Corona SDK Mobile Game Development：Beginner's Guide
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Time for some shapes

Another way of creating display objects is using vector objects. You can use vector objects to create shapes, such as a rectangle, rounded rectangle, and circle by using the following:

  • display.newRect( [parentGroup,] left, top, width, height ) creates a rectangle using width by height. Location starts from the top-left corner of the device screen using left and top as your coordinates of placement.
  • display.newRoundedRect( [parentGroup,] left, top, width, height, cornerRadius ) creates a rounded rectangle using width by height. Location starts from the top-left corner of the device screen using left and top as your coordinates of placement. Rounding off the corners uses cornerRadius.
  • display.newCircle( [parentGroup,] xCenter, yCenter, radius ) creates a circle using radius centered at xCenter, yCenter.

Applying stroke width, fill color, and stroke color

All vector objects can be outlined using strokes. You can set the stroke width, fill color and stroke color.

  • object.strokeWidth—Creates the stroke width in pixels.
  • object:setFillColor( r, g, b [, a] )—Using the r,g,b codes between 0 and 255. a refers to the alpha, which is optional and defaulted at 255.
  • object:setStrokeColor( r, g, b [, a] )—Using the r,g,b codes between 0 and 255. a refers to the alpha, which is optional and defaulted at 255.

The following is an example of displaying vector objects using strokes:

local rect = display.newRect(110, 100, 250, 250)
rect:setFillColor(255, 255, 255) 
rect:setStrokeColor(45, 180, 100) 
rect.strokeWidth = 10
Applying stroke width, fill color, and stroke color

Text, text, text

In Chapter 1, Getting Started With Corona SDK, we created the Hello World application using a text display object. Let's go in detail on how text is implemented onscreen.

display.newText( [parentGroup,] string, x, y, font, size ) creates a text object using x and y values. There is no text color by default. In the font parameter, apply any of the font names in the library. The size parameter displays the size of the text. Some of the default constants can be used if you don't want to apply a font name:

  • native.systemFont
  • native.systemFontBold

Applying color and string value

The size, color, and text fields can be set or retrieved in text display objects.

  • object.size—The size of the text
  • object:setTextColor( r, g, b [, a] )—Using the r,g,b codes between 0 and 255. a refers to the alpha, which is optional and defaulted at 255
  • object.text—Contains the text of the textfield. It allows you to update a string value for a test object
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