Android example source code file (Selection.java)
The Selection.java Android example source code/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.text;
/**
* Utility class for manipulating cursors and selections in CharSequences.
* A cursor is a selection where the start and end are at the same offset.
*/
public class Selection {
private Selection() { /* cannot be instantiated */ }
/*
* Retrieving the selection
*/
/**
* Return the offset of the selection anchor or cursor, or -1 if
* there is no selection or cursor.
*/
public static final int getSelectionStart(CharSequence text) {
if (text instanceof Spanned)
return ((Spanned) text).getSpanStart(SELECTION_START);
else
return -1;
}
/**
* Return the offset of the selection edge or cursor, or -1 if
* there is no selection or cursor.
*/
public static final int getSelectionEnd(CharSequence text) {
if (text instanceof Spanned)
return ((Spanned) text).getSpanStart(SELECTION_END);
else
return -1;
}
/*
* Setting the selection
*/
// private static int pin(int value, int min, int max) {
// return value < min ? 0 : (value > max ? max : value);
// }
/**
* Set the selection anchor to <code>start and the selection edge
* to <code>stop.
*/
public static void setSelection(Spannable text, int start, int stop) {
// int len = text.length();
// start = pin(start, 0, len); XXX remove unless we really need it
// stop = pin(stop, 0, len);
int ostart = getSelectionStart(text);
int oend = getSelectionEnd(text);
if (ostart != start || oend != stop) {
text.setSpan(SELECTION_START, start, start,
Spanned.SPAN_POINT_POINT|Spanned.SPAN_INTERMEDIATE);
text.setSpan(SELECTION_END, stop, stop,
Spanned.SPAN_POINT_POINT);
}
}
/**
* Move the cursor to offset <code>index.
*/
public static final void setSelection(Spannable text, int index) {
setSelection(text, index, index);
}
/**
* Select the entire text.
*/
public static final void selectAll(Spannable text) {
setSelection(text, 0, text.length());
}
/**
* Move the selection edge to offset <code>index.
*/
public static final void extendSelection(Spannable text, int index) {
if (text.getSpanStart(SELECTION_END) != index)
text.setSpan(SELECTION_END, index, index, Spanned.SPAN_POINT_POINT);
}
/**
* Remove the selection or cursor, if any, from the text.
*/
public static final void removeSelection(Spannable text) {
text.removeSpan(SELECTION_START);
text.removeSpan(SELECTION_END);
}
/*
* Moving the selection within the layout
*/
/**
* Move the cursor to the buffer offset physically above the current
* offset, or return false if the cursor is already on the top line.
*/
public static boolean moveUp(Spannable text, Layout layout) {
int start = getSelectionStart(text);
int end = getSelectionEnd(text);
if (start != end) {
int min = Math.min(start, end);
int max = Math.max(start, end);
setSelection(text, min);
if (min == 0 && max == text.length()) {
return false;
}
return true;
} else {
int line = layout.getLineForOffset(end);
if (line > 0) {
int move;
if (layout.getParagraphDirection(line) ==
layout.getParagraphDirection(line - 1)) {
float h = layout.getPrimaryHorizontal(end);
move = layout.getOffsetForHorizontal(line - 1, h);
} else {
move = layout.getLineStart(line - 1);
}
setSelection(text, move);
return true;
}
}
return false;
}
/**
* Move the cursor to the buffer offset physically below the current
* offset, or return false if the cursor is already on the bottom line.
*/
public static boolean moveDown(Spannable text, Layout layout) {
int start = getSelectionStart(text);
int end = getSelectionEnd(text);
if (start != end) {
int min = Math.min(start, end);
int max = Math.max(start, end);
setSelection(text, max);
if (min == 0 && max == text.length()) {
return false;
}
return true;
} else {
int line = layout.getLineForOffset(end);
if (line < layout.getLineCount() - 1) {
int move;
if (layout.getParagraphDirection(line) ==
layout.getParagraphDirection(line + 1)) {
float h = layout.getPrimaryHorizontal(end);
move = layout.getOffsetForHorizontal(line + 1, h);
} else {
move = layout.getLineStart(line + 1);
}
setSelection(text, move);
return true;
}
}
return false;
}
/**
* Move the cursor to the buffer offset physically to the left of
* the current offset, or return false if the cursor is already
* at the left edge of the line and there is not another line to move it to.
*/
public static boolean moveLeft(Spannable text, Layout layout) {
int start = getSelectionStart(text);
int end = getSelectionEnd(text);
if (start != end) {
setSelection(text, chooseHorizontal(layout, -1, start, end));
return true;
} else {
int to = layout.getOffsetToLeftOf(end);
if (to != end) {
setSelection(text, to);
return true;
}
}
return false;
}
/**
* Move the cursor to the buffer offset physically to the right of
* the current offset, or return false if the cursor is already at
* at the right edge of the line and there is not another line
* to move it to.
*/
public static boolean moveRight(Spannable text, Layout layout) {
int start = getSelectionStart(text);
int end = getSelectionEnd(text);
if (start != end) {
setSelection(text, chooseHorizontal(layout, 1, start, end));
return true;
} else {
int to = layout.getOffsetToRightOf(end);
if (to != end) {
setSelection(text, to);
return true;
}
}
return false;
}
/**
* Move the selection end to the buffer offset physically above
* the current selection end.
*/
public static boolean extendUp(Spannable text, Layout layout) {
int end = getSelectionEnd(text);
int line = layout.getLineForOffset(end);
if (line > 0) {
int move;
if (layout.getParagraphDirection(line) ==
layout.getParagraphDirection(line - 1)) {
float h = layout.getPrimaryHorizontal(end);
move = layout.getOffsetForHorizontal(line - 1, h);
} else {
move = layout.getLineStart(line - 1);
}
extendSelection(text, move);
return true;
} else if (end != 0) {
extendSelection(text, 0);
return true;
}
return true;
}
/**
* Move the selection end to the buffer offset physically below
* the current selection end.
*/
public static boolean extendDown(Spannable text, Layout layout) {
int end = getSelectionEnd(text);
int line = layout.getLineForOffset(end);
if (line < layout.getLineCount() - 1) {
int move;
if (layout.getParagraphDirection(line) ==
layout.getParagraphDirection(line + 1)) {
float h = layout.getPrimaryHorizontal(end);
move = layout.getOffsetForHorizontal(line + 1, h);
} else {
move = layout.getLineStart(line + 1);
}
extendSelection(text, move);
return true;
} else if (end != text.length()) {
extendSelection(text, text.length());
return true;
}
return true;
}
/**
* Move the selection end to the buffer offset physically to the left of
* the current selection end.
*/
public static boolean extendLeft(Spannable text, Layout layout) {
int end = getSelectionEnd(text);
int to = layout.getOffsetToLeftOf(end);
if (to != end) {
extendSelection(text, to);
return true;
}
return true;
}
/**
* Move the selection end to the buffer offset physically to the right of
* the current selection end.
*/
public static boolean extendRight(Spannable text, Layout layout) {
int end = getSelectionEnd(text);
int to = layout.getOffsetToRightOf(end);
if (to != end) {
extendSelection(text, to);
return true;
}
return true;
}
public static boolean extendToLeftEdge(Spannable text, Layout layout) {
int where = findEdge(text, layout, -1);
extendSelection(text, where);
return true;
}
public static boolean extendToRightEdge(Spannable text, Layout layout) {
int where = findEdge(text, layout, 1);
extendSelection(text, where);
return true;
}
public static boolean moveToLeftEdge(Spannable text, Layout layout) {
int where = findEdge(text, layout, -1);
setSelection(text, where);
return true;
}
public static boolean moveToRightEdge(Spannable text, Layout layout) {
int where = findEdge(text, layout, 1);
setSelection(text, where);
return true;
}
private static int findEdge(Spannable text, Layout layout, int dir) {
int pt = getSelectionEnd(text);
int line = layout.getLineForOffset(pt);
int pdir = layout.getParagraphDirection(line);
if (dir * pdir < 0) {
return layout.getLineStart(line);
} else {
int end = layout.getLineEnd(line);
if (line == layout.getLineCount() - 1)
return end;
else
return end - 1;
}
}
private static int chooseHorizontal(Layout layout, int direction,
int off1, int off2) {
int line1 = layout.getLineForOffset(off1);
int line2 = layout.getLineForOffset(off2);
if (line1 == line2) {
// same line, so it goes by pure physical direction
float h1 = layout.getPrimaryHorizontal(off1);
float h2 = layout.getPrimaryHorizontal(off2);
if (direction < 0) {
// to left
if (h1 < h2)
return off1;
else
return off2;
} else {
// to right
if (h1 > h2)
return off1;
else
return off2;
}
} else {
// different line, so which line is "left" and which is "right"
// depends upon the directionality of the text
// This only checks at one end, but it's not clear what the
// right thing to do is if the ends don't agree. Even if it
// is wrong it should still not be too bad.
int line = layout.getLineForOffset(off1);
int textdir = layout.getParagraphDirection(line);
if (textdir == direction)
return Math.max(off1, off2);
else
return Math.min(off1, off2);
}
}
private static final class START implements NoCopySpan { };
private static final class END implements NoCopySpan { };
/*
* Public constants
*/
public static final Object SELECTION_START = new START();
public static final Object SELECTION_END = new END();
}
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