From f7289be8a5f29893d346b6818c16a6a95529a2ef Mon Sep 17 00:00:00 2001
From: Antoine d'Aligny <antoinedaligny@outlook.fr>
Date: Sat, 5 Oct 2019 16:00:25 +0200
Subject: [PATCH] Move gesture detectors and listeners in the GestureHelper
 class/file

---
 .../grapheneos/pdfviewer/GestureHelper.java   | 71 +++++++++++++++++++
 .../org/grapheneos/pdfviewer/PdfViewer.java   | 56 ++++-----------
 2 files changed, 84 insertions(+), 43 deletions(-)
 create mode 100644 app/src/main/java/org/grapheneos/pdfviewer/GestureHelper.java

diff --git a/app/src/main/java/org/grapheneos/pdfviewer/GestureHelper.java b/app/src/main/java/org/grapheneos/pdfviewer/GestureHelper.java
new file mode 100644
index 0000000..743a989
--- /dev/null
+++ b/app/src/main/java/org/grapheneos/pdfviewer/GestureHelper.java
@@ -0,0 +1,71 @@
+package org.grapheneos.pdfviewer;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.view.GestureDetector;
+import android.view.MotionEvent;
+import android.view.ScaleGestureDetector;
+import android.view.View;
+
+/*
+    The GestureHelper present a simple gesture api for the PdfViewer
+*/
+
+class GestureHelper {
+    public interface GestureListener {
+        boolean onTapUp();
+        // Can be replaced with ratio when supported
+        void onZoomIn(int steps);
+        void onZoomOut(int steps);
+    }
+
+    @SuppressLint("ClickableViewAccessibility")
+    static void attach(Context context, View gestureView, GestureListener listener) {
+
+        final GestureDetector detector = new GestureDetector(context,
+                new GestureDetector.SimpleOnGestureListener() {
+                    @Override
+                    public boolean onSingleTapUp(MotionEvent motionEvent) {
+                        return listener.onTapUp();
+                    }
+                });
+
+        final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(context,
+                new ScaleGestureDetector.SimpleOnScaleGestureListener() {
+                    // As the zoom value is discrete we listen to scaling step and not scaling ratio
+                    float SPAN_STEP = 150;
+                    float initialSpan;
+                    int prevNbStep;
+
+                    @Override
+                    public boolean onScaleBegin(ScaleGestureDetector detector) {
+                        initialSpan = detector.getCurrentSpan();
+                        prevNbStep = 0;
+                        return super.onScaleBegin(detector);
+                    }
+
+                    @Override
+                    public boolean onScale(ScaleGestureDetector detector) {
+                        float spanDiff = initialSpan - detector.getCurrentSpan();
+                        int curNbStep = (int) (spanDiff/SPAN_STEP);
+                        if (curNbStep != prevNbStep) {
+                            int stepDiff = curNbStep - prevNbStep;
+                            if (stepDiff > 0) {
+                                listener.onZoomOut(stepDiff);
+                            } else {
+                                listener.onZoomIn(Math.abs(stepDiff));
+                            }
+                            prevNbStep = curNbStep;
+                        }
+                        return true;
+                    }
+                });
+
+        gestureView.setOnTouchListener((view, motionEvent) -> {
+            detector.onTouchEvent(motionEvent);
+            scaleDetector.onTouchEvent(motionEvent);
+            return false;
+        });
+    }
+
+}
diff --git a/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java b/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
index 354805a..737786d 100644
--- a/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
+++ b/app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
@@ -8,13 +8,10 @@ import android.graphics.Color;
 import android.net.Uri;
 import android.os.Bundle;
 import android.util.Log;
-import android.view.GestureDetector;
 import android.view.Gravity;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
-import android.view.MotionEvent;
-import android.view.ScaleGestureDetector;
 import android.view.View;
 import android.webkit.CookieManager;
 import android.webkit.JavascriptInterface;
@@ -235,10 +232,10 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
 
         showSystemUi();
 
-        final GestureDetector detector = new GestureDetector(PdfViewer.this,
-                new GestureDetector.SimpleOnGestureListener() {
+        GestureHelper.attach(PdfViewer.this, mWebView,
+                new GestureHelper.GestureListener() {
                     @Override
-                    public boolean onSingleTapUp(MotionEvent motionEvent) {
+                    public boolean onTapUp() {
                         if (mUri != null) {
                             mWebView.evaluateJavascript("isTextSelected()", selection -> {
                                 if (!Boolean.valueOf(selection)) {
@@ -254,49 +251,22 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
                         }
                         return false;
                     }
-                });
-
-        final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(PdfViewer.this,
-                new ScaleGestureDetector.SimpleOnScaleGestureListener() {
-                    // As the zoom value is discrete we listen to scaling step and not scaling ratio
-                    float SPAN_STEP = 150;
-                    float initialSpan;
-                    int prevNbStep;
 
                     @Override
-                    public boolean onScaleBegin(ScaleGestureDetector detector) {
-                        initialSpan = detector.getCurrentSpan();
-                        prevNbStep = 0;
-                        return super.onScaleBegin(detector);
-                    }
-
-                    @Override
-                    public boolean onScale(ScaleGestureDetector detector) {
-                        float spanDiff = initialSpan - detector.getCurrentSpan();
-                        int curNbStep = (int) (spanDiff/SPAN_STEP);
-                        if (curNbStep != prevNbStep) {
-                            int stepDiff = curNbStep - prevNbStep;
-                            if (stepDiff > 0) {
-                                for (int i = prevNbStep; i < curNbStep; i++) {
-                                    zoomOut();
-                                }
-                            } else {
-                                for (int i = prevNbStep; i > curNbStep; i--) {
-                                    zoomIn();
-                                }
-                            }
-                            prevNbStep = curNbStep;
+                    public void onZoomIn(int steps) {
+                        for (int i = 0; i < steps; i++) {
+                            zoomIn();
+                        }
+                    }
+
+                    @Override
+                    public void onZoomOut(int steps) {
+                        for (int i = 0; i < steps; i++) {
+                            zoomOut();
                         }
-                        return true;
                     }
                 });
 
-        mWebView.setOnTouchListener((view, motionEvent) -> {
-            detector.onTouchEvent(motionEvent);
-            scaleDetector.onTouchEvent(motionEvent);
-            return false;
-        });
-
         mTextView = new TextView(this);
         mTextView.setBackgroundColor(Color.DKGRAY);
         mTextView.setTextColor(ColorStateList.valueOf(Color.WHITE));