Home | History | Annotate | Download | only in method 
      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.view.KeyEvent;
     20 import android.view.View;
     21 import android.text.*;
     22 import android.text.method.TextKeyListener.Capitalize;
     23 import android.widget.TextView;
     24 
     25 /**
     26  * Abstract base class for key listeners.
     27  *
     28  * Provides a basic foundation for entering and editing text.
     29  * Subclasses should override {@link #onKeyDown} and {@link #onKeyUp} to insert
     30  * characters as keys are pressed.
     31  */
     32 public abstract class BaseKeyListener extends MetaKeyKeyListener
     33         implements KeyListener {
     34     /* package */ static final Object OLD_SEL_START = new NoCopySpan.Concrete();
     35 
     36     /**
     37      * Performs the action that happens when you press the {@link KeyEvent#KEYCODE_DEL} key in
     38      * a {@link TextView}.  If there is a selection, deletes the selection; otherwise,
     39      * deletes the character before the cursor, if any; ALT+DEL deletes everything on
     40      * the line the cursor is on.
     41      *
     42      * @return true if anything was deleted; false otherwise.
     43      */
     44     public boolean backspace(View view, Editable content, int keyCode, KeyEvent event) {
     45         return backspaceOrForwardDelete(view, content, keyCode, event, false);
     46     }
     47 
     48     /**
     49      * Performs the action that happens when you press the {@link KeyEvent#KEYCODE_FORWARD_DEL}
     50      * key in a {@link TextView}.  If there is a selection, deletes the selection; otherwise,
     51      * deletes the character before the cursor, if any; ALT+FORWARD_DEL deletes everything on
     52      * the line the cursor is on.
     53      *
     54      * @return true if anything was deleted; false otherwise.
     55      */
     56     public boolean forwardDelete(View view, Editable content, int keyCode, KeyEvent event) {
     57         return backspaceOrForwardDelete(view, content, keyCode, event, true);
     58     }
     59 
     60     private boolean backspaceOrForwardDelete(View view, Editable content, int keyCode,
     61             KeyEvent event, boolean isForwardDelete) {
     62         // Ensure the key event does not have modifiers except ALT or SHIFT.
     63         if (!KeyEvent.metaStateHasNoModifiers(event.getMetaState()
     64                 & ~(KeyEvent.META_SHIFT_MASK | KeyEvent.META_ALT_MASK))) {
     65             return false;
     66         }
     67 
     68         // If there is a current selection, delete it.
     69         if (deleteSelection(view, content)) {
     70             return true;
     71         }
     72 
     73         // Alt+Backspace or Alt+ForwardDelete deletes the current line, if possible.
     74         if (event.isAltPressed() || getMetaState(content, META_ALT_ON) == 1) {
     75             if (deleteLine(view, content)) {
     76                 return true;
     77             }
     78         }
     79 
     80         // Delete a character.
     81         final int start = Selection.getSelectionEnd(content);
     82         final int end;
     83         if (isForwardDelete || event.isShiftPressed()
     84                 || getMetaState(content, META_SHIFT_ON) == 1) {
     85             end = TextUtils.getOffsetAfter(content, start);
     86         } else {
     87             end = TextUtils.getOffsetBefore(content, start);
     88         }
     89         if (start != end) {
     90             content.delete(Math.min(start, end), Math.max(start, end));
     91             return true;
     92         }
     93         return false;
     94     }
     95 
     96     private boolean deleteSelection(View view, Editable content) {
     97         int selectionStart = Selection.getSelectionStart(content);
     98         int selectionEnd = Selection.getSelectionEnd(content);
     99         if (selectionEnd < selectionStart) {
    100             int temp = selectionEnd;
    101             selectionEnd = selectionStart;
    102             selectionStart = temp;
    103         }
    104         if (selectionStart != selectionEnd) {
    105             content.delete(selectionStart, selectionEnd);
    106             return true;
    107         }
    108         return false;
    109     }
    110 
    111     private boolean deleteLine(View view, Editable content) {
    112         if (view instanceof TextView) {
    113             final Layout layout = ((TextView) view).getLayout();
    114             if (layout != null) {
    115                 final int line = layout.getLineForOffset(Selection.getSelectionStart(content));
    116                 final int start = layout.getLineStart(line);
    117                 final int end = layout.getLineEnd(line);
    118                 if (end != start) {
    119                     content.delete(start, end);
    120                     return true;
    121                 }
    122             }
    123         }
    124         return false;
    125     }
    126 
    127     static int makeTextContentType(Capitalize caps, boolean autoText) {
    128         int contentType = InputType.TYPE_CLASS_TEXT;
    129         switch (caps) {
    130             case CHARACTERS:
    131                 contentType |= InputType.TYPE_TEXT_FLAG_CAP_CHARACTERS;
    132                 break;
    133             case WORDS:
    134                 contentType |= InputType.TYPE_TEXT_FLAG_CAP_WORDS;
    135                 break;
    136             case SENTENCES:
    137                 contentType |= InputType.TYPE_TEXT_FLAG_CAP_SENTENCES;
    138                 break;
    139         }
    140         if (autoText) {
    141             contentType |= InputType.TYPE_TEXT_FLAG_AUTO_CORRECT;
    142         }
    143         return contentType;
    144     }
    145 
    146     public boolean onKeyDown(View view, Editable content,
    147                              int keyCode, KeyEvent event) {
    148         boolean handled;
    149         switch (keyCode) {
    150             case KeyEvent.KEYCODE_DEL:
    151                 handled = backspace(view, content, keyCode, event);
    152                 break;
    153             case KeyEvent.KEYCODE_FORWARD_DEL:
    154                 handled = forwardDelete(view, content, keyCode, event);
    155                 break;
    156             default:
    157                 handled = false;
    158                 break;
    159         }
    160 
    161         if (handled) {
    162             adjustMetaAfterKeypress(content);
    163         }
    164 
    165         return super.onKeyDown(view, content, keyCode, event);
    166     }
    167 
    168     /**
    169      * Base implementation handles ACTION_MULTIPLE KEYCODE_UNKNOWN by inserting
    170      * the event's text into the content.
    171      */
    172     public boolean onKeyOther(View view, Editable content, KeyEvent event) {
    173         if (event.getAction() != KeyEvent.ACTION_MULTIPLE
    174                 || event.getKeyCode() != KeyEvent.KEYCODE_UNKNOWN) {
    175             // Not something we are interested in.
    176             return false;
    177         }
    178 
    179         int selectionStart = Selection.getSelectionStart(content);
    180         int selectionEnd = Selection.getSelectionEnd(content);
    181         if (selectionEnd < selectionStart) {
    182             int temp = selectionEnd;
    183             selectionEnd = selectionStart;
    184             selectionStart = temp;
    185         }
    186 
    187         CharSequence text = event.getCharacters();
    188         if (text == null) {
    189             return false;
    190         }
    191 
    192         content.replace(selectionStart, selectionEnd, text);
    193         return true;
    194     }
    195 }
    196 
    197