From f780734c9c3cd4e4b54c9e1624760e8e9143b2f1 Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Sat, 4 Apr 2020 12:14:38 -0400
Subject: [PATCH] use CSS zooming until end of zoom gesture

---
 app/src/main/assets/viewer.js                 | 24 ++++++++++++-------
 .../org/grapheneos/pdfviewer/PdfViewer.java   | 14 +++++------
 2 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/app/src/main/assets/viewer.js b/app/src/main/assets/viewer.js
index fcfe366..c11db9b 100644
--- a/app/src/main/assets/viewer.js
+++ b/app/src/main/assets/viewer.js
@@ -4,7 +4,7 @@ const padding = document.getElementById("padding");
 let pdfDoc = null;
 let pageRendering = false;
 let renderPending = false;
-let renderPendingZoom = false;
+let renderPendingZoom = 0;
 const canvas = document.getElementById('content');
 let orientationDegrees = 0;
 let zoomRatio = 1;
@@ -95,15 +95,7 @@ function renderPage(pageNumber, zoom, prerender, prerenderTrigger=0) {
             return;
         }
 
-        const newCanvas = document.createElement("canvas");
         const viewport = page.getViewport({scale: newZoomRatio, rotation: orientationDegrees})
-        const ratio = window.devicePixelRatio;
-        newCanvas.height = viewport.height * ratio;
-        newCanvas.width = viewport.width * ratio;
-        newCanvas.style.height = viewport.height + "px";
-        newCanvas.style.width = viewport.width + "px";
-        const newContext = newCanvas.getContext("2d", { alpha: false });
-        newContext.scale(ratio, ratio);
 
         if (useRender) {
             if (newZoomRatio !== zoomRatio) {
@@ -113,6 +105,20 @@ function renderPage(pageNumber, zoom, prerender, prerenderTrigger=0) {
             zoomRatio = newZoomRatio;
         }
 
+        if (zoom == 2) {
+            pageRendering = false;
+            return;
+        }
+
+        const newCanvas = document.createElement("canvas");
+        const ratio = window.devicePixelRatio;
+        newCanvas.height = viewport.height * ratio;
+        newCanvas.width = viewport.width * ratio;
+        newCanvas.style.height = viewport.height + "px";
+        newCanvas.style.width = viewport.width + "px";
+        const newContext = newCanvas.getContext("2d", { alpha: false });
+        newContext.scale(ratio, ratio);
+
         task = page.render({
             canvasContext: newContext,
             viewport: viewport
diff --git a/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java b/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
index 566ae51..ac0335c 100644
--- a/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
+++ b/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
@@ -330,8 +330,8 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
         mWebView.loadUrl("https://localhost/viewer.html");
     }
 
-    private void renderPage(final boolean zoom) {
-        mWebView.evaluateJavascript(zoom ? "onRenderPage(true)" : "onRenderPage(false)", null);
+    private void renderPage(final int zoom) {
+        mWebView.evaluateJavascript("onRenderPage(" + zoom + ")", null);
     }
 
     private void documentOrientationChanged(final int orientationDegreesOffset) {
@@ -339,7 +339,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
         if (mDocumentOrientationDegrees < 0) {
             mDocumentOrientationDegrees += 360;
         }
-        renderPage(false);
+        renderPage(0);
     }
 
     private void openDocument() {
@@ -352,7 +352,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private void zoomIn(float value) {
         if (mZoomRatio < MAX_ZOOM_RATIO) {
             mZoomRatio += value;
-            renderPage(true);
+            renderPage(2);
             invalidateOptionsMenu();
         }
     }
@@ -360,13 +360,13 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private void zoomOut(float value) {
         if (mZoomRatio > MIN_ZOOM_RATIO) {
             mZoomRatio -= value;
-            renderPage(true);
+            renderPage(2);
             invalidateOptionsMenu();
         }
     }
 
     private void zoomEnd() {
-        renderPage(true);
+        renderPage(1);
     }
 
     private static void enableDisableMenuItem(MenuItem item, boolean enable) {
@@ -384,7 +384,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     public void onJumpToPageInDocument(final int selected_page) {
         if (selected_page >= 1 && selected_page <= mNumPages && mPage != selected_page) {
             mPage = selected_page;
-            renderPage(false);
+            renderPage(0);
             showPageNumber();
         }
     }