Add support to drag and drop recent file items

The items are still not persisted/synchronized with the .ini file.

src/app/ui/draggable_widget.h

@@ -0,0 +1,165 @@
+// Aseprite
+// Copyright (C) 2018  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_UI_DRAGGABLE_WIDGET_H_INCLUDED
+#define APP_UI_DRAGGABLE_WIDGET_H_INCLUDED
+#pragma once
+
+#include "os/surface.h"
+#include "os/system.h"
+#include "ui/graphics.h"
+#include "ui/message.h"
+#include "ui/overlay.h"
+#include "ui/overlay_manager.h"
+#include "ui/paint_event.h"
+#include "ui/system.h"
+#include "ui/view.h"
+
+namespace app {
+
+template<typename Base>
+class DraggableWidget : public Base {
+public:
+  template<typename...Args>
+  DraggableWidget(Args...args) : Base(args...) { }
+
+  bool onProcessMessage(ui::Message* msg) override {
+    switch (msg->type()) {
+
+      case ui::kSetCursorMessage:
+        if (m_floatingOverlay) {
+          ui::set_mouse_cursor(ui::kMoveCursor);
+          return true;
+        }
+        break;
+
+      case ui::kMouseDownMessage: {
+        const bool wasCaptured = this->hasCapture();
+        const bool result = Base::onProcessMessage(msg);
+
+        if (!wasCaptured && this->hasCapture()) {
+          const ui::MouseMessage* mouseMsg = static_cast<ui::MouseMessage*>(msg);
+          const gfx::Point mousePos = mouseMsg->position();
+          m_dragMousePos = mousePos;
+          m_floatingOffset = mouseMsg->position() - this->bounds().origin();
+          m_createFloatingOverlay = true;
+        }
+        return result;
+      }
+
+      case ui::kMouseMoveMessage: {
+        const ui::MouseMessage* mouseMsg = static_cast<ui::MouseMessage*>(msg);
+        const gfx::Point mousePos = mouseMsg->position();
+
+        if (this->hasCapture() && m_createFloatingOverlay) {
+          if (this->manager()->pick(mousePos) != this) {
+            m_createFloatingOverlay = false;
+            if (!m_floatingOverlay)
+              createFloatingOverlay();
+          }
+        }
+
+        if (m_floatingOverlay) {
+          m_floatingOverlay->moveOverlay(mousePos - m_floatingOffset);
+          onReorderWidgets(mousePos);
+        }
+        break;
+      }
+
+      case ui::kMouseUpMessage: {
+        m_wasDragged = (this->hasCapture() && m_floatingOverlay);
+        const bool result = Base::onProcessMessage(msg);
+        m_wasDragged = false;
+
+        if (!this->hasCapture()) {
+          if (m_floatingOverlay) {
+            destroyFloatingOverlay();
+            ASSERT(!m_createFloatingOverlay);
+          }
+          else if (m_createFloatingOverlay)
+            m_createFloatingOverlay = false;
+        }
+        return result;
+      }
+
+    }
+    return Base::onProcessMessage(msg);
+  }
+
+  bool wasDragged() const {
+    return m_wasDragged;
+  }
+
+private:
+
+  void createFloatingOverlay() {
+    ASSERT(!m_floatingOverlay);
+
+    gfx::Size sz = getFloatingOverlaySize();
+    os::Surface* surface = os::instance()->createRgbaSurface(sz.w, sz.h);
+
+    {
+      os::SurfaceLock lock(surface);
+      surface->fillRect(gfx::rgba(0, 0, 0, 0),
+                        gfx::Rect(0, 0, surface->width(), surface->height()));
+    }
+    {
+      ui::Graphics g(surface, 0, 0);
+      g.setFont(this->font());
+      drawFloatingOverlay(g);
+    }
+
+    m_floatingOverlay.reset(new ui::Overlay(surface, gfx::Point(),
+                                            ui::Overlay::MouseZOrder-1));
+    ui::OverlayManager::instance()->addOverlay(m_floatingOverlay.get());
+  }
+
+  void destroyFloatingOverlay() {
+    ui::OverlayManager::instance()->removeOverlay(m_floatingOverlay.get());
+    m_floatingOverlay.reset();
+  }
+
+  gfx::Size getFloatingOverlaySize() {
+    auto view = ui::View::getView(this);
+    if (!view)
+      view = ui::View::getView(this->parent());
+    if (view)
+      return (view->viewportBounds() & this->bounds()).size();
+    else
+      return this->size();
+  }
+
+  void drawFloatingOverlay(ui::Graphics& g) {
+    ui::PaintEvent ev(this, &g);
+    this->onPaint(ev);
+  }
+
+  virtual void onReorderWidgets(const gfx::Point& mousePos) = 0;
+
+  // True if we should create the floating overlay after leaving the
+  // widget bounds.
+  bool m_createFloatingOverlay = false;
+
+  // True when the mouse button is released (drop operation) and we've
+  // dragged the widget to other position. Can be used to avoid
+  // triggering the default click operation by derived classes when
+  // we've dragged the widget.
+  bool m_wasDragged = false;
+
+  // Initial mouse position when we start the dragging process.
+  gfx::Point m_dragMousePos;
+
+  // Overlay used to show the floating widget (this overlay floats
+  // next to the mouse cursor).
+  std::unique_ptr<ui::Overlay> m_floatingOverlay;
+
+  // Relative mouse position between the widget and the overlay.
+  gfx::Point m_floatingOffset;
+};
+
+} // namespace app
+
+#endif

src/app/ui/recent_listbox.cpp

@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2018  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -16,6 +17,7 @@
 #include "app/i18n/strings.h"
 #include "app/pref/preferences.h"
 #include "app/recent_files.h"
+#include "app/ui/draggable_widget.h"
 #include "app/ui/skin/skin_theme.h"
 #include "app/ui_context.h"
 #include "base/bind.h"
@@ -38,10 +40,10 @@ using namespace skin;
 //////////////////////////////////////////////////////////////////////
 // RecentFileItem
 
-class RecentFileItem : public LinkLabel {
+class RecentFileItem : public DraggableWidget<LinkLabel> {
 public:
   RecentFileItem(const std::string& file)
-    : LinkLabel("")
+    : DraggableWidget<LinkLabel>("")
     , m_fullpath(file)
     , m_name(base::get_file_name(file))
     , m_path(base::get_file_path(file)) {
@@ -89,7 +91,17 @@ protected:
   }
 
   void onClick() override {
-    static_cast<RecentListBox*>(parent())->onClick(m_fullpath);
+    if (!wasDragged())
+      static_cast<RecentListBox*>(parent())->onClick(m_fullpath);
+  }
+
+  void onReorderWidgets(const gfx::Point& mousePos) override {
+    auto parent = this->parent();
+    auto other = manager()->pick(mousePos);
+    if (other && other != this && other->parent() == parent) {
+      parent->moveChildTo(this, other);
+      parent->layout();
+    }
   }
 
 private:

src/ui/move_region.cpp

@@ -1,4 +1,5 @@
 // Aseprite UI Library
+// Copyright (C) 2018  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -13,6 +14,7 @@
 #include "os/display.h"
 #include "os/surface.h"
 #include "os/system.h"
+#include "ui/overlay_manager.h"
 
 #include <vector>
 
@@ -27,6 +29,11 @@ void move_region(Manager* manager, const Region& region, int dx, int dy)
   if (!display)
     return;
 
+  auto overlays = ui::OverlayManager::instance();
+  gfx::Rect bounds = region.bounds();
+  bounds |= gfx::Rect(bounds).offset(dx, dy);
+  overlays->restoreOverlappedAreas(bounds);
+
   os::Surface* surface = display->getSurface();
   os::SurfaceLock lock(surface);
   std::size_t nrects = region.size();
@@ -83,6 +90,8 @@ void move_region(Manager* manager, const Region& region, int dx, int dy)
       manager->dirtyRect(rc);
     }
   }
+
+  overlays->drawOverlays();
 }
 
 } // namespace ui

src/ui/widget.cpp

@@ -577,6 +577,19 @@ void Widget::insertChild(int index, Widget* child)
   child->m_parent = this;
 }
 
+void Widget::moveChildTo(Widget* thisChild, Widget* toThisPosition)
+{
+  auto itA = std::find(m_children.begin(), m_children.end(), thisChild);
+  auto itB = std::find(m_children.begin(), m_children.end(), toThisPosition);
+  if (itA == m_children.end()) {
+    ASSERT(false);
+    return;
+  }
+  int index = itB - m_children.begin();
+  m_children.erase(itA);
+  m_children.insert(m_children.begin() + index, thisChild);
+}
+
 // ===============================================================
 // LAYOUT & CONSTRAINT
 // ===============================================================

src/ui/widget.h

@@ -212,6 +212,7 @@ namespace ui {
     void removeAllChildren();
     void replaceChild(Widget* oldChild, Widget* newChild);
     void insertChild(int index, Widget* child);
+    void moveChildTo(Widget* thisChild, Widget* toThisPosition);
 
     // ===============================================================
     // LAYOUT & CONSTRAINT