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Flying Saucer is a CSS 2.1 renderer written in Java. This artifact contains the core rendering and layout code as well as Java2D output.
/*
* {{{ header & license
* Copyright (c) 2005 Wisconsin Court System
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* of the License, or (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
* }}}
*/
package org.xhtmlrenderer.layout;
import org.xhtmlrenderer.css.constants.CSSName;
import org.xhtmlrenderer.css.constants.IdentValue;
import org.xhtmlrenderer.render.Box;
import org.xhtmlrenderer.render.InlineLayoutBox;
import java.util.ArrayList;
import java.util.List;
/**
* This class performs the real work of vertically positioning inline boxes
* within a line (i.e. implementing the vertical-align property). Because
* of the requirements of vertical-align: top/bottom, a {@code VerticalAlignContext}
* is actually a tree of {@code VerticalAlignContext} objects which all
* must be taken into consideration when aligning content.
*/
public class VerticalAlignContext {
private final List _measurements = new ArrayList<>();
private int _inlineTop;
private boolean _inlineTopSet = false;
private int _inlineBottom;
private boolean _inlineBottomSet = false;
private int _paintingTop;
private boolean _paintingTopSet = false;
private int _paintingBottom;
private boolean _paintingBottomSet = false;
private final List _children = new ArrayList<>();
private VerticalAlignContext _parent = null;
private void moveTrackedValues(int ty) {
if (_inlineTopSet) {
_inlineTop += ty;
}
if (_inlineBottomSet) {
_inlineBottom += ty;
}
if (_paintingTopSet) {
_paintingTop += ty;
}
if (_paintingBottomSet) {
_paintingBottom += ty;
}
}
public int getInlineBottom() {
return _inlineBottom;
}
public int getInlineTop() {
return _inlineTop;
}
public void updateInlineTop(int inlineTop) {
if (! _inlineTopSet || inlineTop < _inlineTop) {
_inlineTop = inlineTop;
_inlineTopSet = true;
}
}
public void updatePaintingTop(int paintingTop) {
if (! _paintingTopSet || paintingTop < _paintingTop) {
_paintingTop = paintingTop;
_paintingTopSet = true;
}
}
public void updateInlineBottom(int inlineBottom) {
if (! _inlineBottomSet || inlineBottom > _inlineBottom) {
_inlineBottom = inlineBottom;
_inlineBottomSet = true;
}
}
public void updatePaintingBottom(int paintingBottom) {
if (! _paintingBottomSet || paintingBottom > _paintingBottom) {
_paintingBottom = paintingBottom;
_paintingBottomSet = true;
}
}
public int getLineBoxHeight() {
return _inlineBottom - _inlineTop;
}
public void pushMeasurements(InlineBoxMeasurements measurements) {
_measurements.add(measurements);
updateInlineTop(measurements.getInlineTop());
updateInlineBottom(measurements.getInlineBottom());
updatePaintingTop(measurements.getPaintingTop());
updatePaintingBottom(measurements.getPaintingBottom());
}
public InlineBoxMeasurements getParentMeasurements() {
return _measurements.get(_measurements.size()-1);
}
public void popMeasurements() {
_measurements.remove(_measurements.size()-1);
}
public int getPaintingBottom() {
return _paintingBottom;
}
public int getPaintingTop() {
return _paintingTop;
}
public VerticalAlignContext createChild(Box root) {
VerticalAlignContext result = new VerticalAlignContext();
VerticalAlignContext vaRoot = getRoot();
result.setParent(vaRoot);
InlineBoxMeasurements initial = vaRoot._measurements.get(0);
result.pushMeasurements(initial);
vaRoot._children.add(new ChildContextData(root, result));
return result;
}
private List getChildren() {
return _children;
}
public VerticalAlignContext getParent() {
return _parent;
}
public void setParent(VerticalAlignContext parent) {
_parent = parent;
}
private VerticalAlignContext getRoot() {
VerticalAlignContext result = this;
return result.getParent() != null ? result.getParent() : this;
}
private void merge(VerticalAlignContext context) {
updateInlineBottom(context.getInlineBottom());
updateInlineTop(context.getInlineTop());
updatePaintingBottom(context.getPaintingBottom());
updatePaintingTop(context.getPaintingTop());
}
public void alignChildren() {
List children = getChildren();
for (ChildContextData data : children) {
data.align();
merge(data.getVerticalAlignContext());
}
}
public void setInitialMeasurements(InlineBoxMeasurements measurements) {
_measurements.add(measurements);
}
private static final class ChildContextData {
private final Box _root;
private final VerticalAlignContext _verticalAlignContext;
public ChildContextData(Box root, VerticalAlignContext vaContext) {
_root = root;
_verticalAlignContext = vaContext;
}
public Box getRoot() {
return _root;
}
public VerticalAlignContext getVerticalAlignContext() {
return _verticalAlignContext;
}
private void moveContextContents(int ty) {
moveInlineContents(_root, ty);
}
private void moveInlineContents(Box box, int ty) {
if (canBeMoved(box)) {
box.setY(box.getY() + ty);
if (box instanceof InlineLayoutBox iB) {
for (int i = 0; i < iB.getInlineChildCount(); i++) {
Object child = iB.getInlineChild(i);
if (child instanceof Box) {
moveInlineContents((Box)child, ty);
}
}
}
}
}
private boolean canBeMoved(Box box) {
IdentValue vAlign = box.getStyle().getIdent(CSSName.VERTICAL_ALIGN);
return box == _root ||
! (vAlign == IdentValue.TOP || vAlign == IdentValue.BOTTOM);
}
public void align() {
IdentValue vAlign = _root.getStyle().getIdent(CSSName.VERTICAL_ALIGN);
final int delta;
if (vAlign == IdentValue.TOP) {
delta = _verticalAlignContext.getRoot().getInlineTop() -
_verticalAlignContext.getInlineTop();
} else if (vAlign == IdentValue.BOTTOM) {
delta = _verticalAlignContext.getRoot().getInlineBottom() -
_verticalAlignContext.getInlineBottom();
} else {
throw new RuntimeException("internal error");
}
_verticalAlignContext.moveTrackedValues(delta);
moveContextContents(delta);
}
}
}