vaadin-framework/server/src/main/java/com/vaadin/ui/GridLayout.java

/*
 * Copyright 2000-2016 Vaadin Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.vaadin.ui;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.jsoup.nodes.Attributes;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import com.vaadin.event.LayoutEvents.LayoutClickEvent;
import com.vaadin.event.LayoutEvents.LayoutClickListener;
import com.vaadin.event.LayoutEvents.LayoutClickNotifier;
import com.vaadin.shared.Connector;
import com.vaadin.shared.EventId;
import com.vaadin.shared.MouseEventDetails;
import com.vaadin.shared.Registration;
import com.vaadin.shared.ui.MarginInfo;
import com.vaadin.shared.ui.gridlayout.GridLayoutServerRpc;
import com.vaadin.shared.ui.gridlayout.GridLayoutState;
import com.vaadin.shared.ui.gridlayout.GridLayoutState.ChildComponentData;
import com.vaadin.ui.declarative.DesignAttributeHandler;
import com.vaadin.ui.declarative.DesignContext;

/**
 * A layout where the components are laid out on a grid using cell coordinates.
 *
 * <p>
 * The GridLayout also maintains a cursor for adding components in
 * left-to-right, top-to-bottom order.
 * </p>
 *
 * <p>
 * Each component in a <code>GridLayout</code> uses a defined
 * {@link GridLayout.Area area} (column1,row1,column2,row2) from the grid. The
 * components may not overlap with the existing components - if you try to do so
 * you will get an {@link OverlapsException}. Adding a component with cursor
 * automatically extends the grid by increasing the grid height.
 * </p>
 *
 * <p>
 * The grid coordinates, which are specified by a row and column index, always
 * start from 0 for the topmost row and the leftmost column.
 * </p>
 *
 * @author Vaadin Ltd.
 * @since 3.0
 */
@SuppressWarnings("serial")
public class GridLayout extends AbstractLayout
        implements Layout.AlignmentHandler, Layout.SpacingHandler,
        Layout.MarginHandler, LayoutClickNotifier {

    private GridLayoutServerRpc rpc = (MouseEventDetails mouseDetails,
            Connector clickedConnector) -> fireEvent(
                    LayoutClickEvent.createEvent(GridLayout.this, mouseDetails,
                            clickedConnector));

    /**
     * Cursor X position: this is where the next component with unspecified x,y
     * is inserted
     */
    private int cursorX = 0;

    /**
     * Cursor Y position: this is where the next component with unspecified x,y
     * is inserted
     */
    private int cursorY = 0;

    private final LinkedList<Component> components = new LinkedList<>();

    private Map<Integer, Float> columnExpandRatio = new HashMap<>();
    private Map<Integer, Float> rowExpandRatio = new HashMap<>();
    private Alignment defaultComponentAlignment = Alignment.TOP_LEFT;

    /**
     * Constructor for a grid of given size (number of columns and rows).
     *
     * The grid may grow or shrink later. Grid grows automatically if you add
     * components outside its area.
     *
     * @param columns
     *            Number of columns in the grid.
     * @param rows
     *            Number of rows in the grid.
     */
    public GridLayout(int columns, int rows) {
        setColumns(columns);
        setRows(rows);
        registerRpc(rpc);
    }

    /**
     * Constructs an empty (1x1) grid layout that is extended as needed.
     */
    public GridLayout() {
        this(1, 1);
    }

    /**
     * Constructs a GridLayout of given size (number of columns and rows) and
     * adds the given components in order to the grid.
     *
     * @see #addComponents(Component...)
     *
     * @param columns
     *            Number of columns in the grid.
     * @param rows
     *            Number of rows in the grid.
     * @param children
     *            Components to add to the grid.
     */
    public GridLayout(int columns, int rows, Component... children) {
        this(columns, rows);
        addComponents(children);
    }

    @Override
    protected GridLayoutState getState() {
        return (GridLayoutState) super.getState();
    }

    @Override
    protected GridLayoutState getState(boolean markAsDirty) {
        return (GridLayoutState) super.getState(markAsDirty);
    }

    /**
     * <p>
     * Adds a component to the grid in the specified area. The area is defined
     * by specifying the upper left corner (column1, row1) and the lower right
     * corner (column2, row2) of the area. The coordinates are zero-based.
     * </p>
     *
     * <p>
     * If the area overlaps with any of the existing components already present
     * in the grid, the operation will fail and an {@link OverlapsException} is
     * thrown.
     * </p>
     *
     * @param component
     *            the component to be added, not <code>null</code>.
     * @param column1
     *            the column of the upper left corner of the area <code>c</code>
     *            is supposed to occupy. The leftmost column has index 0.
     * @param row1
     *            the row of the upper left corner of the area <code>c</code> is
     *            supposed to occupy. The topmost row has index 0.
     * @param column2
     *            the column of the lower right corner of the area
     *            <code>c</code> is supposed to occupy.
     * @param row2
     *            the row of the lower right corner of the area <code>c</code>
     *            is supposed to occupy.
     * @throws OverlapsException
     *             if the new component overlaps with any of the components
     *             already in the grid.
     * @throws OutOfBoundsException
     *             if the cells are outside the grid area.
     */
    public void addComponent(Component component, int column1, int row1,
            int column2, int row2)
            throws OverlapsException, OutOfBoundsException {

        if (component == null) {
            throw new NullPointerException("Component must not be null");
        }

        // Checks that the component does not already exist in the container
        if (components.contains(component)) {
            throw new IllegalArgumentException(
                    "Component is already in the container");
        }

        // Creates the area
        final Area area = new Area(component, column1, row1, column2, row2);

        // Checks the validity of the coordinates
        if (column2 < column1 || row2 < row1) {
            throw new IllegalArgumentException(
                    "Illegal coordinates for the component");
        }
        if (column1 < 0 || row1 < 0 || column2 >= getColumns()
                || row2 >= getRows()) {
            throw new OutOfBoundsException(area);
        }

        // Checks that newItem does not overlap with existing items
        checkExistingOverlaps(area);

        // Inserts the component to right place at the list
        // Respect top-down, left-right ordering
        // component.setParent(this);
        final Map<Connector, ChildComponentData> childDataMap = getState().childData;
        int index = 0;
        boolean done = false;
        for (Component c : components) {
            final ChildComponentData existingArea = childDataMap.get(c);
            if ((existingArea.row1 >= row1 && existingArea.column1 > column1)
                    || existingArea.row1 > row1) {
                components.add(index, component);
                done = true;
                break;
            }
            index++;
        }
        if (!done) {
            components.addLast(component);
        }

        childDataMap.put(component, area.childData);

        // Attempt to add to super
        try {
            super.addComponent(component);
        } catch (IllegalArgumentException e) {
            childDataMap.remove(component);
            components.remove(component);
            throw e;
        }

        // update cursor position, if it's within this area; use first position
        // outside this area, even if it's occupied
        if (cursorX >= column1 && cursorX <= column2 && cursorY >= row1
                && cursorY <= row2) {
            // cursor within area
            cursorX = column2 + 1; // one right of area
            if (cursorX >= getColumns()) {
                // overflowed columns
                cursorX = 0; // first col
                // move one row down, or one row under the area
                cursorY = (column1 == 0 ? row2 : row1) + 1;
            } else {
                cursorY = row1;
            }
        }
    }

    /**
     * Tests if the given area overlaps with any of the items already on the
     * grid.
     *
     * @param area
     *            the Area to be checked for overlapping.
     * @throws OverlapsException
     *             if <code>area</code> overlaps with any existing area.
     */
    private void checkExistingOverlaps(Area area) throws OverlapsException {
        for (Entry<Connector, ChildComponentData> entry : getState().childData
                .entrySet()) {
            if (componentsOverlap(entry.getValue(), area.childData)) {
                // Component not added, overlaps with existing component
                throw new OverlapsException(
                        new Area(entry.getValue(), (Component) entry.getKey()));
            }
        }
    }

    /**
     * Adds the component to the grid in cells column1,row1 (NortWest corner of
     * the area.) End coordinates (SouthEast corner of the area) are the same as
     * column1,row1. The coordinates are zero-based. Component width and height
     * is 1.
     *
     * @param component
     *            the component to be added, not <code>null</code>.
     * @param column
     *            the column index, starting from 0.
     * @param row
     *            the row index, starting from 0.
     * @throws OverlapsException
     *             if the new component overlaps with any of the components
     *             already in the grid.
     * @throws OutOfBoundsException
     *             if the cell is outside the grid area.
     */
    public void addComponent(Component component, int column, int row)
            throws OverlapsException, OutOfBoundsException {
        this.addComponent(component, column, row, column, row);
    }

    /**
     * Forces the next component to be added at the beginning of the next line.
     *
     * <p>
     * Sets the cursor column to 0 and increments the cursor row by one.
     * </p>
     *
     * <p>
     * By calling this function you can ensure that no more components are added
     * right of the previous component.
     * </p>
     *
     * @see #space()
     */
    public void newLine() {
        cursorX = 0;
        cursorY++;
    }

    /**
     * Moves the cursor forward by one. If the cursor goes out of the right grid
     * border, it is moved to the first column of the next row.
     *
     * @see #newLine()
     */
    public void space() {
        cursorX++;
        if (cursorX >= getColumns()) {
            cursorX = 0;
            cursorY++;
        }
    }

    /**
     * Adds the component into this container to the cursor position. If the
     * cursor position is already occupied, the cursor is moved forwards to find
     * free position. If the cursor goes out from the bottom of the grid, the
     * grid is automatically extended.
     *
     * @param component
     *            the component to be added, not <code>null</code>.
     */
    @Override
    public void addComponent(Component component) {
        if (component == null) {
            throw new IllegalArgumentException("Component must not be null");
        }

        // Finds first available place from the grid
        Area area;
        boolean done = false;
        while (!done) {
            try {
                area = new Area(component, cursorX, cursorY, cursorX, cursorY);
                checkExistingOverlaps(area);
                done = true;
            } catch (final OverlapsException e) {
                space();
            }
        }

        // Extends the grid if needed
        if (cursorX >= getColumns()) {
            setColumns(cursorX + 1);
        }
        if (cursorY >= getRows()) {
            setRows(cursorY + 1);
        }

        addComponent(component, cursorX, cursorY);
    }

    /**
     * Removes the specified component from the layout.
     *
     * @param component
     *            the component to be removed.
     */
    @Override
    public void removeComponent(Component component) {

        // Check that the component is contained in the container
        if (component == null || !components.contains(component)) {
            return;
        }

        getState().childData.remove(component);
        components.remove(component);
        super.removeComponent(component);
    }

    /**
     * Removes the component specified by its cell coordinates.
     *
     * @param column
     *            the component's column, starting from 0.
     * @param row
     *            the component's row, starting from 0.
     */
    public void removeComponent(int column, int row) {

        // Finds the area
        for (final Component component : components) {
            final ChildComponentData childData = getState().childData
                    .get(component);
            if (childData.column1 == column && childData.row1 == row) {
                removeComponent(component);
                return;
            }
        }
    }

    /**
     * Gets an Iterator for the components contained in the layout. By using the
     * Iterator it is possible to step through the contents of the layout.
     *
     * @return the Iterator of the components inside the layout.
     */
    @Override
    public Iterator<Component> iterator() {
        return Collections.unmodifiableCollection(components).iterator();
    }

    /**
     * Gets the number of components contained in the layout. Consistent with
     * the iterator returned by {@link #getComponentIterator()}.
     *
     * @return the number of contained components
     */
    @Override
    public int getComponentCount() {
        return components.size();
    }

    @Override
    public void beforeClientResponse(boolean initial) {
        super.beforeClientResponse(initial);

        getState().colExpand = new float[getColumns()];
        float colSum = getExpandRatioSum(columnExpandRatio);
        if (colSum == 0) {
            // no cols have been expanded
            for (int i = 0; i < getColumns(); i++) {
                getState().colExpand[i] = 1f;
            }
        } else {
            for (int i = 0; i < getColumns(); i++) {
                getState().colExpand[i] = getColumnExpandRatio(i);
            }
        }

        getState().rowExpand = new float[getRows()];
        float rowSum = getExpandRatioSum(rowExpandRatio);
        if (rowSum == 0) {
            // no rows have been expanded
            for (int i = 0; i < getRows(); i++) {
                getState().rowExpand[i] = 1f;
            }
        } else {
            for (int i = 0; i < getRows(); i++) {
                getState().rowExpand[i] = getRowExpandRatio(i);
            }
        }

    }

    private float getExpandRatioSum(Map<Integer, Float> ratioMap) {
        float sum = 0;
        for (Float expandRatio : ratioMap.values()) {
            sum += expandRatio;
        }
        return sum;
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.AlignmentHandler#getComponentAlignment(com
     * .vaadin.ui.Component)
     */
    @Override
    public Alignment getComponentAlignment(Component childComponent) {
        ChildComponentData childComponentData = getState(false).childData
                .get(childComponent);
        if (childComponentData == null) {
            throw new IllegalArgumentException(
                    "The given component is not a child of this layout");
        } else {
            return new Alignment(childComponentData.alignment);
        }
    }

    /**
     * Defines a rectangular area of cells in a GridLayout.
     *
     * <p>
     * Also maintains a reference to the component contained in the area.
     * </p>
     *
     * <p>
     * The area is specified by the cell coordinates of its upper left corner
     * (column1,row1) and lower right corner (column2,row2). As otherwise with
     * GridLayout, the column and row coordinates start from zero.
     * </p>
     *
     * @author Vaadin Ltd.
     * @since 3.0
     */
    public class Area implements Serializable {
        private final ChildComponentData childData;
        private final Component component;

        /**
         * <p>
         * Construct a new area on a grid.
         * </p>
         *
         * @param component
         *            the component connected to the area.
         * @param column1
         *            The column of the upper left corner cell of the area. The
         *            leftmost column has index 0.
         * @param row1
         *            The row of the upper left corner cell of the area. The
         *            topmost row has index 0.
         * @param column2
         *            The column of the lower right corner cell of the area. The
         *            leftmost column has index 0.
         * @param row2
         *            The row of the lower right corner cell of the area. The
         *            topmost row has index 0.
         */
        public Area(Component component, int column1, int row1, int column2,
                int row2) {
            this.component = component;
            childData = new ChildComponentData();
            childData.alignment = getDefaultComponentAlignment().getBitMask();
            childData.column1 = column1;
            childData.row1 = row1;
            childData.column2 = column2;
            childData.row2 = row2;
        }

        public Area(ChildComponentData childData, Component component) {
            this.childData = childData;
            this.component = component;
        }

        /**
         * Tests if this Area overlaps with another Area.
         *
         * @param other
         *            the other Area that is to be tested for overlap with this
         *            area
         * @return <code>true</code> if <code>other</code> area overlaps with
         *         this on, <code>false</code> if it does not.
         */
        public boolean overlaps(Area other) {
            return componentsOverlap(childData, other.childData);
        }

        /**
         * Gets the component connected to the area.
         *
         * @return the Component.
         */
        public Component getComponent() {
            return component;
        }

        /**
         * Gets the column of the top-left corner cell.
         *
         * @return the column of the top-left corner cell.
         */
        public int getColumn1() {
            return childData.column1;
        }

        /**
         * Gets the column of the bottom-right corner cell.
         *
         * @return the column of the bottom-right corner cell.
         */
        public int getColumn2() {
            return childData.column2;
        }

        /**
         * Gets the row of the top-left corner cell.
         *
         * @return the row of the top-left corner cell.
         */
        public int getRow1() {
            return childData.row1;
        }

        /**
         * Gets the row of the bottom-right corner cell.
         *
         * @return the row of the bottom-right corner cell.
         */
        public int getRow2() {
            return childData.row2;
        }

    }

    private static boolean componentsOverlap(ChildComponentData a,
            ChildComponentData b) {
        return a.column1 <= b.column2 && a.row1 <= b.row2
                && a.column2 >= b.column1 && a.row2 >= b.row1;
    }

    /**
     * Gridlayout does not support laying components on top of each other. An
     * <code>OverlapsException</code> is thrown when a component already exists
     * (even partly) at the same space on a grid with the new component.
     *
     * @author Vaadin Ltd.
     * @since 3.0
     */
    public class OverlapsException extends RuntimeException {

        private final Area existingArea;

        /**
         * Constructs an <code>OverlapsException</code>.
         *
         * @param existingArea
         */
        public OverlapsException(Area existingArea) {
            this.existingArea = existingArea;
        }

        @Override
        public String getMessage() {
            StringBuilder sb = new StringBuilder();
            Component component = existingArea.getComponent();
            sb.append(component);
            sb.append("( type = ");
            sb.append(component.getClass().getName());
            if (component.getCaption() != null) {
                sb.append(", caption = \"");
                sb.append(component.getCaption());
                sb.append("\"");
            }
            sb.append(')');
            sb.append(" is already added to ");
            sb.append(existingArea.childData.column1);
            sb.append(',');
            sb.append(existingArea.childData.column1);
            sb.append(',');
            sb.append(existingArea.childData.row1);
            sb.append(',');
            sb.append(existingArea.childData.row2);
            sb.append("(column1, column2, row1, row2).");

            return sb.toString();
        }

        /**
         * Gets the area .
         *
         * @return the existing area.
         */
        public Area getArea() {
            return existingArea;
        }
    }

    /**
     * An <code>Exception</code> object which is thrown when an area exceeds the
     * bounds of the grid.
     *
     * @author Vaadin Ltd.
     * @since 3.0
     */
    public class OutOfBoundsException extends RuntimeException {

        private final Area areaOutOfBounds;

        /**
         * Constructs an <code>OoutOfBoundsException</code> with the specified
         * detail message.
         *
         * @param areaOutOfBounds
         */
        public OutOfBoundsException(Area areaOutOfBounds) {
            this.areaOutOfBounds = areaOutOfBounds;
        }

        /**
         * Gets the area that is out of bounds.
         *
         * @return the area out of Bound.
         */
        public Area getArea() {
            return areaOutOfBounds;
        }
    }

    /**
     * Sets the number of columns in the grid. The column count can not be
     * reduced if there are any areas that would be outside of the shrunk grid.
     *
     * @param columns
     *            the new number of columns in the grid.
     */
    public void setColumns(int columns) {

        // The the param
        if (columns < 1) {
            throw new IllegalArgumentException(
                    "The number of columns and rows in the grid must be at least 1");
        }

        // In case of no change
        if (getColumns() == columns) {
            return;
        }

        // Checks for overlaps
        if (getColumns() > columns) {
            for (Entry<Connector, ChildComponentData> entry : getState().childData
                    .entrySet()) {
                if (entry.getValue().column2 >= columns) {
                    throw new OutOfBoundsException(new Area(entry.getValue(),
                            (Component) entry.getKey()));
                }
            }
        }

        // Forget expands for removed columns
        if (columns < getColumns()) {
            for (int i = columns; i < getColumns(); i++) {
                columnExpandRatio.remove(i);
                getState().explicitColRatios.remove(i);
            }
        }

        getState().columns = columns;
    }

    /**
     * Get the number of columns in the grid.
     *
     * @return the number of columns in the grid.
     */
    public int getColumns() {
        return getState(false).columns;
    }

    /**
     * Sets the number of rows in the grid. The number of rows can not be
     * reduced if there are any areas that would be outside of the shrunk grid.
     *
     * @param rows
     *            the new number of rows in the grid.
     */
    public void setRows(int rows) {

        // The the param
        if (rows < 1) {
            throw new IllegalArgumentException(
                    "The number of columns and rows in the grid must be at least 1");
        }

        // In case of no change
        if (getRows() == rows) {
            return;
        }

        // Checks for overlaps
        if (getRows() > rows) {
            for (Entry<Connector, ChildComponentData> entry : getState().childData
                    .entrySet()) {
                if (entry.getValue().row2 >= rows) {
                    throw new OutOfBoundsException(new Area(entry.getValue(),
                            (Component) entry.getKey()));
                }
            }
        }
        // Forget expands for removed rows
        if (rows < getRows()) {
            for (int i = rows; i < getRows(); i++) {
                rowExpandRatio.remove(i);
                getState().explicitRowRatios.remove(i);
            }
        }

        getState().rows = rows;
    }

    /**
     * Get the number of rows in the grid.
     *
     * @return the number of rows in the grid.
     */
    public int getRows() {
        return getState(false).rows;
    }

    /**
     * Gets the current x-position (column) of the cursor.
     *
     * <p>
     * The cursor position points the position for the next component that is
     * added without specifying its coordinates (grid cell). When the cursor
     * position is occupied, the next component will be added to first free
     * position after the cursor.
     * </p>
     *
     * @return the grid column the cursor is on, starting from 0.
     */
    public int getCursorX() {
        return cursorX;
    }

    /**
     * Sets the current cursor x-position. This is usually handled automatically
     * by GridLayout.
     *
     * @param cursorX
     */
    public void setCursorX(int cursorX) {
        this.cursorX = cursorX;
    }

    /**
     * Gets the current y-position (row) of the cursor.
     *
     * <p>
     * The cursor position points the position for the next component that is
     * added without specifying its coordinates (grid cell). When the cursor
     * position is occupied, the next component will be added to the first free
     * position after the cursor.
     * </p>
     *
     * @return the grid row the Cursor is on.
     */
    public int getCursorY() {
        return cursorY;
    }

    /**
     * Sets the current y-coordinate (row) of the cursor. This is usually
     * handled automatically by GridLayout.
     *
     * @param cursorY
     *            the row number, starting from 0 for the topmost row.
     */
    public void setCursorY(int cursorY) {
        this.cursorY = cursorY;
    }

    /* Documented in superclass */
    @Override
    public void replaceComponent(Component oldComponent,
            Component newComponent) {

        // Gets the locations
        ChildComponentData oldLocation = getState().childData.get(oldComponent);
        ChildComponentData newLocation = getState().childData.get(newComponent);

        if (oldLocation == null) {
            addComponent(newComponent);
        } else if (newLocation == null) {
            removeComponent(oldComponent);
            addComponent(newComponent, oldLocation.column1, oldLocation.row1,
                    oldLocation.column2, oldLocation.row2);
        } else {
            int oldAlignment = oldLocation.alignment;
            oldLocation.alignment = newLocation.alignment;
            newLocation.alignment = oldAlignment;

            getState().childData.put(newComponent, oldLocation);
            getState().childData.put(oldComponent, newLocation);
        }
    }

    /*
     * Removes all components from this container.
     *
     * @see com.vaadin.ui.ComponentContainer#removeAllComponents()
     */
    @Override
    public void removeAllComponents() {
        super.removeAllComponents();
        cursorX = 0;
        cursorY = 0;
    }

    @Override
    public void setComponentAlignment(Component childComponent,
            Alignment alignment) {
        ChildComponentData childComponentData = getState().childData
                .get(childComponent);
        if (childComponentData == null) {
            throw new IllegalArgumentException(
                    "Component must be added to layout before using setComponentAlignment()");
        } else {
            if (alignment == null) {
                childComponentData.alignment = GridLayoutState.ALIGNMENT_DEFAULT
                        .getBitMask();
            } else {
                childComponentData.alignment = alignment.getBitMask();
            }
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.SpacingHandler#setSpacing(boolean)
     */
    @Override
    public void setSpacing(boolean spacing) {
        getState().spacing = spacing;
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.SpacingHandler#isSpacing()
     */
    @Override
    public boolean isSpacing() {
        return getState(false).spacing;
    }

    /**
     * Inserts an empty row at the specified position in the grid.
     *
     * @param row
     *            Index of the row before which the new row will be inserted.
     *            The leftmost row has index 0.
     */
    public void insertRow(int row) {
        if (row > getRows()) {
            throw new IllegalArgumentException("Cannot insert row at " + row
                    + " in a gridlayout with height " + getRows());
        }

        for (ChildComponentData existingArea : getState().childData.values()) {
            // Areas ending below the row needs to be moved down or stretched
            if (existingArea.row2 >= row) {
                existingArea.row2++;

                // Stretch areas that span over the selected row
                if (existingArea.row1 >= row) {
                    existingArea.row1++;
                }

            }
        }

        if (cursorY >= row) {
            cursorY++;
        }

        setRows(getRows() + 1);
        markAsDirty();
    }

    /**
     * Removes a row and all the components in the row.
     *
     * <p>
     * Components which span over several rows are removed if the selected row
     * is on the first row of such a component.
     * </p>
     *
     * <p>
     * If the last row is removed then all remaining components will be removed
     * and the grid will be reduced to one row. The cursor will be moved to the
     * upper left cell of the grid.
     * </p>
     *
     * @param row
     *            Index of the row to remove. The leftmost row has index 0.
     */
    public void removeRow(int row) {
        if (row >= getRows()) {
            throw new IllegalArgumentException("Cannot delete row " + row
                    + " from a gridlayout with height " + getRows());
        }

        // Remove all components in row
        for (int col = 0; col < getColumns(); col++) {
            removeComponent(col, row);
        }

        // Shrink or remove areas in the selected row
        for (ChildComponentData existingArea : getState().childData.values()) {
            if (existingArea.row2 >= row) {
                existingArea.row2--;

                if (existingArea.row1 > row) {
                    existingArea.row1--;
                }
            }
        }

        if (getRows() == 1) {
            /*
             * Removing the last row means that the dimensions of the Grid
             * layout will be truncated to 1 empty row and the cursor is moved
             * to the first cell
             */
            cursorX = 0;
            cursorY = 0;
        } else {
            setRows(getRows() - 1);
            if (cursorY > row) {
                cursorY--;
            }
        }

        markAsDirty();

    }

    /**
     * Sets the expand ratio of given column.
     *
     * <p>
     * The expand ratio defines how excess space is distributed among columns.
     * Excess space means space that is left over from components that are not
     * sized relatively. By default, the excess space is distributed evenly.
     * </p>
     *
     * <p>
     * Note, that width of this GridLayout needs to be defined (fixed or
     * relative, as opposed to undefined height) for this method to have any
     * effect.
     * <p>
     * Note that checking for relative width for the child components is done on
     * the server so you cannot set a child component to have undefined width on
     * the server and set it to <code>100%</code> in CSS. You must set it to
     * <code>100%</code> on the server.
     *
     * @see #setWidth(float, Unit)
     *
     * @param columnIndex
     * @param ratio
     */
    public void setColumnExpandRatio(int columnIndex, float ratio) {
        columnExpandRatio.put(columnIndex, ratio);
        getState().explicitColRatios.add(columnIndex);
        markAsDirty();
    }

    /**
     * Returns the expand ratio of given column.
     *
     * @see #setColumnExpandRatio(int, float)
     *
     * @param columnIndex
     * @return the expand ratio, 0.0f by default
     */
    public float getColumnExpandRatio(int columnIndex) {
        Float r = columnExpandRatio.get(columnIndex);
        return r == null ? 0 : r.floatValue();
    }

    /**
     * Sets the expand ratio of given row.
     *
     * <p>
     * Expand ratio defines how excess space is distributed among rows. Excess
     * space means the space left over from components that are not sized
     * relatively. By default, the excess space is distributed evenly.
     * </p>
     *
     * <p>
     * Note, that height of this GridLayout needs to be defined (fixed or
     * relative, as opposed to undefined height) for this method to have any
     * effect.
     * <p>
     * Note that checking for relative height for the child components is done
     * on the server so you cannot set a child component to have undefined
     * height on the server and set it to <code>100%</code> in CSS. You must set
     * it to <code>100%</code> on the server.
     *
     * @see #setHeight(float, Unit)
     *
     * @param rowIndex
     *            The row index, starting from 0 for the topmost row.
     * @param ratio
     */
    public void setRowExpandRatio(int rowIndex, float ratio) {
        rowExpandRatio.put(rowIndex, ratio);
        getState().explicitRowRatios.add(rowIndex);
        markAsDirty();
    }

    /**
     * Returns the expand ratio of given row.
     *
     * @see #setRowExpandRatio(int, float)
     *
     * @param rowIndex
     *            The row index, starting from 0 for the topmost row.
     * @return the expand ratio, 0.0f by default
     */
    public float getRowExpandRatio(int rowIndex) {
        Float r = rowExpandRatio.get(rowIndex);
        return r == null ? 0 : r.floatValue();
    }

    /**
     * Gets the Component at given index.
     *
     * @param x
     *            The column index, starting from 0 for the leftmost column.
     * @param y
     *            The row index, starting from 0 for the topmost row.
     * @return Component in given cell or null if empty
     */
    public Component getComponent(int x, int y) {
        for (Entry<Connector, ChildComponentData> entry : getState(
                false).childData.entrySet()) {
            ChildComponentData childData = entry.getValue();
            if (childData.column1 <= x && x <= childData.column2
                    && childData.row1 <= y && y <= childData.row2) {
                return (Component) entry.getKey();
            }
        }
        return null;
    }

    /**
     * Returns information about the area where given component is laid in the
     * GridLayout.
     *
     * @param component
     *            the component whose area information is requested.
     * @return an Area object that contains information how component is laid in
     *         the grid
     */
    public Area getComponentArea(Component component) {
        ChildComponentData childComponentData = getState(false).childData
                .get(component);
        if (childComponentData == null) {
            return null;
        } else {
            return new Area(childComponentData, component);
        }
    }

    @Override
    public Registration addLayoutClickListener(LayoutClickListener listener) {
        return addListener(EventId.LAYOUT_CLICK_EVENT_IDENTIFIER,
                LayoutClickEvent.class, listener,
                LayoutClickListener.clickMethod);
    }

    @Override
    @Deprecated
    public void removeLayoutClickListener(LayoutClickListener listener) {
        removeListener(EventId.LAYOUT_CLICK_EVENT_IDENTIFIER,
                LayoutClickEvent.class, listener);
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.MarginHandler#setMargin(boolean)
     */
    @Override
    public void setMargin(boolean enabled) {
        setMargin(new MarginInfo(enabled));
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.MarginHandler#setMargin(com.vaadin.shared.ui.
     * MarginInfo )
     */
    @Override
    public void setMargin(MarginInfo marginInfo) {
        getState().marginsBitmask = marginInfo.getBitMask();
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.MarginHandler#getMargin()
     */
    @Override
    public MarginInfo getMargin() {
        return new MarginInfo(getState(false).marginsBitmask);
    }

    /*
     * (non-Javadoc)
     *
     * @see com.vaadin.ui.Layout.AlignmentHandler#getDefaultComponentAlignment()
     */
    @Override
    public Alignment getDefaultComponentAlignment() {
        return defaultComponentAlignment;
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * com.vaadin.ui.Layout.AlignmentHandler#setDefaultComponentAlignment(com
     * .vaadin.ui.Alignment)
     */
    @Override
    public void setDefaultComponentAlignment(Alignment defaultAlignment) {
        defaultComponentAlignment = defaultAlignment;
    }

    /**
     * Sets whether empty rows and columns should be considered as non-existent
     * when rendering or not. If this is set to true then the spacing between
     * multiple empty columns (or rows) will be collapsed.
     *
     * The default behavior is to consider all rows and columns as visible
     *
     * NOTE that this must be set before the initial rendering takes place.
     * Updating this on the fly is not supported.
     *
     * @since 7.3
     * @param hideEmptyRowsAndColumns
     *            true to hide empty rows and columns, false to leave them as-is
     */
    public void setHideEmptyRowsAndColumns(boolean hideEmptyRowsAndColumns) {
        getState().hideEmptyRowsAndColumns = hideEmptyRowsAndColumns;
    }

    /**
     * Checks whether whether empty rows and columns should be considered as
     * non-existent when rendering or not.
     *
     * @see #setHideEmptyRowsAndColumns(boolean)
     * @since 7.3
     * @return true if empty rows and columns are hidden, false otherwise
     */
    public boolean isHideEmptyRowsAndColumns() {
        return getState(false).hideEmptyRowsAndColumns;
    }

    /**
     * {@inheritDoc}
     * <p>
     * After reading the design, cursorY is set to point to a row outside of the
     * GridLayout area. CursorX is reset to 0.
     */
    @Override
    public void readDesign(Element design, DesignContext designContext) {
        super.readDesign(design, designContext);

        setMargin(readMargin(design, getMargin(), designContext));
        if (design.childNodeSize() > 0) {
            // Touch content only if there is some content specified. This is
            // needed to be able to use extended GridLayouts which add
            // components in the constructor (e.g. Designs based on GridLayout).
            readChildComponents(design.children(), designContext);
        }

        // Set cursor position explicitly
        setCursorY(getRows());
        setCursorX(0);
    }

    private void readChildComponents(Elements childElements,
            DesignContext designContext) {
        List<Element> rowElements = new ArrayList<>();
        List<Map<Integer, Component>> rows = new ArrayList<>();
        // Prepare a 2D map for reading column contents
        for (Element e : childElements) {
            if (e.tagName().equalsIgnoreCase("row")) {
                rowElements.add(e);
                rows.add(new HashMap<>());

            }
        }
        setRows(Math.max(rows.size(), 1));
        Map<Component, Alignment> alignments = new HashMap<>();
        List<Float> columnExpandRatios = new ArrayList<>();
        for (int row = 0; row < rowElements.size(); ++row) {
            Element rowElement = rowElements.get(row);

            // Row Expand
            if (rowElement.hasAttr("expand")) {
                float expand = DesignAttributeHandler.readAttribute("expand",
                        rowElement.attributes(), float.class);
                setRowExpandRatio(row, expand);
            }

            Elements cols = rowElement.children();

            // Amount of skipped columns due to spanned components
            int skippedColumns = 0;

            for (int column = 0; column < cols.size(); ++column) {
                while (rows.get(row).containsKey(column + skippedColumns)) {
                    // Skip any spanned components
                    skippedColumns++;
                }

                Element col = cols.get(column);
                Component child = null;

                if (!col.children().isEmpty()) {
                    Element childElement = col.child(0);
                    child = designContext.readDesign(childElement);
                    alignments.put(child, DesignAttributeHandler
                            .readAlignment(childElement.attributes()));
                    // TODO: Currently ignoring any extra children.
                    // Needs Error handling?
                } // Else: Empty placeholder. No child component.

                // Handle rowspan and colspan for this child component
                Attributes attr = col.attributes();
                int colspan = DesignAttributeHandler.readAttribute("colspan",
                        attr, 1, int.class);
                int rowspan = DesignAttributeHandler.readAttribute("rowspan",
                        attr, 1, int.class);

                for (int rowIndex = row; rowIndex < row + rowspan; ++rowIndex) {
                    for (int colIndex = column; colIndex < column
                            + colspan; ++colIndex) {
                        if (rowIndex == rows.size()) {
                            // Rowspan with not enough rows. Fix by adding rows.
                            rows.add(new HashMap<>());
                        }
                        rows.get(rowIndex).put(colIndex + skippedColumns,
                                child);
                    }
                }

                // Read column expand ratios if handling the first row.
                if (row == 0) {
                    if (col.hasAttr("expand")) {
                        for (String expand : col.attr("expand").split(",")) {
                            columnExpandRatios.add(Float.parseFloat(expand));
                        }
                    } else {
                        for (int c = 0; c < colspan; ++c) {
                            columnExpandRatios.add(0f);
                        }
                    }
                }

                skippedColumns += (colspan - 1);
            }
        }

        // Calculate highest column count and set columns
        int colMax = 0;
        for (Map<Integer, Component> cols : rows) {
            if (colMax < cols.size()) {
                colMax = cols.size();
            }
        }
        setColumns(Math.max(colMax, 1));

        for (int i = 0; i < columnExpandRatios.size(); ++i) {
            setColumnExpandRatio(i, columnExpandRatios.get(i));
        }

        // Reiterate through the 2D map and add components to GridLayout
        Set<Component> visited = new HashSet<>();

        // Ignore any missing components
        visited.add(null);

        for (int i = 0; i < rows.size(); ++i) {
            Map<Integer, Component> row = rows.get(i);
            for (int j = 0; j < colMax; ++j) {
                Component child = row.get(j);
                if (visited.contains(child)) {
                    // Empty location or already handled child
                    continue;
                }
                visited.add(child);

                // Figure out col and rowspan from 2D map
                int colspan = 0;
                while (j + colspan + 1 < row.size()
                        && row.get(j + colspan + 1) == child) {
                    ++colspan;
                }

                int rowspan = 0;
                while (i + rowspan + 1 < rows.size()
                        && rows.get(i + rowspan + 1).get(j) == child) {
                    ++rowspan;
                }

                // Add component with area
                addComponent(child, j, i, j + colspan, i + rowspan);
                setComponentAlignment(child, alignments.get(child));
            }
        }
    }

    @Override
    public void writeDesign(Element design, DesignContext designContext) {
        super.writeDesign(design, designContext);

        GridLayout def = designContext.getDefaultInstance(this);

        writeMargin(design, getMargin(), def.getMargin(), designContext);

        if (!designContext.shouldWriteChildren(this, def)) {
            return;
        }

        if (components.isEmpty()) {
            writeEmptyColsAndRows(design, designContext);
            return;
        }

        final Map<Connector, ChildComponentData> childData = getState().childData;

        // Make a 2D map of component areas.
        Component[][] componentMap = new Component[getState().rows][getState().columns];
        final Component dummyComponent = new Label("");

        for (Component component : components) {
            ChildComponentData coords = childData.get(component);
            for (int row = coords.row1; row <= coords.row2; ++row) {
                for (int col = coords.column1; col <= coords.column2; ++col) {
                    componentMap[row][col] = component;
                }
            }
        }

        // Go through the map and write only needed column tags
        Set<Connector> visited = new HashSet<>();

        // Skip the dummy placeholder
        visited.add(dummyComponent);

        for (int i = 0; i < componentMap.length; ++i) {
            Element row = design.appendElement("row");

            // Row Expand
            DesignAttributeHandler.writeAttribute("expand", row.attributes(),
                    getRowExpandRatio(i), 0.0f, float.class, designContext);

            int colspan = 1;
            Element col;
            for (int j = 0; j < componentMap[i].length; ++j) {
                Component child = componentMap[i][j];
                if (child != null) {
                    if (visited.contains(child)) {
                        // Child has already been written in the design
                        continue;
                    }
                    visited.add(child);

                    Element childElement = designContext.createElement(child);
                    col = row.appendElement("column");

                    // Write child data into design
                    ChildComponentData coords = childData.get(child);

                    Alignment alignment = getComponentAlignment(child);
                    DesignAttributeHandler.writeAlignment(childElement,
                            alignment);

                    col.appendChild(childElement);
                    if (coords.row1 != coords.row2) {
                        col.attr("rowspan",
                                "" + (1 + coords.row2 - coords.row1));
                    }

                    colspan = 1 + coords.column2 - coords.column1;
                    if (colspan > 1) {
                        col.attr("colspan", "" + colspan);
                    }

                } else {
                    boolean hasExpands = false;
                    if (i == 0 && lastComponentOnRow(componentMap[i], j,
                            visited)) {
                        // A column with expand and no content in the end of
                        // first row needs to be present.
                        for (int c = j; c < componentMap[i].length; ++c) {
                            if (getColumnExpandRatio(c) > 0) {
                                hasExpands = true;
                            }
                        }
                    }

                    if (lastComponentOnRow(componentMap[i], j, visited)
                            && !hasExpands) {
                        continue;
                    }

                    // Empty placeholder tag.
                    col = row.appendElement("column");

                    // Use colspan to make placeholders more pleasant
                    while (j + colspan < componentMap[i].length
                            && componentMap[i][j + colspan] == child) {
                        ++colspan;
                    }

                    int rowspan = getRowSpan(componentMap, i, j, colspan,
                            child);
                    if (colspan > 1) {
                        col.attr("colspan", "" + colspan);
                    }
                    if (rowspan > 1) {
                        col.attr("rowspan", "" + rowspan);
                    }
                    for (int x = 0; x < rowspan; ++x) {
                        for (int y = 0; y < colspan; ++y) {
                            // Mark handled columns
                            componentMap[i + x][j + y] = dummyComponent;
                        }
                    }
                }

                // Column expands
                if (i == 0) {
                    // Only do expands on first row
                    String expands = "";
                    boolean expandRatios = false;
                    for (int c = 0; c < colspan; ++c) {
                        float colExpand = getColumnExpandRatio(j + c);
                        if (colExpand > 0) {
                            expandRatios = true;
                        }
                        expands += (c > 0 ? "," : "") + colExpand;
                    }
                    if (expandRatios) {
                        col.attr("expand", expands);
                    }
                }

                j += colspan - 1;
            }
        }
    }

    /**
     * Fills in the design with rows and empty columns. This needs to be done
     * for empty {@link GridLayout}, because there's no other way to serialize
     * info about number of columns and rows if there are absolutely no
     * components in the {@link GridLayout}
     *
     * @param design
     * @param designContext
     */
    private void writeEmptyColsAndRows(Element design,
            DesignContext designContext) {
        int rowCount = getState(false).rows;
        int colCount = getState(false).columns;

        // only write cols and rows tags if size is not 1x1
        if (rowCount == 1 && colCount == 1) {
            return;
        }

        for (int i = 0; i < rowCount; i++) {
            Element row = design.appendElement("row");
            for (int j = 0; j < colCount; j++) {
                row.appendElement("column");
            }
        }

    }

    private int getRowSpan(Component[][] compMap, int i, int j, int colspan,
            Component child) {
        int rowspan = 1;
        while (i + rowspan < compMap.length
                && compMap[i + rowspan][j] == child) {
            for (int k = 0; k < colspan; ++k) {
                if (compMap[i + rowspan][j + k] != child) {
                    return rowspan;
                }
            }
            rowspan++;
        }
        return rowspan;
    }

    private boolean lastComponentOnRow(Component[] componentArray, int j,
            Set<Connector> visited) {
        while ((++j) < componentArray.length) {
            Component child = componentArray[j];
            if (child != null && !visited.contains(child)) {
                return false;
            }
        }
        return true;
    }

    @Override
    protected Collection<String> getCustomAttributes() {
        Collection<String> result = super.getCustomAttributes();
        result.add("cursor-x");
        result.add("cursor-y");
        result.add("rows");
        result.add("columns");
        result.add("margin");
        result.add("margin-left");
        result.add("margin-right");
        result.add("margin-top");
        result.add("margin-bottom");
        return result;
    }
}