refactor(pixel): convert resize() into class method

- move `IntSampler`, `FloatSampler` types to api.ts - migrate `resize()` to `PackedBuffer.resize()` - replace `PackedBuffer.downsample()` w/ new `PackedBuffer.scale()` - update resize filter arg to also accept custom sampler
thi-ng · Mar 17, 2021 · 1c4dcaa · 1c4dcaa
1 parent 25bcd83
commit 1c4dcaa
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diff --git a/assets/pixel/resize-bicubic.jpg b/assets/pixel/resize-bicubic.jpg
diff --git a/assets/pixel/resize-bilinear.jpg b/assets/pixel/resize-bilinear.jpg
diff --git a/assets/pixel/resize-nearest.png b/assets/pixel/resize-nearest.png
diff --git a/packages/pixel/README.md b/packages/pixel/README.md
@@ -150,7 +150,7 @@ sampler(-1.1, 0.5).toString(16)
 // 'ff79643a'
 
 // resize image to 1024x256 using bicubic sampling
-const img = resize(src, 1024, 256, "cubic");
+const img = src.resize(1024, 256, "cubic");
 ```
 
 | Filter      |                                                                                                                                          |
@@ -259,7 +259,7 @@ yarn add @thi.ng/pixel
 <script src="https://unpkg.com/@thi.ng/pixel/lib/index.umd.js" crossorigin></script>
 ```
 
-Package sizes (gzipped, pre-treeshake): ESM: 8.17 KB / CJS: 8.45 KB / UMD: 8.20 KB
+Package sizes (gzipped, pre-treeshake): ESM: 8.19 KB / CJS: 8.47 KB / UMD: 8.22 KB
 
 ## Dependencies
 

diff --git a/packages/pixel/src/api.ts b/packages/pixel/src/api.ts
@@ -4,6 +4,7 @@ import type {
     Fn2,
     Fn3,
     FnN,
+    FnU2,
     IObjectOf,
     NumericArray,
     TypedArray,
@@ -439,3 +440,7 @@ export interface NormalMapOpts {
      */
     z: number;
 }
+
+export type IntSampler = FnU2<number>;
+
+export type FloatSampler = FnU2<number, FloatArray>;
diff --git a/packages/pixel/src/index.ts b/packages/pixel/src/index.ts
@@ -6,7 +6,6 @@ export * from "./dither";
 export * from "./float";
 export * from "./normal-map";
 export * from "./packed";
-export * from "./resize";
 export * from "./sample";
 export * from "./utils";
 

diff --git a/packages/pixel/src/packed.ts b/packages/pixel/src/packed.ts
@@ -1,12 +1,13 @@
 import {
+    assert,
     Fn,
     ICopy,
     IEmpty,
     typedArray,
     UIntArray,
     uintTypeForBits,
 } from "@thi.ng/api";
-import { isNumber } from "@thi.ng/checks";
+import { isNumber, isString } from "@thi.ng/checks";
 import {
     isPremultipliedInt,
     postmultiplyInt,
@@ -17,6 +18,8 @@ import {
     BayerSize,
     BlendFnInt,
     BlitOpts,
+    Filter,
+    IntSampler,
     IPixelBuffer,
     Lane,
     PackedChannel,
@@ -28,6 +31,7 @@ import { compileGrayFromABGR, compileGrayToABGR } from "./codegen";
 import { defBayer } from "./dither";
 import { ABGR8888 } from "./format/abgr8888";
 import { defPackedFormat } from "./format/packed-format";
+import { defSampler } from "./sample";
 import {
     clampRegion,
     ensureChannel,
@@ -425,27 +429,32 @@ export class PackedBuffer
     }
 
     /**
-     * Returns new buffer of downscaled version (by given integer factor) using
-     * simple nearest neighbor sampling.
+     * Returns scaled version of this buffer using given sampler or filter
+     * (default: `"linear"`) for interpolation. Syntax sugar for
+     * {@link PackedBuffer.resize}.
      *
-     * @param res
+     * @param scale
      */
-    downsample(res: number) {
-        res |= 0;
-        const { width, height, pixels: sbuf } = this;
-        const dest = new PackedBuffer(
-            (width / res) | 0,
-            (height / res) | 0,
-            this.format
-        );
-        const { width: dwidth, height: dheight, pixels: dbuf } = dest;
-        for (let y = 0, i = 0; y < dheight; y++) {
-            for (
-                let x = 0, j = y * res * width;
-                x < dwidth;
-                x++, i++, j += res
-            ) {
-                dbuf[i] = sbuf[j];
+    scale(scale: number, sampler: IntSampler | Filter = "linear") {
+        assert(scale > 0, `scale must be > 0`);
+        return this.resize(this.width * scale, this.height * scale, sampler);
+    }
+
+    resize(w: number, h: number, sampler: IntSampler | Filter = "linear") {
+        w |= 0;
+        h |= 0;
+        assert(w > 0 && h > 0, `target width & height must be > 0`);
+        const dest = packedBuffer(w, h, this.format);
+        const dpix = dest.pixels;
+        const scaleX = w > 0 ? this.width / w : 0;
+        const scaleY = h > 0 ? this.height / h : 0;
+        sampler = isString(sampler)
+            ? defSampler(this, sampler, "repeat")
+            : sampler;
+        for (let y = 0, i = 0; y < h; y++) {
+            const yy = y * scaleY;
+            for (let x = 0; x < w; x++, i++) {
+                dpix[i] = sampler(x * scaleX, yy);
             }
         }
         return dest;

diff --git a/packages/pixel/src/resize.ts b/packages/pixel/src/resize.ts
diff --git a/packages/pixel/src/sample.ts b/packages/pixel/src/sample.ts
@@ -1,19 +1,15 @@
-import {
-    assert,
-    FloatArray,
-    Fn,
-    FnU2,
-    IObjectOf,
-    NumericArray,
-} from "@thi.ng/api";
-import { clamp, fmod, fract, mixBilinear, mixBicubic } from "@thi.ng/math";
-import type { Filter, IPixelBuffer, Wrap } from "./api";
+import { assert, Fn, IObjectOf, NumericArray } from "@thi.ng/api";
+import { clamp, fmod, fract, mixBicubic, mixBilinear } from "@thi.ng/math";
+import type {
+    Filter,
+    FloatSampler,
+    IntSampler,
+    IPixelBuffer,
+    Wrap,
+} from "./api";
 import type { FloatBuffer } from "./float";
 import type { PackedBuffer } from "./packed";
 
-type IntSampler = FnU2<number>;
-type FloatSampler = FnU2<number, FloatArray>;
-
 export function defSampler(
     src: PackedBuffer,
     filter?: Filter,
@@ -188,7 +184,9 @@ const mixBicubicChan = (
     u: number,
     v: number,
     i: number,
-    s = 4
+    s = 4,
+    min = 0,
+    max = 255
 ) =>
     clamp(
         mixBicubic(
@@ -211,14 +209,14 @@ const mixBicubicChan = (
             u,
             v
         ),
-        0,
-        255
+        min,
+        max
     );
 
 const bicubicABGR = (src: PackedBuffer, sample: IntSampler): IntSampler => {
     const { fromABGR, toABGR } = src.format;
-    const buf32 = new Uint32Array(16);
-    const buf8 = new Uint8Array(buf32.buffer);
+    const u32 = new Uint32Array(16);
+    const u8 = new Uint8Array(u32.buffer);
     return (x, y) => {
         x -= 0.5;
         y -= 0.5;
@@ -230,28 +228,28 @@ const bicubicABGR = (src: PackedBuffer, sample: IntSampler): IntSampler => {
         const y3 = y + 2;
         const u = fract(x);
         const v = fract(y);
-        buf32[0] = toABGR(sample(x1, y1));
-        buf32[1] = toABGR(sample(x, y1));
-        buf32[2] = toABGR(sample(x2, y1));
-        buf32[3] = toABGR(sample(x3, y1));
-        buf32[4] = toABGR(sample(x1, y));
-        buf32[5] = toABGR(sample(x, y));
-        buf32[6] = toABGR(sample(x2, y));
-        buf32[7] = toABGR(sample(x3, y));
-        buf32[8] = toABGR(sample(x1, y2));
-        buf32[9] = toABGR(sample(x, y2));
-        buf32[10] = toABGR(sample(x2, y2));
-        buf32[11] = toABGR(sample(x3, y2));
-        buf32[12] = toABGR(sample(x1, y3));
-        buf32[13] = toABGR(sample(x, y3));
-        buf32[14] = toABGR(sample(x2, y3));
-        buf32[15] = toABGR(sample(x3, y3));
+        u32[0] = toABGR(sample(x1, y1));
+        u32[1] = toABGR(sample(x, y1));
+        u32[2] = toABGR(sample(x2, y1));
+        u32[3] = toABGR(sample(x3, y1));
+        u32[4] = toABGR(sample(x1, y));
+        u32[5] = toABGR(sample(x, y));
+        u32[6] = toABGR(sample(x2, y));
+        u32[7] = toABGR(sample(x3, y));
+        u32[8] = toABGR(sample(x1, y2));
+        u32[9] = toABGR(sample(x, y2));
+        u32[10] = toABGR(sample(x2, y2));
+        u32[11] = toABGR(sample(x3, y2));
+        u32[12] = toABGR(sample(x1, y3));
+        u32[13] = toABGR(sample(x, y3));
+        u32[14] = toABGR(sample(x2, y3));
+        u32[15] = toABGR(sample(x3, y3));
         return (
             fromABGR(
-                (mixBicubicChan(buf8, u, v, 3) << 24) |
-                    (mixBicubicChan(buf8, u, v, 2) << 16) |
-                    (mixBicubicChan(buf8, u, v, 1) << 8) |
-                    mixBicubicChan(buf8, u, v, 0)
+                mixBicubicChan(u8, u, v, 0) |
+                    (mixBicubicChan(u8, u, v, 1) << 8) |
+                    (mixBicubicChan(u8, u, v, 2) << 16) |
+                    (mixBicubicChan(u8, u, v, 3) << 24)
             ) >>> 0
         );
     };

diff --git a/packages/pixel/tpl.readme.md b/packages/pixel/tpl.readme.md
@@ -131,7 +131,7 @@ sampler(-1.1, 0.5).toString(16)
 // 'ff79643a'
 
 // resize image to 1024x256 using bicubic sampling
-const img = resize(src, 1024, 256, "cubic");
+const img = src.resize(1024, 256, "cubic");
 ```
 
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