Fix #1046 Remember scroll position in preview mode

app/src/main/java/it/niedermann/owncloud/notes/edit/BaseNoteFragment.java

@@ -135,26 +135,22 @@ public abstract class BaseNoteFragment extends BrandedFragment implements Catego
     @Nullable
     protected abstract ScrollView getScrollView();
 
+    protected abstract void scrollToY(int scrollY);
+
     @Override
     public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);
+        this.originalScrollY = note.getScrollY();
+        scrollToY(originalScrollY);
         final ScrollView scrollView = getScrollView();
         if (scrollView != null) {
-            scrollView.getViewTreeObserver().addOnScrollChangedListener(() -> {
-                if (scrollView.getScrollY() > 0) {
-                    note.setScrollY(scrollView.getScrollY());
-                }
-            });
-        }
-    }
-
-    @Override
-    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
-        super.onActivityCreated(savedInstanceState);
-        final ScrollView scrollView = getScrollView();
-        if (scrollView != null) {
-            this.originalScrollY = note.getScrollY();
-            scrollView.post(() -> scrollView.scrollTo(0, originalScrollY));
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                scrollView.setOnScrollChangeListener((View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) -> {
+                    if (scrollY > 0) {
+                        note.setScrollY(scrollY);
+                    }
+                });
+            }
         }
     }
 

app/src/main/java/it/niedermann/owncloud/notes/edit/NoteEditFragment.java

@@ -78,6 +78,13 @@ public class NoteEditFragment extends SearchableBaseNoteFragment {
         return binding.scrollView;
     }
 
+    @Override
+    protected void scrollToY(int y) {
+        if (binding != null) {
+            binding.scrollView.post(() -> binding.scrollView.setScrollY(y));
+        }
+    }
+
     @Override
     protected Layout getLayout() {
         binding.editContent.onPreDraw();

app/src/main/java/it/niedermann/owncloud/notes/edit/NotePreviewFragment.java

@@ -42,6 +42,9 @@ public class NotePreviewFragment extends SearchableBaseNoteFragment implements O
 
     protected FragmentNotePreviewBinding binding;
 
+    @Nullable
+    private Runnable setScrollY;
+
     @Override
     public void onPrepareOptionsMenu(@NonNull Menu menu) {
         super.onPrepareOptionsMenu(menu);
@@ -54,6 +57,17 @@ public class NotePreviewFragment extends SearchableBaseNoteFragment implements O
         return binding.scrollView;
     }
 
+    @Override
+    protected synchronized void scrollToY(int y) {
+        this.setScrollY = () -> {
+            if (binding != null) {
+                Log.v("SCROLL set (preview) to", y + "");
+                binding.scrollView.post(() -> binding.scrollView.setScrollY(y));
+            }
+            setScrollY = null;
+        };
+    }
+
     @Override
     protected FloatingActionButton getSearchNextButton() {
         return binding.searchNext;
@@ -83,7 +97,7 @@ public class NotePreviewFragment extends SearchableBaseNoteFragment implements O
         super.onActivityCreated(savedInstanceState);
 
         registerInternalNoteLinkHandler();
-        binding.singleNoteContent.setMarkdownString(note.getContent());
+        binding.singleNoteContent.setMarkdownString(note.getContent(), setScrollY);
         binding.singleNoteContent.setMovementMethod(LinkMovementMethod.getInstance());
         changedText = note.getContent();
 

markdown/src/main/java/it/niedermann/android/markdown/MarkdownEditor.java

@@ -25,12 +25,17 @@ public interface MarkdownEditor {
      */
     void setMarkdownString(CharSequence text);
 
+    /**
+     * The given {@link String} will be parsed and rendered and the {@param afterRender} will be called after the rendering finished
+     */
+    void setMarkdownString(CharSequence text, @Nullable Runnable afterRender);
+
     /**
      * Will replace all `@mention`s of Nextcloud users with the avatar and given display name.
      *
      * @param mentions {@link Map} of mentions, where the key is the user id and the value is the display name
      */
-    default void setMarkdownString(CharSequence text, @NonNull Map<String, String> mentions) {
+    default void setMarkdownStringAndHighlightMentions(CharSequence text, @NonNull Map<String, String> mentions) {
         setMarkdownString(text);
     }
 

markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownEditor.java

@@ -14,8 +14,6 @@ import androidx.appcompat.widget.AppCompatEditText;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import java.util.Collection;
-import java.util.LinkedList;
 import java.util.function.Consumer;
 
 import io.noties.markwon.Markwon;
@@ -117,6 +115,11 @@ public class MarkwonMarkdownEditor extends AppCompatEditText implements Markdown
         setMarkdownStringModel(text);
     }
 
+    @Override
+    public void setMarkdownString(CharSequence text, Runnable afterRender) {
+        throw new UnsupportedOperationException("This is not available in " + MarkwonMarkdownEditor.class.getSimpleName() + " because the text is getting rendered all the time.");
+    }
+
     /**
      * Updates the current model which matches the rendered state of the editor *without* triggering
      * anything of the native {@link EditText}

markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownViewer.java

@@ -127,6 +127,11 @@ public class MarkwonMarkdownViewer extends AppCompatTextView implements Markdown
 
     @Override
     public void setMarkdownString(CharSequence text) {
+        setMarkdownString(text, null);
+    }
+
+    @Override
+    public void setMarkdownString(CharSequence text, Runnable afterRender) {
         final CharSequence previousText = this.unrenderedText$.getValue();
         this.unrenderedText$.setValue(text);
         if (listener != null) {
@@ -136,7 +141,12 @@ public class MarkwonMarkdownViewer extends AppCompatTextView implements Markdown
             setText(text);
         } else {
             if (!text.equals(previousText)) {
-                this.renderService.execute(() -> post(() -> this.markwon.setMarkdown(this, text.toString())));
+                this.renderService.execute(() -> post(() -> {
+                    this.markwon.setMarkdown(this, text.toString());
+                    if (afterRender != null) {
+                        afterRender.run();
+                    }
+                }));
             }
         }
     }
@@ -162,7 +172,7 @@ public class MarkwonMarkdownViewer extends AppCompatTextView implements Markdown
     }
 
     @Override
-    public void setMarkdownString(CharSequence text, @NonNull Map<String, String> mentions) {
+    public void setMarkdownStringAndHighlightMentions(CharSequence text, @NonNull Map<String, String> mentions) {
         this.markwon = createMarkwonBuilder(getContext(), mentions).build();
         setMarkdownString(text);
     }