Added support for text alignment

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

@@ -107,6 +107,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
     private SwitchCompat swMonospaced;
     private SwitchCompat swTextColor;
     private SwitchCompat swTextSize;
+    private SwitchCompat swTextAlign;
     private SwitchCompat swCollapseQuotes;
     private SwitchCompat swImagesInline;
     private SwitchCompat swAttachmentsAlt;
@@ -124,7 +125,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             "keywords_header", "flags", "flags_background",
             "preview", "preview_italic", "preview_lines",
             "addresses", "button_archive_trash", "button_move",
-            "contrast", "monospaced", "text_color", "text_size",
+            "contrast", "monospaced", "text_color", "text_size", "text_align",
             "inline_images", "collapse_quotes", "attachments_alt",
             "parse_classes", "authentication"
     };
@@ -189,6 +190,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
         swMonospaced = view.findViewById(R.id.swMonospaced);
         swTextColor = view.findViewById(R.id.swTextColor);
         swTextSize = view.findViewById(R.id.swTextSize);
+        swTextAlign = view.findViewById(R.id.swTextAlign);
         swCollapseQuotes = view.findViewById(R.id.swCollapseQuotes);
         swImagesInline = view.findViewById(R.id.swImagesInline);
         swAttachmentsAlt = view.findViewById(R.id.swAttachmentsAlt);
@@ -602,6 +604,13 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             }
         });
 
+        swTextAlign.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("text_align", checked).apply();
+            }
+        });
+
         swCollapseQuotes.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -776,6 +785,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
         swMonospaced.setChecked(prefs.getBoolean("monospaced", false));
         swTextColor.setChecked(prefs.getBoolean("text_color", true));
         swTextSize.setChecked(prefs.getBoolean("text_size", true));
+        swTextAlign.setChecked(prefs.getBoolean("text_align", true));
         swCollapseQuotes.setChecked(prefs.getBoolean("collapse_quotes", false));
         swImagesInline.setChecked(prefs.getBoolean("inline_images", false));
         swAttachmentsAlt.setChecked(prefs.getBoolean("attachments_alt", false));

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

@@ -36,6 +36,7 @@ import android.text.SpannableStringBuilder;
 import android.text.Spanned;
 import android.text.TextPaint;
 import android.text.TextUtils;
+import android.text.style.AlignmentSpan;
 import android.text.style.BulletSpan;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.ImageSpan;
@@ -50,6 +51,7 @@ import android.text.style.TypefaceSpan;
 import android.text.style.URLSpan;
 import android.text.style.UnderlineSpan;
 import android.util.Base64;
+import android.view.View;
 import android.view.textclassifier.TextClassificationManager;
 import android.view.textclassifier.TextLanguage;
 
@@ -313,6 +315,7 @@ public class HtmlHelper {
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
         boolean text_color = prefs.getBoolean("text_color", true);
         boolean text_size = prefs.getBoolean("text_size", true);
+        boolean text_align = prefs.getBoolean("text_align", true);
         boolean display_hidden = prefs.getBoolean("display_hidden", false);
         boolean disable_tracking = prefs.getBoolean("disable_tracking", true);
         boolean parse_classes = prefs.getBoolean("parse_classes", false);
@@ -449,6 +452,8 @@ public class HtmlHelper {
                 .addProtocols("a", "href", "full");
         if (text_color)
             whitelist.addAttributes("font", "color");
+        if (text_align)
+            whitelist.addTags("center").addAttributes(":all", "align");
         if (!view)
             whitelist.addProtocols("img", "src", "content");
 
@@ -506,6 +511,19 @@ public class HtmlHelper {
             // Element style
             style = mergeStyles(style, element.attr("style"));
 
+            if (text_align) {
+                // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/center
+                if ("center".equals(element.tagName())) {
+                    style = mergeStyles(style, "text-align:center");
+                    element.tagName("div");
+                }
+
+                // https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes
+                String align = element.attr("align");
+                if (!TextUtils.isEmpty(align))
+                    style = mergeStyles(style, "text-align:" + align);
+            }
+
             // Process style
             if (!TextUtils.isEmpty(style)) {
                 StringBuilder sb = new StringBuilder();
@@ -637,6 +655,12 @@ public class HtmlHelper {
                                         element.attr("line-after", "true");
                                 }
                                 break;
+
+                            case "text-align":
+                                // https://developer.mozilla.org/en-US/docs/Web/CSS/text-align
+                                if (text_align)
+                                    sb.append(key).append(':').append(value).append(';');
+                                break;
                         }
                     }
                 }
@@ -1721,6 +1745,7 @@ public class HtmlHelper {
         final int dp3 = Helper.dp2pixels(context, 3);
         final int dp6 = Helper.dp2pixels(context, 6);
         final int dp24 = Helper.dp2pixels(context, 24);
+        final boolean ltr = (TextUtils.getLayoutDirectionFromLocale(Locale.getDefault()) == View.LAYOUT_DIRECTION_LTR);
 
         // https://developer.mozilla.org/en-US/docs/Web/HTML/Block-level_elements
         NodeTraversor.traverse(new NodeVisitor() {
@@ -1871,6 +1896,22 @@ public class HtmlHelper {
                                     if ("line-through".equals(value))
                                         ssb.setSpan(new StrikethroughSpan(), start, ssb.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                                     break;
+                                case "text-align":
+                                    Layout.Alignment alignment = null;
+                                    switch (value) {
+                                        case "left":
+                                            alignment = (ltr ? Layout.Alignment.ALIGN_NORMAL : Layout.Alignment.ALIGN_OPPOSITE);
+                                            break;
+                                        case "center":
+                                            alignment = Layout.Alignment.ALIGN_CENTER;
+                                            break;
+                                        case "right":
+                                            alignment = (ltr ? Layout.Alignment.ALIGN_OPPOSITE : Layout.Alignment.ALIGN_NORMAL);
+                                            break;
+                                    }
+                                    if (alignment != null)
+                                        ssb.setSpan(new AlignmentSpan.Standard(alignment), start, ssb.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+                                    break;
                             }
                         }
                     }

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

@@ -826,6 +826,18 @@
             app:layout_constraintTop_toBottomOf="@id/swTextColor"
             app:switchPadding="12dp" />
 
+        <androidx.appcompat.widget.SwitchCompat
+            android:id="@+id/swTextAlign"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:enabled="true"
+            android:text="@string/title_advanced_text_align"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/swTextSize"
+            app:switchPadding="12dp" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/swCollapseQuotes"
             android:layout_width="0dp"
@@ -834,7 +846,7 @@
             android:text="@string/title_advanced_collapse_quotes"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/swTextSize"
+            app:layout_constraintTop_toBottomOf="@id/swTextAlign"
             app:switchPadding="12dp" />
 
         <androidx.appcompat.widget.SwitchCompat

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

@@ -348,6 +348,7 @@
     <string name="title_advanced_monospaced">Use monospaced font for message text</string>
     <string name="title_advanced_text_color">Show text colors</string>
     <string name="title_advanced_text_size">Show small and large texts</string>
+    <string name="title_advanced_text_align">Show left/center/right aligned texts</string>
     <string name="title_advanced_collapse_quotes">Collapse quoted text</string>
     <string name="title_advanced_images_inline">Automatically show inline images</string>
     <string name="title_advanced_seekbar">Show relative conversation position with a dot</string>