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/*
* Copyright (C) 2020, 2021, 2022 Igalia S.L.
*
* 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.
*/
#pragma once
#include "RenderAncestorIterator.h"
#include "RenderLayer.h"
#include "RenderLayerModelObject.h"
#include "RenderSVGViewportContainer.h"
#include "TransformState.h"
#include <wtf/MathExtras.h>
namespace WebCore {
class SVGLayerTransformComputation {
WTF_MAKE_NONCOPYABLE(SVGLayerTransformComputation);
public:
SVGLayerTransformComputation(const RenderLayerModelObject& renderer)
: m_renderer(renderer)
{
}
~SVGLayerTransformComputation() = default;
AffineTransform computeAccumulatedTransform(const RenderLayerModelObject* stopAtRenderer, TransformState::TransformMatrixTracking trackingMode) const
{
// The mapping into parent coordinate systems stops at this renderer,
// as mapLocalContainer exits if "ancestorContainer == this" is fulfilled.
const RenderLayerModelObject* ancestorContainer = nullptr;
// Special handling of RenderSVGRoot, due to the way we implement the outermost <svg> element.
// When SVGSVGElement::getCTM()/getScreenCTM() is invoked, we want to use information from the
// anonymous RenderSVGViewportContainer (most noticeable: viewBox). Therefore we have to start
// calling mapLocalToContainer() starting from the anonymous RenderSVGViewportContainer, and
// not from its parent - RenderSVGRoot.
auto* renderer = m_renderer.ptr();
if (auto* svgRoot = dynamicDowncast<RenderSVGRoot>(renderer)) {
renderer = svgRoot->viewportContainer();
if (trackingMode == TransformState::TrackSVGCTMMatrix)
ancestorContainer = svgRoot;
else
ASSERT(!stopAtRenderer);
} else if (trackingMode == TransformState::TrackSVGCTMMatrix) {
// Only ever walk up to the anonymous RenderSVGViewportContainer (the first and only child of RenderSVGRoot).
// Proceeding up to RenderSVGRoot would include border/padding/margin information which shouldn't be included for getCTM() (unlike getScreenCTM()).
if (!stopAtRenderer) {
if (auto* svgRoot = ancestorsOfType<RenderSVGRoot>(*renderer).first())
ancestorContainer = svgRoot->viewportContainer();
} else if (const auto* enclosingLayerRenderer = ancestorsOfType<RenderLayerModelObject>(*stopAtRenderer).first())
ancestorContainer = enclosingLayerRenderer;
} else if (trackingMode == TransformState::TrackSVGScreenCTMMatrix && stopAtRenderer) {
ASSERT(stopAtRenderer->isComposited());
ancestorContainer = ancestorsOfType<RenderLayerModelObject>(*stopAtRenderer).first();
}
TransformState transformState(TransformState::ApplyTransformDirection, FloatPoint { });
transformState.setTransformMatrixTracking(trackingMode);
renderer->mapLocalToContainer(ancestorContainer, transformState, { UseTransforms, ApplyContainerFlip });
if (trackingMode == TransformState::TrackSVGCTMMatrix) {
if (auto* svgRoot = dynamicDowncast<RenderSVGRoot>(m_renderer.get()))
transformState.move(-toLayoutSize(svgRoot->contentBoxLocation()));
else if (ancestorContainer) {
// Continue to accumulate container offsets, excluding transforms, from the container of the current element ('ancestorContainer') up to RenderSVGRoot.
// The resulting TransformState is aligned with the 'nominalSVGLayoutLocation()' within the local coordinate system of the 'm_renderer'. (0, 0) in local
// coordinates is mapped to the top-left of the 'objectBoundingBoxWithoutTransforms()' of the SVG renderer.
if (auto* svgRoot = lineageOfType<RenderSVGRoot>(*ancestorContainer).first())
ancestorContainer->mapLocalToContainer(svgRoot->viewportContainer(), transformState, { ApplyContainerFlip });
}
}
transformState.flatten();
auto transform = transformState.releaseTrackedTransform();
if (!transform)
return { };
auto ctm = transform->toAffineTransform();
// When we've climbed the ancestor tree up to and including RenderSVGRoot, the CTM is aligned with the top-left of the renderers bounding box (= nominal SVG layout location).
// However, for getCTM/getScreenCTM we're supposed to align by the top-left corner of the enclosing "viewport element" -- correct for that.
if (m_renderer->isRenderSVGRoot())
return ctm;
ctm.translate(-toFloatSize(m_renderer->nominalSVGLayoutLocation()));
return ctm;
}
float calculateScreenFontSizeScalingFactor() const
{
// Walk up the render tree, accumulating transforms
auto* layer = m_renderer->enclosingLayer();
RenderLayer* stopAtLayer = nullptr;
while (layer) {
// We can stop at compositing layers, to match the backing resolution.
if (layer->isComposited()) {
stopAtLayer = layer;
break;
}
layer = layer->parent();
}
auto ctm = computeAccumulatedTransform(stopAtLayer ? &stopAtLayer->renderer() : nullptr, TransformState::TrackSVGScreenCTMMatrix);
ctm.scale(m_renderer->document().deviceScaleFactor());
if (!m_renderer->document().isSVGDocument())
ctm.scale(m_renderer->style().usedZoom());
return narrowPrecisionToFloat(std::hypot(ctm.xScale(), ctm.yScale()) / sqrtOfTwoDouble);
}
private:
SingleThreadWeakRef<const RenderLayerModelObject> m_renderer;
};
} // namespace WebCore
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