PicTapGo’s crop tool is a unique beast. The tool I envisioned was inspired by Lightroom’s crop/rotate tool, but needed to work within the limitations of a mobile / touch device interface. The requirements for the this feature were essentially:
- Allow the user to simultaneously manipulate rotation and crop;
- Behave the way the user expects (i.e. if you think it should work a certain way, then it will);
- Automatically adjust the image to ensure the crop rectangle is entirely contained within the the image canvas (no “fill pixels” at the edges or corners);
- Work non-destructively;
- Maximize the displayed size of the image; and
- Provide continuous controls, as well as discrete ones (i.e. sliders and buttons) to facilitate quick and fine adjustments, and to increase precision.
The resulting solution is, I think, still the best crop and rotate tool around, period. There are a lot of subtle bits that make it an intuitive, easy, powerful tool.