1 /*
2  * Copyright (C) 2006 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.text.method;
18 
19 import android.text.Layout;
20 import android.text.NoCopySpan;
21 import android.text.Selection;
22 import android.text.Spannable;
23 import android.text.style.ClickableSpan;
24 import android.view.KeyEvent;
25 import android.view.MotionEvent;
26 import android.view.View;
27 import android.widget.TextView;
28 
29 /**
30  * A movement method that traverses links in the text buffer and scrolls if necessary.
31  * Supports clicking on links with DPad Center or Enter.
32  */
33 public class LinkMovementMethod extends ScrollingMovementMethod {
34     private static final int CLICK = 1;
35     private static final int UP = 2;
36     private static final int DOWN = 3;
37 
38     @Override
canSelectArbitrarily()39     public boolean canSelectArbitrarily() {
40         return true;
41     }
42 
43     @Override
handleMovementKey(TextView widget, Spannable buffer, int keyCode, int movementMetaState, KeyEvent event)44     protected boolean handleMovementKey(TextView widget, Spannable buffer, int keyCode,
45             int movementMetaState, KeyEvent event) {
46         switch (keyCode) {
47             case KeyEvent.KEYCODE_DPAD_CENTER:
48             case KeyEvent.KEYCODE_ENTER:
49                 if (KeyEvent.metaStateHasNoModifiers(movementMetaState)) {
50                     if (event.getAction() == KeyEvent.ACTION_DOWN &&
51                             event.getRepeatCount() == 0 && action(CLICK, widget, buffer)) {
52                         return true;
53                     }
54                 }
55                 break;
56         }
57         return super.handleMovementKey(widget, buffer, keyCode, movementMetaState, event);
58     }
59 
60     @Override
up(TextView widget, Spannable buffer)61     protected boolean up(TextView widget, Spannable buffer) {
62         if (action(UP, widget, buffer)) {
63             return true;
64         }
65 
66         return super.up(widget, buffer);
67     }
68 
69     @Override
down(TextView widget, Spannable buffer)70     protected boolean down(TextView widget, Spannable buffer) {
71         if (action(DOWN, widget, buffer)) {
72             return true;
73         }
74 
75         return super.down(widget, buffer);
76     }
77 
78     @Override
left(TextView widget, Spannable buffer)79     protected boolean left(TextView widget, Spannable buffer) {
80         if (action(UP, widget, buffer)) {
81             return true;
82         }
83 
84         return super.left(widget, buffer);
85     }
86 
87     @Override
right(TextView widget, Spannable buffer)88     protected boolean right(TextView widget, Spannable buffer) {
89         if (action(DOWN, widget, buffer)) {
90             return true;
91         }
92 
93         return super.right(widget, buffer);
94     }
95 
action(int what, TextView widget, Spannable buffer)96     private boolean action(int what, TextView widget, Spannable buffer) {
97         Layout layout = widget.getLayout();
98 
99         int padding = widget.getTotalPaddingTop() +
100                       widget.getTotalPaddingBottom();
101         int areatop = widget.getScrollY();
102         int areabot = areatop + widget.getHeight() - padding;
103 
104         int linetop = layout.getLineForVertical(areatop);
105         int linebot = layout.getLineForVertical(areabot);
106 
107         int first = layout.getLineStart(linetop);
108         int last = layout.getLineEnd(linebot);
109 
110         ClickableSpan[] candidates = buffer.getSpans(first, last, ClickableSpan.class);
111 
112         int a = Selection.getSelectionStart(buffer);
113         int b = Selection.getSelectionEnd(buffer);
114 
115         int selStart = Math.min(a, b);
116         int selEnd = Math.max(a, b);
117 
118         if (selStart < 0) {
119             if (buffer.getSpanStart(FROM_BELOW) >= 0) {
120                 selStart = selEnd = buffer.length();
121             }
122         }
123 
124         if (selStart > last)
125             selStart = selEnd = Integer.MAX_VALUE;
126         if (selEnd < first)
127             selStart = selEnd = -1;
128 
129         switch (what) {
130         case CLICK:
131             if (selStart == selEnd) {
132                 return false;
133             }
134 
135             ClickableSpan[] link = buffer.getSpans(selStart, selEnd, ClickableSpan.class);
136 
137             if (link.length != 1)
138                 return false;
139 
140             link[0].onClick(widget);
141             break;
142 
143         case UP:
144             int beststart, bestend;
145 
146             beststart = -1;
147             bestend = -1;
148 
149             for (int i = 0; i < candidates.length; i++) {
150                 int end = buffer.getSpanEnd(candidates[i]);
151 
152                 if (end < selEnd || selStart == selEnd) {
153                     if (end > bestend) {
154                         beststart = buffer.getSpanStart(candidates[i]);
155                         bestend = end;
156                     }
157                 }
158             }
159 
160             if (beststart >= 0) {
161                 Selection.setSelection(buffer, bestend, beststart);
162                 return true;
163             }
164 
165             break;
166 
167         case DOWN:
168             beststart = Integer.MAX_VALUE;
169             bestend = Integer.MAX_VALUE;
170 
171             for (int i = 0; i < candidates.length; i++) {
172                 int start = buffer.getSpanStart(candidates[i]);
173 
174                 if (start > selStart || selStart == selEnd) {
175                     if (start < beststart) {
176                         beststart = start;
177                         bestend = buffer.getSpanEnd(candidates[i]);
178                     }
179                 }
180             }
181 
182             if (bestend < Integer.MAX_VALUE) {
183                 Selection.setSelection(buffer, beststart, bestend);
184                 return true;
185             }
186 
187             break;
188         }
189 
190         return false;
191     }
192 
193     @Override
onTouchEvent(TextView widget, Spannable buffer, MotionEvent event)194     public boolean onTouchEvent(TextView widget, Spannable buffer,
195                                 MotionEvent event) {
196         int action = event.getAction();
197 
198         if (action == MotionEvent.ACTION_UP ||
199             action == MotionEvent.ACTION_DOWN) {
200             int x = (int) event.getX();
201             int y = (int) event.getY();
202 
203             x -= widget.getTotalPaddingLeft();
204             y -= widget.getTotalPaddingTop();
205 
206             x += widget.getScrollX();
207             y += widget.getScrollY();
208 
209             Layout layout = widget.getLayout();
210             int line = layout.getLineForVertical(y);
211             int off = layout.getOffsetForHorizontal(line, x);
212 
213             ClickableSpan[] link = buffer.getSpans(off, off, ClickableSpan.class);
214 
215             if (link.length != 0) {
216                 if (action == MotionEvent.ACTION_UP) {
217                     link[0].onClick(widget);
218                 } else if (action == MotionEvent.ACTION_DOWN) {
219                     Selection.setSelection(buffer,
220                                            buffer.getSpanStart(link[0]),
221                                            buffer.getSpanEnd(link[0]));
222                 }
223 
224                 return true;
225             } else {
226                 Selection.removeSelection(buffer);
227             }
228         }
229 
230         return super.onTouchEvent(widget, buffer, event);
231     }
232 
233     @Override
initialize(TextView widget, Spannable text)234     public void initialize(TextView widget, Spannable text) {
235         Selection.removeSelection(text);
236         text.removeSpan(FROM_BELOW);
237     }
238 
239     @Override
onTakeFocus(TextView view, Spannable text, int dir)240     public void onTakeFocus(TextView view, Spannable text, int dir) {
241         Selection.removeSelection(text);
242 
243         if ((dir & View.FOCUS_BACKWARD) != 0) {
244             text.setSpan(FROM_BELOW, 0, 0, Spannable.SPAN_POINT_POINT);
245         } else {
246             text.removeSpan(FROM_BELOW);
247         }
248     }
249 
getInstance()250     public static MovementMethod getInstance() {
251         if (sInstance == null)
252             sInstance = new LinkMovementMethod();
253 
254         return sInstance;
255     }
256 
257     private static LinkMovementMethod sInstance;
258     private static Object FROM_BELOW = new NoCopySpan.Concrete();
259 }
260