/*
 * Copyright (c) 2021 Samsung Electronics Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

/**
 * @file image-scaling-irregular-grid-example.cpp
 * @brief Demonstrates how to use image scaling modes when loading images.
 *
 * If an image is going to be drawn on-screen at a lower resolution than it is
 * stored at on-disk, the scaling feature of the image loader can be used to
 * reduce the image to save memory, improve performance, and potentially display
 * a better small version of the image than if the default size were loaded.
 *
 * The functions CreateImage and CreateImageView below show how to build an
 * image using a scaling mode to have %Dali resize it during loading.
 *
 * This demo defaults to the SCALE_TO_FILL mode of ImageAttributes which makes
 * sure that every pixel in the loaded image is filled with a source colour
 * from the image's central region while losing the minimum number of pixels
 * from its periphery.
 * It is the best option for producing thumbnails of input images that have
 * diverse aspect ratios.
 *
 * The other four scaling modes of dali can be cycled-through for the whole
 * grid  using the button in the top-right of the toolbar.
 * A single image can be cycled by clicking the image directly.
 *
 * @see CreateImage CreateImageView
 */

// EXTERNAL INCLUDES
#include <dali-toolkit/dali-toolkit.h>
#include <dali-toolkit/devel-api/controls/control-devel.h>
#include <dali-toolkit/devel-api/controls/scroll-bar/scroll-bar.h>
#include <algorithm>
#include <chrono> // std::chrono::system_clock
#include <iostream>
#include <map>
#include <random> // std::default_random_engine

// INTERNAL INCLUDES
#include "grid-flags.h"
#include "shared/view.h"

using namespace Dali;
using namespace Dali::Toolkit;
using namespace Dali::Demo;

namespace
{
/** Controls the output of application logging. */
//#define DEBUG_PRINT_DIAGNOSTICS;

const char* BACKGROUND_IMAGE(DEMO_IMAGE_DIR "background-gradient.jpg");
const char* TOOLBAR_IMAGE(DEMO_IMAGE_DIR "top-bar.png");
const char* APPLICATION_TITLE("Image Scaling Modes");
const char* TOGGLE_SCALING_IMAGE(DEMO_IMAGE_DIR "icon-change.png");
const char* TOGGLE_SCALING_IMAGE_SELECTED(DEMO_IMAGE_DIR "icon-change-selected.png");

/** The width of the grid in whole grid cells. */
const unsigned GRID_WIDTH = 9;
/** Limit the grid to be no higher than this in units of a cell. */
const unsigned GRID_MAX_HEIGHT = 600;

/** The space between the edge of a grid cell and the image embedded within it. */
const unsigned GRID_CELL_PADDING = 4;

/** The aspect ratio of cells in the image grid. */
const float CELL_ASPECT_RATIO = 1.33333333333333333333f;

const Dali::FittingMode::Type DEFAULT_SCALING_MODE = Dali::FittingMode::SCALE_TO_FILL;

/** The number of times to spin an image on touching, each spin taking a second.*/
const float SPIN_DURATION = 1.0f;

/** The target image sizes in grid cells. */
const Vector2 IMAGE_SIZES[] = {
  Vector2(1, 1),
  Vector2(2, 1),
  Vector2(3, 1),
  Vector2(1, 2),
  Vector2(1, 3),
  Vector2(2, 3),
  Vector2(3, 2),
  // Large, tall configuration:
  Vector2(GRID_WIDTH / 2, GRID_WIDTH + GRID_WIDTH / 2),
  // Large, square-ish images to show shrink-to-fit well with wide and tall images:
  Vector2(GRID_WIDTH / 2, GRID_WIDTH / 2.0f * CELL_ASPECT_RATIO + 0.5f),
  Vector2(GRID_WIDTH - 2, (GRID_WIDTH - 2) * CELL_ASPECT_RATIO + 0.5f),
};
const unsigned NUM_IMAGE_SIZES = sizeof(IMAGE_SIZES) / sizeof(IMAGE_SIZES[0]);

/** Images to load into the grid. These are mostly large and non-square to
 *  show the scaling. */
const char* IMAGE_PATHS[] = {

  DEMO_IMAGE_DIR "dali-logo.png",
  DEMO_IMAGE_DIR "com.samsung.dali-demo.ico",
  DEMO_IMAGE_DIR "square_primitive_shapes.bmp",
  DEMO_IMAGE_DIR "gallery-large-14.wbmp",

  // Images that show aspect ratio changes clearly in primitive shapes:

  DEMO_IMAGE_DIR "portrait_screen_primitive_shapes.gif",
  DEMO_IMAGE_DIR "landscape_screen_primitive_shapes.gif",

  // Images from other demos that are tall, wide or just large:

  DEMO_IMAGE_DIR "gallery-large-1.jpg",
  DEMO_IMAGE_DIR "gallery-large-2.jpg",
  DEMO_IMAGE_DIR "gallery-large-3.jpg",
  DEMO_IMAGE_DIR "gallery-large-4.jpg",
  DEMO_IMAGE_DIR "gallery-large-5.jpg",
  DEMO_IMAGE_DIR "gallery-large-6.jpg",
  DEMO_IMAGE_DIR "gallery-large-7.jpg",
  DEMO_IMAGE_DIR "gallery-large-8.jpg",
  DEMO_IMAGE_DIR "gallery-large-9.jpg",
  DEMO_IMAGE_DIR "gallery-large-10.jpg",
  DEMO_IMAGE_DIR "gallery-large-11.jpg",
  DEMO_IMAGE_DIR "gallery-large-12.jpg",
  DEMO_IMAGE_DIR "gallery-large-13.jpg",
  DEMO_IMAGE_DIR "gallery-large-14.jpg",
  DEMO_IMAGE_DIR "gallery-large-15.jpg",
  DEMO_IMAGE_DIR "gallery-large-16.jpg",
  DEMO_IMAGE_DIR "gallery-large-17.jpg",
  DEMO_IMAGE_DIR "gallery-large-18.jpg",
  DEMO_IMAGE_DIR "gallery-large-19.jpg",
  DEMO_IMAGE_DIR "gallery-large-20.jpg",
  DEMO_IMAGE_DIR "gallery-large-21.jpg",

  DEMO_IMAGE_DIR "background-1.jpg",
  DEMO_IMAGE_DIR "background-2.jpg",
  DEMO_IMAGE_DIR "background-3.jpg",
  DEMO_IMAGE_DIR "background-4.jpg",
  DEMO_IMAGE_DIR "background-5.jpg",
  DEMO_IMAGE_DIR "background-blocks.jpg",
  DEMO_IMAGE_DIR "background-magnifier.jpg",

  DEMO_IMAGE_DIR "background-1.jpg",
  DEMO_IMAGE_DIR "background-2.jpg",
  DEMO_IMAGE_DIR "background-3.jpg",
  DEMO_IMAGE_DIR "background-4.jpg",
  DEMO_IMAGE_DIR "background-5.jpg",
  DEMO_IMAGE_DIR "background-blocks.jpg",
  DEMO_IMAGE_DIR "background-magnifier.jpg",

  DEMO_IMAGE_DIR "book-landscape-cover-back.jpg",
  DEMO_IMAGE_DIR "book-landscape-cover.jpg",
  DEMO_IMAGE_DIR "book-landscape-p1.jpg",
  DEMO_IMAGE_DIR "book-landscape-p2.jpg",

  DEMO_IMAGE_DIR "book-portrait-cover.jpg",
  DEMO_IMAGE_DIR "book-portrait-p1.jpg",
  DEMO_IMAGE_DIR "book-portrait-p2.jpg",
  NULL};
const unsigned     NUM_IMAGE_PATHS        = sizeof(IMAGE_PATHS) / sizeof(IMAGE_PATHS[0]) - 1u;
const unsigned int INITIAL_IMAGES_TO_LOAD = 10;

/**
 * Creates an ImageView
 *
 * @param[in] filename The path of the image.
 * @param[in] width The width of the image in pixels.
 * @param[in] height The height of the image in pixels.
 * @param[in] fittingMode The mode to use when scaling the image to fit the desired dimensions.
 */
ImageView CreateImageView(const std::string& filename, int width, int height, Dali::FittingMode::Type fittingMode)
{
  ImageView imageView = ImageView::New();

  Property::Map map;
  map[Toolkit::ImageVisual::Property::URL]            = filename;
  map[Toolkit::ImageVisual::Property::DESIRED_WIDTH]  = width;
  map[Toolkit::ImageVisual::Property::DESIRED_HEIGHT] = height;
  map[Toolkit::ImageVisual::Property::FITTING_MODE]   = fittingMode;
  imageView.SetProperty(Toolkit::ImageView::Property::IMAGE, map);

  imageView.SetProperty(Dali::Actor::Property::NAME, filename);
  imageView.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
  imageView.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);

  return imageView;
}

/** Cycle the scaling mode options. */
Dali::FittingMode::Type NextMode(const Dali::FittingMode::Type oldMode)
{
  Dali::FittingMode::Type newMode = FittingMode::SHRINK_TO_FIT;
  switch(oldMode)
  {
    case FittingMode::SHRINK_TO_FIT:
      newMode = FittingMode::SCALE_TO_FILL;
      break;
    case FittingMode::SCALE_TO_FILL:
      newMode = FittingMode::FIT_WIDTH;
      break;
    case FittingMode::FIT_WIDTH:
      newMode = FittingMode::FIT_HEIGHT;
      break;
    case FittingMode::FIT_HEIGHT:
      newMode = FittingMode::VISUAL_FITTING;
      break;
    case FittingMode::VISUAL_FITTING:
      newMode = FittingMode::SHRINK_TO_FIT;
      break;
  }
  return newMode;
}

/**
 * Bundle an image path with the rectangle to pack it into.
 * */
struct ImageConfiguration
{
  ImageConfiguration(const char* const imagePath, const Vector2 dims)
  : path(imagePath),
    dimensions(dims)
  {
  }
  const char* path;
  Vector2     dimensions;
};

/**
 * Post-layout image data.
 */
struct PositionedImage
{
  PositionedImage(ImageConfiguration& config, unsigned x, unsigned y, Vector2 imageGridDimensions)
  : configuration(config),
    cellX(x),
    cellY(y),
    imageGridDims(imageGridDimensions)
  {
  }

  ImageConfiguration configuration;
  unsigned           cellX;
  unsigned           cellY;
  Vector2            imageGridDims;
};

} // namespace

/**
 * @brief The main class of the demo.
 */
class ImageScalingIrregularGridController : public ConnectionTracker
{
public:
  ImageScalingIrregularGridController(Application& application)
  : mApplication(application),
    mScrolling(false),
    mImagesLoaded(0)
  {
    std::cout << "ImageScalingIrregularGridController::ImageScalingIrregularGridController" << std::endl;

    // Connect to the Application's Init signal
    mApplication.InitSignal().Connect(this, &ImageScalingIrregularGridController::Create);
  }

  ~ImageScalingIrregularGridController()
  {
    // Nothing to do here.
  }

  /**
   * Called everytime an ImageView has loaded it's image
   */
  void ResourceReadySignal(Toolkit::Control control)
  {
    mImagesLoaded++;
    // To allow fast startup, we only place a small number of ImageViews on window first
    if(mImagesLoaded == INITIAL_IMAGES_TO_LOAD)
    {
      // Adding the ImageViews to the window will trigger loading of the Images
      mGridActor.Add(mOffWindowImageViews);
    }
  }

  /**
   * One-time setup in response to Application InitSignal.
   */
  void Create(Application& application)
  {
    std::cout << "ImageScalingIrregularGridController::Create" << std::endl;

    // Get a handle to the window:
    Window window = application.GetWindow();

    // Connect to input event signals:
    window.KeyEventSignal().Connect(this, &ImageScalingIrregularGridController::OnKeyEvent);

    // Create a default view with a default tool bar:
    mContentLayer = DemoHelper::CreateView(mApplication,
                                           mView,
                                           mToolBar,
                                           BACKGROUND_IMAGE,
                                           TOOLBAR_IMAGE,
                                           "");

    // Create an image scaling toggle button. (right of toolbar)
    Toolkit::PushButton toggleScalingButton = Toolkit::PushButton::New();
    toggleScalingButton.SetProperty(Toolkit::Button::Property::UNSELECTED_BACKGROUND_VISUAL, TOGGLE_SCALING_IMAGE);
    toggleScalingButton.SetProperty(Toolkit::Button::Property::SELECTED_BACKGROUND_VISUAL, TOGGLE_SCALING_IMAGE_SELECTED);
    toggleScalingButton.ClickedSignal().Connect(this, &ImageScalingIrregularGridController::OnToggleScalingTouched);
    mToolBar.AddControl(toggleScalingButton, DemoHelper::DEFAULT_VIEW_STYLE.mToolBarButtonPercentage, Toolkit::Alignment::HORIZONTAL_RIGHT, DemoHelper::DEFAULT_MODE_SWITCH_PADDING);

    SetTitle(APPLICATION_TITLE);

    mOffWindowImageViews = Actor::New();
    mOffWindowImageViews.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);
    mOffWindowImageViews.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
    mOffWindowImageViews.SetResizePolicy(ResizePolicy::FILL_TO_PARENT, Dimension::ALL_DIMENSIONS);

    // Build the main content of the widow:
    PopulateContentLayer(DEFAULT_SCALING_MODE);
  }

  /**
   * Build the main part of the application's view.
   */
  void PopulateContentLayer(const Dali::FittingMode::Type fittingMode)
  {
    Window  window     = mApplication.GetWindow();
    Vector2 windowSize = window.GetSize();

    float fieldHeight;
    Actor imageField = BuildImageField(windowSize.x, GRID_WIDTH, GRID_MAX_HEIGHT, fittingMode, fieldHeight);

    mScrollView = ScrollView::New();

    mScrollView.ScrollStartedSignal().Connect(this, &ImageScalingIrregularGridController::OnScrollStarted);
    mScrollView.ScrollCompletedSignal().Connect(this, &ImageScalingIrregularGridController::OnScrollCompleted);

    mScrollView.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);
    mScrollView.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);

    mScrollView.SetResizePolicy(ResizePolicy::FILL_TO_PARENT, Dimension::ALL_DIMENSIONS);

    mScrollView.SetAxisAutoLock(true);
    mScrollView.SetAxisAutoLockGradient(1.0f);

    // Restrict scrolling to mostly vertical only, but with some horizontal wiggle-room:

    RulerPtr rulerX = new FixedRuler(windowSize.width);                                    //< Pull the view back to the grid's centre-line when touch is release using a snapping ruler.
    rulerX->SetDomain(RulerDomain(windowSize.width * -0.125f, windowSize.width * 1.125f)); //< Scroll slightly left/right of image field.
    mScrollView.SetRulerX(rulerX);

    RulerPtr rulerY = new DefaultRuler(); //< Snap in multiples of a screen / window height
    rulerY->SetDomain(RulerDomain(-fieldHeight * 0.5f + windowSize.height * 0.5f - GRID_CELL_PADDING, fieldHeight * 0.5f + windowSize.height * 0.5f + GRID_CELL_PADDING));
    mScrollView.SetRulerY(rulerY);

    mContentLayer.Add(mScrollView);
    mScrollView.Add(imageField);
    mGridActor = imageField;

    // Create the scroll bar
    mScrollBarVertical = ScrollBar::New(Toolkit::ScrollBar::VERTICAL);
    mScrollBarVertical.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::TOP_RIGHT);
    mScrollBarVertical.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::TOP_RIGHT);
    mScrollBarVertical.SetResizePolicy(Dali::ResizePolicy::FILL_TO_PARENT, Dali::Dimension::HEIGHT);
    mScrollBarVertical.SetResizePolicy(Dali::ResizePolicy::FIT_TO_CHILDREN, Dali::Dimension::WIDTH);
    mScrollView.Add(mScrollBarVertical);

    mScrollBarHorizontal = ScrollBar::New(Toolkit::ScrollBar::HORIZONTAL);
    mScrollBarHorizontal.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::BOTTOM_LEFT);
    mScrollBarHorizontal.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::TOP_LEFT);
    mScrollBarHorizontal.SetResizePolicy(Dali::ResizePolicy::FIT_TO_CHILDREN, Dali::Dimension::WIDTH);
    mScrollBarHorizontal.SetProperty(Actor::Property::ORIENTATION, Quaternion(Quaternion(Radian(1.5f * Math::PI), Vector3::ZAXIS)));
    mScrollView.Add(mScrollBarHorizontal);

    mScrollView.OnRelayoutSignal().Connect(this, &ImageScalingIrregularGridController::OnScrollViewRelayout);

    // Scroll to top of grid so first images loaded are on-screen:
    mScrollView.ScrollTo(Vector2(0, -1000000));
  }

  void OnScrollViewRelayout(Actor actor)
  {
    // Make the height of the horizontal scroll bar to be the same as the width of scroll view.
    mScrollBarHorizontal.SetProperty(Actor::Property::SIZE, Vector2(0.0f, mScrollView.GetRelayoutSize(Dimension::WIDTH)));
  }

  /**
   * Build a field of images scaled into a variety of shapes from very wide,
   * through square, to very tall. The images are direct children of the Dali::Actor
   * returned.
   **/
  Actor BuildImageField(const float             fieldWidth,
                        const unsigned          gridWidth,
                        const unsigned          maxGridHeight,
                        Dali::FittingMode::Type fittingMode,
                        float&                  outFieldHeight)
  {
    // Generate the list of image configurations to be fitted into the field:

    std::vector<ImageConfiguration> configurations;
    configurations.reserve(NUM_IMAGE_PATHS * NUM_IMAGE_SIZES);
    for(unsigned imageIndex = 0; imageIndex < NUM_IMAGE_PATHS; ++imageIndex)
    {
      for(unsigned dimensionsIndex = 0; dimensionsIndex < NUM_IMAGE_SIZES; ++dimensionsIndex)
      {
        configurations.push_back(ImageConfiguration(IMAGE_PATHS[imageIndex], IMAGE_SIZES[dimensionsIndex]));
      }
    }
    // Stir-up the list to get some nice irregularity in the generated field:
    unsigned int seed = std::chrono::system_clock::now().time_since_epoch().count();
    std::shuffle(configurations.begin(), configurations.end(), std::default_random_engine(seed));
    seed = std::chrono::system_clock::now().time_since_epoch().count();
    std::shuffle(configurations.begin(), configurations.end(), std::default_random_engine(seed));

    // Place the images in the grid:

    GridFlags                    grid(gridWidth, maxGridHeight);
    std::vector<PositionedImage> placedImages;

    for(std::vector<ImageConfiguration>::iterator config = configurations.begin(), end = configurations.end(); config != end; ++config)
    {
      unsigned cellX, cellY;
      Vector2  imageGridDims;

      // Allocate a region of the grid for the image:
      bool allocated = grid.AllocateRegion(config->dimensions, cellX, cellY, imageGridDims);
      if(!allocated)
      {
#ifdef DEBUG_PRINT_DIAGNOSTICS
        fprintf(stderr, "Failed to allocate image in grid with dims (%f, %f) and path: %s.\n", config->dimensions.x, config->dimensions.y, config->path);
#endif
        continue;
      }

      placedImages.push_back(PositionedImage(*config, cellX, cellY, imageGridDims));
    }
    DALI_ASSERT_DEBUG(grid.DebugCheckGridValid() && "Cells were set more than once, indicating erroneous overlap in placing images on the grid.");
    const unsigned actualGridHeight = grid.GetHighestUsedRow() + 1;

    // Take the images images in the grid and turn their logical locations into
    // coordinates in a frame defined by a parent actor:

    Actor gridActor = Actor::New();
    gridActor.SetResizePolicy(ResizePolicy::FILL_TO_PARENT, Dimension::ALL_DIMENSIONS);
    gridActor.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
    gridActor.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);

    // Work out the constants of the grid and cell dimensions and positions:
    const float   cellWidth  = fieldWidth / gridWidth;
    const float   cellHeight = cellWidth / CELL_ASPECT_RATIO;
    const Vector2 cellSize   = Vector2(cellWidth, cellHeight);
    outFieldHeight           = actualGridHeight * cellHeight;
    const Vector2 gridOrigin = Vector2(-fieldWidth * 0.5f, -outFieldHeight * 0.5);

    unsigned int count = 0;
    // Build the image actors in their right locations in their parent's frame:
    for(std::vector<PositionedImage>::const_iterator i = placedImages.begin(), end = placedImages.end(); i != end; ++i, ++count)
    {
      const PositionedImage& imageSource       = *i;
      const Vector2          imageSize         = imageSource.imageGridDims * cellSize - Vector2(GRID_CELL_PADDING * 2, GRID_CELL_PADDING * 2);
      const Vector2          imageRegionCorner = gridOrigin + cellSize * Vector2(imageSource.cellX, imageSource.cellY);
      const Vector2          imagePosition     = imageRegionCorner + Vector2(GRID_CELL_PADDING, GRID_CELL_PADDING) + imageSize * 0.5f;

      ImageView image = CreateImageView(imageSource.configuration.path, imageSize.x, imageSize.y, fittingMode);
      image.SetProperty(Actor::Property::POSITION, Vector3(imagePosition.x, imagePosition.y, 0));
      image.SetProperty(Actor::Property::SIZE, imageSize);
      image.TouchedSignal().Connect(this, &ImageScalingIrregularGridController::OnTouchImage);
      image.ResourceReadySignal().Connect(this, &ImageScalingIrregularGridController::ResourceReadySignal);
      mFittingModes[image.GetProperty<int>(Actor::Property::ID)] = fittingMode;
      mResourceUrls[image.GetProperty<int>(Actor::Property::ID)] = imageSource.configuration.path;
      mSizes[image.GetProperty<int>(Actor::Property::ID)]        = imageSize;
      if(count < INITIAL_IMAGES_TO_LOAD)
      {
        gridActor.Add(image);
      }
      else
      {
        // Store the ImageView in an offwindow actor until the inital batch of ImageViews have finished loading their images
        // Required
        mOffWindowImageViews.Add(image);
      }
    }

    return gridActor;
  }

  /**
  * Upon Touching an image (Release), change its scaling mode and make it spin, provided we're not scrolling.
  * @param[in] actor The actor touched
  * @param[in] event The Touch information.
  */
  bool OnTouchImage(Actor actor, const TouchEvent& event)
  {
    if((event.GetPointCount() > 0) && (!mScrolling))
    {
      if(event.GetState(0) == PointState::UP)
      {
        // Spin the image a few times:
        Animation animation = Animation::New(SPIN_DURATION);
        animation.AnimateBy(Property(actor, Actor::Property::ORIENTATION), Quaternion(Radian(Degree(360.0f * SPIN_DURATION)), Vector3::XAXIS), AlphaFunction::EASE_OUT);
        animation.Play();

        // Change the scaling mode:
        const unsigned          id        = actor.GetProperty<int>(Actor::Property::ID);
        Dali::FittingMode::Type newMode   = NextMode(mFittingModes[id]);
        const Vector2           imageSize = mSizes[actor.GetProperty<int>(Actor::Property::ID)];

        ImageView imageView = ImageView::DownCast(actor);
        if(imageView)
        {
          Property::Map map;
          map[Visual::Property::TYPE]                = Visual::IMAGE;
          map[ImageVisual::Property::URL]            = mResourceUrls[id];
          map[ImageVisual::Property::DESIRED_WIDTH]  = imageSize.width + 0.5f;
          map[ImageVisual::Property::DESIRED_HEIGHT] = imageSize.height + 0.5f;
          map[ImageVisual::Property::FITTING_MODE]   = newMode;
          imageView.SetProperty(ImageView::Property::IMAGE, map);
        }

        mFittingModes[id] = newMode;
      }
    }
    return false;
  }

  /**
  * Main key event handler.
  * Quit on escape key.
  */
  void OnKeyEvent(const KeyEvent& event)
  {
    if(event.GetState() == KeyEvent::DOWN)
    {
      if(IsKey(event, Dali::DALI_KEY_ESCAPE) || IsKey(event, Dali::DALI_KEY_BACK))
      {
        mApplication.Quit();
      }
    }
  }

  /**
  * Signal handler, called when the 'Scaling' button has been touched.
  *
  * @param[in] button The button that was pressed.
  */
  bool OnToggleScalingTouched(Button button)
  {
    const unsigned numChildren = mGridActor.GetChildCount();

    for(unsigned i = 0; i < numChildren; ++i)
    {
      ImageView gridImageView = ImageView::DownCast(mGridActor.GetChildAt(i));
      if(gridImageView)
      {
        // Cycle the scaling mode options:
        unsigned int id = gridImageView.GetProperty<int>(Actor::Property::ID);

        const Vector2           imageSize = mSizes[id];
        Dali::FittingMode::Type newMode   = NextMode(mFittingModes[id]);

        Property::Map map;
        map[Visual::Property::TYPE]                = Visual::IMAGE;
        map[ImageVisual::Property::URL]            = mResourceUrls[id];
        map[ImageVisual::Property::DESIRED_WIDTH]  = imageSize.width;
        map[ImageVisual::Property::DESIRED_HEIGHT] = imageSize.height;
        map[ImageVisual::Property::FITTING_MODE]   = newMode;
        gridImageView.SetProperty(ImageView::Property::IMAGE, map);

        mFittingModes[id] = newMode;

        SetTitle(std::string(newMode == FittingMode::SHRINK_TO_FIT ? "SHRINK_TO_FIT" : newMode == FittingMode::SCALE_TO_FILL ? "SCALE_TO_FILL"
                                                                                     : newMode == FittingMode::FIT_WIDTH     ? "FIT_WIDTH"
                                                                                                                             : "FIT_HEIGHT"));
      }
    }
    return true;
  }

  /**
   * Sets/Updates the title of the View
   * @param[in] title The new title for the view.
   */
  void SetTitle(const std::string& title)
  {
    if(!mTitleActor)
    {
      mTitleActor = DemoHelper::CreateToolBarLabel("");
      // Add title to the tool bar.
      mToolBar.AddControl(mTitleActor, DemoHelper::DEFAULT_VIEW_STYLE.mToolBarTitlePercentage, Alignment::HORIZONTAL_CENTER);
    }

    mTitleActor.SetProperty(TextLabel::Property::TEXT, title);
  }

  /**
   * When scroll starts (i.e. user starts to drag scrollview),
   * note this state (mScrolling = true)
   * @param[in] position Current Scroll Position
   */
  void OnScrollStarted(const Vector2& position)
  {
    mScrolling = true;
  }

  /**
   * When scroll starts (i.e. user stops dragging scrollview, and scrollview has snapped to destination),
   * note this state (mScrolling = false).
   * @param[in] position Current Scroll Position
   */
  void OnScrollCompleted(const Vector2& position)
  {
    mScrolling = false;
  }

private:
  Application& mApplication;

  Layer                                       mContentLayer;        ///< The content layer (contains non gui chrome actors)
  Toolkit::Control                            mView;                ///< The View instance.
  Toolkit::ToolBar                            mToolBar;             ///< The View's Toolbar.
  TextLabel                                   mTitleActor;          ///< The Toolbar's Title.
  Actor                                       mGridActor;           ///< The container for the grid of images
  Actor                                       mOffWindowImageViews; ///< ImageViews held off window until the inital batch have loaded their images
  ScrollView                                  mScrollView;          ///< ScrollView UI Component
  ScrollBar                                   mScrollBarVertical;
  ScrollBar                                   mScrollBarHorizontal;
  bool                                        mScrolling;    ///< ScrollView scrolling state (true = scrolling, false = stationary)
  std::map<unsigned, Dali::FittingMode::Type> mFittingModes; ///< Stores the current scaling mode of each image, keyed by image actor id.
  std::map<unsigned, std::string>             mResourceUrls; ///< Stores the url of each image, keyed by image actor id.
  std::map<unsigned, Vector2>                 mSizes;        ///< Stores the current size of each image, keyed by image actor id.
  unsigned int                                mImagesLoaded; ///< How many images have been loaded
};

int DALI_EXPORT_API main(int argc, char** argv)
{
  Application                         application = Application::New(&argc, &argv, DEMO_THEME_PATH);
  ImageScalingIrregularGridController test(application);
  application.MainLoop();
  return 0;
}