TextView - fix ClickableSpans always triggering on touch up

* introduce GestureDetector to TextView
* completely remove link click functionality from
  LinkMovementMethod (the interface does not state it
  provides click functionality)
* intercept onSingleTapConfirmed and trigger onClick on the
  link if it exists (simplified duplicated functionality)
* renamed a bunch of LinkMovementMethod variables because
  eyes hurt

Bug: 23692690
Change-Id: Idaf3f3391328207f42521235fb5deb1a11c66aaa

2 files changed, 52 insertions, 46 deletions

diff --git a/core/java/android/text/method/LinkMovementMethod.java b/core/java/android/text/method/LinkMovementMethod.java
index 3855ff3ae44b..24c119f29d71 100644
--- a/core/java/android/text/method/LinkMovementMethod.java
+++ b/core/java/android/text/method/LinkMovementMethod.java
@@ -29,6 +29,9 @@ import android.widget.TextView;
 /**
  * A movement method that traverses links in the text buffer and scrolls if necessary.
  * Supports clicking on links with DPad Center or Enter.
+ *
+ * <p>Note: Starting from Android 8.0 (API level 25) this class no longer handles the touch
+ * clicks.
  */
 public class LinkMovementMethod extends ScrollingMovementMethod {
     private static final int CLICK = 1;
@@ -98,14 +101,14 @@ public class LinkMovementMethod extends ScrollingMovementMethod {
 
         int padding = widget.getTotalPaddingTop() +
                       widget.getTotalPaddingBottom();
-        int areatop = widget.getScrollY();
-        int areabot = areatop + widget.getHeight() - padding;
+        int areaTop = widget.getScrollY();
+        int areaBot = areaTop + widget.getHeight() - padding;
 
-        int linetop = layout.getLineForVertical(areatop);
-        int linebot = layout.getLineForVertical(areabot);
+        int lineTop = layout.getLineForVertical(areaTop);
+        int lineBot = layout.getLineForVertical(areaBot);
 
-        int first = layout.getLineStart(linetop);
-        int last = layout.getLineEnd(linebot);
+        int first = layout.getLineStart(lineTop);
+        int last = layout.getLineEnd(lineBot);
 
         ClickableSpan[] candidates = buffer.getSpans(first, last, ClickableSpan.class);
 
@@ -141,46 +144,46 @@ public class LinkMovementMethod extends ScrollingMovementMethod {
             break;
 
         case UP:
-            int beststart, bestend;
+            int bestStart, bestEnd;
 
-            beststart = -1;
-            bestend = -1;
+            bestStart = -1;
+            bestEnd = -1;
 
             for (int i = 0; i < candidates.length; i++) {
                 int end = buffer.getSpanEnd(candidates[i]);
 
                 if (end < selEnd || selStart == selEnd) {
-                    if (end > bestend) {
-                        beststart = buffer.getSpanStart(candidates[i]);
-                        bestend = end;
+                    if (end > bestEnd) {
+                        bestStart = buffer.getSpanStart(candidates[i]);
+                        bestEnd = end;
                     }
                 }
             }
 
-            if (beststart >= 0) {
-                Selection.setSelection(buffer, bestend, beststart);
+            if (bestStart >= 0) {
+                Selection.setSelection(buffer, bestEnd, bestStart);
                 return true;
             }
 
             break;
 
         case DOWN:
-            beststart = Integer.MAX_VALUE;
-            bestend = Integer.MAX_VALUE;
+            bestStart = Integer.MAX_VALUE;
+            bestEnd = Integer.MAX_VALUE;
 
             for (int i = 0; i < candidates.length; i++) {
                 int start = buffer.getSpanStart(candidates[i]);
 
                 if (start > selStart || selStart == selEnd) {
-                    if (start < beststart) {
-                        beststart = start;
-                        bestend = buffer.getSpanEnd(candidates[i]);
+                    if (start < bestStart) {
+                        bestStart = start;
+                        bestEnd = buffer.getSpanEnd(candidates[i]);
                     }
                 }
             }
 
-            if (bestend < Integer.MAX_VALUE) {
-                Selection.setSelection(buffer, beststart, bestend);
+            if (bestEnd < Integer.MAX_VALUE) {
+                Selection.setSelection(buffer, bestStart, bestEnd);
                 return true;
             }
 
@@ -195,8 +198,7 @@ public class LinkMovementMethod extends ScrollingMovementMethod {
                                 MotionEvent event) {
         int action = event.getAction();
 
-        if (action == MotionEvent.ACTION_UP ||
-            action == MotionEvent.ACTION_DOWN) {
+        if (action == MotionEvent.ACTION_DOWN) {
             int x = (int) event.getX();
             int y = (int) event.getY();
 
@@ -210,17 +212,12 @@ public class LinkMovementMethod extends ScrollingMovementMethod {
             int line = layout.getLineForVertical(y);
             int off = layout.getOffsetForHorizontal(line, x);
 
-            ClickableSpan[] link = buffer.getSpans(off, off, ClickableSpan.class);
-
-            if (link.length != 0) {
-                if (action == MotionEvent.ACTION_UP) {
-                    link[0].onClick(widget);
-                } else if (action == MotionEvent.ACTION_DOWN) {
-                    Selection.setSelection(buffer,
-                                           buffer.getSpanStart(link[0]),
-                                           buffer.getSpanEnd(link[0]));
-                }
+            ClickableSpan[] links = buffer.getSpans(off, off, ClickableSpan.class);
 
+            if (links.length != 0) {
+                Selection.setSelection(buffer,
+                        buffer.getSpanStart(links[0]),
+                        buffer.getSpanEnd(links[0]));
                 return true;
             } else {
                 Selection.removeSelection(buffer);
diff --git a/core/java/android/widget/TextView.java b/core/java/android/widget/TextView.java
index a6d004fd0ec9..6dafe34fdc13 100644
--- a/core/java/android/widget/TextView.java
+++ b/core/java/android/widget/TextView.java
@@ -114,6 +114,7 @@ import android.view.ActionMode;
 import android.view.Choreographer;
 import android.view.ContextMenu;
 import android.view.DragEvent;
+import android.view.GestureDetector;
 import android.view.Gravity;
 import android.view.HapticFeedbackConstants;
 import android.view.KeyCharacterMap;
@@ -650,6 +651,8 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
      */
     private Editor mEditor;
 
+    private final GestureDetector mClickableSpanOnClickGestureDetector;
+
     private static final int DEVICE_PROVISIONED_UNKNOWN = 0;
     private static final int DEVICE_PROVISIONED_NO = 1;
     private static final int DEVICE_PROVISIONED_YES = 2;
@@ -1488,6 +1491,24 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
         if (getImportantForAccessibility() == IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
             setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_YES);
         }
+
+        mClickableSpanOnClickGestureDetector = new GestureDetector(context,
+                new GestureDetector.SimpleOnGestureListener() {
+                    @Override
+                    public boolean onSingleTapConfirmed(MotionEvent e) {
+                        if (mLinksClickable && (mMovement != null) &&
+                                (mMovement instanceof LinkMovementMethod
+                                || (mAutoLinkMask != 0 && isTextSelectable()))) {
+                            ClickableSpan[] links = ((Spannable) mText).getSpans(
+                                    getSelectionStart(), getSelectionEnd(), ClickableSpan.class);
+                            if (links.length > 0) {
+                                links[0].onClick(TextView.this);
+                                return true;
+                            }
+                        }
+                        return false;
+                    }
+                });
     }
 
     private int[] parseDimensionArray(TypedArray dimens) {
@@ -8515,21 +8536,9 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener
             if (mMovement != null) {
                 handled |= mMovement.onTouchEvent(this, (Spannable) mText, event);
             }
+            handled |= mClickableSpanOnClickGestureDetector.onTouchEvent(event);
 
             final boolean textIsSelectable = isTextSelectable();
-            if (touchIsFinished && mLinksClickable && mAutoLinkMask != 0 && textIsSelectable) {
-                // The LinkMovementMethod which should handle taps on links has not been installed
-                // on non editable text that support text selection.
-                // We reproduce its behavior here to open links for these.
-                ClickableSpan[] links = ((Spannable) mText).getSpans(getSelectionStart(),
-                        getSelectionEnd(), ClickableSpan.class);
-
-                if (links.length > 0) {
-                    links[0].onClick(this);
-                    handled = true;
-                }
-            }
-
             if (touchIsFinished && (isTextEditable() || textIsSelectable)) {
                 // Show the IME, except when selecting in read-only text.
                 final InputMethodManager imm = InputMethodManager.peekInstance();