Android 7/8/9: force keyboard to show when ReactEditText is clicked

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactEditText.java

@@ -123,6 +123,8 @@ public class ReactEditText extends AppCompatEditText
   private static final KeyListener sKeyListener = QwertyKeyListener.getInstanceForFullKeyboard();
   private @Nullable EventDispatcher mEventDispatcher;
 
+  private final ReactEditTextClickDetector clickDetector = new ReactEditTextClickDetector(this);
+
   public ReactEditText(Context context) {
     super(context);
     setFocusableInTouchMode(false);
@@ -207,6 +209,13 @@ public boolean onTouchEvent(MotionEvent ev) {
         // Disallow parent views to intercept touch events, until we can detect if we should be
         // capturing these touches or not.
         this.getParent().requestDisallowInterceptTouchEvent(true);
+        clickDetector.handleDown(ev);
+        break;
+      case MotionEvent.ACTION_UP:
+        clickDetector.handleUp(ev);
+        break;
+      case MotionEvent.ACTION_CANCEL:
+        clickDetector.cancelPress();
         break;
       case MotionEvent.ACTION_MOVE:
         if (mDetectScrollMovement) {

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactEditTextClickDetector.java

@@ -0,0 +1,92 @@
+package com.facebook.react.views.textinput;
+
+import android.os.Build;
+import android.view.MotionEvent;
+import android.view.View;
+
+import androidx.annotation.Nullable;
+
+class ReactEditTextClickDetector {
+
+  private static final long MAX_CLICK_DURATION_MS = 250L;
+  private static final int MAX_CLICK_DISTANCE_DP = 12;
+
+  private final ReactEditText reactEditText;
+  private final float screenDensity;
+
+  @Nullable
+  private TimestampedMotionEvent currentDownEvent;
+
+  public ReactEditTextClickDetector(final ReactEditText reactEditText) {
+    this.reactEditText = reactEditText;
+    screenDensity = reactEditText.getResources().getDisplayMetrics().density;
+  }
+
+  void handleDown(final MotionEvent downEvent) {
+    currentDownEvent = new TimestampedMotionEvent(downEvent);
+  }
+
+  void cancelPress() {
+    currentDownEvent = null;
+  }
+
+  void handleUp(final MotionEvent upEvent) {
+    if (currentDownEvent == null) {
+      return;
+    }
+
+    final TimestampedMotionEvent downEvent = currentDownEvent;
+    currentDownEvent = null;
+
+    // for now, if we're not forcing showing the keyboard on clicks, we don't care if it was a
+    // click. we also early return if the view is not enabled.
+    if (!(forceShowKeyboardOnClicks() && reactEditText.isEnabled())) {
+      return;
+    }
+
+    // make sure the press event was close enough in time
+    final long now = System.currentTimeMillis();
+    final long timeDelta = now - downEvent.timestamp;
+    if (timeDelta > MAX_CLICK_DURATION_MS) {
+      return;
+    }
+
+    // make sure the press event was close enough in distance
+    final float oldX = downEvent.motionEvent.getRawX();
+    final float oldY = downEvent.motionEvent.getRawY();
+    final float newX = upEvent.getRawX();
+    final float newY = upEvent.getRawY();
+
+    // distance = sqrt((x2 − x1)^2 + (y2 − y1)^2)
+    final double distancePx = Math.sqrt(
+      Math.pow((newX - oldX), 2) + Math.pow((newY - oldY), 2)
+    );
+
+    double distanceDp = distancePx / screenDensity;
+    if (distanceDp > MAX_CLICK_DISTANCE_DP) {
+      return;
+    }
+
+    reactEditText.showSoftKeyboard();
+  }
+
+  /**
+   * There is a bug on Android 7/8/9 where clicking the view while it is already
+   * focused does not show the keyboard. On those API levels, we force showing
+   * the keyboard when we detect a click.
+   */
+  private static boolean forceShowKeyboardOnClicks() {
+    return Build.VERSION.SDK_INT <= Build.VERSION_CODES.P;
+  }
+
+  private static class TimestampedMotionEvent {
+
+    final long timestamp;
+    final MotionEvent motionEvent;
+
+    TimestampedMotionEvent(final long timestamp, final MotionEvent motionEvent) {
+      this.timestamp = timestamp;
+      this.motionEvent = motionEvent;
+    }
+  }
+}