text: //
  // Copyright (c) 2008-2020 the Urho3D project.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  //
  
  #include <Urho3D/Core/CoreEvents.h>
  #include <Urho3D/UI/Button.h>
  #include <Urho3D/UI/Font.h>
  #include <Urho3D/UI/Text.h>
  #include <Urho3D/UI/UIEvents.h>
  
  #include "UIDrag.h"
  
  #include <Urho3D/DebugNew.h>
  
  
  UIDrag::UIDrag(Context* context) :
      Sample(context)
  {
  }
  
  void UIDrag::Start()
  {
      // Execute base class startup
      Sample::Start();
  
      // Set mouse visible
      ea::string platform = GetPlatform();
      if (platform != "Android" && platform != "iOS")
          GetSubsystem<Input>()->SetMouseVisible(true);
  
      // Create the UI content
      CreateGUI();
      CreateInstructions();
  
      // Hook up to the frame update events
      SubscribeToEvents();
  
      // Set the mouse mode to use in the sample
      Sample::InitMouseMode(MM_FREE);
  }
  
  void UIDrag::CreateGUI()
  {
      auto* cache = GetSubsystem<ResourceCache>();
      auto* ui = GetSubsystem<UI>();
  
      UIElement* root = ui->GetRoot();
      // Load the style sheet from xml
      root->SetDefaultStyle(cache->GetResource<XMLFile>("UI/DefaultStyle.xml"));
  
      for (int i=0; i < 10; i++)
      {
          auto* b = new Button(context_);
          root->AddChild(b);
          // Reference a style from the style sheet loaded earlier:
          b->SetStyleAuto();
          b->SetMinWidth(250);
          b->SetPosition(IntVector2(50*i, 50*i));
  
          // Enable the bring-to-front flag and set the initial priority
          b->SetBringToFront(true);
          b->SetPriority(i);
  
          // Set the layout mode to make the child text elements aligned vertically
          b->SetLayout(LM_VERTICAL, 20, {40, 40, 40, 40});
          auto dragInfos = {"Num Touch", "Text", "Event Touch"};
          for (auto name: dragInfos)
              b->CreateChild<Text>(name)->SetStyleAuto();
  
          if (i % 2 == 0)
              b->AddTag("SomeTag");
  
          SubscribeToEvent(b, E_CLICK, URHO3D_HANDLER(UIDrag, HandleClick));
          SubscribeToEvent(b, E_DRAGMOVE, URHO3D_HANDLER(UIDrag, HandleDragMove));
          SubscribeToEvent(b, E_DRAGBEGIN, URHO3D_HANDLER(UIDrag, HandleDragBegin));
          SubscribeToEvent(b, E_DRAGCANCEL, URHO3D_HANDLER(UIDrag, HandleDragCancel));
      }
  
      for (int i = 0; i < 10; i++)
      {
          auto* t = new Text(context_);
          root->AddChild(t);
          t->SetStyleAuto();
          t->SetName("Touch "+ ea::to_string(i));
          t->SetVisible(false);
          t->SetPriority(100);     // Make sure it has higher priority than the buttons
      }
  }
  
  void UIDrag::CreateInstructions()
  {
      auto* cache = GetSubsystem<ResourceCache>();
      auto* ui = GetSubsystem<UI>();
  
      // Construct new Text object, set string to display and font to use
      auto* instructionText = ui->GetRoot()->CreateChild<Text>();
      instructionText->SetText("Drag on the buttons to move them around.\n"
                               "Touch input allows also multi-drag.\n"
                               "Press SPACE to show/hide tagged UI elements.");
      instructionText->SetFont(cache->GetResource<Font>("Fonts/Anonymous Pro.ttf"), 15);
      instructionText->SetTextAlignment(HA_CENTER);
  
      // Position the text relative to the screen center
      instructionText->SetHorizontalAlignment(HA_CENTER);
      instructionText->SetVerticalAlignment(VA_CENTER);
      instructionText->SetPosition(0, ui->GetRoot()->GetHeight() / 4);
  }
  
  void UIDrag::SubscribeToEvents()
  {
      SubscribeToEvent(E_UPDATE, URHO3D_HANDLER(UIDrag, HandleUpdate));
  }
  
  void UIDrag::HandleClick(StringHash eventType, VariantMap& eventData)
  {
      using namespace Click;
      auto* element = (Button*)eventData[P_ELEMENT].GetVoidPtr();
      element->BringToFront();
  }
  
  void UIDrag::HandleDragBegin(StringHash eventType, VariantMap& eventData)
  {
      using namespace DragBegin;
      auto* element = (Button*)eventData[P_ELEMENT].GetVoidPtr();
  
      int lx = eventData[P_X].GetInt();
      int ly = eventData[P_Y].GetInt();
  
      IntVector2 p = element->GetPosition();
      element->SetVar("START", p);
      element->SetVar("DELTA", IntVector2(p.x_ - lx, p.y_ - ly));
  
      int buttons = eventData[P_BUTTONS].GetInt();
      element->SetVar("BUTTONS", buttons);
  
      auto* t = element->GetChildStaticCast<Text>("Text", false);
      t->SetText("Drag Begin Buttons: " + ea::to_string(buttons));
  
      t = element->GetChildStaticCast<Text>("Num Touch", false);
      t->SetText("Number of buttons: " + ea::to_string(eventData[P_NUMBUTTONS].GetInt()));
  }
  
  void UIDrag::HandleDragMove(StringHash eventType, VariantMap& eventData)
  {
      using namespace DragBegin;
      auto* element = (Button*)eventData[P_ELEMENT].GetVoidPtr();
      int buttons = eventData[P_BUTTONS].GetInt();
      IntVector2 d = element->GetVar("DELTA").GetIntVector2();
      int X = eventData[P_X].GetInt() + d.x_;
      int Y = eventData[P_Y].GetInt() + d.y_;
      int BUTTONS = element->GetVar("BUTTONS").GetInt();
  
      auto* t = element->GetChildStaticCast<Text>("Event Touch", false);
      t->SetText("Drag Move Buttons: " + ea::to_string(buttons));
  
      if (buttons == BUTTONS)
          element->SetPosition(IntVector2(X, Y));
  }
  
  void UIDrag::HandleDragCancel(StringHash eventType, VariantMap& eventData)
  {
      using namespace DragBegin;
      auto* element = (Button*)eventData[P_ELEMENT].GetVoidPtr();
      IntVector2 P = element->GetVar("START").GetIntVector2();
      element->SetPosition(P);
  }
  
  void UIDrag::HandleUpdate(StringHash eventType, VariantMap& eventData)
  {
      auto* ui = GetSubsystem<UI>();
      UIElement* root = ui->GetRoot();
  
      auto* input = GetSubsystem<Input>();
  
      unsigned n = input->GetNumTouches();
      for (unsigned i = 0; i < n; i++)
      {
          Text* t = (Text*)root->GetChild("Touch " + ea::to_string(i));
          TouchState* ts = input->GetTouch(i);
          t->SetText("Touch " + ea::to_string(ts->touchID_));
  
          IntVector2 pos = ts->position_;
          pos.y_ -= 30;
  
          t->SetPosition(pos);
          t->SetVisible(true);
      }
  
      for (unsigned i = n; i < 10; i++)
      {
          Text* t = (Text*)root->GetChild("Touch " + ea::to_string(i));
          t->SetVisible(false);
      }
  
      if (input->GetKeyPress(KEY_SPACE))
      {
          ea::vector<UIElement*> elements;
          root->GetChildrenWithTag(elements, "SomeTag");
          for (auto i = elements.begin(); i != elements.end(); ++i)
          {
              UIElement* element = *i;
              element->SetVisible(!element->IsVisible());
          }
      }
  }
  