Fix 64-bit bilinear scaled image sampling

A constraint ensuring we do not sample beyond the current scan-line was missing in the SSE2 optimized sampling. Discovered with lancelot. Change-Id: Ib0ece8f8bfaa034733873dc5b8baaaad5d4c0380 Reviewed-by: Erik Verbruggen <[email protected]>
boris-fx · Aug 4, 2016 · b643d6f · b643d6f
1 parent bc4ce55
commit b643d6f
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
@@ -2815,10 +2815,16 @@ static const QRgba64 *QT_FASTCALL fetchTransformedBilinear64(QRgba64 *buffer, co
                         sbuf2[i * 2 + 1] = ((const uint*)s2)[x2];
                         fx += fdx;
                     }
+                    int fastLen;
+                    if (fdx > 0)
+                        fastLen = qMin(len, int((image_x2 - (fx >> 16)) / data->m11));
+                    else
+                        fastLen = qMin(len, int((image_x1 - (fx >> 16)) / data->m11));
+                    fastLen -= 3;
 
                     const __m128i v_fdx = _mm_set1_epi32(fdx*4);
                     __m128i v_fx = _mm_setr_epi32(fx, fx + fdx, fx + fdx + fdx, fx + fdx + fdx + fdx);
-                    for (; i < len-3; i+=4) {
+                    for (; i < fastLen; i += 4) {
                         int offset = _mm_extract_epi16(v_fx, 1);
                         sbuf1[i * 2 + 0] = ((const uint*)s1)[offset];
                         sbuf1[i * 2 + 1] = ((const uint*)s1)[offset + 1];