1/* 2 * Copyright (C) 2008 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 17package android.text.method; 18 19import android.text.Layout; 20import android.text.Layout.Alignment; 21import android.text.NoCopySpan; 22import android.text.Spannable; 23import android.view.KeyEvent; 24import android.view.MotionEvent; 25import android.view.ViewConfiguration; 26import android.widget.TextView; 27 28public class Touch { 29 private Touch() { } 30 31 /** 32 * Scrolls the specified widget to the specified coordinates, except 33 * constrains the X scrolling position to the horizontal regions of 34 * the text that will be visible after scrolling to the specified 35 * Y position. 36 */ 37 public static void scrollTo(TextView widget, Layout layout, int x, int y) { 38 final int horizontalPadding = widget.getTotalPaddingLeft() + widget.getTotalPaddingRight(); 39 final int availableWidth = widget.getWidth() - horizontalPadding; 40 41 final int top = layout.getLineForVertical(y); 42 Alignment a = layout.getParagraphAlignment(top); 43 boolean ltr = layout.getParagraphDirection(top) > 0; 44 45 int left, right; 46 if (widget.getHorizontallyScrolling()) { 47 final int verticalPadding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom(); 48 final int bottom = layout.getLineForVertical(y + widget.getHeight() - verticalPadding); 49 50 left = Integer.MAX_VALUE; 51 right = 0; 52 53 for (int i = top; i <= bottom; i++) { 54 left = (int) Math.min(left, layout.getLineLeft(i)); 55 right = (int) Math.max(right, layout.getLineRight(i)); 56 } 57 } else { 58 left = 0; 59 right = availableWidth; 60 } 61 62 final int actualWidth = right - left; 63 64 if (actualWidth < availableWidth) { 65 if (a == Alignment.ALIGN_CENTER) { 66 x = left - ((availableWidth - actualWidth) / 2); 67 } else if ((ltr && (a == Alignment.ALIGN_OPPOSITE)) || (a == Alignment.ALIGN_RIGHT)) { 68 // align_opposite does NOT mean align_right, we need the paragraph 69 // direction to resolve it to left or right 70 x = left - (availableWidth - actualWidth); 71 } else { 72 x = left; 73 } 74 } else { 75 x = Math.min(x, right - availableWidth); 76 x = Math.max(x, left); 77 } 78 79 widget.scrollTo(x, y); 80 } 81 82 /** 83 * Handles touch events for dragging. You may want to do other actions 84 * like moving the cursor on touch as well. 85 */ 86 public static boolean onTouchEvent(TextView widget, Spannable buffer, 87 MotionEvent event) { 88 DragState[] ds; 89 90 switch (event.getActionMasked()) { 91 case MotionEvent.ACTION_DOWN: 92 ds = buffer.getSpans(0, buffer.length(), DragState.class); 93 94 for (int i = 0; i < ds.length; i++) { 95 buffer.removeSpan(ds[i]); 96 } 97 98 buffer.setSpan(new DragState(event.getX(), event.getY(), 99 widget.getScrollX(), widget.getScrollY()), 100 0, 0, Spannable.SPAN_MARK_MARK); 101 return true; 102 103 case MotionEvent.ACTION_UP: 104 ds = buffer.getSpans(0, buffer.length(), DragState.class); 105 106 for (int i = 0; i < ds.length; i++) { 107 buffer.removeSpan(ds[i]); 108 } 109 110 if (ds.length > 0 && ds[0].mUsed) { 111 return true; 112 } else { 113 return false; 114 } 115 116 case MotionEvent.ACTION_MOVE: 117 ds = buffer.getSpans(0, buffer.length(), DragState.class); 118 119 if (ds.length > 0) { 120 if (ds[0].mFarEnough == false) { 121 int slop = ViewConfiguration.get(widget.getContext()).getScaledTouchSlop(); 122 123 if (Math.abs(event.getX() - ds[0].mX) >= slop || 124 Math.abs(event.getY() - ds[0].mY) >= slop) { 125 ds[0].mFarEnough = true; 126 } 127 } 128 129 if (ds[0].mFarEnough) { 130 ds[0].mUsed = true; 131 boolean cap = (event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0 132 || MetaKeyKeyListener.getMetaState(buffer, 133 MetaKeyKeyListener.META_SHIFT_ON) == 1 134 || MetaKeyKeyListener.getMetaState(buffer, 135 MetaKeyKeyListener.META_SELECTING) != 0; 136 float dx; 137 float dy; 138 if (cap) { 139 // if we're selecting, we want the scroll to go in 140 // the direction of the drag 141 dx = event.getX() - ds[0].mX; 142 dy = event.getY() - ds[0].mY; 143 } else { 144 dx = ds[0].mX - event.getX(); 145 dy = ds[0].mY - event.getY(); 146 } 147 ds[0].mX = event.getX(); 148 ds[0].mY = event.getY(); 149 150 int nx = widget.getScrollX() + (int) dx; 151 int ny = widget.getScrollY() + (int) dy; 152 153 int padding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom(); 154 Layout layout = widget.getLayout(); 155 156 ny = Math.min(ny, layout.getHeight() - (widget.getHeight() - padding)); 157 ny = Math.max(ny, 0); 158 159 int oldX = widget.getScrollX(); 160 int oldY = widget.getScrollY(); 161 162 scrollTo(widget, layout, nx, ny); 163 164 // If we actually scrolled, then cancel the up action. 165 if (oldX != widget.getScrollX() || oldY != widget.getScrollY()) { 166 widget.cancelLongPress(); 167 } 168 169 return true; 170 } 171 } 172 } 173 174 return false; 175 } 176 177 /** 178 * @param widget The text view. 179 * @param buffer The text buffer. 180 */ 181 public static int getInitialScrollX(TextView widget, Spannable buffer) { 182 DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class); 183 return ds.length > 0 ? ds[0].mScrollX : -1; 184 } 185 186 /** 187 * @param widget The text view. 188 * @param buffer The text buffer. 189 */ 190 public static int getInitialScrollY(TextView widget, Spannable buffer) { 191 DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class); 192 return ds.length > 0 ? ds[0].mScrollY : -1; 193 } 194 195 private static class DragState implements NoCopySpan { 196 public float mX; 197 public float mY; 198 public int mScrollX; 199 public int mScrollY; 200 public boolean mFarEnough; 201 public boolean mUsed; 202 203 public DragState(float x, float y, int scrollX, int scrollY) { 204 mX = x; 205 mY = y; 206 mScrollX = scrollX; 207 mScrollY = scrollY; 208 } 209 } 210} 211