Merge pull request #703 from vector-im/css-url-variables-plugin

Theming - Postcss plugin to replace URL values with css variable

package.json

@@ -10,7 +10,7 @@
     "lint-ts": "eslint src/ -c .ts-eslintrc.js --ext .ts",
     "lint-ci": "eslint src/",
     "test": "impunity --entry-point src/platform/web/main.js src/platform/web/Platform.js --force-esm-dirs lib/ src/ --root-dir src/",
-    "test:postcss": "impunity --entry-point  scripts/postcss/test.js ",
+    "test:postcss": "impunity --entry-point  scripts/postcss/tests/css-compile-variables.test.js scripts/postcss/tests/css-url-to-variables.test.js",
     "start": "vite --port 3000",
     "build": "vite build",
     "build:sdk": "./scripts/sdk/build.sh"

scripts/postcss/css-url-to-variables.js

@@ -0,0 +1,85 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const valueParser = require("postcss-value-parser");
+
+/**
+ * This plugin extracts content inside url() into css variables and adds the variables to the root section.
+ * This plugin is used in conjunction with css-url-processor plugin to colorize svg icons.
+ */
+let counter;
+let urlVariables;
+const idToPrepend = "icon-url";
+
+function findAndReplaceUrl(decl) {
+    const value = decl.value;
+    const parsed = valueParser(value);
+    parsed.walk(node => {
+        if (node.type !== "function" || node.value !== "url") {
+            return;
+        }
+        const url = node.nodes[0].value;
+        if (!url.match(/\.svg\?primary=.+/)) {
+            return;
+        }
+        const variableName = `${idToPrepend}-${counter++}`;
+        urlVariables.set(variableName, url);
+        node.value = "var";
+        node.nodes = [{ type: "word", value: `--${variableName}` }];
+    });
+    decl.assign({prop: decl.prop, value: parsed.toString()})
+}
+
+function addResolvedVariablesToRootSelector(root, { Rule, Declaration }) {
+    const newRule = new Rule({ selector: ":root", source: root.source });
+    // Add derived css variables to :root
+    urlVariables.forEach((value, key) => {
+        const declaration = new Declaration({ prop: `--${key}`, value: `url("${value}")`});
+        newRule.append(declaration);
+    });
+    root.append(newRule);
+}
+
+function populateMapWithIcons(map, cssFileLocation) {
+    const location = cssFileLocation.match(/(.+)\/.+\.css/)?.[1];
+    const sharedObject = map.get(location);
+    sharedObject["icon"] = Object.fromEntries(urlVariables);
+}
+
+/* *
+ * @type {import('postcss').PluginCreator}
+ */
+module.exports = (opts = {}) => {
+    urlVariables = new Map();
+    counter = 0;
+    return {
+        postcssPlugin: "postcss-url-to-variable",
+
+        Once(root, { Rule, Declaration }) {
+            root.walkDecls(decl => findAndReplaceUrl(decl));
+            if (urlVariables.size) {
+                addResolvedVariablesToRootSelector(root, { Rule, Declaration });
+            }
+            if (opts.compiledVariables){
+                const cssFileLocation = root.source.input.from;
+                populateMapWithIcons(opts.compiledVariables, cssFileLocation);
+            }
+        },
+    };
+};
+
+module.exports.postcss = true;
+

scripts/postcss/tests/common.js

@@ -0,0 +1,30 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const postcss = require("postcss");
+
+module.exports.createTestRunner = function (plugin) {
+    return async function run(input, output, opts = {}, assert) {
+        let result = await postcss([plugin(opts)]).process(input, { from: undefined, });
+        assert.strictEqual(
+            result.css.replaceAll(/\s/g, ""),
+            output.replaceAll(/\s/g, "")
+        );
+        assert.strictEqual(result.warnings().length, 0);
+    };
+}
+
+

scripts/postcss/tests/css-compile-variables.test.js

@@ -16,17 +16,9 @@ limitations under the License.
 
 const offColor = require("off-color").offColor;
 const postcss = require("postcss");
-const plugin = require("./css-compile-variables");
-const derive = require("./color").derive;
-
-async function run(input, output, opts = {}, assert) {
-    let result = await postcss([plugin({ ...opts, derive })]).process(input, { from: undefined, });
-    assert.strictEqual(
-        result.css.replaceAll(/\s/g, ""),
-        output.replaceAll(/\s/g, "")
-    );
-    assert.strictEqual(result.warnings().length, 0);
-}
+const plugin = require("../css-compile-variables");
+const derive = require("../color").derive;
+const run = require("./common").createTestRunner(plugin);
 
 module.exports.tests = function tests() {
     return {
@@ -46,7 +38,7 @@ module.exports.tests = function tests() {
                 --foo-color--lighter-50: ${transformedColor.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, {}, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         },
 
         "derived variables work with alias": async (assert) => {
@@ -66,7 +58,7 @@ module.exports.tests = function tests() {
                 --my-alias--lighter-15: ${aliasLighter};
             }
             `;
-            await run(inputCSS, outputCSS, { }, assert);
+            await run(inputCSS, outputCSS, {derive}, assert);
         },
 
         "derived variable throws if base not present in config": async (assert) => {
@@ -94,7 +86,7 @@ module.exports.tests = function tests() {
                 --foo-color--darker-20: ${transformedColor2.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, { }, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         },
 
         "multiple aliased-derived variable in single declaration is parsed correctly": async (assert) => {
@@ -116,7 +108,7 @@ module.exports.tests = function tests() {
                 --my-alias--darker-20: ${transformedColor2.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, { }, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         },
 
         "compiledVariables map is populated": async (assert) => {
@@ -158,7 +150,7 @@ module.exports.tests = function tests() {
                 --foo-color--darker-5: ${transformedColorDarker.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, {}, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         }
     };
 };

scripts/postcss/tests/css-url-to-variables.test.js

@@ -0,0 +1,71 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const plugin = require("../css-url-to-variables");
+const run = require("./common").createTestRunner(plugin);
+const postcss = require("postcss");
+
+module.exports.tests = function tests() {
+    return {
+        "url is replaced with variable": async (assert) => {
+            const inputCSS = `div {
+                background: no-repeat center/80% url("../img/image.svg?primary=main-color--darker-20");
+            }
+            button {
+                background: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }`;
+            const outputCSS =
+            `div {
+                background: no-repeat center/80% var(--icon-url-0);
+            }
+            button {
+                background: var(--icon-url-1);
+            }`+
+                `
+            :root {
+                --icon-url-0: url("../img/image.svg?primary=main-color--darker-20");
+                --icon-url-1: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }
+            `;
+            await run(inputCSS, outputCSS, { }, assert);
+        },
+        "non svg urls without query params are not replaced": async (assert) => {
+            const inputCSS = `div {
+                background: no-repeat url("./img/foo/bar/image.png");
+            }`;
+            await run(inputCSS, inputCSS, {}, assert);
+        },
+        "map is populated with icons": async (assert) => {
+            const compiledVariables = new Map();
+            compiledVariables.set("/foo/bar", { "derived-variables": ["background-color--darker-20", "accent-color--lighter-15"] });
+            const inputCSS = `div {
+                background: no-repeat center/80% url("../img/image.svg?primary=main-color--darker-20");
+            }
+            button {
+                background: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }`;
+            const expectedObject = {
+                "icon-url-0": "../img/image.svg?primary=main-color--darker-20",
+                "icon-url-1": "/home/foo/bar/cool.svg?primary=blue&secondary=green",
+            };
+            await postcss([plugin({compiledVariables})]).process(inputCSS, { from: "/foo/bar/test.css", });
+            const sharedVariable = compiledVariables.get("/foo/bar");
+            assert.deepEqual(["background-color--darker-20", "accent-color--lighter-15"], sharedVariable["derived-variables"]);
+            assert.deepEqual(expectedObject, sharedVariable["icon"]);
+        }
+    };
+};
+