From 66683bc17d86f3d05a2e882fc09b5b2a5932cb25 Mon Sep 17 00:00:00 2001
From: Christian Schneppe <christian@pix-art.de>
Date: Mon, 20 Nov 2017 20:02:12 +0100
Subject: support for basic IM styling

---
 .../pixart/messenger/ui/ConversationFragment.java  |   2 +
 .../messenger/ui/adapter/MessageAdapter.java       |   2 +
 .../de/pixart/messenger/utils/ImStyleParser.java   | 107 ++++++++++++++++
 .../de/pixart/messenger/utils/StylingHelper.java   | 134 +++++++++++++++++++++
 4 files changed, 245 insertions(+)
 create mode 100644 src/main/java/de/pixart/messenger/utils/ImStyleParser.java
 create mode 100644 src/main/java/de/pixart/messenger/utils/StylingHelper.java

diff --git a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
index d1a007e3b..f76c8a56d 100644
--- a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
+++ b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
@@ -74,6 +74,7 @@ import de.pixart.messenger.ui.adapter.MessageAdapter.OnContactPictureClicked;
 import de.pixart.messenger.ui.adapter.MessageAdapter.OnContactPictureLongClicked;
 import de.pixart.messenger.ui.widget.ListSelectionManager;
 import de.pixart.messenger.utils.NickValidityChecker;
+import de.pixart.messenger.utils.StylingHelper;
 import de.pixart.messenger.utils.UIHelper;
 import de.pixart.messenger.xmpp.XmppConnection;
 import de.pixart.messenger.xmpp.chatstate.ChatState;
@@ -475,6 +476,7 @@ public class ConversationFragment extends Fragment implements EditMessage.Keyboa
                 }
             }
         });
+        mEditMessage.addTextChangedListener(new StylingHelper.MessageEditorStyler(mEditMessage));
         mEditMessage.setOnEditorActionListener(mEditorActionListener);
         mEditMessage.setRichContentListener(new String[]{"image/*"}, mEditorContentListener);
 
diff --git a/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java b/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
index adf366c17..59f054b69 100644
--- a/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
+++ b/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
@@ -74,6 +74,7 @@ import de.pixart.messenger.ui.widget.ListSelectionManager;
 import de.pixart.messenger.utils.CryptoHelper;
 import de.pixart.messenger.utils.GeoHelper;
 import de.pixart.messenger.utils.Patterns;
+import de.pixart.messenger.utils.StylingHelper;
 import de.pixart.messenger.utils.UIHelper;
 import de.pixart.messenger.xmpp.mam.MamReference;
 
@@ -517,6 +518,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
                     body.setSpan(new StyleSpan(Typeface.BOLD), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                 }
             }
+            StylingHelper.format(body, true);
             Linkify.addLinks(body, XMPP_PATTERN, "xmpp");
             Linkify.addLinks(body, Patterns.AUTOLINK_WEB_URL, "http", WEBURL_MATCH_FILTER, WEBURL_TRANSFORM_FILTER);
             Linkify.addLinks(body, GeoHelper.GEO_URI, "geo");
diff --git a/src/main/java/de/pixart/messenger/utils/ImStyleParser.java b/src/main/java/de/pixart/messenger/utils/ImStyleParser.java
new file mode 100644
index 000000000..0046ba464
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/ImStyleParser.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017, Daniel Gultsch All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package de.pixart.messenger.utils;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class ImStyleParser {
+    final static List<Character> KEYWORDS = Arrays.asList('*', '_', '~', '`');
+    final static List<Character> NO_SUB_PARSING_KEYWORDS = Arrays.asList('`');
+    final static boolean ALLOW_EMPTY = false;
+
+    public static List<Style> parse(CharSequence text) {
+        return parse(text, 0, text.length() - 1);
+    }
+
+    public static List<Style> parse(CharSequence text, int start, int end) {
+        List<Style> styles = new ArrayList<>();
+        for (int i = start; i <= end; ++i) {
+            char c = text.charAt(i);
+            if (KEYWORDS.contains(c) && precededByWhiteSpace(text, i, start) && !followedByWhitespace(text, i, end)) {
+                int to = seekEnd(text, c, i + 1, end);
+                if (to != -1 && (to != i + 1 || ALLOW_EMPTY)) {
+                    styles.add(new Style(c, i, to));
+                    if (!NO_SUB_PARSING_KEYWORDS.contains(c)) {
+                        styles.addAll(parse(text, i + 1, to - 1));
+                    }
+                    i = to;
+                }
+            }
+        }
+        return styles;
+    }
+
+    private static boolean precededByWhiteSpace(CharSequence text, int index, int start) {
+        return index == start || Character.isWhitespace(text.charAt(index - 1));
+    }
+
+    private static boolean followedByWhitespace(CharSequence text, int index, int end) {
+        return index >= end || Character.isWhitespace(text.charAt(index + 1));
+    }
+
+    private static int seekEnd(CharSequence text, char needle, int start, int end) {
+        for (int i = start; i <= end; ++i) {
+            char c = text.charAt(i);
+            if (c == needle) {
+                return i;
+            } else if (c == '\n') {
+                return -1;
+            }
+        }
+        return -1;
+    }
+
+    public static class Style {
+
+        private final char c;
+        private final int start;
+        private final int end;
+
+        public Style(char c, int start, int end) {
+            this.c = c;
+            this.start = start;
+            this.end = end;
+        }
+
+        public char getCharacter() {
+            return c;
+        }
+
+        public int getStart() {
+            return start;
+        }
+
+        public int getEnd() {
+            return end;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/utils/StylingHelper.java b/src/main/java/de/pixart/messenger/utils/StylingHelper.java
new file mode 100644
index 000000000..913baa407
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/StylingHelper.java
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2017, Daniel Gultsch All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package de.pixart.messenger.utils;
+
+import android.graphics.Color;
+import android.graphics.Typeface;
+import android.support.annotation.ColorInt;
+import android.text.Editable;
+import android.text.ParcelableSpan;
+import android.text.Spanned;
+import android.text.TextWatcher;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.StrikethroughSpan;
+import android.text.style.StyleSpan;
+import android.text.style.TypefaceSpan;
+import android.widget.EditText;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class StylingHelper {
+
+    private static List<? extends Class<? extends ParcelableSpan>> SPAN_CLASSES = Arrays.asList(
+            StyleSpan.class,
+            StrikethroughSpan.class,
+            TypefaceSpan.class,
+            ForegroundColorSpan.class
+    );
+
+    public static void clear(final Editable editable) {
+        final int end = editable.length() - 1;
+        for (Class<? extends ParcelableSpan> clazz : SPAN_CLASSES) {
+            for (ParcelableSpan span : editable.getSpans(0, end, clazz)) {
+                editable.removeSpan(span);
+            }
+        }
+    }
+
+    public static void format(final Editable editable) {
+        format(editable, false);
+    }
+
+    public static void format(final Editable editable, final boolean replaceStyleAnnotation) {
+        for (ImStyleParser.Style style : ImStyleParser.parse(editable)) {
+            editable.setSpan(createSpanForStyle(style), style.getStart(), style.getEnd(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            if (replaceStyleAnnotation) {
+                editable.replace(style.getStart(), style.getStart() + 1, "\u200B");
+                editable.replace(style.getEnd(), style.getEnd() + 1, "\u200B");
+            }
+        }
+    }
+
+    public static void format(final Editable editable, @ColorInt int color) {
+        for (ImStyleParser.Style style : ImStyleParser.parse(editable)) {
+            editable.setSpan(createSpanForStyle(style), style.getStart() + 1, style.getEnd() - 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            editable.setSpan(new ForegroundColorSpan(color), style.getStart(), style.getStart() + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            editable.setSpan(new ForegroundColorSpan(color), style.getEnd(), style.getEnd() + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        }
+    }
+
+    private static ParcelableSpan createSpanForStyle(ImStyleParser.Style style) {
+        switch (style.getCharacter()) {
+            case '*':
+                return new StyleSpan(Typeface.BOLD);
+            case '_':
+                return new StyleSpan(Typeface.ITALIC);
+            case '~':
+                return new StrikethroughSpan();
+            case '`':
+                return new TypefaceSpan("monospace");
+            default:
+                throw new AssertionError("Unknown Style");
+        }
+    }
+
+    public static class MessageEditorStyler implements TextWatcher {
+
+        private final EditText mEditText;
+
+        public MessageEditorStyler(EditText editText) {
+            this.mEditText = editText;
+        }
+
+        @Override
+        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
+
+        }
+
+        @Override
+        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
+
+        }
+
+        @Override
+        public void afterTextChanged(Editable editable) {
+            clear(editable);
+            final int color = mEditText.getCurrentTextColor();
+            final int syntaxColor = Color.argb(
+                    Math.round(Color.alpha(color) * 0.5f),
+                    Color.red(color),
+                    Color.green(color),
+                    Color.blue(color)
+            );
+            format(editable, syntaxColor);
+        }
+    }
+}
-- 
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