palette based encoding

README.md

@@ -2,6 +2,65 @@
 
 A neopixel animation based on bitmaps
 
+# Animation Sheet
+
+Creates an animation from a pre-rendered set of frames
+
+```sig
+light.animationSheet(null, 50)
+```
+
+## Parameters
+
+* ``buffer``, the buffer containing the data (more below)
+* ``interval``, the time in milliseconds between each frame
+
+## Buffer format
+
+The bitmap format should be specified as follows. All values are little endian.
+
+* magic number ``0x2e0a21``, 4 bytes
+* palette size, 1 byte (``npalette``)
+* reserved padding, 1 byte
+* palette, ``npalette`` x 24bit RGB colors
+* frames, ``nleds`` x number of frames. A contiguous sequence of palette color indices.
+
+## Example
+
+### Generating your own animation
+
+The following sample generates a buffer and uses it to create the animation.
+
+```typescript
+const strip = light.pixels;
+const nleds = strip.length();
+const ncolors = 3;
+const nframes = 10;
+const sheet = pins.createBuffer(6 + ncolors * 3 + nleds * nframes);
+const palette = sheet.slice(6, ncolors * 3);
+const frames = sheet.slice(6 + palette.length);
+
+// magic number
+sheet.setNumber(0, NumberFormat.UInt32LE, 0x2e0a21);
+// palette
+sheet[4] = ncolors;
+palette[0] = 0xff; // red
+palette[4] = 0xff; // green
+palette[8] = 0xff; // blue
+// filing up colors
+let k = 0;
+for (let i = 0; i < nleds; ++i) {
+    for (let j = 0; j < nframes; ++j) {
+        frames[k++] = i + j % ncolors;
+    }
+}
+let anim = light.animationSheet(sheet, 50);
+
+loops.forever(() => {
+    strip.showAnimation(anim, 10000);
+})
+```
+
 ## License
 
 MIT

main.ts

@@ -1 +1,70 @@
+namespace light {
+    /**
+     * Creates a neopixel animation from a raw buffer of colors.
+     */
+    //% help=reference/light/animation-sheet
+    export function animationSheet(buffer: Buffer, interval: number): NeoPixelAnimation {
+        const animation = new BufferAnimation(buffer, interval);
+        return animation;
+    }
 
+    const AnimationSheetMagicNumber = 0x2e0a21;
+
+    class BufferAnimation extends NeoPixelAnimation {
+        private bitmap: Buffer;
+        private interval: number;
+        private step: number;
+
+        constructor(bitmap: Buffer, interval: number) {
+            super();
+
+            this.bitmap = bitmap;
+            this.interval = Math.max(1, interval);
+            this.step = 0;
+        }
+
+        public showFrame(strip: NeoPixelStrip): void {
+            if (this.start < 0) {
+                this.step = 0;
+                this.start = control.millis();
+            }
+
+            // check magic number
+            if (this.bitmap.getNumber(NumberFormat.UInt32LE, 0) != AnimationSheetMagicNumber)
+                return;
+
+            // npalette
+            const npalette = this.bitmap[4];
+            // extract palette and frames
+            const palette = this.bitmap.slice(6, npalette * 3);
+            const frames = this.bitmap.slice(6 + palette.length);
+
+            const n = strip.length();            
+            // the image is written row by row
+            let offset = this.step * n;
+            if (offset + n > frames.length) {
+                // last frame is missing images, reset step
+                this.step = 0;
+                offset = 0;
+            }
+
+            const bf = strip.buffered();
+            strip.setBuffered(true);
+            // scan colors starting at offset, lookup color and set in neopixel     
+            for (let i = 0; i < n; i++) {
+                const k = i + offset;
+                const ci = frames[k];
+                const c = rgb(palette[ci], palette[ci + 1], palette[ci + 2]);
+                strip.setPixelColor(i, c);
+            }
+            strip.show();
+            strip.setBuffered(bf);
+
+            // sleep
+            loops.pause(this.interval);
+
+            // increment step
+            this.step = this.step % n;
+        }
+    }
+}

pxt.json

@@ -4,7 +4,8 @@
     "description": "A neopixel animation based on bitmaps",
     "license": "MIT",
     "dependencies": {
-        "circuit-playground": "*"
+        "core": "*",
+        "light": "*"
     },
     "files": [
         "README.md",

tests.ts

@@ -1 +1,27 @@
-// tests go here; this will not be compiled when this package is used as a library
+const strip = light.pixels;
+const nleds = strip.length();
+const ncolors = 3;
+const nframes = 10;
+const sheet = pins.createBuffer(6 + ncolors * 3 + nleds * nframes);
+const palette = sheet.slice(6, ncolors * 3);
+const frames = sheet.slice(6 + palette.length);
+
+// magic number
+sheet.setNumber(0, NumberFormat.UInt32LE, 0x2e0a21);
+// palette
+sheet[4] = ncolors;
+palette[0] = 0xff; // red
+palette[4] = 0xff; // green
+palette[8] = 0xff; // blue
+// filing up colors
+let k = 0;
+for (let i = 0; i < nleds; ++i) {
+    for (let j = 0; j < nframes; ++j) {
+        frames[k++] = i + j % ncolors;
+    }
+}
+let anim = light.animationSheet(sheet, 50);
+
+loops.forever(() => {
+    strip.showAnimation(anim, 10000);
+})