Correctly render SVG images in export

Resolves #58

Author: karlll

src/engine.ts

@@ -0,0 +1,11 @@
+// To properly export SVGs as data URLs, see https://github.com/orgs/marp-team/discussions/425
+const marpEngineJs = `
+module.exports = ({ marp }) => marp.use((md) => {
+  // https://github.com/markdown-it/markdown-it/issues/447#issuecomment-373408654
+  const defaultValidateLink = md.validateLink;
+  md.validateLink = url => /^data:image\\/.*?;/.test(url) || defaultValidateLink(url);
+})`;
+
+export function getEngine(): string {
+	return marpEngineJs;
+}

src/export.ts

@@ -4,6 +4,7 @@ import { Notice, TFile } from 'obsidian';
 import { convertToBase64 } from './convertImage';
 import { join, normalize } from 'path';
 import fixPath from 'fix-path';
+import { getEngine } from './engine';
 
 const imgPathReg = /!\[[^\]]*\]\(([^)]+)\)/g;
 
@@ -21,6 +22,7 @@ export async function exportSlide(
   if (!file) return;
   const filePath = normalize(join(basePath, file.path));
   const tmpPath = join(exportDir, `${file.basename}.tmp`);
+  const tmpEnginePath = join(exportDir, 'engine.js');
 
   let fileContent = await readFile(filePath, 'utf-8');
 
@@ -43,6 +45,7 @@ export async function exportSlide(
   await mkdir(exportDir, { recursive: true });
   try {
     await writeFile(tmpPath, fileContent);
+    await writeFile(tmpEnginePath, getEngine());
   } catch (e) {
     console.error(e);
   }
@@ -53,18 +56,19 @@ export async function exportSlide(
     cmd = `npx -y @marp-team/marp-cli@latest --bespoke.transition --stdin false --allow-local-files --theme-set "${themeDir}" -o "${join(
       exportDir,
       file.basename,
-    )}.${ext}" -- "${tmpPath}"`;
+    )}.${ext}" --engine ${tmpEnginePath} -- "${tmpPath}"`;
   } catch (e) {
     cmd = `npx -y @marp-team/marp-cli@latest --stdin false --allow-local-files --bespoke.transition -o "${join(
       exportDir,
       file.basename,
-    )}.${ext}" -- "${tmpPath}"`;
+    )}.${ext}" --engine ${tmpEnginePath} -- "${tmpPath}"`;
   }
 
   fixPath();
   new Notice(`Exporting "${file.basename}.${ext}" to "${exportDir}"`, 20000);
   exec(cmd, () => {
     new Notice('Exported successfully', 20000);
     rm(tmpPath);
+    rm(tmpEnginePath);
   });
 }