use measure instead of bounder to find spaces

Pictures do not include white space characters in their
text spans, so they must be deduced. The old method
used drawing through the canvas, compared against
drawing the text directly.

The new method measure and rounds the text to match
how webkit adjusts characters' widths in WidthIterator.

bug:348629
Change-Id: I39fecd274fe0b195fbad13a6083656daa62ed852

1 files changed, 19 insertions, 66 deletions

diff --git a/WebKit/android/nav/SelectText.cpp b/WebKit/android/nav/SelectText.cpp
index a07fa8c..87d1791 100644
--- a/WebKit/android/nav/SelectText.cpp
+++ b/WebKit/android/nav/SelectText.cpp
@@ -141,40 +141,6 @@ void ReverseBidi(UChar* chars, int len) {
 
 namespace android {
 
-/* SpaceBounds and SpaceCanvas are used to measure the left and right side
- * bearings of two consecutive glyphs to help determine if the glyphs were
- * originally laid out with a space character between the glyphs.
- */
-class SpaceBounds : public SkBounder {
-public:
-    virtual bool onIRectGlyph(const SkIRect& , const SkBounder::GlyphRec& rec)
-    {
-        mFirstGlyph = mLastGlyph;
-        mLastGlyph = rec;
-        return false;
-    }
-
-    SkBounder::GlyphRec mFirstGlyph;
-    SkBounder::GlyphRec mLastGlyph;
-};
-
-class SpaceCanvas : public ParseCanvas {
-public:
-    SpaceCanvas()
-    {
-        setBounder(&mBounder);
-        SkBitmap bitmap;
-        // Configure a very large bitmap so the pair of glyphs can be anywhere
-        // on the page. Skia constrains the bitmap to be 2^31-1 bytes. The
-        // bitmap is never allocated, but this constraint avoids triggering
-        // a failure when the configuration is checked.
-        bitmap.setConfig(SkBitmap::kA1_Config, 16383, 1048576);
-        setBitmapDevice(bitmap);
-    }
-
-    SpaceBounds mBounder;
-};
-
 #define HYPHEN_MINUS 0x2D // ASCII hyphen
 #define SOLIDUS 0x2F // ASCII slash
 #define REVERSE_SOLIDUS 0x5C // ASCII backslash
@@ -266,8 +232,7 @@ public:
         if (mLastGlyph.fGlyphID == static_cast<uint16_t>(-1))
             return true;
         DBG_NAV_LOGD("mLastGlyph=((%g, %g),(%g, %g), %d)"
-            " rec=((%g, %g),(%g, %g), %d)"
-            " mMinSpaceWidth=%g mLastUni=0x%04x '%c'",
+            " rec=((%g, %g),(%g, %g), %d) mLastUni=0x%04x '%c'",
             SkFixedToScalar(mLastGlyph.fLSB.fX),
             SkFixedToScalar(mLastGlyph.fLSB.fY),
             SkFixedToScalar(mLastGlyph.fRSB.fX),
@@ -275,7 +240,6 @@ public:
             SkFixedToScalar(rec.fLSB.fX), SkFixedToScalar(rec.fLSB.fY),
             SkFixedToScalar(rec.fRSB.fX), SkFixedToScalar(rec.fRSB.fY),
             rec.fGlyphID,
-            SkFixedToScalar(mMinSpaceWidth),
             mLastUni, mLastUni && mLastUni < 0x7f ? mLastUni : '?');
         bool newBaseLine = mLastGlyph.fLSB.fY != rec.fLSB.fY;
         if (newBaseLine)
@@ -284,35 +248,24 @@ public:
         SkFixed gapTwo = rec.fLSB.fX - mLastGlyph.fRSB.fX;
         if (gapOne < 0 && gapTwo < 0)
             return false; // overlaps
-        uint16_t test[2];
-        test[0] = mLastGlyph.fGlyphID;
-        test[1] = rec.fGlyphID;
-        SpaceCanvas spaceChecker;
-        spaceChecker.drawText(test, sizeof(test),
-            SkFixedToScalar(mLastGlyph.fLSB.fX),
-            SkFixedToScalar(mLastGlyph.fLSB.fY), mPaint);
-        const SkBounder::GlyphRec& g1 = spaceChecker.mBounder.mFirstGlyph;
-        const SkBounder::GlyphRec& g2 = spaceChecker.mBounder.mLastGlyph;
-        DBG_NAV_LOGD("g1=(%g, %g, %g, %g) g2=(%g, %g, %g, %g)",
-            SkFixedToScalar(g1.fLSB.fX), SkFixedToScalar(g1.fLSB.fY),
-            SkFixedToScalar(g1.fRSB.fX), SkFixedToScalar(g1.fRSB.fY),
-            SkFixedToScalar(g2.fLSB.fX), SkFixedToScalar(g2.fLSB.fY),
-            SkFixedToScalar(g2.fRSB.fX), SkFixedToScalar(g2.fRSB.fY));
-        gapOne = SkFixedAbs(gapOne);
-        gapTwo = SkFixedAbs(gapTwo);
-        SkFixed gap = gapOne < gapTwo ? gapOne : gapTwo;
-        SkFixed overlap = g2.fLSB.fX - g1.fRSB.fX;
-        if (overlap < 0)
-            gap -= overlap;
-        DBG_NAV_LOGD("gap=%g overlap=%g gapOne=%g gapTwo=%g minSpaceWidth()=%g",
-            SkFixedToScalar(gap), SkFixedToScalar(overlap),
-            SkFixedToScalar(gapOne), SkFixedToScalar(gapTwo),
-            SkFixedToScalar(minSpaceWidth()));
-        // FIXME: the -1/8 below takes care of slop beween the computed gap
-        // and the actual space width -- it's a rounding error from
-        // moving from fixed to float and back and could be much smaller.
-        spaceChecker.setBounder(0);
-        return gap >= minSpaceWidth() - SK_Fixed1 / 8;
+        const SkBounder::GlyphRec& first = mLastGlyph.fLSB.fX < rec.fLSB.fX
+            ? mLastGlyph : rec;
+        const SkBounder::GlyphRec& second = mLastGlyph.fLSB.fX < rec.fLSB.fX
+            ? rec : mLastGlyph;
+        uint16_t firstGlyph = first.fGlyphID;
+        SkScalar firstWidth = mPaint.measureText(&firstGlyph, sizeof(firstGlyph));
+        SkFixed ceilWidth = SkIntToFixed(SkScalarCeil(firstWidth));
+        SkFixed posNoSpace = first.fLSB.fX + ceilWidth;
+        SkFixed ceilSpace = SkIntToFixed(SkFixedCeil(minSpaceWidth()));
+        SkFixed posWithSpace = posNoSpace + ceilSpace;
+        SkFixed diffNoSpace = SkFixedAbs(second.fLSB.fX - posNoSpace);
+        SkFixed diffWithSpace = SkFixedAbs(second.fLSB.fX - posWithSpace);
+        DBG_NAV_LOGD("second=%g width=%g (%g) noSpace=%g (%g) withSpace=%g (%g)",
+            SkFixedToScalar(second.fLSB.fX),
+            firstWidth, SkFixedToScalar(ceilWidth),
+            SkFixedToScalar(posNoSpace), SkFixedToScalar(diffNoSpace),
+            SkFixedToScalar(posWithSpace), SkFixedToScalar(diffWithSpace));
+        return diffWithSpace < diffNoSpace;
     }
 
     SkFixed minSpaceWidth()