Attempt to remove tracking from original messages

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -1505,9 +1505,9 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
                 new SimpleTask<String>() {
                     @Override
-                    protected String onExecute(Context context, Bundle args) throws Throwable {
+                    protected String onExecute(Context context, Bundle args) throws IOException {
                         long id = args.getLong("id");
-                        return getHtmlEmbedded(id);
+                        return HtmlHelper.removeTracking(context, getHtmlEmbedded(id));
                     }
 
                     @Override
@@ -2207,9 +2207,9 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
             new SimpleTask<String>() {
                 @Override
-                protected String onExecute(Context context, Bundle args) throws Throwable {
+                protected String onExecute(Context context, Bundle args) throws IOException {
                     long id = args.getLong("id");
-                    return getHtmlEmbedded(id);
+                    return HtmlHelper.removeTracking(context, getHtmlEmbedded(id));
                 }
 
                 @Override

app/src/main/java/eu/faircode/email/FragmentOptions.java

@@ -83,6 +83,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
     private SwitchCompat swPreview;
     private SwitchCompat swAddresses;
     private SwitchCompat swHtml;
+    private SwitchCompat swTracking;
     private SwitchCompat swImages;
     private SwitchCompat swActionbar;
 
@@ -109,7 +110,8 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
     private Group grpNotification;
 
     static String[] OPTIONS_RESTART = new String[]{
-            "unified", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview", "addresses", "autoimages", "actionbar",
+            "unified", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview",
+            "addresses", "autohtml", "autoimages", "actionbar",
             "pull", "swipenav", "autoexpand", "autoclose", "autonext",
             "debug"
     };
@@ -117,7 +119,8 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
     private final static String[] ADVANCED_OPTIONS = new String[]{
             "enabled", "schedule_start", "schedule_end",
             "metered", "download",
-            "unified", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview", "addresses", "autoimages", "actionbar",
+            "unified", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview",
+            "addresses", "autohtml", "remove_tracking", "autoimages", "actionbar",
             "pull", "swipenav", "autoexpand", "autoclose", "autonext", "collapse", "autoread", "automove",
             "autoresize", "sender", "autosend",
             "notify_preview", "search_local", "light", "sound",
@@ -155,6 +158,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swPreview = view.findViewById(R.id.swPreview);
         swAddresses = view.findViewById(R.id.swAddresses);
         swHtml = view.findViewById(R.id.swHtml);
+        swTracking = view.findViewById(R.id.swTracking);
         swImages = view.findViewById(R.id.swImages);
         swActionbar = view.findViewById(R.id.swActionbar);
 
@@ -352,6 +356,13 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
             }
         });
 
+        swTracking.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("remove_tracking", checked).apply();
+            }
+        });
+
         swImages.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -576,6 +587,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swPreview.setChecked(prefs.getBoolean("preview", false));
         swAddresses.setChecked(prefs.getBoolean("addresses", true));
         swHtml.setChecked(prefs.getBoolean("autohtml", false));
+        swTracking.setChecked(prefs.getBoolean("remove_tracking", true));
         swImages.setChecked(prefs.getBoolean("autoimages", false));
         swImages.setEnabled(!swHtml.isChecked());
         swActionbar.setChecked(prefs.getBoolean("actionbar", true));

app/src/main/java/eu/faircode/email/HtmlHelper.java

@@ -20,11 +20,13 @@ package eu.faircode.email;
 */
 
 import android.content.Context;
+import android.content.SharedPreferences;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
+import android.preference.PreferenceManager;
 import android.text.Html;
 import android.text.Spanned;
 import android.text.TextUtils;
@@ -65,6 +67,25 @@ public class HtmlHelper {
     private static final List<String> heads = Arrays.asList("h1", "h2", "h3", "h4", "h5", "h6", "p", "table", "ol", "ul", "br", "hr");
     private static final List<String> tails = Arrays.asList("h1", "h2", "h3", "h4", "h5", "h6", "p", "ol", "ul", "li");
 
+    static String removeTracking(Context context, String html) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        boolean remove_tracking = prefs.getBoolean("remove_tracking", true);
+        if (!remove_tracking)
+            return html;
+
+        Document document = Jsoup.parse(html);
+
+        for (Element img : document.select("img")) {
+            String src = img.attr("src");
+            String height = img.attr("height").trim();
+            String width = img.attr("width").trim();
+            if ("1".equals(height) && "1".equals(width) && !TextUtils.isEmpty(src))
+                img.removeAttr("src");
+        }
+
+        return document.outerHtml();
+    }
+
     static String sanitize(Context context, String html, boolean showQuotes) {
         final Document document = Jsoup.parse(Jsoup.clean(html, Whitelist
                 .relaxed()

app/src/main/res/layout/fragment_options.xml

@@ -428,6 +428,18 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/swHtml" />
 
+        <androidx.appcompat.widget.SwitchCompat
+            android:id="@+id/swTracking"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="12dp"
+            android:layout_marginTop="12dp"
+            android:layout_marginEnd="12dp"
+            android:text="@string/title_advanced_tracking"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvHtmlHint"
+            app:switchPadding="12dp" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/swImages"
             android:layout_width="match_parent"
@@ -437,7 +449,7 @@
             android:layout_marginEnd="12dp"
             android:text="@string/title_advanced_images"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvHtmlHint"
+            app:layout_constraintTop_toBottomOf="@id/swTracking"
             app:switchPadding="12dp" />
 
         <TextView

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

@@ -163,6 +163,7 @@
     <string name="title_advanced_preview">Show message preview</string>
     <string name="title_advanced_addresses">Show address details by default</string>
     <string name="title_advanced_html">Automatically show original message for known contacts</string>
+    <string name="title_advanced_tracking">Attempt to remove tracking from original messages</string>
     <string name="title_advanced_images">Automatically show images for known contacts</string>
     <string name="title_advanced_actionbar">Conversation action bar</string>