Use style to adapt WebView for dark themes

FAQ.md

@@ -29,7 +29,6 @@ For authorizing:
 * A [bug in Android](https://issuetracker.google.com/issues/62427912) "*... ActivityRecord not found for ...*" sometimes causes a crash after updating FairEmail.
 * ~~A [bug in Google Drive](https://issuetracker.google.com/issues/126362828) causes files exported to Google Drive to be empty.~~
 * "*... Couldn't read row ...*" causes sometimes a crash. This could be caused by a bug in the [Room Persistence Library](https://developer.android.com/topic/libraries/architecture/room) but more likely indicates a corrupt database.
-* "*... Unable to create layer ...*" causes a crash on some devices when inverting the colors of an original message due to a [bug in AndroidX](https://bugs.chromium.org/p/chromium/issues/detail?id=578150)
 
 ## Planned features
 
@@ -1393,10 +1392,6 @@ FairEmail already tries to workaround these bugs, but if this fail you'll need t
 ~~The original message is shown as the sender has sent it, including all colors.~~
 ~~Changing the background color would not only make the original view not original anymore, it can also result in unreadable messages.~~
 
-Recent versions of FairEmail can invert all colors of the original message when using a dark or black theme.
-You can turn this on the advanced settings.
-Be aware that this can cause [crashes](https://bugs.chromium.org/p/chromium/issues/detail?id=578150) on some devices.
-
 <br />
 
 <a name="faq82"></a>

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

@@ -36,8 +36,6 @@ import android.content.pm.PackageManager;
 import android.content.res.ColorStateList;
 import android.database.Cursor;
 import android.graphics.Color;
-import android.graphics.ColorMatrixColorFilter;
-import android.graphics.Paint;
 import android.graphics.Rect;
 import android.graphics.Typeface;
 import android.graphics.drawable.Drawable;
@@ -150,7 +148,6 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
     private boolean preview;
     private boolean autohtml;
     private boolean autoimages;
-    private boolean invert;
     private boolean authentication;
     private boolean debug;
 
@@ -1402,13 +1399,6 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                     }
                 };
 
-                if (dark && invert) {
-                    // https://bugs.chromium.org/p/chromium/issues/detail?id=578150
-                    Paint paint = new Paint();
-                    paint.setColorFilter(new ColorMatrixColorFilter(Helper.MATRIX_NEGATIVE));
-                    webView.setLayerType(View.LAYER_TYPE_HARDWARE, paint);
-                }
-
                 webView.setWebViewClient(new WebViewClient() {
                     public boolean shouldOverrideUrlLoading(WebView view, String url) {
                         Log.i("Open url=" + url);
@@ -1484,6 +1474,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
             final WebView webView = (WebView) vwBody;
             webView.loadUrl("about:blank");
+            webView.setBackgroundColor(Color.TRANSPARENT);
 
             WebSettings settings = webView.getSettings();
             settings.setUseWideViewPort(true);
@@ -1507,11 +1498,13 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
             if (TextUtils.isEmpty(html)) {
                 Bundle args = new Bundle();
                 args.putLong("id", message.id);
+                args.putBoolean("dark", dark);
 
                 new SimpleTask<OriginalMessage>() {
                     @Override
                     protected OriginalMessage onExecute(Context context, Bundle args) throws IOException {
                         long id = args.getLong("id");
+                        boolean dark = args.getBoolean("dark");
 
                         DB db = DB.getInstance(context);
                         EntityMessage message = db.message().getMessage(id);
@@ -1523,6 +1516,11 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                         original.html = HtmlHelper.getHtmlEmbedded(context, id, original.html);
                         original.html = HtmlHelper.removeTracking(context, original.html);
 
+                        if (dark)
+                            original.html = "<style type=\"text/css\">" +
+                                    "* { background: #000000 !important; color: #FFFFFF !important }" +
+                                    "</style>" + original.html;
+
                         Document doc = Jsoup.parse(original.html);
                         original.has_images = (doc.select("img").size() > 0);
 
@@ -3069,7 +3067,6 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
         this.autohtml = prefs.getBoolean("autohtml", false);
         this.autoimages = prefs.getBoolean("autoimages", false);
         this.authentication = prefs.getBoolean("authentication", false);
-        this.invert = prefs.getBoolean("invert", false);
         this.debug = prefs.getBoolean("debug", false);
 
         this.textSize = Helper.getTextSize(context, zoom);

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

@@ -86,7 +86,6 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
     private SwitchCompat swMonospaced;
     private SwitchCompat swHtml;
     private SwitchCompat swImages;
-    private SwitchCompat swInvert;
     private SwitchCompat swActionbar;
 
     private SwitchCompat swPull;
@@ -121,7 +120,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
 
     static String[] OPTIONS_RESTART = new String[]{
             "startup", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview",
-            "addresses", "monospaced", "autohtml", "autoimages", "invert", "actionbar",
+            "addresses", "monospaced", "autohtml", "autoimages", "actionbar",
             "pull", "swipenav", "autoexpand", "autoclose", "autonext",
             "authentication", "debug"
     };
@@ -130,7 +129,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
             "enabled", "schedule_start", "schedule_end",
             "metered", "download", "roaming",
             "startup", "date", "threading", "avatars", "identicons", "name_email", "subject_italic", "flags", "preview",
-            "addresses", "monospaced", "autohtml", "autoimages", "invert", "actionbar",
+            "addresses", "monospaced", "autohtml", "autoimages", "actionbar",
             "pull", "swipenav", "autoexpand", "autoclose", "autonext", "collapse", "autoread", "automove",
             "autoresize", "resize", "prefix_once", "autosend",
             "notify_preview", "search_local", "light", "sound",
@@ -172,7 +171,6 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swMonospaced = view.findViewById(R.id.swMonospaced);
         swHtml = view.findViewById(R.id.swHtml);
         swImages = view.findViewById(R.id.swImages);
-        swInvert = view.findViewById(R.id.swInvert);
         swActionbar = view.findViewById(R.id.swActionbar);
 
         swPull = view.findViewById(R.id.swPull);
@@ -392,13 +390,6 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
             }
         });
 
-        swInvert.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
-            @Override
-            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
-                prefs.edit().putBoolean("invert", checked).apply();
-            }
-        });
-
         swActionbar.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -695,7 +686,6 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swMonospaced.setChecked(prefs.getBoolean("monospaced", false));
         swHtml.setChecked(prefs.getBoolean("autohtml", false));
         swImages.setChecked(prefs.getBoolean("autoimages", false));
-        swInvert.setChecked(prefs.getBoolean("invert", false));
         swActionbar.setChecked(prefs.getBoolean("actionbar", true));
 
         swPull.setChecked(prefs.getBoolean("pull", true));

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

@@ -132,13 +132,6 @@ public class Helper {
 
     static final float LOW_LIGHT = 0.6f;
 
-    static final float[] MATRIX_NEGATIVE = new float[]{
-            -1, 0, 0, 0, 255, // red
-            0, -1, 0, 0, 255, // green
-            0, 0, -1, 0, 255, // blue
-            0, 0, 0, 1, 0 // alpha
-    };
-
     static final String FAQ_URI = "https://github.com/M66B/open-source-email/blob/master/FAQ.md";
 
     static ThreadFactory backgroundThreadFactory = new ThreadFactory() {

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

@@ -509,31 +509,6 @@
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toBottomOf="@id/swImages" />
 
-            <androidx.appcompat.widget.SwitchCompat
-                android:id="@+id/swInvert"
-                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_invert"
-                app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintTop_toBottomOf="@id/tvImagesHint"
-                app:switchPadding="12dp" />
-
-            <TextView
-                android:id="@+id/tvInvertHint"
-                android:layout_width="0dp"
-                android:layout_height="wrap_content"
-                android:layout_marginStart="12dp"
-                android:layout_marginEnd="60dp"
-                android:text="@string/title_advanced_crash_hint"
-                android:textAppearance="@style/TextAppearance.AppCompat.Small"
-                android:textStyle="italic"
-                app:layout_constraintEnd_toEndOf="parent"
-                app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintTop_toBottomOf="@id/swInvert" />
-
             <androidx.appcompat.widget.SwitchCompat
                 android:id="@+id/swActionbar"
                 android:layout_width="match_parent"
@@ -543,7 +518,7 @@
                 android:layout_marginEnd="12dp"
                 android:text="@string/title_advanced_actionbar"
                 app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintTop_toBottomOf="@id/tvInvertHint"
+                app:layout_constraintTop_toBottomOf="@id/tvImagesHint"
                 app:switchPadding="12dp" />
 
             <TextView

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

@@ -176,7 +176,6 @@
     <string name="title_advanced_monospaced">Use monospaced font for message text</string>
     <string name="title_advanced_html">Automatically show original message for known contacts</string>
     <string name="title_advanced_images">Automatically show images for known contacts</string>
-    <string name="title_advanced_invert">Invert colors of original message when using a dark theme</string>
     <string name="title_advanced_actionbar">Conversation action bar</string>
 
     <string name="title_advanced_pull_refresh">Pull down to refresh</string>
@@ -214,7 +213,6 @@
     <string name="title_advanced_name_email_hint">When disabled only names will be shown when available</string>
     <string name="title_advanced_flags_hint">Note that starred messages will always be kept locally</string>
     <string name="title_advanced_preview_hint">Only available when message text was downloaded</string>
-    <string name="title_advanced_crash_hint">Enabling this option can cause crashes</string>
 
     <string name="title_advanced_autoexpand_hint">Automatically open message when there is just one message or just one unread message in a conversation</string>
     <string name="title_advanced_autocollapse_hint">Multiple expanded messages will always be closed on \'back\'</string>