How to set the master volume and individual channel volume in corona SDK

Dev

This tutorial will help you to change/adjust the volume of the music playing in your corona SDK application.

• To set the master volume, you can simply call the following line:

  audio.setVolume( 0.5 )

This will setup the master volume to half. The value range from 0.0 (min.) to 1.0 (max.).

• And, if you need to set the volume of an individual music channel, then you can use the following:

  audio.setVolume( 0.75, { channel=1 } ) 

This will control the volume of channel 1 (here, it will make the channel 1 volume to 3/4th of the default/full volume).

How to play background music in corona SDK application

This is a simple tutorial, which will teach you how to play background music in your corona SDK applications. 

First, load the music as:

  local backgroundMusic = audio.loadStream("bgMusic.mp3") 

Then you can play the music in loop as:

  local backgroundMusicChannel = audio.play( backgroundMusic, { channel=1,

                                                                                                              loop    s=-1,   

                                                                                                              fadein   =5000 })

where, channel is an integer value representing the music channel (0-32)

And if you want to stop the music, you can use:

  audio.stop( backgroundMusicChannel )

How to fill a rectangle with gradient in corona SDK

Corona has a property called graphics.newGradient(), which will be useful for coloring/filling your rectangle with suitable color gradient.

-- First create the rectangle --

local myRectangle = display.newRect( 0, 0, 200, 200 )

-- Then create the gradient method --

local g = graphics.newGradient(

                            { 255, 255, 255 },     -- This is the first color array

                            { 200, 200, 200 },     -- This is the second color array

                             "down" )                  --[[ This is the gradient direction.

                                                                    Default is "down"

                                                                    Others are "up","right" and "left". --]]

-- Now fill your rectangle with the created gradient as: --

myRectangle:setFillColor( g )

How to check whether the testing device supports vibration facility in corona SDK

You may need to implement vibration feedbacks in many of your applications, especially in games and during warning alerts. In this chapter, you will learn about the a boolean key event to check whether your device supports vibrational feedback for your corona app. If this key event returns true,then your device will support vibration feedbacks, and if it returns false, then your device won't.

--  Function to trigger key event --

local function onKeyEvent( event )

    -- Vibrate the gamepad if its 'A' button was pressed.

    if (event.keyName == "button_A") and (event.phase == "down") then

        if event.device and event.device.canVibrate then

            event.device:vibrate()

        end

    end

end

Runtime:addEventListener( "key", onKeyEvent )

Note: This will not work with Android versions <= 4.0.

How to repeat 2 backgrounds continuously forever in corona SDK game

In this tutorial, we will learn about how to repeat 2 backgrounds forever in our corona SDK game application. The code is as follows:

  
  -- Creating 2 images to run as background --

  local bg1 = display.newImageRect( "bg_1.png" ,480 ,320)
  bg1.x = display.contentWidth/2; bg1.y = display.contentHeight/2

  local bg2 = display.newImageRect( "bg_2.png" ,480 ,320 )
  bg2.x = bg1.x + bg1.width; bg2.y = display.contentHeight/2

-- Declaring a local variable to determine the movement speed --
  local speed = 30

-- Move Function --

  function move()
      bg1.x = bg1.x-speed;
      bg2.x = bg2.x-speed;

      if(bg1.x + bg1.width/2 < 0)then
        bg1.x = bg1.width*3/2-speed
      elseif(bg2.x + bg2.width/2 < 0)then
        bg2.x = bg2.width*3/2-speed
      end
  end
  Runtime:addEventListener( "enterFrame", move )

How to split complex strings in corona SDK

This session will teach you about splitting complex string of data separated with some characters. Lets assume that you have a string as House;home,40|Bed,20|Mirror,10. Now we will show you how to split each word and assigning each to a table.

  local myString = "House;home,40|Bed,20|Mirror,10"

  local myTable = {}

  for word in string.gmatch(myString, '([^,|]+)') do

     -- 'myTable' contains the data you need

    myTable[#myTable+1]=word print( myTable[#myTable] )

   end

Hence you will get the items as each table elements, as:

  

  myTable[1] = House

  myTable[2] = home

  myTable[3] = 40

  myTable[4] = Bed

  myTable[5] = 20

  myTable[6] = Mirror

  myTable[7] = 10

Different device Orientation in Corona SDK

In this tutorial, we will teach you: how to setup different supported orientations
for your Corona SDK application. These tricks are done in the build.settings file.
It will setup app orientation in relation to the device's physical orientation.
This also includes auto orientation triggered by the accelerometer, if the
device is flipped/rotated during runtime.

By this, you can set the orientation for:
    1) Launch image(splash screen).
    2) Native UI elements(like alerts, native keyboard,etc).
    3) The Corona display stage.
   
We will show you some of the examples in different orientations.

Example 1: Only landscapeLeft
 

    settings =
        {
            orientation =
            {
                default = "landscapeRight",
            },
        }

 
Example 2: Both landscapeLeft and landscapeRight

    settings =
    {
        orientation =
        {
            default = "landscapeRight",
            supported = { "landscapeLeft", "landscapeRight" },
        },
    }

   
Example 3: Only portrait    
 

    settings =
        {
            orientation =
            {
                default = "portrait",
            },
        }

Example 4: Both portrait and portraitUpsideDown

    settings =
    {
        orientation =
        {
            default = "portrait",
            supported = { "portrait", "portraitUpsideDown" },
        },
    }

How to create widget button in corona DSK

In this tutorial, we will teach you the method of creating Widget button in your Corona SDK application.

First of all, you need to download the following 2 images and keep it with your 'main.lua'.

myButton_normal.png

 

myButton_press.png

Name the first button as: myButton_normal.png
and name the second as: myButton_press.png

Now we can start coding. Lets open main.lua. In the top of your code, require 'widget' as follows:

    local widget = require( "widget" )  

Now create a label to display the button events:

  

    local myText = display.newText( "Click on the buttons.", 0, 0,nil, 18 )
    myText.x, myText.y = display.contentCenterX, 70

Now we have to create the functions triggered by the buttons:

    local button1Press = function( event )
        myText.text = "Button 1 pressed"
    end

    local button1Release = function( event )
        myText.text = "Button 1 released"
    end

    local buttonHandler = function( event )
        myText.text = "id = " .. event.target.id .. ", phase = " .. event.phase
    end

Then just create first button as follows. This button has individual press and release functions.

    local button1 = widget.newButton{
        defaultFile = "myButton_normal.png",
        overFile = "myButton_press.png",
        onPress = button1Press,
        onRelease = button1Release,
        label = "Button 1 Label",
        emboss = true
    }

    button1.x = 160; button1.y = 160

Now we are going to create the second button. This has a single event handler function.

    

    local button2 = widget.newButton{
        defaultFile = "myButton_normal.png",
        overFile = "myButton_press.png",
        onEvent = buttonHandler,
        label = "Button 2 Label",

        id="myButton_2",
        emboss = true
    }

    button2.x = 160; button2.y = 240

 Now, save and run your application. You can see the event label and two buttons. Perform Touch, Drag and Release on the buttons and check it with the label.

Note: Please update your corona SDK version to include all new widget features.

How to get the device information using corona SDK

In some section of coding, you may need be to find out the current device specifications that you are using to run your corona applications. This article is about how to find out basic device information programmatically for your application using Corona SDK. Lets look at the following sample, it can help you for sure:

 To get the device Name:

        

  print("Name:"..system.getInfo( "name" ))

To get the device Model:

    print("Model:"..system.getInfo( "model" ))

To get the device Environment:

    print("Env:"..system.getInfo( "environment" ))

To get the Platform Name:

    print("Plat:"..system.getInfo( "platformName" ))

To get the Platform Version:

    print("Plat. ver:"..system.getInfo( "platformVersion" ))

To get the device Version:

    print("Ver:"..system.getInfo( "version" ))

To get the device Build:

    print("Build:"..system.getInfo( "build" ))

To get the Device ID:

    print("Dev ID:"..system.getInfo( "deviceID" ))

To get the device Language Code:

    print("Language code:"..system.getPreference( "ui", "language" ))

To get the Country:

   

  print("Country:"..system.getPreference( "locale", "country" ))

To get the Identifier:

    print("Identifier:"..system.getPreference( "locale", "identifier" ))

To get the device Language:

    

  print("Language:"..system.getPreference( "locale", "language" ))

How to create global objects in your corona SDK game

In this tutorial, we will teach you how to make global objects with it's own listeners and properties, and are accessible to any class in your game with corona SDK. Here the director class is used to change from scene to scene.

Here I have my .lua  files: main, status and menu. First, lets start with the main.lua. Do the followings in your main:

main.lua
                                                                                 

     local director=require("director")
     local maingroup=display.newGroup()
     maingroup:insert(director.directorView)
     director:changeScene("menu")
     return maingroup 

                                                                                   

Here, we can see that the director class is loaded, and a main displayGroup is created. Next we need to create a class which contains our global object. I am naming that class as 'status.lua'. Here we can create the object method with its certain object with listener and properties and while calling the method, you can return the object to any scene in your game/application. Just look at the status.lua class:

status.lua
                                                                                

    local function myObject(group,x,y,imagePath)

      local image = display.newImage( imagePath )
      image.x, image.y = x, y
      group:insert( image )

      -- We can even add properties as below--
      transition.to(image, {time=1000, x=160, y=300, transition=easing.inOutQuad}) 

      -- Adding Listener --
      image:addEventListener("touch", function() print("imageClicked") end )
    end

    local status = { myObject = myObject }

    return status

                                                                               

Now we can create our menu scene, which is the menu.lua. Here we have to require the object page ('status') and have to call the object method in the page to get the object in current scene, as follows:

menu.lua
                                                                                

module(...,package.seeall)

function new()

    -- require object page --
    local status = require "status"

    -- create a display group --
    local localGroup = display.newGroup()

    -- call object --
    status.myObject(localGroup, 160, 80, "muImage.png")

 return localGroup
end

                                                                               

Now save your files and run the app in the simulator/device to see what happens...

How to create a native alert view using corona SDK

The below function defines the two alert button ('Learn More' & 'OK') actions:

local function onClick(e) 
    if e.action == "clicked" then 
        if e.index == 1 then 
            -- Do something
        elseif e.index == 2 then 
            system.openURL( "http://devblogdk.blogspot.in/" ) 
        end 
    end 
end 

The below code generates the native alertview with title, subject and two buttons:

local alert = native.showAlert("Welcome", "Development Tutorials on DevBlogDK", {"OK", "Learn More"}, onClick)

How to get the largest integer smaller than or equal to a given number in corona SDK

We can find out the largest integer smaller than or equal to a given number using math.floor(). 

Syntax:
   
    math.floor()
   
Example:

    print(math.floor(0.5))    --->     0
    print(math.floor(-0.5))  --->     -1

How to generate a random number in corona SDK

We can use math.random() for the purpose of generating random numbers in corona SDK.
There are 3 main types for this call. They are:

1) Witout any argument:
        math.random()
        -- This will return a pseudo random number in the range of [0,1)
   
2) With one argument:
        math.random(a)
        -- This will return a pseudo random number in the range of [0,a]
   
        eg: print(math.random(5))  ----> return a number between 1 and 5 (both inclusive)
   
3) With two arguments:
        math.random(a,b)
        -- This will return a pseudo random number in the range of [a,b]
   
        eg: print(math.random(2,10))  ----> return a number between 2 and 10 (both inclusive)

How to load a remote image to your application screen using Corona SDK

 Is it possible to load a picture that is located on a server, and display it on your application screen using corona SDK..? Yes it is...
You can use the following code for achieving this:

local function networkListener( event )
        if ( event.isError ) then
                print ( "Network error - download failed" )
        else
                event.target.alpha = 0
                transition.to( event.target, { alpha = 1.0 } )
        end

        print ( "RESPONSE: " .. event.response )
end

display.loadRemoteImage( "http://goo.gl/FsRnwu", "GET", networkListener, "banner.png", system.TemporaryDirectory, 25, 50 )

How to launch camera in your iOS app using corona SDK

You may need to use the camera in several applications to take photos/videos. In corona SDK, you can launch device camera using the following code:

    local onComplete = function(event)
            local photo = event.target
            print( "photo w,h = " .. photo.width .. "," .. photo.height )
    end
    media.show( media.Camera, onComplete )

How to create a widget button in Corona SDK

Creating a widget button in corona, with a button press effect and a function call is as simple as below:


-- First, require 'widget' --
local widget = require("widget")

-- Create the button --
local myButton = widget.newButton{
    default = "normalImage.png",
    over = "pressedImage.png",
    width = 200, height = 200,
    onRelease = myButtonClickFunction
}

-- Position the button --
myButton.x = display.contentWidth/2
myButton.y = display.contentHeight/2

-- Then create the function you need to trigger on the button press --

function myButtonClickFunction()
    print("myButton is pressed...")
end

Touch listener in Corona SDK

We can assign touch listener to an object in corona as follows:


-- Create the object --
local rect = display.newRect(100,100,50,50)
rect:setFillColor(255,0,0)

-- Create the touch function --
local function myTouchFunction(event)
    if(e.phase=="began")then
         print("Touch begins...")
    elseif(e.phase=="moved")then
         print("Touch moved...")
    elseif(e.phase=="ended")then
         print("Touch ended...")
    end
end

-- Create the listener to the object --
rect:addEventListener("touch",myTouchFunction)

How to capture whole screen in Corona SDK

You can use the following lines of code to capture the device screen in Corona SDK. This will save the screenshot as: Picture 1.png, Picture 2.png, etc in the sandbox, and will show it on the screen with half size(if you do not need this, you can remove it by calling captured_image:removeSelf() and captured_image=nil). It can save upto 10000 files.

Syntax:

    local function captureDeviceScreen()
       local captured_image = display.captureScreen( true )
       captured_image:scale(.5,.5)
       local alert = native.showAlert( "Success", "Captured Image is Saved to Library", { "OK" } )
    end
    Runtime:addEventListener("tap",captureDeviceScreen)


And if you want to save the image with desired name, then you can refer the following post:

How to mail a screen captured image using corona SDK

How to zoom in an object and zoom back to normal state in Corona SDK

In Cocos2d you can easily scale an object within two values. For example, you can scale an object to 0.2, and can restore it to 1, whenever you need. But in Corona, if you scale to an object to a value of 0.2, and try and rescale to 1, it keeps it as 0.2. Because, in corona SDK, when you scale an object to a value other than 1, the system will take the new scaled value as the fullscale of the object. So, here we will teach you a simple technique to scale/zoom in and out an object in corona SDK.

1: Create a scaleFactor :

               local scaleFactor = 0.2;

2: When you want to zoom out, do :

               myObject:scale(scaleFactor ,scaleFactor )

3: When you want to zoom in, do :

              myObject:scale(1/scaleFactor ,1/scaleFactor )

Auto-change the physics of an object (created using Physics Editor) after a change of it's size in corona SDK

If you are using physics editor for making physics objects in your corona game, then at some point you may doubted about how to scale the physics area according to the sprite scale values... But it is very simple.

For doing such alternation, there is scaleFactor provided. You can assign physics to the object with this scale factor, as below:

    local scaleFactor = 1.0
    local physicsData = (require "shapedefs").physicsData(scaleFactor)
    local shape = display.newImage("objectname.png")
    physics.addBody( shape, physicsData:get("objectname") )

And when you change the scaleFactor, the size of physics area will automatically change.