Source/WebKit/WebProcess/WebPage/ViewGestureGeometryCollector.cpp

/*
 * Copyright (C) 2013, 2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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#include "config.h"
#include "ViewGestureGeometryCollector.h"

#include "Logging.h"
#include "ViewGestureGeometryCollectorMessages.h"
#include "WebCoreArgumentCoders.h"
#include "WebFrame.h"
#include "WebPage.h"
#include "WebProcess.h"
#include <WebCore/FontCascade.h>
#include <WebCore/Frame.h>
#include <WebCore/FrameView.h>
#include <WebCore/HTMLImageElement.h>
#include <WebCore/HTMLTextFormControlElement.h>
#include <WebCore/HitTestResult.h>
#include <WebCore/ImageDocument.h>
#include <WebCore/RenderView.h>
#include <WebCore/TextIterator.h>

#if PLATFORM(IOS_FAMILY)
#include "SmartMagnificationControllerMessages.h"
#else
#include "ViewGestureControllerMessages.h"
#endif

namespace WebKit {
using namespace WebCore;

#if PLATFORM(IOS_FAMILY)
static const double minimumScaleDifferenceForZooming = 0.3;
#endif

ViewGestureGeometryCollector::ViewGestureGeometryCollector(WebPage& webPage)
    : m_webPage(webPage)
#if !PLATFORM(IOS_FAMILY)
    , m_renderTreeSizeNotificationThreshold(0)
#endif
{
    WebProcess::singleton().addMessageReceiver(Messages::ViewGestureGeometryCollector::messageReceiverName(), m_webPage.identifier(), *this);
}

ViewGestureGeometryCollector::~ViewGestureGeometryCollector()
{
    WebProcess::singleton().removeMessageReceiver(Messages::ViewGestureGeometryCollector::messageReceiverName(), m_webPage.identifier());
}

void ViewGestureGeometryCollector::dispatchDidCollectGeometryForSmartMagnificationGesture(FloatPoint origin, FloatRect targetRect, FloatRect visibleContentRect, bool fitEntireRect, double viewportMinimumScale, double viewportMaximumScale)
{
#if PLATFORM(MAC)
    m_webPage.send(Messages::ViewGestureController::DidCollectGeometryForSmartMagnificationGesture(origin, targetRect, visibleContentRect, fitEntireRect, viewportMinimumScale, viewportMaximumScale));
#endif
#if PLATFORM(IOS_FAMILY)
    m_webPage.send(Messages::SmartMagnificationController::DidCollectGeometryForSmartMagnificationGesture(origin, targetRect, visibleContentRect, fitEntireRect, viewportMinimumScale, viewportMaximumScale));
#endif
}

void ViewGestureGeometryCollector::collectGeometryForSmartMagnificationGesture(FloatPoint origin)
{
    FloatRect visibleContentRect = m_webPage.mainFrameView()->unobscuredContentRectIncludingScrollbars();

    if (m_webPage.mainWebFrame()->handlesPageScaleGesture())
        return;

    double viewportMinimumScale;
    double viewportMaximumScale;

#if PLATFORM(IOS_FAMILY)
    if (m_webPage.platformPrefersTextLegibilityBasedZoomScaling()) {
        auto textLegibilityScales = computeTextLegibilityScales(viewportMinimumScale, viewportMaximumScale);
        if (!textLegibilityScales) {
            dispatchDidCollectGeometryForSmartMagnificationGesture({ }, { }, { }, false, 0, 0);
            return;
        }

        float targetScale = m_webPage.viewportConfiguration().initialScale();
        float currentScale = m_webPage.pageScaleFactor();
        if (currentScale < textLegibilityScales->first - minimumScaleDifferenceForZooming)
            targetScale = textLegibilityScales->first;
        else if (currentScale < textLegibilityScales->second - minimumScaleDifferenceForZooming)
            targetScale = textLegibilityScales->second;

        FloatRect targetRectInContentCoordinates { origin, FloatSize() };
        targetRectInContentCoordinates.inflate(m_webPage.viewportConfiguration().viewLayoutSize() / (2 * targetScale));

        dispatchDidCollectGeometryForSmartMagnificationGesture(origin, targetRectInContentCoordinates, visibleContentRect, true, viewportMinimumScale, viewportMaximumScale);
        return;
    }
#endif // PLATFORM(IOS_FAMILY)

    IntPoint originInContentsSpace = m_webPage.mainFrameView()->windowToContents(roundedIntPoint(origin));
    HitTestResult hitTestResult = HitTestResult(originInContentsSpace);

    m_webPage.mainFrame()->document()->hitTest(HitTestRequest(), hitTestResult);
    Node* node = hitTestResult.innerNode();
    if (!node) {
        dispatchDidCollectGeometryForSmartMagnificationGesture(FloatPoint(), FloatRect(), FloatRect(), false, 0, 0);
        return;
    }

    bool isReplaced;
    FloatRect renderRect;

    computeZoomInformationForNode(*node, origin, renderRect, isReplaced, viewportMinimumScale, viewportMaximumScale);
    dispatchDidCollectGeometryForSmartMagnificationGesture(origin, renderRect, visibleContentRect, isReplaced, viewportMinimumScale, viewportMaximumScale);
}

#if PLATFORM(IOS_FAMILY)

struct FontSizeAndCount {
    unsigned fontSize;
    unsigned count;
};

Optional<std::pair<double, double>> ViewGestureGeometryCollector::computeTextLegibilityScales(double& viewportMinimumScale, double& viewportMaximumScale)
{
    static const unsigned fontSizeBinningInterval = 2;
    static const double maximumNumberOfTextRunsToConsider = 200;

    static const double targetLegibilityFontSize = 12;
    static const double textLegibilityScaleRatio = 0.1;
    static const double defaultTextLegibilityZoomScale = 1;

    computeMinimumAndMaximumViewportScales(viewportMinimumScale, viewportMaximumScale);
    if (m_cachedTextLegibilityScales)
        return m_cachedTextLegibilityScales;

    auto document = makeRefPtr(m_webPage.mainFrame()->document());
    if (!document)
        return WTF::nullopt;

    document->updateLayoutIgnorePendingStylesheets();

    auto documentRange = Range::create(*document, {{ document->documentElement(), Position::PositionIsBeforeAnchor }}, {{ document->documentElement(), Position::PositionIsAfterAnchor }});
    HashSet<Node*> allTextNodes;
    HashMap<unsigned, unsigned> fontSizeToCountMap;
    unsigned numberOfIterations = 0;
    unsigned totalSampledTextLength = 0;

    for (TextIterator documentTextIterator { documentRange.ptr(), TextIteratorEntersTextControls }; !documentTextIterator.atEnd(); documentTextIterator.advance()) {
        if (++numberOfIterations >= maximumNumberOfTextRunsToConsider)
            break;

        if (!is<Text>(documentTextIterator.node()))
            continue;

        auto& textNode = downcast<Text>(*documentTextIterator.node());
        auto textLength = textNode.length();
        if (!textLength || !textNode.renderer() || allTextNodes.contains(&textNode))
            continue;

        allTextNodes.add(&textNode);

        unsigned fontSizeBin = fontSizeBinningInterval * round(textNode.renderer()->style().fontCascade().size() / fontSizeBinningInterval);
        auto entry = fontSizeToCountMap.find(fontSizeBin);
        fontSizeToCountMap.set(fontSizeBin, textLength + (entry == fontSizeToCountMap.end() ? 0 : entry->value));
        totalSampledTextLength += textLength;
    }

    Vector<FontSizeAndCount> sortedFontSizesAndCounts;
    sortedFontSizesAndCounts.reserveCapacity(fontSizeToCountMap.size());
    for (auto& entry : fontSizeToCountMap)
        sortedFontSizesAndCounts.append({ entry.key, entry.value });

    std::sort(sortedFontSizesAndCounts.begin(), sortedFontSizesAndCounts.end(), [] (auto& first, auto& second) {
        return first.fontSize < second.fontSize;
    });

    double defaultScale = clampTo<double>(defaultTextLegibilityZoomScale, viewportMinimumScale, viewportMaximumScale);
    double textLegibilityScale = defaultScale;
    double currentSampledTextLength = 0;
    for (auto& fontSizeAndCount : sortedFontSizesAndCounts) {
        currentSampledTextLength += fontSizeAndCount.count;
        double ratioOfTextUnderCurrentFontSize = currentSampledTextLength / totalSampledTextLength;
        if (ratioOfTextUnderCurrentFontSize >= textLegibilityScaleRatio) {
            textLegibilityScale = clampTo<double>(targetLegibilityFontSize / fontSizeAndCount.fontSize, viewportMinimumScale, viewportMaximumScale);
            break;
        }
    }

    auto firstTextLegibilityScale = std::min<double>(textLegibilityScale, defaultScale);
    auto secondTextLegibilityScale = std::max<double>(textLegibilityScale, defaultScale);
    if (secondTextLegibilityScale - firstTextLegibilityScale < minimumScaleDifferenceForZooming)
        firstTextLegibilityScale = secondTextLegibilityScale;

    m_cachedTextLegibilityScales.emplace(std::pair<double, double> { firstTextLegibilityScale, secondTextLegibilityScale });
    return m_cachedTextLegibilityScales;
}

#endif // PLATFORM(IOS_FAMILY)

void ViewGestureGeometryCollector::computeZoomInformationForNode(Node& node, FloatPoint& origin, FloatRect& renderRect, bool& isReplaced, double& viewportMinimumScale, double& viewportMaximumScale)
{
    renderRect = node.renderRect(&isReplaced);
    if (node.document().isImageDocument()) {
        if (HTMLImageElement* imageElement = static_cast<ImageDocument&>(node.document()).imageElement()) {
            if (&node != imageElement) {
                renderRect = imageElement->renderRect(&isReplaced);
                FloatPoint newOrigin = origin;
                if (origin.x() < renderRect.x() || origin.x() > renderRect.maxX())
                    newOrigin.setX(renderRect.x() + renderRect.width() / 2);
                if (origin.y() < renderRect.y() || origin.y() > renderRect.maxY())
                    newOrigin.setY(renderRect.y() + renderRect.height() / 2);
                origin = newOrigin;
            }
            isReplaced = true;
        }
    }
    computeMinimumAndMaximumViewportScales(viewportMinimumScale, viewportMaximumScale);
}

void ViewGestureGeometryCollector::computeMinimumAndMaximumViewportScales(double& viewportMinimumScale, double& viewportMaximumScale) const
{
#if PLATFORM(IOS_FAMILY)
    viewportMinimumScale = m_webPage.minimumPageScaleFactor();
    viewportMaximumScale = m_webPage.maximumPageScaleFactor();
#else
    viewportMinimumScale = 0;
    viewportMaximumScale = std::numeric_limits<double>::max();
#endif
}

#if PLATFORM(MAC)
void ViewGestureGeometryCollector::collectGeometryForMagnificationGesture()
{
    FloatRect visibleContentRect = m_webPage.mainFrameView()->unobscuredContentRectIncludingScrollbars();
    bool frameHandlesMagnificationGesture = m_webPage.mainWebFrame()->handlesPageScaleGesture();
    m_webPage.send(Messages::ViewGestureController::DidCollectGeometryForMagnificationGesture(visibleContentRect, frameHandlesMagnificationGesture));
}
#endif

#if !PLATFORM(IOS_FAMILY)
void ViewGestureGeometryCollector::setRenderTreeSizeNotificationThreshold(uint64_t size)
{
    m_renderTreeSizeNotificationThreshold = size;
    sendDidHitRenderTreeSizeThresholdIfNeeded();
}

void ViewGestureGeometryCollector::sendDidHitRenderTreeSizeThresholdIfNeeded()
{
    if (m_renderTreeSizeNotificationThreshold && m_webPage.renderTreeSize() >= m_renderTreeSizeNotificationThreshold) {
        m_webPage.send(Messages::ViewGestureController::DidHitRenderTreeSizeThreshold());
        m_renderTreeSizeNotificationThreshold = 0;
    }
}
#endif

void ViewGestureGeometryCollector::mainFrameDidLayout()
{
#if PLATFORM(IOS_FAMILY)
    m_cachedTextLegibilityScales.reset();
#else
    sendDidHitRenderTreeSizeThresholdIfNeeded();
#endif
}

} // namespace WebKit