From 04ef23660179758d8a1f6d4b7b357dd501840e99 Mon Sep 17 00:00:00 2001
From: Will Scullin <scullin@scullin.com>
Date: Fri, 5 Aug 2022 20:32:55 -0700
Subject: [PATCH] Double Hires preview

---
 js/components/debugger/FileViewer.tsx | 63 +++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/js/components/debugger/FileViewer.tsx b/js/components/debugger/FileViewer.tsx
index da0d4e9..ff02415 100644
--- a/js/components/debugger/FileViewer.tsx
+++ b/js/components/debugger/FileViewer.tsx
@@ -5,19 +5,34 @@ import { Modal, ModalContent, ModalFooter } from '../Modal';
 
 import styles from './css/FileViewer.module.css';
 
+/**
+ * Binary and text representation of file to be previewed
+ */
 export interface FileData {
     fileName: string;
     binary: Uint8Array;
     text: string;
 }
 
+/**
+ * FileViewer props
+ */
 export interface FileViewerProps {
     fileData: FileData | null;
     onClose: () => void;
 }
 
+/**
+ * Preview a file as a hires image if a file is roughly 8192 bytes.
+ * Leverages HiresPage2D.
+ *
+ * @param binary Potential file to preview
+ * @returns HiresPreview component
+ */
 const HiresPreview = ({ binary }: { binary: Uint8Array }) => {
     const canvasRef = useRef<HTMLCanvasElement>(null);
+    // Hires pictures are often a few bytes short of 8192 bytes
+    // because that saves a sector on DOS 3.3 disks.
     if (binary.byteLength < 8184 || binary.byteLength > 8192) {
         return null;
     }
@@ -44,7 +59,54 @@ const HiresPreview = ({ binary }: { binary: Uint8Array }) => {
     return <canvas ref={canvasRef} width={560} height={384} className={styles.hiresPreview} />;
 };
 
+/**
+ * Preview a file as a double hires if a file is roughly 16384 bytes.
+ *
+ * @param binary Potential file to preview
+ * @returns DoubleHiresPreview component
+ */
+const DoubleHiresPreview = ({ binary }: { binary: Uint8Array }) => {
+    const canvasRef = useRef<HTMLCanvasElement>(null);
+    if (binary.byteLength < 16376 || binary.byteLength > 16384) {
+        return null;
+    }
 
+    if (canvasRef.current) {
+        const vm = new VideoModes2D(canvasRef.current, true);
+        const lores = new LoresPage2D(vm, 1, new Uint8Array(), false);
+        const hires = new HiresPage2D(vm, 1);
+        vm.setLoresPage(1, lores);
+        vm.setHiresPage(1, hires);
+        vm.text(false);
+        vm.hires(true);
+        vm._80col(true);
+        vm.doubleHires(true);
+        vm.page(1);
+
+        for (let idx = 0; idx < 0x20; idx++) {
+            for (let jdx = 0; jdx < 0x100; jdx++) {
+                hires.bank1().write(idx + 0x20, jdx, binary[idx * 0x100 + jdx]);
+            }
+        }
+        for (let idx = 0x20; idx < 0x40; idx++) {
+            for (let jdx = 0; jdx < 0x100; jdx++) {
+                hires.bank0().write(idx, jdx, binary[idx * 0x100 + jdx]);
+            }
+        }
+        vm.blit();
+    }
+
+    return <canvas ref={canvasRef} width={560} height={384} className={styles.hiresPreview} />;
+};
+
+/**
+ * Apple file preview component. Supports a binary dump and hires and
+ * double hires images.
+ *
+ * @param fileData
+ * @param onClose Close button callback
+ * @returns
+ */
 export const FileViewer = ({ fileData, onClose }: FileViewerProps) => {
     const [binaryHref, setBinaryHref] = useState('');
     const [textHref, setTextHref] = useState('');
@@ -79,6 +141,7 @@ export const FileViewer = ({ fileData, onClose }: FileViewerProps) => {
                 <ModalContent>
                     <div className={styles.fileViewer}>
                         <HiresPreview binary={binary} />
+                        <DoubleHiresPreview binary={binary} />
                         <pre className={styles.textViewer} tabIndex={-1} >
                             {text}
                         </pre>