Stretching a UIImage across the length of a UIBezierPath

Question

What I basically need to achieve is a Fruit Ninja - style "slash" effect, where the "slash" trails the user's touch and follows the shape of the user's gesture, and is thinner the longer the distance the user has swiped.

The simplest way to achieve this seemed to be to collect all the points the user passes through in a UIBezierPath, and "stretch" an image through the length of the BezierPath. This would achieve the kind of "trailing" effect I was looking for and also ensure that the line is thinner if the distance travelled is longer.

However I can't seem to find a way to actually implement this. Is this even possible?

Alternatives? Thanks.

PS: This is for a low-medium priority section of a regular app and not a game, so I would like to avoid having go down to OpenGL and spend a lot of time to achieve this (with completely custom drawing, etc). Something at the SDK level would be preferred, and if that's not possible at all, we'll just figure out a different UI.

Thanks!

Answer 1

For pretty easy-to-use stretching teqhniques of images/views you could look into

https://github.com/hfossli/AGGeometryKit/

Answer 2

I recommend trying to draw using CoreGraphics. See this link

http://www.effectiveui.com/blog/2011/12/02/how-to-build-a-simple-painting-app-for-ios/

Answer 3

Okay. Maybe you can use this.

https://github.com/hfossli/AGDraw

Just something I wrote a while ago. Hit clear and try to draw something (clear will toggle between two types of strokes). You'll see the width of the penstroke will increase with the velocity you use.. I guess that fits your need. If you fix some bugs, please make a pull request. You are free to use the code, but I will add a MIT license later.