Thrash pixels on some Android phone

Rickyngk · August 2012

I'm using Galaxy Gio: http://www.gsmarena.com/samsung_galaxy_gio_s5660-3741.php
And the following attachment shows exactly that is displayed on phone. There're a lot of black dots

Have you ever got the same issue before, please give me a hint !

Thanks,

moopf · August 2012

That looks a lot like dithering to me. Does it look the same in the Gideros desktop player? If it does, then it's likely to be the bit depth you have saved the images in originally. If it doesn't, do you know what the bit depth of the Gio is?

Rickyngk · August 2012

This issue is not happened on desktop player (and some other device)

The folowing is GIO's detail:

TFT capacitive touchscreen, 16M colors
Device VGA infomation:
+ Vender: Qualcomm
+ Renderer: Adreno 200
+ Version: OpelGLES 2.0

+ Pixel formats (rgba - z - stencil)
5650 - 0 - 0
5650 - 16 - 0
5650 - 24 - 8
8880 - 0 - 0
8880 - 16 - 0
8888 - 0 - 0
8888 - 16 - 0
8888 - 24 - 8
0008 - 0 - 0
0008 - 16 - 0

moopf · August 2012

OK, what format are you saving the images in? My only other guess would be that however you're saving them, this is being downgraded for display by the Gio. I don't know the phone at all, so it's purely a guess.

Rickyngk · August 2012

I find-out that many phones which support only 16M color, 256K color have got this issue.
I used 24/32bit png file. So, should I reduce to 16 bits (and how ?) ?

moopf · August 2012

What image package are you using?

Rickyngk · August 2012

image package ? What do you mean ?

moopf · August 2012

I mean what application are you using to create the images in the first place.

Rickyngk · August 2012

I use both ps and paint.net

moopf · August 2012

You should be able to change it to save a 16-bit PNG in PS, try that. Not sure about paint.net

Rickyngk · August 2012

Thank @moopf. I'll try when back to my office in next week

Rickyngk · August 2012

Finally, I've found the reason behind. I can't give exactly my code, but it works in the same way with following code:

function GetWatermark(alpha, rgb, x, y, w, h)
	local obj = Shape.new()
	obj:setLineStyle(0, rgb)
	obj:setFillStyle(Shape.SOLID, rgb, alpha)
	obj:beginPath()
	obj:moveTo(x, y)
	obj:lineTo(x, y + h)
	obj:lineTo(x + w, y + h)
	obj:lineTo(x + w, y)
	obj:lineTo(x, y)
	obj:closePath()
	obj:endPath()
	obj:setVisible(alpha > 0)
	return obj
end
 
spr = Sprite.new()
sprChild = {Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new(), Sprite.new()}
 
for _,v in pairs(sprChild) do
	v:addChild(GetWatermark(0, 0xFFFFFF, 0, 0, 320, 240))
	spr:addChild(v)
end
 
local texture = Texture.new("logo.png")
local bitmap = Bitmap.new(texture)
 
sprChild[1]:addChild(bitmap)
 
stage:addChild(spr)

This bug is come from

v:addChild(GetWatermark(0, 0xFFFFFF, 0, 0, 320, 240))

@atilim: would you please explain why?

I fixed by checking if alpha is zero, I set visible to false.

(Note: this bug happen on Android device, which support 16M color or 256K color)

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