564,7 @@ DENG2_OBSERVES(App,              StartupComplete)
         if(sidebar) container().add(sidebar);
         container().add(notifications);
         container().add(taskBar);
+        container().add(cursor);
 
         if(mode == Normal)
         {
@@ -555,14 +580,37 @@ DENG2_OBSERVES(App,              StartupComplete)
 
         if(VR::mode() == VR::MODE_OCULUS_RIFT)
         {
-            compositor->setCompositeProjection(Matrix4f::ortho(-1, 2, -1, 2));
+            compositor->setCompositeProjection(Matrix4f::ortho(-1.1f, 2.2f, -1.1f, 2.2f));
         }
         else
         {
             // We'll simply cover the entire view.
             compositor->useDefaultCompositeProjection();
         }
     }
+
+    void updateMouseCursor()
+    {
+        // The cursor is only needed if the content is warped.
+        cursor->show(!self.canvas().isMouseTrapped() && VR::mode() == VR::MODE_OCULUS_RIFT);
+
+        if(cursor->isVisible())
+        {
+            if(!cursorHasBeenHidden)
+            {
+                qApp->setOverrideCursor(QCursor(Qt::BlankCursor));
+                cursorHasBeenHidden = true;
+            }
+
+            Vector2i cp = ClientApp::windowSystem().latestMousePosition();
+            cursorX->set(cp.x);
+            cursorY->set(cp.y);
+        }
+        else
+        {
+            cursorHasBeenHidden = false;
+        }
+    }
 };
 
 ClientWindow::ClientWindow(String const &id)
@@ -679,6 +727,9 @@ void ClientWindow::canvasGLDraw(Canvas &canvas)
     DENG_ASSERT_IN_MAIN_THREAD();
     DENG_ASSERT_GL_CONTEXT_ACTIVE();
 
+    // Cursor position (if cursor is visible).
+    d->updateMouseCursor();
+
     if(d->needRootSizeUpdate)
     {
         d->updateRootSize();
@@ -873,6 +924,9 @@ void ClientWindow::showColorAdjustments()
 void ClientWindow::addOnTop(GuiWidget *widget)
 {
     d->container().add(widget);
+
+    // Make sure the cursor remains the topmost widget.
+    d->container().moveChildToLast(*d->cursor);
 }
 
 void ClientWindow::setSidebar(SidebarLocation location, GuiWidget *sidebar)

doomsday/client/src/ui/windowsystem.cpp

@@ -127,6 +127,11 @@ void WindowSystem::dispatchLatestMousePosition()
     d->processLatestMousePosition();
 }
 
+Vector2i WindowSystem::latestMousePosition() const
+{
+    return d->latestMousePos;
+}
+
 bool WindowSystem::processEvent(Event const &event)
 {
     /*

doomsday/libdeng2/include/de/widgets/widget.h

@@ -194,7 +194,9 @@ class DENG2_PUBLIC Widget
 
     bool isEventRouted(int type, Widget *to) const;
 
-    // Tree organization.
+    /*
+     * Tree organization.
+     */
     void clearTree();
 
     /**
@@ -213,9 +215,12 @@ class DENG2_PUBLIC Widget
     Widget *find(String const &name);
     Widget const *find(String const &name) const;
     void moveChildBefore(Widget *child, Widget const &otherChild);
+    void moveChildToLast(Widget &child);
     Children children() const;
     dsize childCount() const;
     Widget *parent() const;
+    bool isFirstChild() const;
+    bool isLastChild() const;
 
     // Utilities.
     String uniqueName(String const &name) const;

doomsday/libdeng2/src/widgets/widget.cpp

@@ -356,11 +356,33 @@ void Widget::moveChildBefore(Widget *child, Widget const &otherChild)
     d->children.insert(to, child);
 }
 
+void Widget::moveChildToLast(Widget &child)
+{
+    DENG2_ASSERT(child->parent() == this);
+    if(!child.isLastChild())
+    {
+        remove(child);
+        add(&child);
+    }
+}
+
 Widget *Widget::parent() const
 {
     return d->parent;
 }
 
+bool Widget::isFirstChild() const
+{
+    if(!parent()) return false;
+    return this == parent()->d->children.first();
+}
+
+bool Widget::isLastChild() const
+{
+    if(!parent()) return false;
+    return this == parent()->d->children.last();
+}
+
 String Widget::uniqueName(String const &name) const
 {
     return String("#%1.%2").arg(id().asInt64()).arg(name);