PasswordView


1   /*
2    * @(#)PasswordView.java    1.20 04/04/15
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package javax.swing.text;
8   
9   import com.sun.java.swing.SwingUtilities2;
10  import java.awt.*;
11  import javax.swing.JPasswordField  ;
12  
13  /**
14   * Implements a View suitable for use in JPasswordField
15   * UI implementations.  This is basically a field ui that
16   * renders its contents as the echo character specified
17   * in the associated component (if it can narrow the
18   * component to a JPasswordField).
19   *
20   * @author  Timothy Prinzing
21   * @version 1.20 04/15/04
22   * @see     View
23   */
24  public class PasswordView extends FieldView   {
25  
26      /**
27       * Constructs a new view wrapped on an element.
28       *
29       * @param elem the element
30       */
31      public PasswordView(Element   elem) {
32      super(elem);
33      }
34  
35      /**
36       * Renders the given range in the model as normal unselected
37       * text.  This sets the foreground color and echos the characters
38       * using the value returned by getEchoChar().
39       *
40       * @param g the graphics context
41       * @param x the starting X coordinate >= 0
42       * @param y the starting Y coordinate >= 0
43       * @param p0 the starting offset in the model >= 0
44       * @param p1 the ending offset in the model >= p0
45       * @return the X location of the end of the range >= 0
46       * @exception BadLocationException if p0 or p1 are out of range
47       */
48      protected int drawUnselectedText(Graphics g, int x, int y,
49                       int p0, int p1) throws BadLocationException   {
50  
51      Container c = getContainer();
52      if (c instanceof JPasswordField  ) {
53          JPasswordField   f = (JPasswordField  ) c;
54          if (! f.echoCharIsSet()) {
55          return super.drawUnselectedText(g, x, y, p0, p1);
56          }
57              if (f.isEnabled()) {
58                  g.setColor(f.getForeground());
59              }
60              else {
61                  g.setColor(f.getDisabledTextColor());
62              }
63          char echoChar = f.getEchoChar();
64          int n = p1 - p0;
65          for (int i = 0; i < n; i++) {
66          x = drawEchoCharacter(g, x, y, echoChar);
67          }
68      }
69      return x;
70      }
71  
72      /**
73       * Renders the given range in the model as selected text.  This
74       * is implemented to render the text in the color specified in
75       * the hosting component.  It assumes the highlighter will render
76       * the selected background.  Uses the result of getEchoChar() to
77       * display the characters.
78       *
79       * @param g the graphics context
80       * @param x the starting X coordinate >= 0
81       * @param y the starting Y coordinate >= 0
82       * @param p0 the starting offset in the model >= 0
83       * @param p1 the ending offset in the model >= p0
84       * @return the X location of the end of the range >= 0
85       * @exception BadLocationException if p0 or p1 are out of range
86       */
87      protected int drawSelectedText(Graphics g, int x,
88                     int y, int p0, int p1) throws BadLocationException   {
89      g.setColor(selected);
90      Container c = getContainer();
91      if (c instanceof JPasswordField  ) {
92          JPasswordField   f = (JPasswordField  ) c;
93          if (! f.echoCharIsSet()) {
94          return super.drawSelectedText(g, x, y, p0, p1);
95          }
96          char echoChar = f.getEchoChar();
97          int n = p1 - p0;
98          for (int i = 0; i < n; i++) {
99          x = drawEchoCharacter(g, x, y, echoChar);
100         }
101     }
102     return x;
103     }
104 
105     /**
106      * Renders the echo character, or whatever graphic should be used
107      * to display the password characters.  The color in the Graphics
108      * object is set to the appropriate foreground color for selected
109      * or unselected text.
110      *
111      * @param g the graphics context
112      * @param x the starting X coordinate >= 0
113      * @param y the starting Y coordinate >= 0
114      * @param c the echo character
115      * @return the updated X position >= 0
116      */
117     protected int drawEchoCharacter(Graphics g, int x, int y, char c) {
118     ONE[0] = c;
119         SwingUtilities2.drawChars(Utilities.getJComponent(this),
120                                   g, ONE, 0, 1, x, y);
121     return x + g.getFontMetrics().charWidth(c);
122     }
123 
124     /**
125      * Provides a mapping from the document model coordinate space
126      * to the coordinate space of the view mapped to it.
127      *
128      * @param pos the position to convert >= 0
129      * @param a the allocated region to render into
130      * @return the bounding box of the given position
131      * @exception BadLocationException  if the given position does not
132      *   represent a valid location in the associated document
133      * @see View#modelToView
134      */
135     public Shape modelToView(int pos, Shape a, Position.Bias   b) throws BadLocationException   {
136     Container c = getContainer();
137     if (c instanceof JPasswordField  ) {
138         JPasswordField   f = (JPasswordField  ) c;
139         if (! f.echoCharIsSet()) {
140         return super.modelToView(pos, a, b);
141         }
142         char echoChar = f.getEchoChar();
143         FontMetrics m = f.getFontMetrics(f.getFont());
144         
145         Rectangle alloc = adjustAllocation(a).getBounds();
146         int dx = (pos - getStartOffset()) * m.charWidth(echoChar);
147         alloc.x += dx;
148         alloc.width = 1;
149         return alloc;
150     }
151     return null;
152     }
153 
154     /**
155      * Provides a mapping from the view coordinate space to the logical
156      * coordinate space of the model.
157      *
158      * @param fx the X coordinate >= 0.0f
159      * @param fy the Y coordinate >= 0.0f
160      * @param a the allocated region to render into
161      * @return the location within the model that best represents the
162      *  given point in the view
163      * @see View#viewToModel
164      */
165     public int viewToModel(float fx, float fy, Shape a, Position.Bias  [] bias) {
166     bias[0] = Position.Bias.Forward;
167     int n = 0;
168     Container c = getContainer();
169     if (c instanceof JPasswordField  ) {
170         JPasswordField   f = (JPasswordField  ) c;
171         if (! f.echoCharIsSet()) {
172         return super.viewToModel(fx, fy, a, bias);
173         }
174         char echoChar = f.getEchoChar();
175         FontMetrics m = f.getFontMetrics(f.getFont());
176         a = adjustAllocation(a);
177         Rectangle alloc = (a instanceof Rectangle) ? (Rectangle)a :
178                               a.getBounds();
179         n = ((int)fx - alloc.x) / m.charWidth(echoChar);
180         if (n < 0) {
181         n = 0;
182         }
183         else if (n > (getStartOffset() + getDocument().getLength())) {
184         n = getDocument().getLength() - getStartOffset();
185         }
186     }
187     return getStartOffset() + n;
188     }
189 
190     /**
191      * Determines the preferred span for this view along an
192      * axis.
193      *
194      * @param axis may be either View.X_AXIS or View.Y_AXIS
195      * @return   the span the view would like to be rendered into >= 0.
196      *           Typically the view is told to render into the span
197      *           that is returned, although there is no guarantee.  
198      *           The parent may choose to resize or break the view.
199      */
200     public float getPreferredSpan(int axis) {
201     switch (axis) {
202     case View.X_AXIS:
203             Container c = getContainer();
204             if (c instanceof JPasswordField  ) {
205                 JPasswordField   f = (JPasswordField  ) c;
206                 if (f.echoCharIsSet()) {
207                     char echoChar = f.getEchoChar();
208                     FontMetrics m = f.getFontMetrics(f.getFont());
209                     Document   doc = getDocument();
210                     return m.charWidth(echoChar) * getDocument().getLength();
211                 }
212             }
213         }
214         return super.getPreferredSpan(axis);
215     }
216 
217     static char[] ONE = new char[1];
218 }
219
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