Fix bug #5332081 TextLayoutCache needs to be able to have more cache hits

- makes TextLayoutCache not carring about start/count. Basically he will cache the result for
the full string and gives back the "chunk" corresponding to start/count
- changed the TextLayoutCacheValue API to take start/count parameters
- added the Harfbuzz LogClusters in TextLayoutCacheValue as it is needed for extracting the start/count "chunk"
- fix potential issue of cache key leaking

Change-Id: I9276f9bec744e8de36349acfba8429f7c6f83394

1 files changed, 80 insertions, 10 deletions

diff --git a/core/jni/android/graphics/TextLayout.cpp b/core/jni/android/graphics/TextLayout.cpp
index fa9a7b7..97a3cde 100644
--- a/core/jni/android/graphics/TextLayout.cpp
+++ b/core/jni/android/graphics/TextLayout.cpp
@@ -253,21 +253,22 @@ void TextLayout::drawTextRun(SkPaint* paint, const jchar* chars,
 
 void TextLayout::getTextRunAdvances(SkPaint* paint, const jchar* chars, jint start,
                                     jint count, jint contextCount, jint dirFlags,
-                                    jfloat* resultAdvances, jfloat& resultTotalAdvance) {
+                                    jfloat* resultAdvances, jfloat* resultTotalAdvance) {
     sp<TextLayoutCacheValue> value;
 #if USE_TEXT_LAYOUT_CACHE
     // Return advances from the cache. Compute them if needed
-    value = TextLayoutCache::getInstance().getValue(
-            paint, chars, start, count, contextCount, dirFlags);
+    value = TextLayoutCache::getInstance().getValue(paint, chars, contextCount, dirFlags);
 #else
     value = new TextLayoutCacheValue();
-    value->computeValues(paint, chars, start, count, contextCount, dirFlags);
+    value->computeValues(paint, chars, contextCount, dirFlags);
 #endif
     if (value != NULL) {
-        if (resultAdvances != NULL) {
-            memcpy(resultAdvances, value->getAdvances(), value->getAdvancesCount() * sizeof(jfloat));
+        if (resultAdvances) {
+            value->getAdvances(start, count, resultAdvances);
+        }
+        if (resultTotalAdvance) {
+            *resultTotalAdvance = value->getTotalAdvance(start, count);
         }
-        resultTotalAdvance = value->getTotalAdvance();
     }
 }
 
@@ -275,18 +276,87 @@ void TextLayout::getTextRunAdvancesHB(SkPaint* paint, const jchar* chars, jint s
                                     jint count, jint contextCount, jint dirFlags,
                                     jfloat* resultAdvances, jfloat& resultTotalAdvance) {
     // Compute advances and return them
-    TextLayoutCacheValue::computeValuesWithHarfbuzz(paint, chars, start, count, contextCount,
-            dirFlags, resultAdvances, &resultTotalAdvance, NULL, NULL);
+    TextLayoutCacheValue::computeValuesWithHarfbuzz(paint, chars, contextCount,
+            dirFlags, resultAdvances, &resultTotalAdvance, NULL, NULL, NULL);
 }
 
 void TextLayout::getTextRunAdvancesICU(SkPaint* paint, const jchar* chars, jint start,
                                     jint count, jint contextCount, jint dirFlags,
                                     jfloat* resultAdvances, jfloat& resultTotalAdvance) {
     // Compute advances and return them
-    TextLayoutCacheValue::computeAdvancesWithICU(paint, chars, start, count, contextCount, dirFlags,
+    computeAdvancesWithICU(paint, chars, start, count, contextCount, dirFlags,
             resultAdvances, &resultTotalAdvance);
 }
 
+void TextLayout::computeAdvancesWithICU(SkPaint* paint, const UChar* chars,
+        size_t start, size_t count, size_t contextCount, int dirFlags,
+        jfloat* outAdvances, jfloat* outTotalAdvance) {
+    SkAutoSTMalloc<CHAR_BUFFER_SIZE, jchar> tempBuffer(contextCount);
+    jchar* buffer = tempBuffer.get();
+    SkScalar* scalarArray = (SkScalar*)outAdvances;
+
+    // this is where we'd call harfbuzz
+    // for now we just use ushape.c
+    size_t widths;
+    const jchar* text;
+    if (dirFlags & 0x1) { // rtl, call arabic shaping in case
+        UErrorCode status = U_ZERO_ERROR;
+        // Use fixed length since we need to keep start and count valid
+        u_shapeArabic(chars, contextCount, buffer, contextCount,
+                U_SHAPE_LENGTH_FIXED_SPACES_NEAR |
+                U_SHAPE_TEXT_DIRECTION_LOGICAL | U_SHAPE_LETTERS_SHAPE |
+                U_SHAPE_X_LAMALEF_SUB_ALTERNATE, &status);
+        // we shouldn't fail unless there's an out of memory condition,
+        // in which case we're hosed anyway
+        for (int i = start, e = i + count; i < e; ++i) {
+            if (buffer[i] == UNICODE_NOT_A_CHAR) {
+                buffer[i] = UNICODE_ZWSP; // zero-width-space for skia
+            }
+        }
+        text = buffer + start;
+        widths = paint->getTextWidths(text, count << 1, scalarArray);
+    } else {
+        text = chars + start;
+        widths = paint->getTextWidths(text, count << 1, scalarArray);
+    }
+
+    jfloat totalAdvance = 0;
+    if (widths < count) {
+#if DEBUG_ADVANCES
+    LOGD("ICU -- count=%d", widths);
+#endif
+        // Skia operates on code points, not code units, so surrogate pairs return only
+        // one value. Expand the result so we have one value per UTF-16 code unit.
+
+        // Note, skia's getTextWidth gets confused if it encounters a surrogate pair,
+        // leaving the remaining widths zero.  Not nice.
+        for (size_t i = 0, p = 0; i < widths; ++i) {
+            totalAdvance += outAdvances[p++] = SkScalarToFloat(scalarArray[i]);
+            if (p < count &&
+                    text[p] >= UNICODE_FIRST_LOW_SURROGATE &&
+                    text[p] < UNICODE_FIRST_PRIVATE_USE &&
+                    text[p-1] >= UNICODE_FIRST_HIGH_SURROGATE &&
+                    text[p-1] < UNICODE_FIRST_LOW_SURROGATE) {
+                outAdvances[p++] = 0;
+            }
+#if DEBUG_ADVANCES
+            LOGD("icu-adv = %f - total = %f", outAdvances[i], totalAdvance);
+#endif
+        }
+    } else {
+#if DEBUG_ADVANCES
+    LOGD("ICU -- count=%d", count);
+#endif
+        for (size_t i = 0; i < count; i++) {
+            totalAdvance += outAdvances[i] = SkScalarToFloat(scalarArray[i]);
+#if DEBUG_ADVANCES
+            LOGD("icu-adv = %f - total = %f", outAdvances[i], totalAdvance);
+#endif
+        }
+    }
+    *outTotalAdvance = totalAdvance;
+}
+
 // Draws a paragraph of text on a single line, running bidi and shaping
 void TextLayout::drawText(SkPaint* paint, const jchar* text, jsize len,
                           int bidiFlags, jfloat x, jfloat y, SkCanvas* canvas) {