It should be fairly simple to narrow these elements down, if you still have something left on the list from the first step. You should always consider each function that you want to implement yourself, if it might be better to let the framework handle it (if it can...).
I need the following to functions in my current project:
- Basic image manipulation
- Drawing/Painting
Let's have a closer look:
Basic image manipulation: I need crop, rotate and zoom. These are fairly simple to implement. If the framework has image manipulation, I will weigh towards it, but it's not that critical. My current project can even survive without it.
Drawing/Painting: I need to be able to draw simple figures. I do have some SVG's that I do want to use for drawing some simple images, which should be possible to fill. I've added a google presentation below to show it. This can be implemented as a canvas (html5), opengl, some native drawing wrapper, or other options. I prefer if it has some built in 2d vector functionality, but falling back to opengl is also acceptable. (And would probably perform better as well)
As my app cannot function without drawing/painting, I do feel this is so critical, that it's worth using most of the development time on this area.
Here's what it should be able to do:
Note about the image: I've used images from google image search, so if you do have a copyright on any of the images, please let me know, and I'll be sure to mention you in the post, or remove the image if you don't want it in the sketch.
Some of these features might require quite an amount of work to implement, so always consider if you either learn a great deal about the framework, the platforms, programming techniques, and if you can reuse any of the code in a later project. Also consider if you can use any third party helper libraries to ease your development, and probably speed the development time up as well. However, you are in full control when you write from scratch.