feat(applyTransformsShapes): new plugin

docs/03-plugins/apply-transforms-shapes.mdx

@@ -0,0 +1,31 @@
+---
+title: Apply Transforms to Shapes
+svgo:
+  pluginId: applyTransformsShapes
+  parameters:
+    floatPrecision:
+      description: Number of decimal places to round to, using conventional rounding rules.
+      default: 3
+    leadingZero:
+      description: If to trim leading zeros.
+      default: true
+  defaultPlugin: true
+---
+
+Applies the `transform` attribute directly to `<circle>`, `<ellipse>`, `<rect>`, and `<image>` when possible.
+
+## Usage
+
+<PluginUsage />
+
+### Parameters
+
+<PluginParams />
+
+## Demo
+
+<PluginDemo />
+
+## Implementation
+
+- https://github.com/svg/svgo/blob/main/plugins/applyTransformsShapes.js

lib/builtin.js

@@ -1,6 +1,7 @@
 import presetDefault from '../plugins/preset-default.js';
 import * as addAttributesToSVGElement from '../plugins/addAttributesToSVGElement.js';
 import * as addClassesToSVGElement from '../plugins/addClassesToSVGElement.js';
+import * as applyTransformsShapes from '../plugins/applyTransformsShapes.js';
 import * as cleanupAttrs from '../plugins/cleanupAttrs.js';
 import * as cleanupEnableBackground from '../plugins/cleanupEnableBackground.js';
 import * as cleanupIds from '../plugins/cleanupIds.js';
@@ -57,6 +58,7 @@ export const builtin = [
   presetDefault,
   addAttributesToSVGElement,
   addClassesToSVGElement,
+  applyTransformsShapes,
   cleanupAttrs,
   cleanupEnableBackground,
   cleanupIds,

lib/svgo/tools.js

@@ -192,6 +192,28 @@ export const includesUrlReference = (body) => {
   return new RegExp(regReferencesUrl).test(body);
 };
 
+/**
+ * Checks if changing the position or size of an element would
+ * cause the element to look different.
+ * @param {import('../types.js').ComputedStyles} computedStyle
+ * @returns {boolean} If it's safe to change the position.
+ */
+export const canChangePosition = (computedStyle) => {
+  if (computedStyle['marker-start']) return false;
+  if (computedStyle['marker-mid']) return false;
+  if (computedStyle['marker-end']) return false;
+  if (computedStyle['clip-path']) return false;
+  if (computedStyle['mask']) return false;
+  if (computedStyle['mask-image']) return false;
+  for (const name of ['fill', 'filter', 'stroke']) {
+    const value = computedStyle[name];
+    if (value?.type == 'static' && includesUrlReference(value.value))
+      return false;
+  }
+
+  return true;
+};
+
 /**
  * @param {string} attribute
  * @param {string} value

plugins/applyTransformsShapes.js

@@ -0,0 +1,291 @@
+import { collectStylesheet, computeStyle } from '../lib/style.js';
+import {
+  toFixed,
+  removeLeadingZero,
+  canChangePosition,
+} from '../lib/svgo/tools.js';
+import { transform2js, transformsMultiply } from './_transforms.js';
+
+export const name = 'applyTransformsShapes';
+export const description = 'Applies transforms to some shapes.';
+
+const APPLICABLE_SHAPES = ['circle', 'ellipse', 'rect', 'image'];
+
+/**
+ * Applies transforms to some shapes.
+ *
+ * @author Kendell R
+ *
+ * @type {import('./plugins-types.js').Plugin<'applyTransformsShapes'>}
+ */
+export const fn = (root, params) => {
+  const { floatPrecision = 3, leadingZero = true } = params;
+  const stylesheet = collectStylesheet(root);
+  return {
+    element: {
+      enter: (node) => {
+        if (
+          !APPLICABLE_SHAPES.includes(node.name) ||
+          !node.attributes.transform
+        ) {
+          return;
+        }
+
+        const computedStyle = computeStyle(stylesheet, node);
+        if (computedStyle.filter) return;
+        if (!canChangePosition(computedStyle)) {
+          return;
+        }
+
+        const transformStyle = computedStyle.transform;
+        if (
+          transformStyle.type !== 'static' ||
+          transformStyle.value !== node.attributes.transform
+        ) {
+          return;
+        }
+        const matrix = transformsMultiply(
+          transform2js(node.attributes.transform),
+        );
+
+        if (
+          computedStyle.stroke?.type === 'dynamic' ||
+          computedStyle['stroke-width']?.type === 'dynamic'
+        ) {
+          return;
+        }
+        let strokeWidth = 0;
+        if (computedStyle['stroke-width']) {
+          if (!node.attributes['stroke-width']) {
+            return;
+          }
+          strokeWidth = +computedStyle['stroke-width'].value;
+        } else if (
+          computedStyle.stroke &&
+          computedStyle.stroke.value !== 'none'
+        ) {
+          strokeWidth = 1;
+        }
+
+        const isSimilar =
+          (matrix.data[0] === matrix.data[3] &&
+            matrix.data[1] === -matrix.data[2]) ||
+          (matrix.data[0] === -matrix.data[3] &&
+            matrix.data[1] === matrix.data[2]);
+        const isLinear =
+          (matrix.data[0] != 0 &&
+            matrix.data[1] == 0 &&
+            matrix.data[2] == 0 &&
+            matrix.data[3] != 0) ||
+          (matrix.data[0] == 0 &&
+            matrix.data[1] != 0 &&
+            matrix.data[2] != 0 &&
+            matrix.data[3] == 0);
+        const isTranslation =
+          matrix.data[0] == 1 &&
+          matrix.data[1] == 0 &&
+          matrix.data[2] == 0 &&
+          matrix.data[3] == 1;
+        const scale = Math.sqrt(
+          matrix.data[0] * matrix.data[0] + matrix.data[1] * matrix.data[1],
+        );
+        if (node.name == 'circle') {
+          if (!isSimilar) return;
+
+          const cx = Number(node.attributes.cx || '0');
+          const cy = Number(node.attributes.cy || '0');
+          const r = Number(node.attributes.r || '0');
+
+          const newCenter = transformAbsolutePoint(matrix.data, cx, cy);
+          if (strokeWidth) {
+            node.attributes['stroke-width'] = stringifyNumber(
+              strokeWidth * scale,
+              floatPrecision,
+              leadingZero,
+            );
+          }
+          node.attributes.cx = stringifyNumber(
+            newCenter[0],
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.cy = stringifyNumber(
+            newCenter[1],
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.r = stringifyNumber(
+            r * scale,
+            floatPrecision,
+            leadingZero,
+          );
+          delete node.attributes.transform;
+        } else if (node.name == 'ellipse') {
+          if (!isLinear) return;
+          if (strokeWidth && !isSimilar) return;
+
+          const cx = Number(node.attributes.cx || '0');
+          const cy = Number(node.attributes.cy || '0');
+          const rx = Number(node.attributes.rx || '0');
+          const ry = Number(node.attributes.ry || '0');
+
+          const newCenter = transformAbsolutePoint(matrix.data, cx, cy);
+          const [newRx, newRy] = transformSize(matrix.data, rx, ry);
+
+          if (strokeWidth) {
+            node.attributes['stroke-width'] = stringifyNumber(
+              strokeWidth * scale,
+              floatPrecision,
+              leadingZero,
+            );
+          }
+          node.attributes.cx = stringifyNumber(
+            newCenter[0],
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.cy = stringifyNumber(
+            newCenter[1],
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.rx = stringifyNumber(
+            newRx,
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.ry = stringifyNumber(
+            newRy,
+            floatPrecision,
+            leadingZero,
+          );
+          delete node.attributes.transform;
+        } else if (node.name == 'rect') {
+          if (!isLinear) return;
+          if (strokeWidth && !isSimilar) return;
+
+          const x = Number(node.attributes.x || '0');
+          const y = Number(node.attributes.y || '0');
+          const width = Number(node.attributes.width || '0');
+          const height = Number(node.attributes.height || '0');
+          let rx = node.attributes.rx ? Number(node.attributes.rx) : NaN;
+          let ry = node.attributes.ry ? Number(node.attributes.ry) : NaN;
+          rx = Number.isNaN(rx) ? ry || 0 : rx;
+          ry = Number.isNaN(ry) ? rx || 0 : ry;
+
+          const cornerA = transformAbsolutePoint(matrix.data, x, y);
+          const cornerB = transformAbsolutePoint(
+            matrix.data,
+            x + width,
+            y + height,
+          );
+          const cornerX = Math.min(cornerA[0], cornerB[0]);
+          const cornerY = Math.min(cornerA[1], cornerB[1]);
+          const [newW, newH] = transformSize(matrix.data, width, height);
+          const [newRx, newRy] = transformSize(matrix.data, rx, ry);
+
+          if (strokeWidth) {
+            node.attributes['stroke-width'] = stringifyNumber(
+              strokeWidth * scale,
+              floatPrecision,
+              leadingZero,
+            );
+          }
+          node.attributes.x = stringifyNumber(
+            cornerX,
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.y = stringifyNumber(
+            cornerY,
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.width = stringifyNumber(
+            newW,
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.height = stringifyNumber(
+            newH,
+            floatPrecision,
+            leadingZero,
+          );
+          if (newRx < 1 / floatPrecision && newRy < 1 / floatPrecision) {
+            delete node.attributes.rx;
+            delete node.attributes.ry;
+          } else if (Math.abs(newRx - newRy) < 1 / floatPrecision) {
+            node.attributes.rx = stringifyNumber(
+              newRx,
+              floatPrecision,
+              leadingZero,
+            );
+            delete node.attributes.ry;
+          } else {
+            node.attributes.rx = stringifyNumber(
+              newRx,
+              floatPrecision,
+              leadingZero,
+            );
+            node.attributes.ry = stringifyNumber(
+              newRy,
+              floatPrecision,
+              leadingZero,
+            );
+          }
+          delete node.attributes.transform;
+        } else if (node.name == 'image') {
+          if (!isTranslation) return;
+
+          const x = Number(node.attributes.x || '0');
+          const y = Number(node.attributes.y || '0');
+          const corner = transformAbsolutePoint(matrix.data, x, y);
+
+          node.attributes.x = stringifyNumber(
+            corner[0],
+            floatPrecision,
+            leadingZero,
+          );
+          node.attributes.y = stringifyNumber(
+            corner[1],
+            floatPrecision,
+            leadingZero,
+          );
+          delete node.attributes.transform;
+        }
+      },
+    },
+  };
+};
+
+/**
+ * @param {number[]} matrix
+ * @param {number} x
+ * @param {number} y
+ */
+const transformAbsolutePoint = (matrix, x, y) => {
+  const newX = matrix[0] * x + matrix[2] * y + matrix[4];
+  const newY = matrix[1] * x + matrix[3] * y + matrix[5];
+  return [newX, newY];
+};
+
+/**
+ * @param {number[]} matrix
+ * @param {number} w
+ * @param {number} h
+ */
+const transformSize = (matrix, w, h) => {
+  const newW = matrix[0] * w + matrix[1] * h;
+  const newH = matrix[2] * w + matrix[3] * h;
+  return [Math.abs(newW), Math.abs(newH)];
+};
+
+/**
+ * @param {number} number
+ * @param {number} precision
+ * @param {boolean} leadingZero
+ */
+const stringifyNumber = (number, precision, leadingZero) => {
+  const rounded = toFixed(number, precision);
+  return leadingZero ? removeLeadingZero(rounded) : rounded.toString();
+};