1 files changed, 103 insertions, 0 deletions
diff --git a/WebCore/platform/image-decoders/ImageDecoder.cpp b/WebCore/platform/image-decoders/ImageDecoder.cpp
new file mode 100644
index 0000000..9c723cc
--- /dev/null
+++ b/WebCore/platform/image-decoders/ImageDecoder.cpp
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2008-2009 Torch Mobile, Inc.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Library General Public License
+ *  along with this library; see the file COPYING.LIB.  If not, write to
+ *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA 02110-1301, USA.
+ *
+ */
+
+#if ENABLE(IMAGE_DECODER_DOWN_SAMPLING)
+
+#include "config.h"
+#include "ImageDecoder.h"
+
+#include <algorithm>
+
+namespace WebCore {
+
+namespace {
+
+enum MatchType {
+    Exact,
+    UpperBound,
+    LowerBound
+};
+
+}
+
+template <MatchType type> static int getScaledValue(const Vector<int>& scaledValues, int valueToMatch, int searchStart)
+{
+    const int* dataStart = scaledValues.data();
+    const int* dataEnd = dataStart + scaledValues.size();
+    const int* matched = std::lower_bound(dataStart + searchStart, dataEnd, valueToMatch);
+    switch (type) {
+    case Exact:
+        return matched != dataEnd && *matched == valueToMatch ? matched - dataStart : -1;
+    case LowerBound:
+        return matched != dataEnd && *matched == valueToMatch ? matched - dataStart : matched - dataStart - 1;
+    case UpperBound:
+    default:
+        return matched != dataEnd ? matched - dataStart : -1;
+    }
+}
+
+int ImageDecoder::upperBoundScaledX(int origX, int searchStart)
+{
+    return getScaledValue<UpperBound>(m_scaledColumns, origX, searchStart);
+}
+
+int ImageDecoder::lowerBoundScaledX(int origX, int searchStart)
+{
+    return getScaledValue<LowerBound>(m_scaledColumns, origX, searchStart);
+}
+
+int ImageDecoder::scaledY(int origY, int searchStart)
+{
+    return getScaledValue<Exact>(m_scaledRows, origY, searchStart);
+}
+
+static inline void fillScaledValues(Vector<int>& scaledValues, double scaleRate, int length)
+{
+    double inflateRate = 1. / scaleRate;
+    scaledValues.reserveCapacity(static_cast<int>(length * scaleRate + 0.5));
+    for (int scaledIndex = 0;;) {
+        int index = static_cast<int>(scaledIndex * inflateRate + 0.5);
+        if (index < length) {
+            scaledValues.append(index);
+            ++scaledIndex;
+        } else
+            break;
+    }
+}
+
+void ImageDecoder::prepareScaleDataIfNecessary()
+{
+    int width = m_size.width();
+    int height = m_size.height();
+    int numPixels = height * width;
+    if (m_maxNumPixels <= 0 || numPixels <= m_maxNumPixels) {
+        m_scaled = false;
+        return;
+    }
+
+    m_scaled = true;
+    double scale = sqrt(m_maxNumPixels / (double)numPixels);
+    fillScaledValues(m_scaledColumns, scale, width);
+    fillScaledValues(m_scaledRows, scale, height);
+}
+
+}
+
+#endif // ENABLE(IMAGE_DECODER_DOWN_SAMPLING)