haikuwebkit/PerformanceTests/SVG/TextOnPathSimple.html

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textPath layout performance improvement. https://bugs.webkit.org/show_bug.cgi?id=141570. Patch by Said Abou-Hallawa <sabouhallawa@apple.com> on 2015-04-14 Reviewed by Darin Adler. PerformanceTests: Cut down the time spent in traversing the path for text by 50%. Instead of traversing the path twice at a certain length: one time for the position and the second time for the angle, we can merge these two passes into one. * SVG/TextOnPathSimple.html: Added. * SVG/resources/TextOnPathSimple.svg: Added. Source/WebCore: The bottleneck of the text-on-path performance is the position and angle calculations for every single character. If the number of characters is 'n' and the number of path elements is 'm', the total number of processing the path elements is O(2 x n x m). What makes it really worse is, for every curve we keep splitting the curve till the split curve is almost a straight line. The changes we need to do are: 1. Merge the position and the angle traversals in one pass since they are returning info for the same length on the path. There is a degenerate case for the starting point when calculating the angle. The original code was solving this problem by passing an epsilon instead of zero but because traversing the path for position and angle are now merged, we will pass zero for the starting point as is. All we need is to move one step ahead without moving the position. We need the extra step forward to calculate the slope of the path at the starting point. 2. We need to add a new mode to traversing a path. The new mode will take a vector of lengths and returns a vector of arrow vectors. Every arrow vector represents a position and an angle on the path at a certain length. This requires changing the SVGTextLayoutEngine to calculate the lengths of the characters on the curve first and then passing all of them to the path traversal function. Instead of traversing the path for every length, we are going to get the required point and angle from the vector of arrow vectors. This patch is addressing the first fix only. The second one will require refactoring the SVGTextLayoutEngine so I am going to address it in a different patch. * platform/graphics/Path.cpp: (WebCore::pathLengthApplierFunction): It is cleaner to move the function of this method to PathTraversalState::processPathElement(). (WebCore::Path::length): Use new enum Action value and access methods. (WebCore::Path::traversalStateAtLength): New function which returns the traversalState at a certain length on a path. (WebCore::Path::pointAtLength): (WebCore::Path::normalAngleAtLength): Use traversalStateAtLength() to get the traversalState and from it return either the position or the angle. * platform/graphics/Path.h: Define traversalStateAtLength(). * platform/graphics/PathTraversalState.cpp: (WebCore::distanceLine): Code clean up. (WebCore::curveLength): Make the setting of m_previous and m_current happens only in this function. (WebCore::PathTraversalState::PathTraversalState): Add an optional parameter for the desired length and move the initialization of the other members to the class definition. (WebCore::PathTraversalState::closeSubpath): (WebCore::PathTraversalState::moveTo): (WebCore::PathTraversalState::lineTo): Add the distance to the m_totalLength instead of returning it since this is what all the callers were doing. (WebCore::PathTraversalState::quadraticBezierTo): (WebCore::PathTraversalState::cubicBezierTo): Add the distance to the m_totalLength. Move the setting of m_previous and m_current to curveLength(). Remove unused members m_control1 and m_control2. (WebCore::PathTraversalState::processSegment): Deleted. (WebCore::PathTraversalState::finalizeAppendPathElement): Create a new name for the function. Handle the case of the angle at the starting point where m_desiredLength is set to zero. The new flag m_isZeroVector will be set to notify the caller that the next iteration will be the last one and it is only needed for the calculating the angle of a zero vector. m_current should not change by this last iteration. (WebCore::PathTraversalState::appendPathElement): This code is moved from pathLengthApplierFunction(). (WebCore::PathTraversalState::processPathElement): This function is used by the class Path. It is a wrapper for appendPathElement(). If m_isZeroVector is set we append the new element to a copy for the PathTraversalState just to get the angle for the zero vector. * platform/graphics/PathTraversalState.h: Change the enum values to not not include the class or the enum class. Make the data members private and expose the needed ones through access methods. Make all the internal methods to be private. (WebCore::PathTraversalState::processPathElement): Another wrapper for appendPathElement() which is used by SVGPathTraversalStateBuilder. (WebCore::PathTraversalState::action): (WebCore::PathTraversalState::setAction): (WebCore::PathTraversalState::desiredLength): (WebCore::PathTraversalState::setDesiredLength): (WebCore::PathTraversalState::success): (WebCore::PathTraversalState::totalLength): (WebCore::PathTraversalState::current): (WebCore::PathTraversalState::normalAngle): New access methods which are now needed after making the data members private. * rendering/svg/SVGRootInlineBox.cpp: (WebCore::SVGRootInlineBox::layoutCharactersInTextBoxes): Make the casting of the renderer on the caller side. * rendering/svg/SVGTextChunk.cpp: (WebCore::SVGTextChunk::SVGTextChunk): The constructor should append the elements of m_boxes instead of making this from outside the class. (WebCore::SVGTextChunk::totalCharacters): (WebCore::SVGTextChunk::totalLength): (WebCore::SVGTextChunk::calculateLength): Deleted. Replace calculateLength() by totalCharacters() and totalLength() to make the interface cleaner. (WebCore::SVGTextChunk::totalAnchorShift): (WebCore::SVGTextChunk::calculateTextAnchorShift): Deleted. Rename the function name. (WebCore::SVGTextChunk::layout): (WebCore::SVGTextChunk::processTextLengthSpacingCorrection): (WebCore::SVGTextChunk::buildBoxTransformations): (WebCore::SVGTextChunk::boxSpacingAndGlyphsTransform): (WebCore::SVGTextChunk::processTextAnchorCorrection): Move the chunk layout code from SVGTextChunkBuilder::layoutTextChunks() to the SVGTextChunk::layout(). Move all the helper functions as well. * rendering/svg/SVGTextChunk.h: (WebCore::SVGTextChunk::hasTextAnchor): (WebCore::SVGTextChunk::boxes): Deleted. Add the new methods and change most of the public methods to be private. * rendering/svg/SVGTextChunkBuilder.cpp: (WebCore::SVGTextChunkBuilder::totalCharacters): (WebCore::SVGTextChunkBuilder::totalLength): (WebCore::SVGTextChunkBuilder::totalAnchorShift): This code is moved from SVGTextLayoutEngine. It scans the boxes stored in the SVGTextChunkBuilder and sums up the total values. (WebCore::SVGTextChunkBuilder::transformationForTextBox): (WebCore::SVGTextChunkBuilder::buildTextChunks): (WebCore::SVGTextChunkBuilder::layoutTextChunks): Code clean up. (WebCore::SVGTextChunkBuilder::addTextChunk): Deleted. (WebCore::SVGTextChunkBuilder::processTextChunk): Deleted. (WebCore::SVGTextChunkBuilder::processTextLengthSpacingCorrection): Deleted. (WebCore::SVGTextChunkBuilder::processTextAnchorCorrection): Deleted. (WebCore::SVGTextChunkBuilder::buildSpacingAndGlyphsTransform): Deleted. This code now lives in SVGTextChunk. * rendering/svg/SVGTextChunkBuilder.h: Add new methods for code which was moved from SVGTextLayoutEngine and remove methods for code which was removed to SVGTextChunk. * rendering/svg/SVGTextLayoutEngine.cpp: (WebCore::SVGTextLayoutEngine::beginTextPathLayout): Use the sum up methods from SVGTextChunkBuilder instead of looping through the chunks. Also get a clean order for defining variables and doing the calculations. (WebCore::SVGTextLayoutEngine::finalizeTransformMatrices): Code clean up. (WebCore::SVGTextLayoutEngine::layoutTextOnLineOrPath): Do a single path traversal to get the position and the angle for a length on a path. * svg/SVGAnimateMotionElement.cpp: (WebCore::SVGAnimateMotionElement::buildTransformForProgress): Do a single path traversal to get the position and the angle at a length on a path. * svg/SVGPathTraversalStateBuilder.cpp: (WebCore::SVGPathTraversalStateBuilder::SVGPathTraversalStateBuilder): (WebCore::SVGPathTraversalStateBuilder::moveTo): (WebCore::SVGPathTraversalStateBuilder::lineTo): (WebCore::SVGPathTraversalStateBuilder::curveToCubic): (WebCore::SVGPathTraversalStateBuilder::closePath): (WebCore::SVGPathTraversalStateBuilder::setDesiredLength): (WebCore::SVGPathTraversalStateBuilder::continueConsuming): (WebCore::SVGPathTraversalStateBuilder::totalLength): (WebCore::SVGPathTraversalStateBuilder::currentPoint): (WebCore::SVGPathTraversalStateBuilder::incrementPathSegmentCount): Deleted. (WebCore::SVGPathTraversalStateBuilder::pathSegmentIndex): Deleted. * svg/SVGPathTraversalStateBuilder.h: (WebCore::SVGPathTraversalStateBuilder::pathSegmentIndex): Code clean up. * svg/SVGPathUtilities.cpp: (WebCore::getSVGPathSegAtLengthFromSVGPathByteStream): (WebCore::getTotalLengthOfSVGPathByteStream): (WebCore::getPointAtLengthOfSVGPathByteStream): Use new TraversalState::Action enum values. Canonical link: https://commits.webkit.org/161776@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@182828 268f45cc-cd09-0410-ab3c-d52691b4dbfc 2015-04-15 01:34:25 +00:00			`<!DOCTYPE html>`
			`<body>`
			`<script src="../resources/runner.js"></script>`
			`<script>`
			`window.onload = function() {`
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			`}`
			`</script>`
			`</body>`