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--
-- All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
-- its licensors.
--
-- For complete copyright and license terms please see the LICENSE at the root of this
-- distribution (the "License"). All use of this software is governed by the License,
-- or, if provided, by the license below or the license accompanying this file. Do not
-- remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
--
--
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local ZoomSlider = 
{
    Properties = 
    {
		ScrollBox = {default = EntityId()},
		Content = {default = EntityId()},
		MaxZoomMultiplier = {default = 2, min = 1, description = "How much the map can be zoomed in at its maximum zoom (multiplier)."},
		MinZoomMultiplier = {default = 0.5, min = 0.1, max = 1, description = "How much the map can be zoomed out at its minimum zoom (multiplier)."},
    },
}

function ZoomSlider:OnActivate()
	-- Connect to the slider notification bus
	self.sliderHandler = UiSliderNotificationBus.Connect(self, self.entityId)
	-- Initialize first zoom
	self.currentZoom = 1.0
end

function ZoomSlider:OnDeactivate()
	-- Deactivate from the slider notification bus only if we managed to connect
	if (self.sliderHandler ~= nil) then
		self.sliderHandler:Disconnect()
	end
end

-- Multiply an offset by a number
function MultiplyOffset(offset, multiplier)
	local newOffset = UiOffsets()
	newOffset.bottom = offset.bottom * multiplier
	newOffset.left = offset.left * multiplier
	newOffset.right = offset.right * multiplier
	newOffset.top = offset.top * multiplier
	return newOffset
end

-- Multiply a Vector2 by a number
function MultiplyVec2(vector, multiplier)
	local newVector = Vector2(0, 0)
	newVector.x = vector.x * multiplier
	newVector.y = vector.y * multiplier
	return newVector
end

function ZoomSlider:OnSliderValueChanging(percent)
	-- Recompute the base offsets and scrollOffsets based on our current zoom (offsets change both the position and the scale)
	local baseOffsets = UiTransform2dBus.Event.GetOffsets(self.Properties.Content)
	baseOffsets = MultiplyOffset(baseOffsets, 1 / self.currentZoom) -- current zoom will never be 0 due to property min
 	local baseScrollOffsets = UiScrollBoxBus.Event.GetScrollOffset(self.Properties.ScrollBox)
	baseScrollOffsets = MultiplyVec2(baseScrollOffsets, 1 / self.currentZoom)
	
	-- Then recompute min and max offsets based on new base offsets
	local minOffsets = MultiplyOffset(baseOffsets, self.Properties.MinZoomMultiplier)
	local maxOffsets = MultiplyOffset(baseOffsets, self.Properties.MaxZoomMultiplier)
	local minScrollOffsets = MultiplyVec2(baseScrollOffsets, self.Properties.MinZoomMultiplier)
	local maxScrollOffsets = MultiplyVec2(baseScrollOffsets, self.Properties.MaxZoomMultiplier)
	
	-- Calculate new offsets based on percentage of slider ( x = (max - min) * percentage + min )
	-- Content offsets
	-- (max - min)
 	local newOffset = UiOffsets()
 	newOffset.bottom = maxOffsets.bottom - minOffsets.bottom
 	newOffset.left = maxOffsets.left - minOffsets.left
 	newOffset.right = maxOffsets.right - minOffsets.right
 	newOffset.top = maxOffsets.top - minOffsets.top
 	-- * percentage
 	newOffset = MultiplyOffset(newOffset, percent / 100)
 	-- + min
 	newOffset.bottom = newOffset.bottom + minOffsets.bottom
 	newOffset.left = newOffset.left + minOffsets.left
 	newOffset.right = newOffset.right + minOffsets.right
 	newOffset.top = newOffset.top + minOffsets.top

	-- Scroll offsets
	-- (max - min)
 	local newScrollOffset = Vector2(0, 0)
 	newScrollOffset.x = maxScrollOffsets.x - minScrollOffsets.x
 	newScrollOffset.y = maxScrollOffsets.y - minScrollOffsets.y
 	-- * percentage
 	newScrollOffset = MultiplyVec2(newScrollOffset, percent / 100)
 	-- + min
 	newScrollOffset.x = newScrollOffset.x + minScrollOffsets.x
 	newScrollOffset.y = newScrollOffset.y + minScrollOffsets.y
 	
 	-- Set the map offsets to the newly calculated offsets
 	UiTransform2dBus.Event.SetOffsets(self.Properties.Content, newOffset)
	-- Set the scrollbox offsets to the newly calculated scroll offsets
 	UiScrollBoxBus.Event.SetScrollOffset(self.Properties.ScrollBox, newScrollOffset)

	-- Update the zoom level
	self.currentZoom = (self.Properties.MaxZoomMultiplier - self.Properties.MinZoomMultiplier) * percent / 100 + self.Properties.MinZoomMultiplier
end

return ZoomSlider