core/java/android/text/Selection.java - platform/frameworks/base - Git at Google

 /*
  * 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;

 import java.text.BreakIterator;


 /**
  * 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</code> and the selection edge
      * to <code>stop</code>.
      */
     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</code>.
      */
     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</code>.
      */
     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, to the beginning if it is on the top line but not at the
      * start, 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;
             } else if (end != 0) {
                 setSelection(text, 0);
                 return true;
             }
         }

         return false;
     }

     /**
      * Move the cursor to the buffer offset physically below the current
      * offset, to the end of the buffer if it is on the bottom line but
      * not at the end, or return false if the cursor is already at the
      * end of the buffer.
      */
     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;
             } else if (end != text.length()) {
                 setSelection(text, text.length());
                 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;
     }

     /** {@hide} */
     public static interface PositionIterator {
         public static final int DONE = BreakIterator.DONE;

         public int preceding(int position);
         public int following(int position);
     }

     /** {@hide} */
     public static boolean moveToPreceding(
             Spannable text, PositionIterator iter, boolean extendSelection) {
         final int offset = iter.preceding(getSelectionEnd(text));
         if (offset != PositionIterator.DONE) {
             if (extendSelection) {
                 extendSelection(text, offset);
             } else {
                 setSelection(text, offset);
             }
         }
         return true;
     }

     /** {@hide} */
     public static boolean moveToFollowing(
             Spannable text, PositionIterator iter, boolean extendSelection) {
         final int offset = iter.following(getSelectionEnd(text));
         if (offset != PositionIterator.DONE) {
             if (extendSelection) {
                 extendSelection(text, offset);
             } else {
                 setSelection(text, offset);
             }
         }
         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();
 }
	/*
	* 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;

	import java.text.BreakIterator;


	/**
	* 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</code> and the selection edge
	* to <code>stop</code>.
	*/
	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</code>.
	*/
	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</code>.
	*/
	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, to the beginning if it is on the top line but not at the
	* start, 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;
	} else if (end != 0) {
	setSelection(text, 0);
	return true;
	}
	}

	return false;
	}

	/**
	* Move the cursor to the buffer offset physically below the current
	* offset, to the end of the buffer if it is on the bottom line but
	* not at the end, or return false if the cursor is already at the
	* end of the buffer.
	*/
	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;
	} else if (end != text.length()) {
	setSelection(text, text.length());
	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;
	}

	/** {@hide} */
	public static interface PositionIterator {
	public static final int DONE = BreakIterator.DONE;

	public int preceding(int position);
	public int following(int position);
	}

	/** {@hide} */
	public static boolean moveToPreceding(
	Spannable text, PositionIterator iter, boolean extendSelection) {
	final int offset = iter.preceding(getSelectionEnd(text));
	if (offset != PositionIterator.DONE) {
	if (extendSelection) {
	extendSelection(text, offset);
	} else {
	setSelection(text, offset);
	}
	}
	return true;
	}

	/** {@hide} */
	public static boolean moveToFollowing(
	Spannable text, PositionIterator iter, boolean extendSelection) {
	final int offset = iter.following(getSelectionEnd(text));
	if (offset != PositionIterator.DONE) {
	if (extendSelection) {
	extendSelection(text, offset);
	} else {
	setSelection(text, offset);
	}
	}
	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();
	}