Add rotate document option

app/src/main/assets/viewer.js

@@ -5,6 +5,7 @@ let pageRendering = false;
 let renderPending = false;
 let renderPendingLazy = false;
 const canvas = document.getElementById('content');
+let orientationDegrees = 0;
 let zoomLevel = 100;
 let textLayerDiv = document.getElementById("text");
 const zoomLevels = [50, 75, 100, 125, 150];
@@ -63,10 +64,13 @@ function renderPage(pageNumber, lazy, prerender, prerenderTrigger=0) {
 
     newPageNumber = pageNumber;
     newZoomLevel = zoomLevels[channel.getZoomLevel()];
-    console.log("page: " + pageNumber + ", zoom: " + newZoomLevel + ", prerender: " + prerender);
+    orientationDegrees = channel.getDocumentOrientationDegrees();
+    console.log("page: " + pageNumber + ", zoom: " + newZoomLevel +
+                ", orientationDegrees: " + orientationDegrees + ", prerender: " + prerender);
     for (let i = 0; i < cache.length; i++) {
         const cached = cache[i];
-        if (cached.pageNumber === pageNumber && cached.zoomLevel === newZoomLevel) {
+        if (cached.pageNumber === pageNumber && cached.zoomLevel === newZoomLevel &&
+                cache.orientationDegrees == orientationDegrees) {
             if (useRender) {
                 cache.splice(i, 1);
                 cache.push(cached);
@@ -89,7 +93,7 @@ function renderPage(pageNumber, lazy, prerender, prerenderTrigger=0) {
         }
 
         const newCanvas = document.createElement("canvas");
-        const viewport = page.getViewport(newZoomLevel / 100)
+        const viewport = page.getViewport(newZoomLevel / 100, orientationDegrees)
         const ratio = window.devicePixelRatio;
         newCanvas.height = viewport.height * ratio;
         newCanvas.width = viewport.width * ratio;
@@ -150,6 +154,7 @@ function renderPage(pageNumber, lazy, prerender, prerenderTrigger=0) {
                 cache.push({
                     pageNumber: pageNumber,
                     zoomLevel: newZoomLevel,
+                    orientationDegrees: orientationDegrees,
                     canvas: newCanvas,
                     textLayerDiv: newTextLayerDiv
                 });
@@ -163,7 +168,8 @@ function renderPage(pageNumber, lazy, prerender, prerenderTrigger=0) {
 
 function onRenderPage(lazy) {
     if (pageRendering) {
-        if (newPageNumber === channel.getPage() && newZoomLevel === zoomLevels[channel.getZoomLevel()]) {
+        if (newPageNumber === channel.getPage() && newZoomLevel === zoomLevels[channel.getZoomLevel()] &&
+                orientationDegrees === channel.getDocumentOrientationDegrees()) {
             useRender = true;
             return;
         }

app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java

@@ -86,6 +86,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     public int mPage;
     public int mNumPages;
     private int mZoomLevel = 2;
+    private int mDocumentOrientationDegrees;
     private int mDocumentState;
     private List<CharSequence> mDocumentProperties;
     private InputStream mInputStream;
@@ -105,6 +106,11 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
             return mZoomLevel;
         }
 
+        @JavascriptInterface
+        public int getDocumentOrientationDegrees() {
+            return mDocumentOrientationDegrees;
+        }
+
         @JavascriptInterface
         public void setNumPages(int numPages) {
             mNumPages = numPages;
@@ -274,6 +280,14 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
         mWebView.evaluateJavascript(lazy ? "onRenderPage(true)" : "onRenderPage(false)", null);
     }
 
+    private void documentOrientationChanged(final int orientationDegreesOffset) {
+        mDocumentOrientationDegrees = (mDocumentOrientationDegrees + orientationDegreesOffset) % 360;
+        if (mDocumentOrientationDegrees < 0) {
+            mDocumentOrientationDegrees += 360;
+        }
+        renderPage(true);
+    }
+
     private void openDocument() {
         Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
         intent.addCategory(Intent.CATEGORY_OPENABLE);
@@ -345,7 +359,8 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     @Override
     public boolean onPrepareOptionsMenu(Menu menu) {
         final int ids[] = { R.id.action_zoom_in, R.id.action_zoom_out, R.id.action_jump_to_page,
-                R.id.action_next, R.id.action_previous, R.id.action_view_document_properties };
+                R.id.action_next, R.id.action_previous, R.id.action_rotate_clockwise,
+                R.id.action_rotate_counterclockwise, R.id.action_view_document_properties };
         if (mDocumentState < STATE_LOADED) {
             for (final int id : ids) {
                 final MenuItem item = menu.findItem(id);
@@ -416,6 +431,14 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
                 }
                 return true;
 
+            case R.id.action_rotate_clockwise:
+                documentOrientationChanged(90);
+                return true;
+
+            case R.id.action_rotate_counterclockwise:
+                documentOrientationChanged(-90);
+                return true;
+
             case R.id.action_view_document_properties:
                 DocumentPropertiesFragment
                         .newInstance(mDocumentProperties)

app/src/main/res/menu/pdf_viewer.xml

@@ -43,6 +43,18 @@
         android:title="@string/action_jump_to_page"
         app:showAsAction="ifRoom" />
 
+    <item
+        android:id="@+id/action_rotate_clockwise"
+        android:icon="@drawable/ic_rotate_right_white_24dp"
+        android:title="@string/action_rotate_clockwise"
+        app:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/action_rotate_counterclockwise"
+        android:icon="@drawable/ic_rotate_left_white_24dp"
+        android:title="@string/action_rotate_counterclockwise"
+        app:showAsAction="ifRoom" />
+
     <item
         android:id="@+id/action_view_document_properties"
         android:title="@string/action_view_document_properties"

app/src/main/res/values/strings.xml

@@ -7,6 +7,8 @@
     <string name="action_open">Open document</string>
     <string name="action_zoom_out">Zoom out</string>
     <string name="action_zoom_in">Zoom in</string>
+    <string name="action_rotate_clockwise">Rotate clockwise</string>
+    <string name="action_rotate_counterclockwise">Rotate counterclockwise</string>
     <string name="action_jump_to_page">Jump to page</string>
     <string name="action_view_document_properties">Properties</string>