How can I get the colour (fill) of a DisplayObject in response to an event like a touch in Corona SDK?

问题

Can anyone help me find out how can I can get the color of rectangle in corona? That rectangle I already filled with color, so now I want to get that color when I touch on rectangle.

回答1:

Create your rectangle:

local rectangle = display.newRect(0, 0, 100, 100)

Put your color in RGBA (you can leave out the A) format in a table, and store it as a "custom property" for the rectangle:

rectangle.fillColor = {110, 30, 25}

Through the magic of the unpack function, which returns the values of a table, pass the table to setFillColor:

rectangle:setFillColor( unpack(rectangle.fillColor) )

Now you can always get the color like so:

print( unpack(rectangle.fillColor) ) --> 110    30    25

print( rectangle.fillColor ) -- simply returns the table

or to put each color in a variable:

local red, green, blue, alpha = unpack(rectangle.fillColor)

You'll see how this can come in handy for other things as well.

EDIT

Just thought of another cool way of doing it, by highjacking the setFillColor function:

local function decorateRectangle(rect)
    rect.cachedSetFillColor = rect.setFillColor -- store setFillColor function

    function rect:setFillColor(...) -- replace it with our own function
        self:cachedSetFillColor(...)
        self.storedColor = {...} -- store color
    end

    function rect:getFillColor()
        return unpack(self.storedColor)
    end
end

local rectangle = display.newRect(0, 0, 100, 100)

decorateRectangle(rectangle) -- "decorates" rectangle with more awesomeness

Now you can use setFillColor to set color as normal, AND getFillColor to return it :)

rectangle:setFillColor(100, 30, 255, 255)

print(rectangle:getFillColor())

回答2:

in short: you cannot 'get' the fill colour. you have to save it yourself..

回答3:

This is also another method to obtain color of the rect.

create a table of colors

local colors = {    {255,0,0},  {0,0,255},  {0,255,0},  {255, 255, 0},  {255,0,255}}

Then when you create your rectangle, make it look like this:

local rect = display.newRect(0, 0,100,100)
rect.color = math.random(1,5)
rect:setFillColor(unpack(colors[rect.color]))

Now if you want to obtain the color of the rect do like this
```
local appliedcolor = colors[rect.color];
```

Thanks to https://forums.coronalabs.com/topic/18414-get-fill-color-of-an-object/

回答4:

A DisplayObject's many property values, including RGB values for the fill color, can be inspected using object._properties. DisplayObject introspection was added in Build 2014.2511, i.e. two years after this question was asked.

The information is returned as a JSON formatted string, so the json.* library is used to extract the property (properties) of interest.

Assuming a DisplayObject called object, you would do something like:

local json = require( "json" )
local decoded, pos, msg = json.decode( object._properties )
if not decoded then
    -- handle the error (which you're not likely to get)
else
    local fill = decoded.fill
    print( fill.r, fill.g, fill.b, fill.a )
end

来源：https://stackoverflow.com/questions/11239054/how-can-i-get-the-colour-fill-of-a-displayobject-in-response-to-an-event-like

标签

corona