Java tutorial
/* * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.text; import java.awt.*; import javax.swing.*; import javax.swing.event.*; /** * Extends the multi-line plain text view to be suitable * for a single-line editor view. If the view is * allocated extra space, the field must adjust for it. * If the hosting component is a JTextField, this view * will manage the ranges of the associated BoundedRangeModel * and will adjust the horizontal allocation to match the * current visibility settings of the JTextField. * * @author Timothy Prinzing * @see View */ public class FieldView extends PlainView { /** * Constructs a new FieldView wrapped on an element. * * @param elem the element */ public FieldView(Element elem) { super(elem); } /** * Fetches the font metrics associated with the component hosting * this view. * * @return the metrics */ protected FontMetrics getFontMetrics() { Component c = getContainer(); return c.getFontMetrics(c.getFont()); } /** * Adjusts the allocation given to the view * to be a suitable allocation for a text field. * If the view has been allocated more than the * preferred span vertically, the allocation is * changed to be centered vertically. Horizontally * the view is adjusted according to the horizontal * alignment property set on the associated JTextField * (if that is the type of the hosting component). * * @param a the allocation given to the view, which may need * to be adjusted. * @return the allocation that the superclass should use. */ protected Shape adjustAllocation(Shape a) { if (a != null) { Rectangle bounds = a.getBounds(); int vspan = (int) getPreferredSpan(Y_AXIS); int hspan = (int) getPreferredSpan(X_AXIS); if (bounds.height != vspan) { int slop = bounds.height - vspan; bounds.y += slop / 2; bounds.height -= slop; } // horizontal adjustments Component c = getContainer(); if (c instanceof JTextField) { JTextField field = (JTextField) c; BoundedRangeModel vis = field.getHorizontalVisibility(); int max = Math.max(hspan, bounds.width); int value = vis.getValue(); int extent = Math.min(max, bounds.width - 1); if ((value + extent) > max) { value = max - extent; } vis.setRangeProperties(value, extent, vis.getMinimum(), max, false); if (hspan < bounds.width) { // horizontally align the interior int slop = bounds.width - 1 - hspan; int align = ((JTextField) c).getHorizontalAlignment(); if (Utilities.isLeftToRight(c)) { if (align == LEADING) { align = LEFT; } else if (align == TRAILING) { align = RIGHT; } } else { if (align == LEADING) { align = RIGHT; } else if (align == TRAILING) { align = LEFT; } } switch (align) { case SwingConstants.CENTER: bounds.x += slop / 2; bounds.width -= slop; break; case SwingConstants.RIGHT: bounds.x += slop; bounds.width -= slop; break; } } else { // adjust the allocation to match the bounded range. bounds.width = hspan; bounds.x -= vis.getValue(); } } return bounds; } return null; } /** * Update the visibility model with the associated JTextField * (if there is one) to reflect the current visibility as a * result of changes to the document model. The bounded * range properties are updated. If the view hasn't yet been * shown the extent will be zero and we just set it to be full * until determined otherwise. */ void updateVisibilityModel() { Component c = getContainer(); if (c instanceof JTextField) { JTextField field = (JTextField) c; BoundedRangeModel vis = field.getHorizontalVisibility(); int hspan = (int) getPreferredSpan(X_AXIS); int extent = vis.getExtent(); int maximum = Math.max(hspan, extent); extent = (extent == 0) ? maximum : extent; int value = maximum - extent; int oldValue = vis.getValue(); if ((oldValue + extent) > maximum) { oldValue = maximum - extent; } value = Math.max(0, Math.min(value, oldValue)); vis.setRangeProperties(value, extent, 0, maximum, false); } } // --- View methods ------------------------------------------- /** * Renders using the given rendering surface and area on that surface. * The view may need to do layout and create child views to enable * itself to render into the given allocation. * * @param g the rendering surface to use * @param a the allocated region to render into * * @see View#paint */ public void paint(Graphics g, Shape a) { Rectangle r = (Rectangle) a; g.clipRect(r.x, r.y, r.width, r.height); super.paint(g, a); } /** * Adjusts <code>a</code> based on the visible region and returns it. */ Shape adjustPaintRegion(Shape a) { return adjustAllocation(a); } /** * Determines the preferred span for this view along an * axis. * * @param axis may be either View.X_AXIS or View.Y_AXIS * @return the span the view would like to be rendered into >= 0. * Typically the view is told to render into the span * that is returned, although there is no guarantee. * The parent may choose to resize or break the view. */ @SuppressWarnings("deprecation") public float getPreferredSpan(int axis) { switch (axis) { case View.X_AXIS: Segment buff = SegmentCache.getSharedSegment(); Document doc = getDocument(); int width; try { FontMetrics fm = getFontMetrics(); doc.getText(0, doc.getLength(), buff); width = Utilities.getTabbedTextWidth(buff, fm, 0, this, 0); if (buff.count > 0) { Component c = getContainer(); firstLineOffset = sun.swing.SwingUtilities2.getLeftSideBearing( (c instanceof JComponent) ? (JComponent) c : null, fm, buff.array[buff.offset]); firstLineOffset = Math.max(0, -firstLineOffset); } else { firstLineOffset = 0; } } catch (BadLocationException bl) { width = 0; } SegmentCache.releaseSharedSegment(buff); return width + firstLineOffset; default: return super.getPreferredSpan(axis); } } /** * Determines the resizability of the view along the * given axis. A value of 0 or less is not resizable. * * @param axis View.X_AXIS or View.Y_AXIS * @return the weight -> 1 for View.X_AXIS, else 0 */ public int getResizeWeight(int axis) { if (axis == View.X_AXIS) { return 1; } return 0; } /** * Provides a mapping from the document model coordinate space * to the coordinate space of the view mapped to it. * * @param pos the position to convert >= 0 * @param a the allocated region to render into * @return the bounding box of the given position * @exception BadLocationException if the given position does not * represent a valid location in the associated document * @see View#modelToView */ public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException { return super.modelToView(pos, adjustAllocation(a), b); } /** * Provides a mapping from the view coordinate space to the logical * coordinate space of the model. * * @param fx the X coordinate >= 0.0f * @param fy the Y coordinate >= 0.0f * @param a the allocated region to render into * @return the location within the model that best represents the * given point in the view * @see View#viewToModel */ public int viewToModel(float fx, float fy, Shape a, Position.Bias[] bias) { return super.viewToModel(fx, fy, adjustAllocation(a), bias); } /** * Gives notification that something was inserted into the document * in a location that this view is responsible for. * * @param changes the change information from the associated document * @param a the current allocation of the view * @param f the factory to use to rebuild if the view has children * @see View#insertUpdate */ public void insertUpdate(DocumentEvent changes, Shape a, ViewFactory f) { super.insertUpdate(changes, adjustAllocation(a), f); updateVisibilityModel(); } /** * Gives notification that something was removed from the document * in a location that this view is responsible for. * * @param changes the change information from the associated document * @param a the current allocation of the view * @param f the factory to use to rebuild if the view has children * @see View#removeUpdate */ public void removeUpdate(DocumentEvent changes, Shape a, ViewFactory f) { super.removeUpdate(changes, adjustAllocation(a), f); updateVisibilityModel(); } }