Reland "Fixes android voice access delete text, redo, and undo action"

shell/platform/android/io/flutter/view/AccessibilityBridge.java

@@ -34,6 +34,8 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.*;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Bridge between Android's OS accessibility system and Flutter's accessibility system.
@@ -633,8 +635,7 @@ public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualViewId) {
     }
 
     // These are non-ops on older devices. Attempting to interact with the text will cause Talkback
-    // to read the
-    // contents of the text box instead.
+    // to read the contents of the text box instead.
     if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2) {
       if (semanticsNode.hasAction(Action.SET_SELECTION)) {
         result.addAction(AccessibilityNodeInfo.ACTION_SET_SELECTION);
@@ -650,6 +651,13 @@ public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualViewId) {
       }
     }
 
+    // Set text API isn't available until API 21.
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+      if (semanticsNode.hasAction(Action.SET_TEXT)) {
+        result.addAction(AccessibilityNodeInfo.ACTION_SET_TEXT);
+      }
+    }
+
     if (semanticsNode.hasFlag(Flag.IS_BUTTON) || semanticsNode.hasFlag(Flag.IS_LINK)) {
       result.setClassName("android.widget.Button");
     }
@@ -1034,6 +1042,12 @@ public boolean performAction(
           }
           accessibilityChannel.dispatchSemanticsAction(
               virtualViewId, Action.SET_SELECTION, selection);
+          // The voice access expects the semantics node to update immediately. We update the
+          // semantics node based on prediction. If the result is incorrect, it will be updated in
+          // the next frame.
+          SemanticsNode node = flutterSemanticsTree.get(virtualViewId);
+          node.textSelectionBase = selection.get("base");
+          node.textSelectionExtent = selection.get("extent");
           return true;
         }
       case AccessibilityNodeInfo.ACTION_COPY:
@@ -1064,7 +1078,7 @@ public boolean performAction(
           if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
             return false;
           }
-          return performSetText(virtualViewId, arguments);
+          return performSetText(semanticsNode, virtualViewId, arguments);
         }
       default:
         // might be a custom accessibility accessibilityAction.
@@ -1094,6 +1108,9 @@ private boolean performCursorMoveAction(
         arguments.getInt(AccessibilityNodeInfo.ACTION_ARGUMENT_MOVEMENT_GRANULARITY_INT);
     final boolean extendSelection =
         arguments.getBoolean(AccessibilityNodeInfo.ACTION_ARGUMENT_EXTEND_SELECTION_BOOLEAN);
+    // The voice access expects the semantics node to update immediately. We update the semantics
+    // node based on prediction. If the result is incorrect, it will be updated in the next frame.
+    predictCursorMovement(semanticsNode, granularity, forward, extendSelection);
     switch (granularity) {
       case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_CHARACTER:
         {
@@ -1121,23 +1138,99 @@ private boolean performCursorMoveAction(
           return true;
         }
         break;
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_LINE:
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PARAGRAPH:
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PAGE:
+        return true;
     }
     return false;
   }
 
+  private void predictCursorMovement(
+      @NonNull SemanticsNode node, int granularity, boolean forward, boolean extendSelection) {
+    if (node.textSelectionExtent < 0 || node.textSelectionBase < 0) {
+      return;
+    }
+
+    switch (granularity) {
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_CHARACTER:
+        if (forward && node.textSelectionExtent < node.value.length()) {
+          node.textSelectionExtent += 1;
+        } else if (!forward && node.textSelectionExtent > 0) {
+          node.textSelectionExtent -= 1;
+        }
+        break;
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_WORD:
+        if (forward && node.textSelectionExtent < node.value.length()) {
+          Pattern pattern = Pattern.compile("\\p{L}(\\b)");
+          Matcher result = pattern.matcher(node.value.substring(node.textSelectionExtent));
+          // we discard the first result because we want to find the "next" word
+          result.find();
+          if (result.find()) {
+            node.textSelectionExtent += result.start(1);
+          } else {
+            node.textSelectionExtent = node.value.length();
+          }
+        } else if (!forward && node.textSelectionExtent > 0) {
+          // Finds last beginning of the word boundary.
+          Pattern pattern = Pattern.compile("(?s:.*)(\\b)\\p{L}");
+          Matcher result = pattern.matcher(node.value.substring(0, node.textSelectionExtent));
+          if (result.find()) {
+            node.textSelectionExtent = result.start(1);
+          }
+        }
+        break;
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_LINE:
+        if (forward && node.textSelectionExtent < node.value.length()) {
+          // Finds the next new line.
+          Pattern pattern = Pattern.compile("(?!^)(\\n)");
+          Matcher result = pattern.matcher(node.value.substring(node.textSelectionExtent));
+          if (result.find()) {
+            node.textSelectionExtent += result.start(1);
+          } else {
+            node.textSelectionExtent = node.value.length();
+          }
+        } else if (!forward && node.textSelectionExtent > 0) {
+          // Finds the last new line.
+          Pattern pattern = Pattern.compile("(?s:.*)(\\n)");
+          Matcher result = pattern.matcher(node.value.substring(0, node.textSelectionExtent));
+          if (result.find()) {
+            node.textSelectionExtent = result.start(1);
+          } else {
+            node.textSelectionExtent = 0;
+          }
+        }
+        break;
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PARAGRAPH:
+      case AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PAGE:
+        if (forward) {
+          node.textSelectionExtent = node.value.length();
+        } else {
+          node.textSelectionExtent = 0;
+        }
+        break;
+    }
+    if (!extendSelection) {
+      node.textSelectionBase = node.textSelectionExtent;
+    }
+  }
+
   /**
    * Handles the responsibilities of {@link #performAction(int, int, Bundle)} for the specific
    * scenario of cursor movement.
    */
   @TargetApi(21)
   @RequiresApi(21)
-  private boolean performSetText(int virtualViewId, @NonNull Bundle arguments) {
+  private boolean performSetText(SemanticsNode node, int virtualViewId, @NonNull Bundle arguments) {
     String newText = "";
     if (arguments != null
         && arguments.containsKey(AccessibilityNodeInfo.ACTION_ARGUMENT_SET_TEXT_CHARSEQUENCE)) {
       newText = arguments.getString(AccessibilityNodeInfo.ACTION_ARGUMENT_SET_TEXT_CHARSEQUENCE);
     }
     accessibilityChannel.dispatchSemanticsAction(virtualViewId, Action.SET_TEXT, newText);
+    // The voice access expects the semantics node to update immediately. We update the semantics
+    // node based on prediction. If the result is incorrect, it will be updated in the next frame.
+    node.value = newText;
     return true;
   }