plugins/sqltools/org.eclipse.datatools.sqltools.common.ui/src/org/eclipse/datatools/sqltools/common/ui/util/TableLayoutComposite.java

/**
 * Created on 2005-5-25
 * 
 * Copyright (c) Sybase, Inc. 2004-2006 All rights reserved.
 */
package org.eclipse.datatools.sqltools.common.ui.util;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.viewers.ColumnLayoutData;
import org.eclipse.jface.viewers.ColumnPixelData;
import org.eclipse.jface.viewers.ColumnWeightData;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;

/**
 * A special composite to layout columns inside a table. The composite is needed since we have to layout the columns
 * "before" the actual table gets layouted. Hence we can't use a normal layout manager.
 * 
 * @author Li Huang
 */
public class TableLayoutComposite extends Composite
{

    private List _columns = new ArrayList();

    /**
     * Creates a new <code>TableLayoutComposite</code>.
     */
    public TableLayoutComposite(Composite parent, int style)
    {
        super(parent, style);
        addControlListener(new ControlAdapter()
        {
            public void controlResized(ControlEvent e)
            {
                Rectangle area = getClientArea();
                Table table = (Table) getChildren()[0];
                Point preferredSize = computeTableSize(table);
                int width = area.width - 2 * table.getBorderWidth();
                if (preferredSize.y > area.height)
                {
                    // Subtract the scrollbar width from the total column width
                    // if a vertical scrollbar will be required
                    Point vBarSize = table.getVerticalBar().getSize();
                    width -= vBarSize.x;
                }
                layoutTable(table, width, area, table.getSize().x < area.width);
            }
        }
        );
    }

    /**
     * Adds a new column of data to this table layout.
     * 
     * @param data the column layout data
     */
    public void addColumnData(ColumnLayoutData data)
    {
        _columns.add(data);
    }

    //---- Helpers -------------------------------------------------------------------------------------

    private Point computeTableSize(Table table)
    {
        Point result = table.computeSize(SWT.DEFAULT, SWT.DEFAULT);

        int width = 0;
        int size = _columns.size();
        for (int i = 0; i < size; ++i)
        {
            ColumnLayoutData layoutData = (ColumnLayoutData) _columns.get(i);
            if (layoutData instanceof ColumnPixelData)
            {
                ColumnPixelData col = (ColumnPixelData) layoutData;
                width += col.width;
            }
            else if (layoutData instanceof ColumnWeightData)
            {
                ColumnWeightData col = (ColumnWeightData) layoutData;
                width += col.minimumWidth;
            }
            else
            {
                Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
            }
        }
        if (width > result.x)
        result.x = width;
        return result;
    }

    private void layoutTable(Table table, int width, Rectangle area, boolean increase)
    {
        // XXX: Layout is being called with an invalid value the first time
        // it is being called on Linux. This method resets the
        // Layout to null so we make sure we run it only when
        // the value is OK.
        if (width <= 1)
        return;

        TableColumn[] tableColumns = table.getColumns();
        int size = Math.min(_columns.size(), tableColumns.length);
        int[] widths = new int[size];
        int fixedWidth = 0;
        int numberOfWeightColumns = 0;
        int totalWeight = 0;

        // First calc space occupied by fixed columns
        for (int i = 0; i < size; i++)
        {
            ColumnLayoutData col = (ColumnLayoutData) _columns.get(i);
            if (col instanceof ColumnPixelData)
            {
                int pixels = ((ColumnPixelData) col).width;
                widths[i] = pixels;
                fixedWidth += pixels;
            }
            else if (col instanceof ColumnWeightData)
            {
                ColumnWeightData cw = (ColumnWeightData) col;
                numberOfWeightColumns++;
                // first time, use the weight specified by the column data, otherwise use the actual width as the weight
                // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
                int weight = cw.weight;
                totalWeight += weight;
            }
            else
            {
                Assert.isTrue(false, "Unknown column layout data"); //$NON-NLS-1$
            }
        }

        // Do we have columns that have a weight
        if (numberOfWeightColumns > 0)
        {
            // Now distribute the rest to the columns with weight.

            int rest1 = width - fixedWidth;
            int totalDistributed = 0;
            for (int i = 0; i < size; ++i)
            {
                ColumnLayoutData col = (ColumnLayoutData) _columns.get(i);
                if (col instanceof ColumnWeightData)
                {
                    ColumnWeightData cw = (ColumnWeightData) col;
                    // calculate weight as above
                    // int weight = firstTime ? cw.weight : tableColumns[i].getWidth();
                    int weight = cw.weight;
                    int pixels = totalWeight == 0 ? 0 : weight * rest1 / totalWeight;
                    if (pixels < cw.minimumWidth)
                    pixels = cw.minimumWidth;
                    totalDistributed += pixels;
                    widths[i] = pixels;
                }
            }

            // Distribute any remaining pixels to columns with weight.
            int diff = rest1 - totalDistributed;
            for (int i = 0; diff > 0; ++i)
            {
                if (i == size)
                i = 0;
                ColumnLayoutData col = (ColumnLayoutData) _columns.get(i);
                if (col instanceof ColumnWeightData)
                {
                    ++widths[i];
                    --diff;
                }
            }
        }

        if (increase)
        {
            table.setSize(area.width, area.height);
        }
        for (int i = 0; i < size; i++)
        {
            tableColumns[i].setWidth(widths[i]);
        }
        if (!increase)
        {
            table.setSize(area.width, area.height);
        }
    }
}