Started migrating workflow controller

shared-operations/src/functions/scalePage.ts

@@ -0,0 +1,56 @@
+
+import { PDFPage } from 'pdf-lib';
+import { PdfFile, fromPdfLib } from '../wrappers/PdfFile';
+
+export async function scalePage(file: PdfFile, pageSize: {width?:number,height?:number}|{width?:number,height?:number}[]): Promise<PdfFile> {
+    const pdfDoc = await file.getAsPdfLib();
+    const pages = pdfDoc.getPages();
+
+    if (Array.isArray(pageSize)) {
+        if (pageSize.length != pages.length) {
+            throw new Error(`Number of given sizes '${pageSize.length}' is not the same as the number of pages '${pages.length}'`)
+        }
+        for (let i=0; i<pageSize.length; i++) {
+            resize(pages[i], pageSize[i]);
+        }
+    } else {
+        pages.forEach(page => resize(page, pageSize));
+    }
+    
+    return fromPdfLib(pdfDoc, file.filename);
+};
+
+function resize(page: PDFPage, newSize: {width?:number,height?:number}) {
+    const calculatedSize = calculateSize(page, newSize);
+    page.setSize(calculatedSize.width, calculatedSize.height);
+
+    const xRatio = calculatedSize.width / page.getWidth();
+    const yRatio = calculatedSize.height / page.getHeight();
+    page.scaleContent(xRatio, yRatio);
+}
+
+function calculateSize(page: PDFPage, newSize: {width?:number,height?:number}): {width:number,height:number} {
+    if (!newSize.width && !newSize.height){
+        throw new Error(`Sizes '${newSize}' cannot have null width and null height`);
+    } else if (!newSize.width && newSize.height) {
+        const oldSize = page.getSize();
+        const ratio = oldSize.width / oldSize.height;
+        return { width: newSize.height * ratio, height: newSize.height };
+    } else if (newSize.width && !newSize.height) {
+        const oldSize = page.getSize();
+        const ratio = oldSize.height / oldSize.width;
+        return { width: newSize.width, height: newSize.width * ratio };
+    }
+    return { width: newSize.width!, height: newSize.height! };
+}
+
+export const PageSize = Object.freeze({
+    a4: {
+        width: 594.96,
+        height: 841.92
+    },
+    letter: {
+        width: 612,
+        height: 792
+    }
+});