Applying transparency to only a part of a stack?

[Zax]

Hello,

Is there a way to apply transparency to only a part of a stack like the following demo (made with Photoshop) with LC Indy 9.04?
If the blendLevel of a stack is modified, all its controls will be transparent. On the other hand, if the blendLevel of an image is modified, the stack background is still visible.

Thank you.

[Klaus]

Hi Zax,

I think this may get you started:
https://lessons.livecode.com/m/4071/l/2 ... ks-windows

Best

Klaus

[bogs]

Yes, it is possible (and fairly easy).

I recreated the look of the stack you posted, but I prefer cars to dogs. The settings and controls are included in the picture (Lc 6.5.2, will work in any version later I suspect).

[Zax]

Thanks for your answers.

@Klaus: I'm studying this lesson but I'm not sure it will help me.

@bogs: I don't understand because this is what I have with a default stack, only applying a 50% blendSrcIn effect of an image object :

Making the image transparent only reveals stack's background (default grey).
But you're right, cars are better than dogs

[bogs]

@bogs: I don't understand because this is what I have with a default stack, only applying a 50% blendSrcIn effect of an image object :

screen.jpg

Making the image transparent only reveals stack's background (default grey).
But you're right, cars are better than dogs

Heh, I dunno what to tell you there, I rarely venture higher than 6.5.x, and usually am far lower in version numbers (like Mc 2.5) as far as IDEs go, but since your test flopped, I dragged some of the newer IDEs out of storage to see what was going on.

What I found out (on linux) was -

1. I couldn't get 9.6 to even resize the image, and changing blend levels for various inks did nothing. { This is no surprise to me, LOTS of things in 9.6 don't work here worth squat }
2. 9.5 - was at least able to assemble a copy stack for demonstration and worked as far as the topic is concerned.
   
3. I guess I didn't even try to download any versions between 8.1.2 and 9.5, 8.1.2 is iffy here, even 8.0.1 is no wonder shakes.
4. 8.0.1 and 8.1.2 *were* able to do exactly that same trick, though.

So, my guess would be that, much like 9.6 here, something is going on in that version your using, or, alternately, there is some conflict between that version ( or version range ) and your OS.

The only way to know that would be to post your OS specs ( guessing OSX, but which one? ) and see if someone else using it in combination with LC 9.04 can duplicate the problem.

Likely suspects for testing would be Klaus, Richmond, or Jacque off the top of my head.

Alternately, make the stack in an earlier (or later) version of Lc, save it setup how you like, then open it in 9.04 and see if the transparency stuck while in that IDE or after building. I don't see why it shouldn't as long as it is properly set.

[Zax]

OK, I finally understand the lesson linked by Klaus. It's very helpful, though it could be a little bit more accurate.

I still have a problem about the ink: I would like to a assign a "blendMultiply" ink to the process but it doesn't seem to work as intended.

(the red border is for development purpose)

@bogs: I'm using LC 9.04 on MacOS Sierra 10.12.6.
Maybe it depends on car model

[bogs]

@bogs: I'm using LC 9.04 on MacOS Sierra 10.12.6.
Maybe it depends on car model

No, it is almost certainly that the ink isn't being properly applied heh, but I'm sure you already know that

You know, it also came to my mind that there is a (relatively) simple way to accomplish this outside of Lc, but I hesitate to mention it as some people don't care for windowShape.

WindowShape requires a bit more massaging as well, but the basic idea is, you take a picture of your stack in it's solid shape with all areas defined, make whatever area you want to be transparent more transparent in a paint program, and then set the window shape to that image after you import it as a control (or reference it, but then your dealing with file systems as well).

This would be an example of using windowShape and an image to define solid / non solid parts of the window.


I'll work up an example of some different ways to accomplish what I mean and post a link to it.

[Zax]

Thanks bogs for your time
I would like to manage transparency from inside LC because I would like to adjust it with the scroller (shown at the topleft of my screenshot).

When my user interface (and my scripts) will work, I'll try to make more accurate ink transformation, like full transparency on white or black areas.

[bogs]

This would be the brute force method, just using windowShape (and an image editor!). Mind you, for what your doing, I would just find out which vers. of Lc accomplishes what you want, and use that to make the stack initially.

1. Here I blatantly ripped off your smug dog picture stack and imported it into a paint program (GIMP).
   
2. I used the rectangle select tool and cut the area I want transparent.
   
   
   *Note - make sure you put some kind of fill color with the opacity desired into that area, or you will see nothing.
3. Save the file as a .png and import it as a control to the stack you want this ultimately to wind up in.
   
4. Set the windowShape of the stack to that image.
   
5. Put another image control on top of that and set it's size appropriately...
   
   
   As you can see, you have your semi transparent image at this point.
6. PROFIT !

Mind you, you will have to write a (small to medium) amount of code to handle things like dragging the window, resizing it, etc., there are a lot of examples around on how to do this. Me, I would probably stick to the inks and blendlevels for this kind of effect though.

**Edit - you posted as I was composing this ...

Thanks bogs for your time
I would like to manage transparency from inside LC because I would like to adjust it with the scroller (shown at the topleft of my screenshot).

In the case of the above method, the only thing that would change is that you would group the image on top of the windowShape image, the group would provide scrollbars for you if the image is larger than the group.

Some caveats to that would be that the region itself couldn't be resized, so the group's size would have to be locked at the size of that region.

[Zax]

I spent some time trying to make the picture resizable but finally it works
Thanks again for all your help.

As you can see, it works with cars and dogs. I didn't try with cats but it should work

Now ink effects remain rather mysterious for me... For example, is there a way to make transparency only for white, or only for black?

[bogs]

Unfortunately, I don't have the answer to the question about black and white, we'll need someone that actually knows more about inks and blending to step up to answer for you

[jmburnod]

Hi Zax,

For example, is there a way to make transparency only for white, or only for black?

Not sure I understand correctly

If you want apply transparency to an image I think yes but i never did it.

From dictionary

Use the alphaData property to control the transparency of the pixels in an image.
Each pixel is represented by 8 bits (1 byte) of alpha channel data, with pixels numbered from the top left corner of the image, left to right, then top to bottom.
A value of zero means the pixel is fully transparent; a value of 255 is fully opaque; and values in between indicate a level of partial translucency.

Best regards
Jean-Marc

[Zax]

Not sure I understand correctly

Sorry, for a given image, I would like to make the darker parts more transparent than the brighter ones, and conversely. It can be done with softwares like Photoshop.

I tried to play with alphaData but didn't understand. In fact, I was wondering if there is a preset ink mode in LC that would do what I want.

[jacque]

I can never remember what each ink does. I just select the image and click my way through them all. Sometimes twice.

[bogs]

That is my method usually as well, sometimes I see an effect that is more desirable than what I was shooting for to begin with