Is there a way to get graphic transparency in IOS?
Just circling back here to see is there a way to make a graphic in iOS to have a level of transparency like on Desktop?
IOSBitmap has iOSGraphics
iOSGraphics has .Alpha properties, so yes.
Also see .cliptoPath
also, in the iosLibs I find ImageWithMaskXC
all looks promising?
1 Like
SO, looking to achieve this in 2022, I cannot get it to work. A deep search of the forum finds this( our own) posts from a year ago.
@Martin_Fitzgibbons … did you have any success?
Hi Jeff,
I don’t think so as I didn’t reply back. I think I was exploring MBS but got distracted and moved on 
I think the reason could be iOSGraphics is missing the BlendMode property that makes it possible to overlay drawings in a way they don’t simply overpaint. I’m pretty sure you will find the necessary declares in one of the extensions/modules/plugins that enable full CGContext access.
Then arguably Xojo can find the necessary declares too. 
Hmm…
I’ll work something.
Does iOSGraphics.Alpha not do what you need?
Does iOSGraphics.Alpha not do what you need?
Nope.
That makes the whole ‘sprite’ transparent.
Imagine a square image with a cherry
I would want the cherry solid, and the rest transparent.
So that I can .drawpicture the image onto a wall, and see wall around cherry, rather than a while square on the wall with a cherry in it
MASK does that on desktop, as does a PNG image with transparency
I can find no way to take a solid image and make part of it transparent afterwards
.CliptoPath should do it… applied to the target so that I can only paste into a cherry shaped hole
But it doesn’t.
My current work around is to use a grab of the background, then pixel by pixel, copy the wanted parts from the source into, using RGBSurface
I found a bug related to transparency last month; I haven’t filed it yet. Not sure if it pertains to the OP’s problem:
Top code:
g.Scale(0.25, 0.25)
g.Transparency = 75
g.DrawPicture(DogSign, 0, 0)
Bottom code:
g.Scale(0.25, 0.25)
g.Transparency = 75
g.DrawPicture(DogSign, 0, 0, DogSign.Width, DogSign.Height, 0, 0, DogSign.Width, DogSign.Height)
'g.DrawPicture(DogSign, 0, 0, DogSign.Width, DogSign.Height) // This works too
On iOS, Graphics.Transparency only works if you use a longer DrawPicture method signature.
On macOS, the same code produces the correct result in both examples.