AsyncDrawable defer invalidation

CHANGELOG.md

@@ -7,6 +7,7 @@
 * Add `requirePlugin(Class)` and `getPlugins` for `Markwon` instance
 * TablePlugin -> defer table invalidation (via `View.post`), so only one invalidation 
 happens with each draw-call
+* AsyncDrawableSpan -> defer invalidation
 
 # 4.0.2
 * Fix `JLatexMathPlugin` formula placeholder (cannot have line breaks) ([#149])

markwon-core/src/main/java/io/noties/markwon/image/AsyncDrawableScheduler.java

@@ -57,11 +57,14 @@ public abstract class AsyncDrawableScheduler {
                 textView.setTag(R.id.markwon_drawables_scheduler, listener);
             }
 
+            // @since 4.1.0-SNAPSHOT
+            final DrawableCallbackImpl.Invalidator invalidator = new TextViewInvalidator(textView);
+
             AsyncDrawable drawable;
 
             for (AsyncDrawableSpan span : spans) {
                 drawable = span.getDrawable();
-                drawable.setCallback2(new DrawableCallbackImpl(textView, drawable.getBounds()));
+                drawable.setCallback2(new DrawableCallbackImpl(textView, invalidator, drawable.getBounds()));
             }
         }
     }
@@ -109,11 +112,23 @@ public abstract class AsyncDrawableScheduler {
 
     private static class DrawableCallbackImpl implements Drawable.Callback {
 
+        // @since 4.1.0-SNAPSHOT
+        // interface to be used when bounds change and view must be invalidated
+        interface Invalidator {
+            void invalidate();
+        }
+
         private final TextView view;
+        private final Invalidator invalidator; // @since 4.1.0-SNAPSHOT
+
         private Rect previousBounds;
 
-        DrawableCallbackImpl(TextView view, Rect initialBounds) {
+        DrawableCallbackImpl(
+                @NonNull TextView view,
+                @NonNull Invalidator invalidator,
+                Rect initialBounds) {
             this.view = view;
+            this.invalidator = invalidator;
             this.previousBounds = new Rect(initialBounds);
         }
 
@@ -136,8 +151,10 @@ public abstract class AsyncDrawableScheduler {
             // but if the size has changed, then we need to update the whole layout...
 
             if (!previousBounds.equals(rect)) {
-                // the only method that seems to work when bounds have changed
+                // @since 4.1.0-SNAPSHOT
-                view.setText(view.getText());
+                // invalidation moved to upper level (so invalidation can be deferred,
+                // and multiple calls combined)
+                invalidator.invalidate();
                 previousBounds = new Rect(rect);
             } else {
 
@@ -156,4 +173,24 @@ public abstract class AsyncDrawableScheduler {
             view.removeCallbacks(what);
         }
     }
+
+    private static class TextViewInvalidator implements DrawableCallbackImpl.Invalidator, Runnable {
+
+        private final TextView textView;
+
+        TextViewInvalidator(@NonNull TextView textView) {
+            this.textView = textView;
+        }
+
+        @Override
+        public void invalidate() {
+            textView.removeCallbacks(this);
+            textView.post(this);
+        }
+
+        @Override
+        public void run() {
+            textView.setText(textView.getText());
+        }
+    }
 }