Added editor tests

.github/workflows/develop.yml

@@ -15,7 +15,7 @@ jobs:
         with:
           java-version: 1.8
       - name: Build with Gradle
-        run: ./gradlew build
+        run: ./gradlew build -Prelease
 
   deploy:
     needs: build

docs/.vuepress/.artifacts.js

@@ -1,4 +1,4 @@
 
 // this is a generated file, do not modify. To update it run 'collectArtifacts.js' script
-const artifacts = [{"id":"core","name":"Core","group":"io.noties.markwon","description":"Core Markwon artifact that includes basic markdown parsing and rendering"},{"id":"ext-latex","name":"LaTeX","group":"io.noties.markwon","description":"Extension to add LaTeX formulas to Markwon markdown"},{"id":"ext-strikethrough","name":"Strikethrough","group":"io.noties.markwon","description":"Extension to add strikethrough markup to Markwon markdown"},{"id":"ext-tables","name":"Tables","group":"io.noties.markwon","description":"Extension to add tables markup (GFM) to Markwon markdown"},{"id":"ext-tasklist","name":"Task List","group":"io.noties.markwon","description":"Extension to add task lists (GFM) to Markwon markdown"},{"id":"html","name":"HTML","group":"io.noties.markwon","description":"Provides HTML parsing functionality"},{"id":"image","name":"Image","group":"io.noties.markwon","description":"Markwon image loading module (with optional GIF and SVG support)"},{"id":"image-glide","name":"Image Glide","group":"io.noties.markwon","description":"Markwon image loading module (based on Glide library)"},{"id":"image-picasso","name":"Image Picasso","group":"io.noties.markwon","description":"Markwon image loading module (based on Picasso library)"},{"id":"linkify","name":"Linkify","group":"io.noties.markwon","description":"Markwon plugin to linkify text (based on Android Linkify)"},{"id":"recycler","name":"Recycler","group":"io.noties.markwon","description":"Provides RecyclerView.Adapter to display Markwon markdown"},{"id":"recycler-table","name":"Recycler Table","group":"io.noties.markwon","description":"Provides MarkwonAdapter.Entry to render TableBlocks inside Android-native TableLayout widget"},{"id":"simple-ext","name":"Simple Extension","group":"io.noties.markwon","description":"Custom extension based on simple delimiter usage"},{"id":"syntax-highlight","name":"Syntax Highlight","group":"io.noties.markwon","description":"Add syntax highlight to Markwon markdown via Prism4j library"}];
+const artifacts = [{"id":"core","name":"Core","group":"io.noties.markwon","description":"Core Markwon artifact that includes basic markdown parsing and rendering"},{"id":"editor","name":"Editor","group":"io.noties.markwon","description":"Markdown editor based on Markwon"},{"id":"ext-latex","name":"LaTeX","group":"io.noties.markwon","description":"Extension to add LaTeX formulas to Markwon markdown"},{"id":"ext-strikethrough","name":"Strikethrough","group":"io.noties.markwon","description":"Extension to add strikethrough markup to Markwon markdown"},{"id":"ext-tables","name":"Tables","group":"io.noties.markwon","description":"Extension to add tables markup (GFM) to Markwon markdown"},{"id":"ext-tasklist","name":"Task List","group":"io.noties.markwon","description":"Extension to add task lists (GFM) to Markwon markdown"},{"id":"html","name":"HTML","group":"io.noties.markwon","description":"Provides HTML parsing functionality"},{"id":"image","name":"Image","group":"io.noties.markwon","description":"Markwon image loading module (with optional GIF and SVG support)"},{"id":"image-glide","name":"Image Glide","group":"io.noties.markwon","description":"Markwon image loading module (based on Glide library)"},{"id":"image-picasso","name":"Image Picasso","group":"io.noties.markwon","description":"Markwon image loading module (based on Picasso library)"},{"id":"linkify","name":"Linkify","group":"io.noties.markwon","description":"Markwon plugin to linkify text (based on Android Linkify)"},{"id":"recycler","name":"Recycler","group":"io.noties.markwon","description":"Provides RecyclerView.Adapter to display Markwon markdown"},{"id":"recycler-table","name":"Recycler Table","group":"io.noties.markwon","description":"Provides MarkwonAdapter.Entry to render TableBlocks inside Android-native TableLayout widget"},{"id":"simple-ext","name":"Simple Extension","group":"io.noties.markwon","description":"Custom extension based on simple delimiter usage"},{"id":"syntax-highlight","name":"Syntax Highlight","group":"io.noties.markwon","description":"Add syntax highlight to Markwon markdown via Prism4j library"}];
 export { artifacts };

docs/.vuepress/config.js

@@ -95,6 +95,7 @@ module.exports = {
                         '/docs/v4/core/text-setter.md'
                     ]
                 },
+                '/docs/v4/editor/',
                 '/docs/v4/ext-latex/',
                 '/docs/v4/ext-strikethrough/',
                 '/docs/v4/ext-tables/',

docs/README.md

@@ -21,6 +21,11 @@ but also gives all the means to tweak the appearance if desired. All markdown fe
 listed in <Link name="commonmark-spec" /> are supported (including support for **inlined/block HTML code**, 
 **markdown tables**, **images** and **syntax highlight**).
 
+Since version <Badge text="4.2.0" /> **Markwon** comes with an [editor] to _highlight_ markdown input
+as user types for example in **EditText**.
+
+[editor]: /docs/v4/editor/
+
 ## Supported markdown features
 
 * Emphasis (`*`, `_`)

docs/docs/v4/editor/README.md

@@ -0,0 +1,25 @@
+# Editor <Badge text="4.2.0" />
+
+<MavenBadge4 :artifact="'editor'" />
+
+Markdown editing highlight for Android based on **Markwon**.
+
+<style>
+video {
+    max-height: 82vh;
+}
+</style>
+
+<video controls="true" loop="" :poster="$withBase('/assets/markwon-editor-preview.jpg')">
+    <source :src="$withBase('/assets/markwon-editor.mp4')" type="video/mp4">
+    You browser does not support mp4 playback, try downloading video file 
+    <a :href="$withBase('/assets/markwon-editor.mp4')">directly</a>
+</video>
+
+## Getting started with editor
+
+:::warning Implementation Detail
+It must be mentioned that highlight is implemented via text diff. Everything
+that is present in raw markdown input and missing from rendered result is considered
+to be _punctuation_.
+:::

markwon-editor/README.md

@@ -4,3 +4,10 @@ Markdown editor for Android based on `Markwon`.
 
 Main principle: _difference_ between input text and rendered markdown is considered to be
 _punctuation_.
+
+
+## Limitations
+
+Tables and LaTeX nodes won't be rendered correctly. They will be treated as _punctuation_
+as whole. This comes from their implementation - they are _mocked_ and do not present
+in final result as text and thus cannot be _diffed_. 

markwon-editor/src/main/java/io/noties/markwon/editor/EditSpanHandlerBuilder.java

@@ -31,7 +31,7 @@ public class EditSpanHandlerBuilder {
     private final Map<Class<?>, EditSpanHandlerTyped> map = new HashMap<>(3);
 
     @NonNull
-    public <T> EditSpanHandlerBuilder include(
+    public <T> EditSpanHandlerBuilder handleMarkdownSpan(
             @NonNull Class<T> type,
             @NonNull EditSpanHandlerTyped<T> handler) {
         map.put(type, handler);

markwon-editor/src/main/java/io/noties/markwon/editor/MarkwonEditor.java

@@ -10,11 +10,6 @@ import java.util.Map;
 
 import io.noties.markwon.Markwon;
 
-// todo: how to reuse existing spanFactories? to obtain a value they require render-props....
-//  maybe.. mock them? plus, spanFactory can return multiple spans
-
-// todo: as we do text-diff, then images, latex and tables won't be handled... they will be treated as punctuation as-whole..
-
 /**
  * @see #builder(Markwon)
  * @see #create(Markwon)
@@ -24,6 +19,9 @@ import io.noties.markwon.Markwon;
  */
 public abstract class MarkwonEditor {
 
+    /**
+     * Represents cache of spans that are used during highlight
+     */
     public interface EditSpanStore {
 
         /**

markwon-editor/src/test/java/io/noties/markwon/editor/MarkwonEditorImplTest.java

@@ -0,0 +1,166 @@
+package io.noties.markwon.editor;
+
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+
+import androidx.annotation.NonNull;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import io.noties.markwon.Markwon;
+import io.noties.markwon.editor.MarkwonEditorImpl.EditSpanStoreImpl;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class MarkwonEditorImplTest {
+
+    @Test
+    public void extract_spans() {
+
+        final class One {
+        }
+        final class Two {
+        }
+        final class Three {
+        }
+
+        final SpannableStringBuilder builder = new SpannableStringBuilder();
+        append(builder, "one", new One());
+        append(builder, "two", new Two(), new Two());
+        append(builder, "three", new Three(), new Three(), new Three());
+
+        final Map<Class<?>, List<Object>> map = MarkwonEditorImpl.extractSpans(
+                builder,
+                Arrays.asList(One.class, Three.class));
+
+        assertEquals(2, map.size());
+
+        assertNotNull(map.get(One.class));
+        assertNull(map.get(Two.class));
+        assertNotNull(map.get(Three.class));
+
+        //noinspection ConstantConditions
+        assertEquals(1, map.get(One.class).size());
+        //noinspection ConstantConditions
+        assertEquals(3, map.get(Three.class).size());
+    }
+
+    private static void append(@NonNull SpannableStringBuilder builder, @NonNull String text, Object... spans) {
+        final int start = builder.length();
+        builder.append(text);
+        final int end = builder.length();
+        for (Object span : spans) {
+            builder.setSpan(span, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        }
+    }
+
+    @Test
+    public void edit_span_store_span_not_included() {
+        // When store is requesting a span that is not included -> exception is raised
+
+        final Map<Class<?>, MarkwonEditor.EditSpanFactory> map = Collections.emptyMap();
+
+        final EditSpanStoreImpl impl = new EditSpanStoreImpl(new SpannableStringBuilder(), map);
+
+        try {
+            impl.get(Object.class);
+            fail();
+        } catch (IllegalStateException e) {
+            assertTrue(e.getMessage(), e.getMessage().contains("not registered, use Builder#includeEditSpan method to register"));
+        }
+    }
+
+    @Test
+    public void edit_span_store_reuse() {
+        // when a span is present in supplied spannable -> it will be used
+
+        final class One {
+        }
+        final SpannableStringBuilder builder = new SpannableStringBuilder();
+        final One one = new One();
+        append(builder, "One", one);
+
+        final Map<Class<?>, MarkwonEditor.EditSpanFactory> map = new HashMap<Class<?>, MarkwonEditor.EditSpanFactory>() {{
+            // null in case it _will_ be used -> thus NPE
+            put(One.class, null);
+        }};
+
+        final EditSpanStoreImpl impl = new EditSpanStoreImpl(builder, map);
+
+        assertEquals(one, impl.get(One.class));
+    }
+
+    @Test
+    public void edit_span_store_factory_create() {
+        // when span is not present in spannable -> new one will be created via factory
+
+        final class Two {
+        }
+
+        final SpannableStringBuilder builder = new SpannableStringBuilder();
+        final Two two = new Two();
+        append(builder, "two", two);
+
+        final MarkwonEditor.EditSpanFactory factory = mock(MarkwonEditor.EditSpanFactory.class);
+
+        final Map<Class<?>, MarkwonEditor.EditSpanFactory> map = new HashMap<Class<?>, MarkwonEditor.EditSpanFactory>() {{
+            put(Two.class, factory);
+        }};
+
+        final EditSpanStoreImpl impl = new EditSpanStoreImpl(builder, map);
+
+        // first one will be the same as we had created before,
+        // second one will be created via factory
+
+        assertEquals(two, impl.get(Two.class));
+
+        verify(factory, never()).create();
+
+        impl.get(Two.class);
+        verify(factory, times(1)).create();
+    }
+
+    @Test
+    public void process() {
+        // create markwon
+        final Markwon markwon = Markwon.create(RuntimeEnvironment.application);
+
+        // default punctuation
+        final MarkwonEditor editor = MarkwonEditor.create(markwon);
+
+        final SpannableStringBuilder builder = new SpannableStringBuilder("**bold**");
+
+        editor.process(builder);
+
+        final PunctuationSpan[] spans = builder.getSpans(0, builder.length(), PunctuationSpan.class);
+        assertEquals(2, spans.length);
+
+        final PunctuationSpan first = spans[0];
+        assertEquals(0, builder.getSpanStart(first));
+        assertEquals(2, builder.getSpanEnd(first));
+
+        final PunctuationSpan second = spans[1];
+        assertEquals(6, builder.getSpanStart(second));
+        assertEquals(8, builder.getSpanEnd(second));
+    }
+}

markwon-editor/src/test/java/io/noties/markwon/editor/MarkwonEditorTest.java

@@ -0,0 +1,45 @@
+package io.noties.markwon.editor;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import io.noties.markwon.Markwon;
+import io.noties.markwon.editor.MarkwonEditor.Builder;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.mock;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class MarkwonEditorTest {
+
+    @Test
+    public void builder_no_config() {
+        // must create a default instance without exceptions
+
+        try {
+            new Builder(mock(Markwon.class)).build();
+            assertTrue(true);
+        } catch (Throwable t) {
+            fail(t.getMessage());
+        }
+    }
+
+    @Test
+    public void builder_with_edit_spans_but_no_handler() {
+        // if edit spans are specified, but no edit span handler is present -> exception is thrown
+
+        try {
+            //noinspection unchecked
+            new Builder(mock(Markwon.class))
+                    .includeEditSpan(Object.class, mock(MarkwonEditor.EditSpanFactory.class))
+                    .build();
+            fail();
+        } catch (IllegalStateException e) {
+            assertTrue(e.getMessage(), e.getMessage().contains("There is no need to include edit spans "));
+        }
+    }
+}

markwon-editor/src/test/java/io/noties/markwon/editor/MarkwonEditorTextWatcherTest.java

@@ -0,0 +1,94 @@
+package io.noties.markwon.editor;
+
+import android.text.Editable;
+import android.widget.EditText;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import java.util.concurrent.ExecutorService;
+
+import io.noties.markwon.editor.MarkwonEditor.PreRenderResult;
+import io.noties.markwon.editor.MarkwonEditor.PreRenderResultListener;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class MarkwonEditorTextWatcherTest {
+
+    @Test
+    public void w_process() {
+
+        final MarkwonEditor editor = mock(MarkwonEditor.class);
+        final Editable editable = mock(Editable.class);
+
+        final MarkwonEditorTextWatcher watcher = MarkwonEditorTextWatcher.withProcess(editor);
+
+        watcher.afterTextChanged(editable);
+
+        verify(editor, times(1)).process(eq(editable));
+    }
+
+    @Test
+    public void w_pre_render() {
+
+        final MarkwonEditor editor = mock(MarkwonEditor.class);
+        final Editable editable = mock(Editable.class);
+        final ExecutorService service = mock(ExecutorService.class);
+        final EditText editText = mock(EditText.class);
+
+        when(editText.getText()).thenReturn(editable);
+
+        when(service.submit(any(Runnable.class))).thenAnswer(new Answer<Object>() {
+            @Override
+            public Object answer(InvocationOnMock invocation) {
+                ((Runnable) invocation.getArgument(0)).run();
+                return null;
+            }
+        });
+
+        doAnswer(new Answer() {
+            @Override
+            public Object answer(InvocationOnMock invocation) {
+                ((Runnable) invocation.getArgument(0)).run();
+                return null;
+            }
+        }).when(editText).post(any(Runnable.class));
+
+        final MarkwonEditorTextWatcher watcher = MarkwonEditorTextWatcher.withPreRender(
+                editor,
+                service,
+                editText);
+
+        watcher.afterTextChanged(editable);
+
+        final ArgumentCaptor<PreRenderResultListener> captor =
+                ArgumentCaptor.forClass(PreRenderResultListener.class);
+
+        verify(service, times(1)).submit(any(Runnable.class));
+        verify(editor, times(1)).preRender(eq(editable), captor.capture());
+
+        final PreRenderResultListener listener = captor.getValue();
+        final PreRenderResult result = mock(PreRenderResult.class);
+
+        // for simplicity return the same editable instance (same hashCode)
+        when(result.resultEditable()).thenReturn(editable);
+
+        listener.onPreRenderResult(result);
+
+        verify(result, times(1)).resultEditable();
+        verify(result, times(1)).dispatchTo(eq(editable));
+    }
+}

sample/src/main/AndroidManifest.xml

@@ -28,7 +28,10 @@
         <activity android:name=".simpleext.SimpleExtActivity" />
         <activity android:name=".customextension2.CustomExtensionActivity2" />
         <activity android:name=".precomputed.PrecomputedActivity" />
-        <activity android:name=".editor.EditorActivity" />
+
+        <activity
+            android:name=".editor.EditorActivity"
+            android:windowSoftInputMode="adjustResize" />
 
     </application>
 

sample/src/main/java/io/noties/markwon/sample/editor/EditorActivity.java

@@ -3,17 +3,23 @@ package io.noties.markwon.sample.editor;
 import android.app.Activity;
 import android.os.Bundle;
 import android.text.Editable;
+import android.text.SpannableStringBuilder;
 import android.text.Spanned;
 import android.text.TextPaint;
 import android.text.style.CharacterStyle;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.MetricAffectingSpan;
 import android.text.style.StrikethroughSpan;
+import android.view.View;
+import android.widget.Button;
 import android.widget.EditText;
+import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.Executors;
 
 import io.noties.markwon.Markwon;
@@ -40,7 +46,7 @@ public class EditorActivity extends Activity {
         setContentView(R.layout.activity_editor);
 
         this.editText = findViewById(R.id.edit_text);
-
+        initBottomBar();
 
 //        simple_process();
 
@@ -164,7 +170,7 @@ public class EditorActivity extends Activity {
     private static MarkwonEditor.EditSpanHandler createEditSpanHandler() {
         // Please note that here we specify spans THAT ARE USED IN MARKDOWN
         return EditSpanHandlerBuilder.create()
-                .include(StrongEmphasisSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(StrongEmphasisSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     editable.setSpan(
                             store.get(StrongEmphasisSpan.class),
                             spanStart,
@@ -172,7 +178,7 @@ public class EditorActivity extends Activity {
                             Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
                     );
                 })
-                .include(EmphasisSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(EmphasisSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     editable.setSpan(
                             store.get(EmphasisSpan.class),
                             spanStart,
@@ -180,7 +186,7 @@ public class EditorActivity extends Activity {
                             Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
                     );
                 })
-                .include(StrikethroughSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(StrikethroughSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     editable.setSpan(
                             store.get(StrikethroughSpan.class),
                             spanStart,
@@ -188,7 +194,7 @@ public class EditorActivity extends Activity {
                             Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
                     );
                 })
-                .include(CodeSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(CodeSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     // we do not add offset here because markwon (by default) adds spaces
                     // around inline code
                     editable.setSpan(
@@ -198,7 +204,7 @@ public class EditorActivity extends Activity {
                             Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
                     );
                 })
-                .include(CodeBlockSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(CodeBlockSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     // we do not handle indented code blocks here
                     if (input.charAt(spanStart) == '`') {
                         final int firstLineEnd = input.indexOf('\n', spanStart);
@@ -214,7 +220,7 @@ public class EditorActivity extends Activity {
                         );
                     }
                 })
-                .include(BlockQuoteSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(BlockQuoteSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     editable.setSpan(
                             store.get(BlockQuoteSpan.class),
                             spanStart,
@@ -222,7 +228,7 @@ public class EditorActivity extends Activity {
                             Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
                     );
                 })
-                .include(LinkSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
+                .handleMarkdownSpan(LinkSpan.class, (store, editable, input, span, spanStart, spanTextLength) -> {
                     editable.setSpan(
                             store.get(EditLinkSpan.class),
                             // add underline only for link text
@@ -235,6 +241,81 @@ public class EditorActivity extends Activity {
                 .build();
     }
 
+    private void initBottomBar() {
+        // all except block-quote wraps if have selection, or inserts at current cursor position
+
+        final Button bold = findViewById(R.id.bold);
+        final Button italic = findViewById(R.id.italic);
+        final Button strike = findViewById(R.id.strike);
+        final Button quote = findViewById(R.id.quote);
+        final Button code = findViewById(R.id.code);
+
+        addSpan(bold, new StrongEmphasisSpan());
+        addSpan(italic, new EmphasisSpan());
+        addSpan(strike, new StrikethroughSpan());
+
+        bold.setOnClickListener(new InsertOrWrapClickListener(editText, "**"));
+        italic.setOnClickListener(new InsertOrWrapClickListener(editText, "_"));
+        strike.setOnClickListener(new InsertOrWrapClickListener(editText, "~~"));
+        code.setOnClickListener(new InsertOrWrapClickListener(editText, "`"));
+
+        quote.setOnClickListener(v -> {
+            final int start = editText.getSelectionStart();
+            final int end = editText.getSelectionEnd();
+            if (start == end) {
+                editText.getText().insert(start, "> ");
+            } else {
+                // wrap the whole selected area in a quote
+                final List<Integer> newLines = new ArrayList<>(3);
+                newLines.add(start);
+
+                final String text = editText.getText().subSequence(start, end).toString();
+                int index = text.indexOf('\n');
+                while (index != -1) {
+                    newLines.add(start + index);
+                    index = text.indexOf('\n', index + 1);
+                }
+
+                for (int i = newLines.size() - 1; i >= 0; i--) {
+                    editText.getText().insert(newLines.get(i), "> ");
+                }
+            }
+        });
+    }
+
+    private static void addSpan(@NonNull TextView textView, Object... spans) {
+        final SpannableStringBuilder builder = new SpannableStringBuilder(textView.getText());
+        final int end = builder.length();
+        for (Object span : spans) {
+            builder.setSpan(span, 0, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        }
+        textView.setText(builder);
+    }
+
+    private static class InsertOrWrapClickListener implements View.OnClickListener {
+
+        private final EditText editText;
+        private final String text;
+
+        InsertOrWrapClickListener(@NonNull EditText editText, @NonNull String text) {
+            this.editText = editText;
+            this.text = text;
+        }
+
+        @Override
+        public void onClick(View v) {
+            final int start = editText.getSelectionStart();
+            final int end = editText.getSelectionEnd();
+            if (start == end) {
+                // insert at current position
+                editText.getText().insert(start, text);
+            } else {
+                editText.getText().insert(end, text);
+                editText.getText().insert(start, text);
+            }
+        }
+    }
+
     private static class CustomPunctuationSpan extends ForegroundColorSpan {
         CustomPunctuationSpan() {
             super(0xFFFF0000); // RED

sample/src/main/res/layout/activity_editor.xml

@@ -1,17 +1,72 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:clipToPadding="false"
+    android:orientation="vertical"
     android:padding="8dip">
 
-    <EditText
+    <FrameLayout
-        android:id="@+id/edit_text"
+        android:layout_width="match_parent"
+        android:layout_height="0px"
+        android:layout_weight="1">
+
+        <EditText
+            android:id="@+id/edit_text"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:autofillHints="none"
+            android:hint="Markdown..."
+            android:inputType="text|textLongMessage|textMultiLine"
+            android:maxLines="100" />
+
+    </FrameLayout>
+
+    <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:autofillHints="none"
+        android:orientation="horizontal">
-        android:hint="Markdown..."
-        android:inputType="text|textLongMessage|textMultiLine"
-        android:maxLines="100" />
 
-</FrameLayout>
+        <Button
+            android:id="@+id/bold"
+            android:layout_width="0px"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="B"
+            android:typeface="monospace" />
+
+        <Button
+            android:id="@+id/italic"
+            android:layout_width="0px"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="I"
+            android:typeface="monospace" />
+
+        <Button
+            android:id="@+id/strike"
+            android:layout_width="0px"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="S"
+            android:typeface="monospace" />
+
+        <Button
+            android:id="@+id/quote"
+            android:layout_width="0px"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text=">"
+            android:typeface="monospace" />
+
+        <Button
+            android:id="@+id/code"
+            android:layout_width="0px"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="`"
+            android:typeface="monospace" />
+
+    </LinearLayout>
+
+</LinearLayout>