urho3d/Bin/Data/LuaScripts/37_UIDrag.lua

-- Urho3D UI Drag Example:
-- This sample demonstrates:
--     - Creating GUI elements from AngelScript
--     - Loading GUI Style from xml
--     - Subscribing to GUI drag events and handling them.

require "LuaScripts/Utilities/Sample"
VAR_BUTTONS = StringHash("BUTTONS")
VAR_START = StringHash("START")
VAR_DELTA = StringHash("DELTA")

function Start()
    -- Execute base class startup
    SampleStart()

    -- Create the scene content
    CreateScene()

    -- Create the UI content
    CreateGUI()
    CreateInstructions()

    -- Setup the viewport for displaying the scene
    SetupViewport()

    -- Hook up to the frame update events
    SubscribeToEvents()
end

function CreateScene()
    scene_ = Scene()

    -- Create the Octree component to the scene. This is required before adding any drawable components, or else nothing will
    -- show up. The default octree volume will be from (-1000, -1000, -1000) to (1000, 1000, 1000) in world coordinates it
    -- is also legal to place objects outside the volume but their visibility can then not be checked in a hierarchically
    -- optimizing manner
    scene_:CreateComponent("Octree")

    -- Create a scene node for the camera, which we will move around
    -- The camera will use default settings (1000 far clip distance, 45 degrees FOV, set aspect ratio automatically)
    cameraNode = scene_:CreateChild("Camera")
    -- Set an initial position for the camera scene node above the plane
    cameraNode.position = Vector3(0.0, 0.0, -10.0)
    local camera = cameraNode:CreateComponent("Camera")
    camera.orthographic = true
    camera.orthoSize = graphics.height * PIXEL_SIZE

    input:SetMouseVisible(true)
end

function CreateInstructions()
    -- Construct new Text object, set string to display and font to use
    local instructionText = ui.root:CreateChild("Text")
    instructionText:SetText("Drag on the buttons to move them around.\nMulti- button drag also supported.")
    instructionText:SetFont(cache:GetResource("Font", "Fonts/Anonymous Pro.ttf"), 15)

    -- Position the text relative to the screen center
    instructionText.horizontalAlignment = HA_CENTER
    instructionText.verticalAlignment = VA_CENTER
    instructionText:SetPosition(0, ui.root.height / 4)
end

function CreateGUI()
    -- Load the style sheet from xml
    ui.root.defaultStyle = cache:GetResource("XMLFile", "UI/DefaultStyle.xml")

    for i=0, 9, 1 do
        local b = Button:new()
        ui.root:AddChild(b)
        -- Reference a style from the style sheet loaded earlier:
        b:SetStyle("Button")
        b:SetMinSize(IntVector2(300, 100))
        b:SetPosition(IntVector2(50*i, 50*i))

        SubscribeToEvent(b, "DragMove", "HandleDragMove")
        SubscribeToEvent(b, "DragBegin", "HandleDragBegin")
        SubscribeToEvent(b, "DragCancel", "HandleDragCancel")

        local t = Text:new()
        b:AddChild(t)
        t:SetStyle("Text")
        t:SetHorizontalAlignment(HA_CENTER)
        t:SetVerticalAlignment(VA_CENTER)
        t:SetName("Text")

        t = Text:new()
        b:AddChild(t)
        t:SetStyle("Text")
        t:SetName("Event Touch")
        t:SetHorizontalAlignment(HA_CENTER)
        t:SetVerticalAlignment(VA_BOTTOM)

        t = Text:new()
        b:AddChild(t)
        t:SetStyle("Text")
        t:SetName("Num Touch")
        t:SetHorizontalAlignment(HA_CENTER)
        t:SetVerticalAlignment(VA_TOP)
    end

    for i = 0, 9, 1 do
        local t = Text:new()
        ui.root:AddChild(t)
        t:SetStyle("Text")
        t:SetText("Touch " .. i)
        t:SetName("Touch " .. i)
        t:SetVisible(false)
    end
end

function SetupViewport()
    -- Set up a viewport to the Renderer subsystem so that the 3D scene can be seen. We need to define the scene and the camera
    -- at minimum. Additionally we could configure the viewport screen size and the rendering path (eg. forward / deferred) to
    -- use, but now we just use full screen and default render path configured in the engine command line options
    local viewport = Viewport:new(scene_, cameraNode:GetComponent("Camera"))
    renderer:SetViewport(0, viewport)
end

function SubscribeToEvents()
    -- Subscribe HandleUpdate() function for processing update events
    SubscribeToEvent("Update", "HandleUpdate")

    -- Unsubscribe the SceneUpdate event from base class to prevent camera pitch and yaw in 2D sample
    UnsubscribeFromEvent("SceneUpdate")
end

function HandleDragBegin(eventType, eventData)
    local element = eventData:GetPtr("UIElement", "Element")

    local lx = eventData:GetInt("X")
    local ly = eventData:GetInt("Y")

    local p = element.position
    element:SetVar(VAR_START, Variant(p))
    element:SetVar(VAR_DELTA, Variant(Vector2(p.x - lx, p.y - ly)))

    local buttons = eventData:GetInt("Buttons")
    element:SetVar(VAR_BUTTONS, Variant(buttons))

    local t = tolua.cast(element:GetChild("Text"), 'Text')
    t:SetText("Drag Begin Buttons: " .. buttons)

    t = tolua.cast(element:GetChild("Num Touch"), 'Text')
    t:SetText("Number of buttons: " .. eventData:GetInt("NumButtons"))
end

function HandleDragMove(eventType, eventData)
    local element = eventData:GetPtr("UIElement", "Element")
    local buttons = eventData:GetInt("Buttons")
    local d = element:GetVar(VAR_DELTA):GetVector2()
    local X = eventData:GetInt("X") + d.x
    local Y = eventData:GetInt("Y") + d.y
    local BUTTONS = element:GetVar(VAR_BUTTONS):GetInt()

    local t = tolua.cast(element:GetChild("Event Touch"), 'Text')
    t:SetText("Drag Move Buttons: " .. buttons)

    element:SetPosition(IntVector2(X, Y))
end

function HandleDragCancel(eventType, eventData)
    local element = eventData:GetPtr("UIElement", "Element")
    local P = element:GetVar(VAR_START):GetIntVector2()
    element:SetPosition(P)
end

function HandleUpdate(eventType, eventData)
    local n = input:GetNumTouches()
    local i = 0
    while i < n do
        local t = tolua.cast(ui.root:GetChild("Touch " .. i), 'Text')
        local ts = input:GetTouch(i)

        local pos = ts.position
        pos.y = pos.y - 30

        t:SetPosition(pos)
        t:SetVisible(true)
        
        i = i + 1
    end

    i = n
    while i < 10 do
        local t = tolua.cast(ui.root:GetChild("Touch " .. i), 'Text')
        t:SetVisible(false)
        i = i + 1
    end
end

-- Create XML patch instructions for screen joystick layout specific to this sample app
function GetScreenJoystickPatchString()
    return "<patch>" ..
        "    <add sel=\"/element/element[./attribute[@name='Name' and @value='Hat0']]\">" ..
        "        <attribute name=\"Is Visible\" value=\"false\" />" ..
        "    </add>" ..
        "</patch>"
        
end