This library is heavily inspired by kadenzipfel's bit-packed-map (https://github.com/kadenzipfel/bit-packed-map) which was originally written in solidity. The goal of this repo is to allow users to store and render svgs on chain (starknet) with little to no gas fees involved by storing them in the form of a compact bit-packed map.
Consider the following bitmap: 0x7624778dedc75f8b322b9fa1632a610d40b85e106c7d9bf0e743a9ce291b9c63. We can see how each 4 bit value is assigned to a square according to the above color pallet.
| 7 | 6 | 2 | 4 | 7 | 7 | 8 | d |
|---|---|---|---|---|---|---|---|
| e | d | c | 7 | 5 | f | 8 | b |
| 3 | 2 | 2 | b | 9 | f | a | 1 |
| 6 | 2 | 3 | a | 6 | 1 | 0 | d |
| 4 | 0 | b | 8 | 5 | e | 1 | 0 |
| 6 | c | 7 | d | 9 | b | f | 0 |
| e | 7 | 4 | 3 | a | 9 | c | e |
| 2 | 9 | 1 | b | 9 | c | 6 | 3 |
Each character in the bitmap corresponds to a single color in the color pallet. With bitwise operations, each individual pixel can be searched and rendered on an svg.
The render_svg function can be used to obtain an svg of the bitmap.
Git clone the repo and run the command protostar test
Try the contract out by using this link: https://goerli.voyager.online/contract/0x0211c191fff62591f22bed8086ac2d1e96456c01fc4fd96f2be0a6d6dfe25fbb
Put in 0x7624778dedc75f8b322b9fa1632a610d,0x40b85e106c7d9bf0e743a9ce291b9c63 as input of render_svg function and delete all the commas to produce an svg ready to be rendered!
So far, a bitmap of an 8x8 image of 4 bit colors can be rendered with 59,385 steps used, which is way below the 1,000,000 step limit. More testing is due to be done to test its limits, feel free to contribute!