Hey everyone. I think I found a way to accomplish this. It seems like a bit of a hackish way to accomplish it. It may be the right way, but it does seem a little overly complicated to me. In any event, here are the steps I followed to achieve a PNG sequence from a shape tween animated line that contains all line width animation:
- create the animation, like I did in my question (create a line, create several key frames on the timeline that have line width changes [like making it a sword or hammer or whatever], then highlight all key frames and make a shape tween animation)
- highlight all animated frames in the timeline, even the non-keyframes
- right click on the selected frames and choose 'Convert to Key Frames', making all frames key frames. now you have discreet images for each frame of the animation
- while all the new key frames are still highlighted (should be one keyframe every frame now), right click the selected frames and choose 'Copy Frames'
- insert a new symbol (Insert menu -> New Symbol...)
- select type 'Movie Clip', and click OK
- in the timeline of the symbol itself, right click the first frame on the first layer, and select 'Paste Frames'
- scrub that timeline to verify your pasted frames produce the animation you think it should
- if it does, goto your Library window, right click on the symbol you just created, and choose 'Generate Sprite Sheet'
- use the sprite sheet creation tool to create and export your PNG sequence, with a transparent background
- use your game IDE to import the sprite sheet
I hope this helps someone. There may be a better way to do it, but hey, this way works. So until I learn of a better way to do it, I will just use this, and you are welcome to as well
You can use: File menu > Export > Export Movie.
Choose the file type as PNG Sequence and proceed.
It should export all the frames on your timeline as PNG files in a sequence.