Java tutorial
/******************************************************************************* * Copyright (c) 2008, 2017 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.examples.accessibility; import java.text.MessageFormat; import java.util.ArrayList; import java.util.List; import java.util.ResourceBundle; import org.eclipse.swt.SWT; import org.eclipse.swt.accessibility.ACC; import org.eclipse.swt.accessibility.AccessibleAdapter; import org.eclipse.swt.accessibility.AccessibleControlAdapter; import org.eclipse.swt.accessibility.AccessibleControlEvent; import org.eclipse.swt.accessibility.AccessibleEvent; import org.eclipse.swt.events.FocusAdapter; import org.eclipse.swt.events.FocusEvent; import org.eclipse.swt.events.KeyAdapter; import org.eclipse.swt.events.KeyEvent; import org.eclipse.swt.events.MouseListener; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Display; /** * Instances of this class represent a very simple accessible bar chart. * From an accessibility point of view, they present the data as a "list" with "list items". */ public class BarChart extends Canvas { static ResourceBundle bundle = ResourceBundle.getBundle("examples_accessibility"); List<Object[]> data = new ArrayList<>(); String title; int color = SWT.COLOR_RED; int selectedItem = -1; int valueMin = 0; int valueMax = 10; int valueIncrement = 1; static final int GAP = 4; static final int AXIS_WIDTH = 2; /** * Constructs a new instance of this class given its parent * and a style value describing its behavior and appearance. * * @param parent a composite control which will be the parent of the new instance (cannot be null) * @param style the style of control to construct */ public BarChart(Composite parent, int style) { super(parent, style); addListeners(); } void addListeners() { addPaintListener(e -> { GC gc = e.gc; Rectangle rect = getClientArea(); Display display = getDisplay(); int count = data.size(); Point valueSize = gc.stringExtent(Integer.valueOf(valueMax).toString()); int leftX = rect.x + 2 * GAP + valueSize.x; int bottomY = rect.y + rect.height - 2 * GAP - valueSize.y; int unitWidth = (rect.width - 4 * GAP - valueSize.x - AXIS_WIDTH) / count - GAP; int unitHeight = (rect.height - 3 * GAP - AXIS_WIDTH - 2 * valueSize.y) / ((valueMax - valueMin) / valueIncrement); // draw the title int titleWidth = gc.stringExtent(title).x; int center = (Math.max(titleWidth, count * (unitWidth + GAP) + GAP) - titleWidth) / 2; gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK)); gc.drawString(title, leftX + AXIS_WIDTH + center, rect.y + GAP); // draw the y axis and value labels gc.setLineWidth(AXIS_WIDTH); gc.drawLine(leftX, rect.y + GAP + valueSize.y, leftX, bottomY); for (int i1 = valueMin; i1 <= valueMax; i1 += valueIncrement) { int y = bottomY - i1 * unitHeight; gc.drawLine(leftX, y, leftX - GAP, y); gc.drawString(Integer.valueOf(i1).toString(), rect.x + GAP, y - valueSize.y); } // draw the x axis and item labels gc.drawLine(leftX, bottomY, rect.x + rect.width - GAP, bottomY); for (int i2 = 0; i2 < count; i2++) { Object[] dataItem1 = data.get(i2); String itemLabel = (String) dataItem1[0]; int x1 = leftX + AXIS_WIDTH + GAP + i2 * (unitWidth + GAP); gc.drawString(itemLabel, x1, bottomY + GAP); } // draw the bars gc.setBackground(display.getSystemColor(color)); for (int i3 = 0; i3 < count; i3++) { Object[] dataItem2 = data.get(i3); int itemValue1 = ((Integer) dataItem2[1]).intValue(); int x2 = leftX + AXIS_WIDTH + GAP + i3 * (unitWidth + GAP); gc.fillRectangle(x2, bottomY - AXIS_WIDTH - itemValue1 * unitHeight, unitWidth, itemValue1 * unitHeight); } if (isFocusControl()) { if (selectedItem == -1) { // draw the focus rectangle around the whole bar chart gc.drawFocus(rect.x, rect.y, rect.width, rect.height); } else { // draw the focus rectangle around the selected item Object[] dataItem3 = data.get(selectedItem); int itemValue2 = ((Integer) dataItem3[1]).intValue(); int x3 = leftX + AXIS_WIDTH + GAP + selectedItem * (unitWidth + GAP); gc.drawFocus(x3, bottomY - itemValue2 * unitHeight - AXIS_WIDTH, unitWidth, itemValue2 * unitHeight + AXIS_WIDTH + GAP + valueSize.y); } } }); addFocusListener(new FocusAdapter() { @Override public void focusGained(FocusEvent e) { redraw(); } @Override public void focusLost(FocusEvent e) { redraw(); } }); addMouseListener(MouseListener.mouseDownAdapter(e -> { if (getClientArea().contains(e.x, e.y)) { setFocus(); int item = -1; int count = data.size(); for (int i = 0; i < count; i++) { if (itemBounds(i).contains(e.x, e.y)) { item = i; break; } } if (item != selectedItem) { selectedItem = item; redraw(); getAccessible().setFocus(item); getAccessible().selectionChanged(); } } })); addKeyListener(new KeyAdapter() { @Override public void keyPressed(KeyEvent e) { boolean change = false; switch (e.keyCode) { case SWT.ARROW_DOWN: case SWT.ARROW_RIGHT: selectedItem++; if (selectedItem >= data.size()) selectedItem = 0; change = true; break; case SWT.ARROW_UP: case SWT.ARROW_LEFT: selectedItem--; if (selectedItem <= -1) selectedItem = data.size() - 1; change = true; break; case SWT.HOME: selectedItem = 0; change = true; break; case SWT.END: selectedItem = data.size() - 1; change = true; break; } if (change) { redraw(); getAccessible().setFocus(selectedItem); getAccessible().selectionChanged(); } } }); addTraverseListener(e -> { switch (e.detail) { case SWT.TRAVERSE_TAB_NEXT: case SWT.TRAVERSE_TAB_PREVIOUS: e.doit = true; break; } }); getAccessible().addAccessibleListener(new AccessibleAdapter() { @Override public void getName(AccessibleEvent e) { MessageFormat formatter = new MessageFormat(""); //$NON_NLS$ formatter.applyPattern(bundle.getString("name")); //$NON_NLS$ int childID = e.childID; if (childID == ACC.CHILDID_SELF) { e.result = title; } else { Object[] item = data.get(childID); e.result = formatter.format(item); } } @Override public void getDescription(AccessibleEvent e) { int childID = e.childID; if (childID != ACC.CHILDID_SELF) { Object[] item = data.get(childID); String value = item[1].toString(); String colorName = bundle.getString("color" + color); //$NON_NLS$ MessageFormat formatter = new MessageFormat(""); //$NON_NLS$ formatter.applyPattern(bundle.getString("color_value")); //$NON_NLS$ e.result = formatter.format(new String[] { colorName, value }); } } }); getAccessible().addAccessibleControlListener(new AccessibleControlAdapter() { @Override public void getRole(AccessibleControlEvent e) { if (e.childID == ACC.CHILDID_SELF) { e.detail = ACC.ROLE_LIST; } else { e.detail = ACC.ROLE_LISTITEM; } } @Override public void getChildCount(AccessibleControlEvent e) { e.detail = data.size(); } @Override public void getChildren(AccessibleControlEvent e) { int count = data.size(); Object[] children = new Object[count]; for (int i = 0; i < count; i++) { children[i] = Integer.valueOf(i); } e.children = children; } @Override public void getChildAtPoint(AccessibleControlEvent e) { Point testPoint = toControl(e.x, e.y); int childID = ACC.CHILDID_NONE; if (getClientArea().contains(testPoint)) { childID = ACC.CHILDID_SELF; int count = data.size(); for (int i = 0; i < count; i++) { if (itemBounds(i).contains(testPoint)) { childID = i; break; } } } e.childID = childID; } @Override public void getLocation(AccessibleControlEvent e) { Rectangle location = null; Point pt = null; int childID = e.childID; if (childID == ACC.CHILDID_SELF) { location = getClientArea(); pt = getParent().toDisplay(location.x, location.y); } else { location = itemBounds(childID); pt = toDisplay(location.x, location.y); } e.x = pt.x; e.y = pt.y; e.width = location.width; e.height = location.height; } @Override public void getFocus(AccessibleControlEvent e) { int childID = ACC.CHILDID_NONE; if (isFocusControl()) { if (selectedItem == -1) { childID = ACC.CHILDID_SELF; } else { childID = selectedItem; } } e.childID = childID; } @Override public void getSelection(AccessibleControlEvent e) { e.childID = (selectedItem == -1) ? ACC.CHILDID_NONE : selectedItem; } @Override public void getValue(AccessibleControlEvent e) { int childID = e.childID; if (childID != ACC.CHILDID_SELF) { Object[] dataItem = data.get(childID); e.result = ((Integer) dataItem[1]).toString(); } } @Override public void getState(AccessibleControlEvent e) { int childID = e.childID; e.detail = ACC.STATE_FOCUSABLE; if (isFocusControl()) e.detail |= ACC.STATE_FOCUSED; if (childID != ACC.CHILDID_SELF) { e.detail |= ACC.STATE_SELECTABLE; if (childID == selectedItem) e.detail |= ACC.STATE_SELECTED; } } }); } @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); int count = data.size(); GC gc = new GC(this); int titleWidth = gc.stringExtent(title).x; Point valueSize = gc.stringExtent(Integer.valueOf(valueMax).toString()); int itemWidth = 0; for (int i = 0; i < count; i++) { Object[] dataItem = data.get(i); String itemLabel = (String) dataItem[0]; itemWidth = Math.max(itemWidth, gc.stringExtent(itemLabel).x); } gc.dispose(); int width = Math.max(titleWidth, count * (itemWidth + GAP) + GAP) + 3 * GAP + AXIS_WIDTH + valueSize.x; int height = 3 * GAP + AXIS_WIDTH + valueSize.y * ((valueMax - valueMin) / valueIncrement + 3); if (wHint != SWT.DEFAULT) width = wHint; if (hHint != SWT.DEFAULT) height = hHint; int border = getBorderWidth(); Rectangle trim = computeTrim(0, 0, width + border * 2, height + border * 2); return new Point(trim.width, trim.height); } /** * Add a labeled data value to the bar chart. * * @param label a string describing the value * @param value the data value */ public void addData(String label, int value) { checkWidget(); data.add(new Object[] { label, Integer.valueOf(value) }); } /** * Set the title of the bar chart. * * @param title a string to display as the bar chart's title. */ public void setTitle(String title) { checkWidget(); this.title = title; } /** * Set the bar color to the specified color. * The default color is SWT.COLOR_RED. * * @param color any of the SWT.COLOR_* constants */ public void setColor(int color) { checkWidget(); this.color = color; } /** * Set the minimum value for the y axis. * The default minimum is 0. * * @param min the minimum value */ public void setValueMin(int min) { checkWidget(); valueMin = min; } /** * Set the maximum value for the y axis. * The default maximum is 10. * * @param max the maximum value */ public void setValueMax(int max) { checkWidget(); valueMax = max; } /** * Set the increment value for the y axis. * The default increment is 1. * * @param increment the increment value */ public void setValueIncrement(int increment) { checkWidget(); valueIncrement = increment; } /* The bounds of the specified item in the coordinate system of the BarChart. */ Rectangle itemBounds(int index) { Rectangle rect = getClientArea(); GC gc = new GC(BarChart.this); Point valueSize = gc.stringExtent(Integer.valueOf(valueMax).toString()); gc.dispose(); int leftX = rect.x + 2 * GAP + valueSize.x; int bottomY = rect.y + rect.height - 2 * GAP - valueSize.y; int unitWidth = (rect.width - 4 * GAP - valueSize.x - AXIS_WIDTH) / data.size() - GAP; int unitHeight = (rect.height - 3 * GAP - AXIS_WIDTH - 2 * valueSize.y) / ((valueMax - valueMin) / valueIncrement); Object[] dataItem = data.get(index); int itemValue = ((Integer) dataItem[1]).intValue(); int x = leftX + AXIS_WIDTH + GAP + index * (unitWidth + GAP); return new Rectangle(x, bottomY - itemValue * unitHeight - AXIS_WIDTH, unitWidth, itemValue * unitHeight + AXIS_WIDTH + GAP + valueSize.y); } }