A sizes attribute parser

Source/core/css/MediaValuesCached.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/css/MediaValuesCached.h"
+
+#include "core/css/CSSHelper.h"
+#include "core/css/CSSPrimitiveValue.h"
+#include "core/dom/Document.h"
+#include "core/rendering/RenderObject.h"
+
+namespace WebCore {
+
+PassRefPtr<MediaValues> MediaValuesCached::create(MediaValuesCachedData& data)
+{
+    return adoptRef(new MediaValuesCached(data));
+}
+
+PassRefPtr<MediaValues> MediaValuesCached::create(Document& document)
+{
+    Document* executingDocument = getExecutingDocument(document);
+    return MediaValuesCached::create(executingDocument->frame(), executingDocument->renderer()->style());
+}
+
+PassRefPtr<MediaValues> MediaValuesCached::create(LocalFrame* frame, RenderStyle* style)
+{
+    return adoptRef(new MediaValuesCached(frame, style));
+}
+
+MediaValuesCached::MediaValuesCached(LocalFrame* frame, RenderStyle* style)
+{
+    ASSERT(frame && style);
+    ASSERT(isMainThread());
+    m_data.viewportWidth = calculateViewportWidth(frame);
+    m_data.viewportHeight = calculateViewportHeight(frame);
+    m_data.deviceWidth = calculateDeviceWidth(frame);
+    m_data.deviceHeight = calculateDeviceHeight(frame);
+    m_data.devicePixelRatio = calculateDevicePixelRatio(frame);
+    m_data.colorBitsPerComponent = calculateColorBitsPerComponent(frame);
+    m_data.monochromeBitsPerComponent = calculateMonochromeBitsPerComponent(frame);
+    m_data.pointer = calculateLeastCapablePrimaryPointerDeviceType(frame);
+    m_data.defaultFontSize = calculateDefaultFontSize(style);
+    m_data.computedFontSize = calculateComputedFontSize(style);
+    m_data.threeDEnabled = calculateThreeDEnabled(frame);
+    m_data.scanMediaType = calculateScanMediaType(frame);
+    m_data.screenMediaType = calculateScreenMediaType(frame);
+    m_data.printMediaType = calculatePrintMediaType(frame);
+    m_data.strictMode = calculateStrictMode(frame);
+}
+
+MediaValuesCached::MediaValuesCached(const MediaValuesCachedData& data)
+    : m_data(data)
+{
+}
+
+PassRefPtr<MediaValues> MediaValuesCached::copy() const
+{
+    return adoptRef(new MediaValuesCached(m_data));
+}
+
+bool MediaValuesCached::computeLength(double value, unsigned short type, int& result) const
+{
+    // We're running in a background thread, so RenderStyle is not available.
+    // Nevertheless, we can evaluate lengths using cached values.
+    //
+    // The logic in this function is duplicated from CSSPrimitiveValue::computeLengthDouble
+    // because MediaValues::computeLength needs nearly identical logic, but we haven't found a way to make
+    // CSSPrimitiveValue::computeLengthDouble more generic (to solve both cases) without hurting performance.
+
+    // FIXME - Unite the logic here with CSSPrimitiveValue is a performant way.
+    int factor = 0;
+    switch (type) {
+    case CSSPrimitiveValue::CSS_EMS:
+    case CSSPrimitiveValue::CSS_REMS:
+        factor = m_data.defaultFontSize;
+        break;
+    case CSSPrimitiveValue::CSS_PX:
+        factor = 1;
+        break;
+    case CSSPrimitiveValue::CSS_EXS:
+        // FIXME: We have a bug right now where the zoom will be applied twice to EX units.
+        // FIXME: We don't seem to be able to cache fontMetrics related values.
+        // Trying to access them is triggering some sort of microtask. Serving the spec's default instead.
+        factor = m_data.defaultFontSize / 2.0;
+        break;
+    case CSSPrimitiveValue::CSS_CHS:
+        // FIXME: We don't seem to be able to cache fontMetrics related values.
+        // Trying to access them is triggering some sort of microtask. Serving the (future) spec default instead.
+        factor = m_data.defaultFontSize / 2.0;
+        break;
+    case CSSPrimitiveValue::CSS_VW:
+        factor = m_data.viewportWidth / 100;
+        break;
+    case CSSPrimitiveValue::CSS_VH:
+        factor = m_data.viewportHeight / 100;
+        break;
+    case CSSPrimitiveValue::CSS_VMIN:
+        factor = std::min(m_data.viewportWidth, m_data.viewportHeight) / 100;
+        break;
+    case CSSPrimitiveValue::CSS_VMAX:
+        factor = std::max(m_data.viewportWidth, m_data.viewportHeight) / 100;
+        break;
+    case CSSPrimitiveValue::CSS_CM:
+        factor = cssPixelsPerCentimeter;
+        break;
+    case CSSPrimitiveValue::CSS_MM:
+        factor = cssPixelsPerMillimeter;
+        break;
+    case CSSPrimitiveValue::CSS_IN:
+        factor = cssPixelsPerInch;
+        break;
+    case CSSPrimitiveValue::CSS_PT:
+        factor = cssPixelsPerPoint;
+        break;
+    case CSSPrimitiveValue::CSS_PC:
+        factor = cssPixelsPerPica;
+        break;
+    default:
+        return false;
+    }
+
+    ASSERT(factor > 0);
+    result = roundForImpreciseConversion<int>(value*factor);
+    return true;
+}
+
+bool MediaValuesCached::isSafeToSendToAnotherThread() const
+{
+    return hasOneRef();
+}
+
+int MediaValuesCached::viewportWidth() const
+{
+    return m_data.viewportWidth;
+}
+
+int MediaValuesCached::viewportHeight() const
+{
+    return m_data.viewportHeight;
+}
+
+int MediaValuesCached::deviceWidth() const
+{
+    return m_data.deviceWidth;
+}
+
+int MediaValuesCached::deviceHeight() const
+{
+    return m_data.deviceHeight;
+}
+
+float MediaValuesCached::devicePixelRatio() const
+{
+    return m_data.devicePixelRatio;
+}
+
+int MediaValuesCached::colorBitsPerComponent() const
+{
+    return m_data.colorBitsPerComponent;
+}
+
+int MediaValuesCached::monochromeBitsPerComponent() const
+{
+    return m_data.monochromeBitsPerComponent;
+}
+
+MediaValues::PointerDeviceType MediaValuesCached::pointer() const
+{
+    return m_data.pointer;
+}
+
+bool MediaValuesCached::threeDEnabled() const
+{
+    return m_data.threeDEnabled;
+}
+
+bool MediaValuesCached::scanMediaType() const
+{
+    return m_data.scanMediaType;
+}
+
+bool MediaValuesCached::screenMediaType() const
+{
+    return m_data.screenMediaType;
+}
+
+bool MediaValuesCached::printMediaType() const
+{
+    return m_data.printMediaType;
+}
+
+bool MediaValuesCached::strictMode() const
+{
+    return m_data.strictMode;
+}
+
+Document* MediaValuesCached::document() const
+{
+    return 0;
+}
+
+bool MediaValuesCached::hasValues() const
+{
+    return true;
+}
+
+} // namespace