Write a more proper README

README.md

@@ -1,3 +1,62 @@
 # kanjivg-tools
 
-Various utilities for working with the kanjivg dataset.
+WIP
+
+## Kanimaji & KanimajiTool
+
+This is a library & program pair that implements CSS animations for SVG files in the KanjiVG
+dataset, roughly based on the original [kanimaji.py](https://github.com/maurimo/kanimaji) script
+([mirror](https://code.3011.io/Mirrors/kanimaji)).
+
+The program is just a dead simple executable driver for the library.
+This project is currently still work in progress, but it is feature complete, and no major changes
+are expected in the public API (apart for error handling).
+
+### Library usage
+
+In the simplest usecase, the library consists of just two public functions:
+```cpp
+void AnimateFile(const Path& source, const Path& destination,
+                 const AnimationSettings& settings = AnimationSettings::Default());
+
+std::string Animate(const std::string& source,
+                    const AnimationSettings& settings = AnimationSettings::Default());
+```
+
+The former function takes in two paths, where the first one specifies the file to be read, and
+the second one specified a path where the resulting animated SVG image shoule be stored.
+
+The latter takes in a string that already contains the SVG kanji data, and returns a string
+containing the animated SVG file. This function performs all operations in memory.
+
+The default settings (currently) approximate the default settings in the kanimaji.py script.
+In case these are not desired, it is possible to configure the animation to an extent, e.g. like
+this:
+```cpp
+AnimateFile("084b8.svg", "084b8-out.svg", AnimationSettings {
+    .StrokeProgression = Progression::EaseInOut,
+    .UnfilledStroke = StrokeStyle {
+        .Width = 2.0,
+        .Colour = RGB::FromHex("#EEEEEE"),
+    },
+    .FilledStroke = StrokeStyle {
+        .Width = 3.0,
+        .Colour = RGB::FromHex("#000000"),
+    },
+    .StrokeFillingColour = RGB::FromHex("#FF0000"),
+    .EnableBrush = Flag::Enable,
+    .Brush = StrokeStyle {
+        .Width = 5.5,
+        .Colour = RGB::FromHex("#FF0000"),
+    },
+    .BrushBorder = StrokeStyle {
+        .Width = 7.0,
+        .Colour = RGB::FromHex("#666666"),
+    },
+    .LengthToTimeScaling = [] (double length) -> double {
+        return std::pow(length, 1.0 / 3.0) / 6.0;
+    },
+    .WaitBeforeRepeating = 1s,
+    .DelayBetweenStrokes = 50ms,
+});
+```