compute select text distance biasing x over y

Rather than using a regular distance function, first
find the closest match in Y then look for the closest
match in X. This allows the touch point to be well to
the right or left of the paragraph and still move the
selection to the next or preceeding line while the
selection is extended.

bug:3183434
Change-Id: I6abf14b9dbca4b7bafe2cb9a96a2915732038ce1

1 files changed, 23 insertions, 17 deletions

diff --git a/WebKit/android/nav/SelectText.cpp b/WebKit/android/nav/SelectText.cpp
index f6548cf..36530b6 100644
--- a/WebKit/android/nav/SelectText.cpp
+++ b/WebKit/android/nav/SelectText.cpp
@@ -423,23 +423,26 @@ public:
          */
         int dx = rect.fLeft + rect.fRight - (mFocusX << 1);
         int dy = top() + bottom() - (mFocusY << 1);
-        int distance = dx * dx + dy * dy;
+        dx = abs(dx);
+        dy = abs(dy);
 #ifdef EXTRA_NOISY_LOGGING
-        if (distance < 500 || abs(distance - mDistance) < 500)
-            DBG_NAV_LOGD("FirstCheck distance=%d mDistance=%d", distance, mDistance);
+        if (dy < 15)
+            DBG_NAV_LOGD("FirstCheck dx/y=(%d, %d) mDx/y=(%d, %d)",
+                dx>>1, dy>>1, mDx>>1, mDy>>1);
 #endif
-        if (mDistance > distance) {
+        if (mDy > dy || (mDy == dy && mDx > dx)) {
             mBestBase = base();
             mBestBounds.set(rect.fLeft, top(), rect.fRight, bottom());
 #ifndef EXTRA_NOISY_LOGGING
-            if (distance < 100) 
+            if (dy < 10 && dx < 10)
 #endif
             {
-                DBG_NAV_LOGD("FirstCheck mBestBounds={%d,%d,r=%d,b=%d} distance=%d",
+                DBG_NAV_LOGD("FirstCheck mBestBounds={%d,%d,r=%d,b=%d} dx/y=(%d, %d)",
                     mBestBounds.fLeft, mBestBounds.fTop,
-                    mBestBounds.fRight, mBestBounds.fBottom, distance >> 2);
+                    mBestBounds.fRight, mBestBounds.fBottom, dx>>1, dy>>1);
             }
-            mDistance = distance;
+            mDx = dx;
+            mDy = dy;
             if (mRecordGlyph)
                 recordGlyph(rec);
         }
@@ -449,7 +452,7 @@ public:
     void reset()
     {
         mBestBounds.setEmpty();
-        mDistance = INT_MAX;
+        mDx = mDy = INT_MAX;
     }
 
     void setRecordGlyph()
@@ -460,7 +463,8 @@ public:
 protected:
     int mBestBase;
     SkIRect mBestBounds;
-    int mDistance;
+    int mDx;
+    int mDy;
     int mFocusX;
     int mFocusY;
     bool mRecordGlyph;
@@ -496,28 +500,30 @@ public:
     {
         int dx = mLeft ? mFocusX - rect.fRight : rect.fLeft - mFocusX;
         int dy = ((top() + bottom()) >> 1) - mFocusY;
+        dx = abs(dx);
+        dy = abs(dy);
         if (mLeft ? mFocusX <= rect.fLeft : mFocusX >= rect.fRight) {
-            if (abs(dx) <= 10 && abs(dy) <= 10) {
+            if (dx <= 10 && dy <= 10) {
                 DBG_NAV_LOGD("EdgeCheck fLeft=%d fRight=%d mFocusX=%d dx=%d dy=%d",
                     rect.fLeft, rect.fRight, mFocusX, dx, dy);
             }
             return false;
         }
-        int distance = dx * dx + dy * dy;
-        if (mDistance > distance) {
+        if (mDy > dy || (mDy == dy && mDx > dx)) {
             if (rec.fLSB == mLastGlyph.fLSB && rec.fRSB == mLastGlyph.fRSB) {
                 DBG_NAV_LOGD("dup rec.fLSB.fX=%g rec.fRSB.fX=%g",
                 SkFixedToScalar(rec.fLSB.fX), SkFixedToScalar(rec.fRSB.fX));
                 return false;
             }
             recordGlyph(rec);
-            mDistance = distance;
+            mDx = dx;
+            mDy = dy;
             mBestBase = base();
             mBestBounds.set(rect.fLeft, top(), rect.fRight, bottom());
-            if (distance <= 100) {
-                DBG_NAV_LOGD("EdgeCheck mBestBounds={%d,%d,r=%d,b=%d} distance=%d",
+            if (dx <= 10 && dy <= 10) {
+                DBG_NAV_LOGD("EdgeCheck mBestBounds={%d,%d,r=%d,b=%d} dx/y=(%d, %d)",
                     mBestBounds.fLeft, mBestBounds.fTop,
-                    mBestBounds.fRight, mBestBounds.fBottom, distance);
+                    mBestBounds.fRight, mBestBounds.fBottom, dx, dy);
             }
         }
         return false;