Feature/195 basic markdown support

app/src/main/java/com/git/amarradi/leafpad/NoteEditActivity.java

@@ -31,22 +31,29 @@
 import com.google.android.material.appbar.MaterialToolbar;
 import com.google.android.material.textfield.TextInputLayout;
 
+import android.text.method.LinkMovementMethod;
+import android.widget.TextView;
+
 import java.util.List;
 import java.util.Objects;
 
 public class NoteEditActivity extends AppCompatActivity {
 
     private EditText titleEdit;
     private EditText bodyEdit;
+    private TextView previewBody;
+    private Note note;
     private NoteViewModel noteViewModel;
     private MaterialToolbar toolbar;
     private Resources res;
     private boolean shouldPersistOnPause = true;
     private boolean isNoteDeleted = false;
     private NestedScrollView bodyScroll;
+
     private boolean isNewNote = false;
     private boolean fromSearch = false;
     private boolean isUIConfigured = false;
+
     private MenuItem saveMenuItem;
 
     @SuppressLint("MissingInflatedId")
@@ -88,7 +95,7 @@ protected void onCreate(Bundle savedInstanceState) {
         }
         handleIntent(getIntent());
         fromSearch = getIntent().getBooleanExtra("fromSearch", false);
-        observeNote();
+        observeViewModel();
 
         View rootEdit = findViewById(R.id.all);
         View toolbar = findViewById(R.id.toolbar);
@@ -170,35 +177,50 @@ private void configureUIFromNote(Note note) {
     }
 
     private void initViews() {
-        TextInputLayout titleLayout = findViewById(R.id.default_text_input_layout);
-        TextInputLayout bodyLayout = findViewById(R.id.body_text_input_layout);
         titleEdit = findViewById(R.id.title_edit);
         bodyEdit = findViewById(R.id.body_edit);
+
+        previewBody = findViewById(R.id.preview_body); // Initialize TextView
         bodyScroll = findViewById(R.id.body_scroll);
 
-        bodyEdit.addTextChangedListener(new TextWatcher() {
-            @Override
-            public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
+        // clickable links on preview
+        previewBody.setMovementMethod(LinkMovementMethod.getInstance());
+
+        // one TextWatcher to update ViewModel on real time
+        TextWatcher textWatcher = new TextWatcher() {
             @Override
-            public void onTextChanged(CharSequence s, int start, int before, int count) { }
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
+
             @Override
-            public void afterTextChanged(Editable s) {
-                bodyEdit.post(() -> scrollToCursor());
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+                if (noteViewModel.getSelectedNote().getValue() != null) {
+                    if (getCurrentFocus() == titleEdit) {
+                        noteViewModel.updateNoteTitle(s.toString());
+                    } else if (getCurrentFocus() == bodyEdit) {
+                        noteViewModel.updateNoteBody(s.toString());
+                    }
+                }
             }
-        });
 
-        bodyEdit.setOnFocusChangeListener((v, hasFocus) -> {
-            if (hasFocus) {
-                bodyEdit.postDelayed(this::scrollToCursor, 250);
+            @Override
+            public void afterTextChanged(Editable s) {
+                if (getCurrentFocus() == bodyEdit) {
+                    // Stelle sicher, dass Cursor immer sichtbar ist
+                    bodyEdit.post(() -> {
+                        int selection = bodyEdit.getSelectionStart();
+                        Layout layout = bodyEdit.getLayout();
+                        if (layout != null && selection > 0) {
+                            int line = layout.getLineForOffset(selection);
+                            int y = layout.getLineBottom(line);
+                            bodyScroll.smoothScrollTo(0, y);
+                        }
+                    });
+                }
             }
-        });
-
-        bodyEdit.setOnClickListener(v -> {
-            bodyEdit.postDelayed(this::scrollToCursor, 250);
-        });
+        };
 
-        titleLayout.setHintEnabled(false);
-        bodyLayout.setHintEnabled(false);
+        titleEdit.addTextChangedListener(textWatcher);
+        bodyEdit.addTextChangedListener(textWatcher);
     }
 
     private void scrollToCursor() {
@@ -216,15 +238,50 @@ private boolean isNewEntry(Note note) {
                 note.getBody() == null || note.getBody().isEmpty());
     }
 
+    private void observeViewModel() {
+        // Observer for selected note (initial launch)
+        noteViewModel.getSelectedNote().observe(this, currentNote -> {
+            if (currentNote != null && !isUIConfigured) {
+                this.note = currentNote;
+                titleEdit.setText(currentNote.getTitle());
+                bodyEdit.setText(currentNote.getBody());
+                isUIConfigured = true; // Prevents reload when rotating screen
+                invalidateOptionsMenu();
+            }
+        });
+
+        // observer for state of the preview
+        noteViewModel.isPreviewActive().observe(this, isActive -> {
+            bodyEdit.setVisibility(isActive ? View.GONE : View.VISIBLE);
+            previewBody.setVisibility(isActive ? View.VISIBLE : View.GONE);
+
+            // if preview is active, force refresh of Spanned
+            if (isActive) {
+                noteViewModel.getSelectedNote().setValue(noteViewModel.getSelectedNote().getValue());
+            }
+
+            invalidateOptionsMenu(); // refresh menu icon
+        });
+
+        // Observer for parsed body (updates TextView of the preview)
+        noteViewModel.parsedBodyAsSpanned.observe(this, spanned -> {
+            previewBody.setText(spanned);
+        });
+    }
+
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         getMenuInflater().inflate(R.menu.menu_note_edit, menu);
-        saveMenuItem = menu.findItem(R.id.action_save);
-        if (saveMenuItem != null) {
-            saveMenuItem.setEnabled(false); // Initial disabled
+
+        // Updates preview icon depending on state
+        MenuItem previewItem = menu.findItem(R.id.action_preview);
+        if (noteViewModel.isPreviewActive().getValue() != null && noteViewModel.isPreviewActive().getValue()) {
+            previewItem.setIcon(R.drawable.ic_edit); // Changes to icon "edit"
+        } else {
+            previewItem.setIcon(R.drawable.ic_preview); // icon "preview"
         }
-        Note current = noteViewModel.getSelectedNote().getValue();
-        if (current != null) {
+
+        if (note != null) {
             MenuItem recipeItem = menu.findItem(R.id.action_recipe);
             boolean isRecipe = current.getCategory() != null &&
                     current.getCategory().equals(res.getStringArray(R.array.category)[0]);
@@ -242,6 +299,12 @@ public boolean onCreateOptionsMenu(Menu menu) {
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         int id = item.getItemId();
+
+        if (id == R.id.action_preview) {
+            noteViewModel.togglePreview();
+            return true;
+        }
+
         switch (id) {
             case R.id.action_recipe: {
                 Note current = noteViewModel.getSelectedNote().getValue();

app/src/main/java/com/git/amarradi/leafpad/helper/MarkdownParser.java

@@ -0,0 +1,33 @@
+package com.git.amarradi.leafpad.helper;
+
+public class MarkdownParser {
+
+    public static String parse(String rawText) {
+        StringBuilder result = new StringBuilder();
+        String[] lines = rawText.split("\n");
+
+        for (String line : lines) {
+            String parsedLine = line;
+
+            // Heading: "# Heading"
+            if (parsedLine.startsWith("# ")) {
+                parsedLine = "<h1>" + parsedLine.substring(2).trim() + "</h1>";
+            }
+
+            // Bullet point: "* bullet"
+            else if (parsedLine.startsWith("* ")) {
+                parsedLine = context.getString(R.string.bullet_point_symbol) + parsedLine.substring(2).trim();
+            }
+
+            // Underline: "__underlined__"
+            parsedLine = parsedLine.replaceAll("__(.*?)__", "<u>$1</u>");
+
+            // Link: [text](url)
+            parsedLine = parsedLine.replaceAll("\\[(.+?)\\]\\((http.*?)\\)", "<a href=\"$2\">$1</a>");
+
+            result.append(parsedLine).append("<br>");
+        }
+
+        return result.toString();
+    }
+}

app/src/main/java/com/git/amarradi/leafpad/viewmodel/NoteViewModel.java

@@ -2,6 +2,9 @@
 
 import android.app.Application;
 import android.content.Context;
+import android.os.Build;
+import android.text.Html;
+import android.text.Spanned;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
@@ -12,6 +15,7 @@
 import androidx.lifecycle.Transformations;
 
 import com.git.amarradi.leafpad.Leafpad;
+import com.git.amarradi.leafpad.helper.MarkdownParser;
 import com.git.amarradi.leafpad.helper.ReleaseNoteHelper;
 import com.git.amarradi.leafpad.model.Leaf;
 import com.git.amarradi.leafpad.model.Note;
@@ -21,7 +25,8 @@
 import java.util.List;
 import java.util.Objects;
 
-public class    NoteViewModel extends AndroidViewModel {
+
+public class NoteViewModel extends AndroidViewModel {
 
     private final MutableLiveData<List<Note>> notesLiveData = new MutableLiveData<>();
     private static final MutableLiveData<Note> selectedNote = new MutableLiveData<>();
@@ -44,10 +49,30 @@ public LiveData<ReleaseNote> getReleaseNote() {
     }
     private final MediatorLiveData<List<Object>> combinedNotes = new MediatorLiveData<>();
     public LiveData<List<Object>> getCombinedNotes() { return combinedNotes; }
+    private final MutableLiveData<Boolean> isPreviewActive = new MutableLiveData<>(false);
+
+    public final LiveData<Spanned> parsedBodyAsSpanned = Transformations.map(selectedNote, note -> {
+        if (note == null || note.getBody() == null) {
+            return Html.fromHtml("", Html.FROM_HTML_MODE_LEGACY);
+        }
+        String html = MarkdownParser.parse(note.getBody());
+        // Use Html.fromHtml to convert our HTML to an Spanned object that TextView can render
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+            return Html.fromHtml(html, Html.FROM_HTML_MODE_LEGACY);
+        } else {
+            return Html.fromHtml(html);
+        }
+    });
     private final MediatorLiveData<Boolean> isNoteModified = new MediatorLiveData<>();
 
 
+    public LiveData<Boolean> isPreviewActive() {
+        return isPreviewActive;
+    }
 
+    public void togglePreview() {
+        isPreviewActive.setValue(Boolean.FALSE.equals(isPreviewActive.getValue()));
+    }
 
     public void checkAndLoadReleaseNote(Context context) {
         int savedVersion = Leafpad.getCurrentLeafpadVersionCode(context); // default = 0
@@ -285,6 +310,19 @@ public void setNote(Note note) {
             selectedNote.setValue(new Note(note));
         }
     }
+    public void updateNoteBody(String newBody) {
+        Note currentNote = selectedNote.getValue();
+        if (currentNote != null && !Objects.equals(currentNote.getBody(), newBody)) {
+            currentNote.setBody(newBody);
+        }
+    }
+
+    public void updateNoteTitle(String newTitle) {
+        Note currentNote = selectedNote.getValue();
+        if (currentNote != null && !Objects.equals(currentNote.getTitle(), newTitle)) {
+            currentNote.setTitle(newTitle);
+        }
+    }
     public void loadNotes() {
         Boolean showHidden = showHiddenLiveData.getValue();
         if (showHidden == null) showHidden = false;

app/src/main/res/drawable/ic_edit.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24"
+        android:viewportHeight="24"
+        android:tint="?attr/colorControlNormal">
+    <path
+            android:fillColor="@android:color/white"
+            android:pathData="M3,17.25V21h3.75L17.81,9.94l-3.75,-3.75L3,17.25zM20.71,7.04c0.39,-0.39 0.39,-1.02 0,-1.41l-2.34,-2.34c-0.39,-0.39 -1.02,-0.39 -1.41,0l-1.83,1.83 3.75,3.75 1.83,-1.83z"/>
+</vector>

app/src/main/res/drawable/ic_preview.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24"
+        android:viewportHeight="24"
+        android:tint="?attr/colorControlNormal">
+    <path
+            android:fillColor="@android:color/white"
+            android:pathData="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5C21.27,7.61 17,4.5 12,4.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
+</vector>

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

@@ -73,16 +73,33 @@
                 android:paddingStart="@dimen/switch_layout_margin_start"
                 android:paddingEnd="@dimen/switch_layout_margin_end">
 
-                <com.google.android.material.textfield.TextInputEditText
-                    android:id="@+id/body_edit"
-                    android:layout_width="match_parent"
-                    android:layout_height="wrap_content"
-                    android:gravity="top|start"
-                    android:inputType="textMultiLine|textCapSentences|textAutoCorrect"
-                    android:overScrollMode="always"
-                    android:scrollbars="vertical"
-                    android:background="@android:color/transparent"
-                    android:textAlignment="viewStart" />
+                <FrameLayout
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:minHeight="300dp">
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/body_edit"
+                        android:layout_width="match_parent"
+                        android:layout_height="match_parent"
+                        android:gravity="top|start"
+                        android:inputType="textMultiLine|textCapSentences|textAutoCorrect"
+                        android:overScrollMode="always"
+                        android:scrollbars="vertical"
+                        android:background="@android:color/transparent"
+                        android:textAlignment="viewStart"
+                        android:visibility="visible" />
+                    <TextView
+                        android:id="@+id/preview_body"
+                        android:layout_width="match_parent"
+                        android:layout_height="match_parent"
+                        android:paddingTop="16dp"
+                        android:paddingBottom="16dp"
+                        android:textSize="16sp"
+                        android:textColor="?android:attr/textColorPrimary"
+                        android:lineSpacingExtra="4dp"
+                        android:textIsSelectable="true"
+                        android:visibility="gone" />
+                </FrameLayout>
             </com.google.android.material.textfield.TextInputLayout>
         </LinearLayout>
     </androidx.core.widget.NestedScrollView>

app/src/main/res/menu/menu_note_edit.xml

@@ -20,6 +20,13 @@
         android:icon="@drawable/ic_share"
         android:title="@string/action_share_note"
         app:showAsAction="ifRoom" />
+
+    <item
+            android:id="@+id/action_preview"
+            android:icon="@drawable/ic_preview"
+            android:title="@string/action_preview"
+            app:showAsAction="ifRoom" />
+
     <item
         android:id="@+id/action_save"
         android:icon="@drawable/btn_save_note"

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

@@ -16,6 +16,8 @@
     <string name="contentDescription">add new Note</string>
     <string name="imported">note was send to leafpad</string>
     <string name="edited_text">edited at</string>
+    <string name="action_preview">preview</string>
+    <string name="bullet_point_symbol">• </string>
     <string name="new_note">new Note</string>
     <string name="satisfied">Enjoying leafpad?</string>
     <string name="rate_the_app">How about a review in Google\'s PlayStore?</string>