Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2015 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation * Florian Priester - bug 106059 *******************************************************************************/ package org.eclipse.jface.viewers; import java.util.ArrayList; import java.util.List; import org.eclipse.core.runtime.Assert; import org.eclipse.jface.layout.TableColumnLayout; import org.eclipse.jface.util.Util; import org.eclipse.swt.SWT; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Item; import org.eclipse.swt.widgets.Layout; import org.eclipse.swt.widgets.Table; import org.eclipse.swt.widgets.TableColumn; import org.eclipse.swt.widgets.Tree; import org.eclipse.swt.widgets.TreeColumn; /** * A layout for a table. Call <code>addColumnData</code> to add columns. * The TableLayout {@link ColumnLayoutData} is only valid until the table * is resized. To keep the proportions constant when the table is resized * see {@link TableColumnLayout} */ public class TableLayout extends Layout { /** * The number of extra pixels taken as horizontal trim by the table column. * To ensure there are N pixels available for the content of the column, * assign N+COLUMN_TRIM for the column width. * * @since 3.1 */ private static int COLUMN_TRIM; static { if (Util.isWindows()) { COLUMN_TRIM = 4; } else if (Util.isMac()) { COLUMN_TRIM = 24; } else { COLUMN_TRIM = 3; } } /** * The list of column layout data (element type: * <code>ColumnLayoutData</code>). */ private List columns = new ArrayList(); /** * Indicates whether <code>layout</code> has yet to be called. */ private boolean firstTime = true; private boolean adjustForScrollBar; /** * Creates a new table layout. */ public TableLayout() { } /** * Creates a new table layout. * * @param adjustForScrollBar <code>true</code> if the layout should reserve space for the * vertical scroll bar * @since 3.9 */ public TableLayout(boolean adjustForScrollBar) { this.adjustForScrollBar = adjustForScrollBar; } /** * Adds a new column of data to this table layout. * * @param data * the column layout data */ public void addColumnData(ColumnLayoutData data) { columns.add(data); } @Override public Point computeSize(Composite c, int wHint, int hHint, boolean flush) { if (wHint != SWT.DEFAULT && hHint != SWT.DEFAULT) { return new Point(wHint, hHint); } Table table = (Table) c; // To avoid recursions. table.setLayout(null); // Use native layout algorithm Point result = table.computeSize(wHint, hHint, flush); table.setLayout(this); 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; if (col.addTrim) { width += COLUMN_TRIM; } } 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; } @Override public void layout(Composite c, boolean flush) { // Only do initial layout. Trying to maintain proportions when resizing // is too hard, // causes lots of widget flicker, causes scroll bars to appear and // occasionally stick around (on Windows), // requires hooking column resizing as well, and may not be what the // user wants anyway. if (!firstTime) { return; } int width = c.getClientArea().width; // 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; } Item[] tableColumns = getColumns(c); 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) { ColumnPixelData cpd = (ColumnPixelData) col; int pixels = cpd.width; if (cpd.addTrim) { pixels += COLUMN_TRIM; } 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) { if (adjustForScrollBar && c.getVerticalBar() != null) width -= c.getVerticalBar().getThumbTrackBounds().width; // Now distribute the rest to the columns with weight. int rest = 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 * rest / totalWeight; if (pixels < cw.minimumWidth) { pixels = cw.minimumWidth; } totalDistributed += pixels; widths[i] = pixels; } } // Distribute any remaining pixels to columns with weight. int diff = rest - 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; } } } firstTime = false; for (int i = 0; i < size; i++) { setWidth(tableColumns[i], widths[i]); } } /** * Set the width of the item. * * @param item * @param width */ private void setWidth(Item item, int width) { if (item instanceof TreeColumn) { ((TreeColumn) item).setWidth(width); } else { ((TableColumn) item).setWidth(width); } } /** * Return the columns for the receiver. * * @param composite * @return Item[] */ private Item[] getColumns(Composite composite) { if (composite instanceof Tree) { return ((Tree) composite).getColumns(); } return ((Table) composite).getColumns(); } }