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.view; 18 19 import android.graphics.Rect; 20 import android.view.accessibility.AccessibilityEvent; 21 22 /** 23 * Defines the responsibilities for a class that will be a parent of a View. 24 * This is the API that a view sees when it wants to interact with its parent. 25 * 26 */ 27 public interface ViewParent { 28 /** 29 * Called when something has changed which has invalidated the layout of a 30 * child of this view parent. This will schedule a layout pass of the view 31 * tree. 32 */ 33 public void requestLayout(); 34 35 /** 36 * Indicates whether layout was requested on this view parent. 37 * 38 * @return true if layout was requested, false otherwise 39 */ 40 public boolean isLayoutRequested(); 41 42 /** 43 * Called when a child wants the view hierarchy to gather and report 44 * transparent regions to the window compositor. Views that "punch" holes in 45 * the view hierarchy, such as SurfaceView can use this API to improve 46 * performance of the system. When no such a view is present in the 47 * hierarchy, this optimization in unnecessary and might slightly reduce the 48 * view hierarchy performance. 49 * 50 * @param child the view requesting the transparent region computation 51 * 52 */ 53 public void requestTransparentRegion(View child); 54 55 /** 56 * All or part of a child is dirty and needs to be redrawn. 57 * 58 * @param child The child which is dirty 59 * @param r The area within the child that is invalid 60 */ 61 public void invalidateChild(View child, Rect r); 62 63 /** 64 * All or part of a child is dirty and needs to be redrawn. 65 * 66 * <p>The location array is an array of two int values which respectively 67 * define the left and the top position of the dirty child.</p> 68 * 69 * <p>This method must return the parent of this ViewParent if the specified 70 * rectangle must be invalidated in the parent. If the specified rectangle 71 * does not require invalidation in the parent or if the parent does not 72 * exist, this method must return null.</p> 73 * 74 * <p>When this method returns a non-null value, the location array must 75 * have been updated with the left and top coordinates of this ViewParent.</p> 76 * 77 * @param location An array of 2 ints containing the left and top 78 * coordinates of the child to invalidate 79 * @param r The area within the child that is invalid 80 * 81 * @return the parent of this ViewParent or null 82 */ 83 public ViewParent invalidateChildInParent(int[] location, Rect r); 84 85 /** 86 * Returns the parent if it exists, or null. 87 * 88 * @return a ViewParent or null if this ViewParent does not have a parent 89 */ 90 public ViewParent getParent(); 91 92 /** 93 * Called when a child of this parent wants focus 94 * 95 * @param child The child of this ViewParent that wants focus. This view 96 * will contain the focused view. It is not necessarily the view that 97 * actually has focus. 98 * @param focused The view that is a descendant of child that actually has 99 * focus 100 */ 101 public void requestChildFocus(View child, View focused); 102 103 /** 104 * Tell view hierarchy that the global view attributes need to be 105 * re-evaluated. 106 * 107 * @param child View whose attributes have changed. 108 */ 109 public void recomputeViewAttributes(View child); 110 111 /** 112 * Called when a child of this parent is giving up focus 113 * 114 * @param child The view that is giving up focus 115 */ 116 public void clearChildFocus(View child); 117 118 /** 119 * Compute the visible part of a rectangular region defined in terms of a child view's 120 * coordinates. 121 * 122 * <p>Returns the clipped visible part of the rectangle <code>r</code>, defined in the 123 * <code>child</code>'s local coordinate system. <code>r</code> is modified by this method to 124 * contain the result, expressed in the global (root) coordinate system.</p> 125 * 126 * <p>The resulting rectangle is always axis aligned. If a rotation is applied to a node in the 127 * View hierarchy, the result is the axis-aligned bounding box of the visible rectangle.</p> 128 * 129 * @param child A child View, whose rectangular visible region we want to compute 130 * @param r The input rectangle, defined in the child coordinate system. Will be overwritten to 131 * contain the resulting visible rectangle, expressed in global (root) coordinates 132 * @param offset The input coordinates of a point, defined in the child coordinate system. 133 * As with the <code>r</code> parameter, this will be overwritten to contain the global (root) 134 * coordinates of that point. 135 * A <code>null</code> value is valid (in case you are not interested in this result) 136 * @return true if the resulting rectangle is not empty, false otherwise 137 */ 138 public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset); 139 140 /** 141 * Find the nearest view in the specified direction that wants to take focus 142 * 143 * @param v The view that currently has focus 144 * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT 145 */ 146 public View focusSearch(View v, int direction); 147 148 /** 149 * Change the z order of the child so it's on top of all other children 150 * 151 * @param child 152 */ 153 public void bringChildToFront(View child); 154 155 /** 156 * Tells the parent that a new focusable view has become available. This is 157 * to handle transitions from the case where there are no focusable views to 158 * the case where the first focusable view appears. 159 * 160 * @param v The view that has become newly focusable 161 */ 162 public void focusableViewAvailable(View v); 163 164 /** 165 * Bring up a context menu for the specified view or its ancestors. 166 * 167 * <p>In most cases, a subclass does not need to override this. However, if 168 * the subclass is added directly to the window manager (for example, 169 * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)}) 170 * then it should override this and show the context menu.</p> 171 * 172 * @param originalView The source view where the context menu was first invoked 173 * @return true if a context menu was displayed 174 */ 175 public boolean showContextMenuForChild(View originalView); 176 177 /** 178 * Have the parent populate the specified context menu if it has anything to 179 * add (and then recurse on its parent). 180 * 181 * @param menu The menu to populate 182 */ 183 public void createContextMenu(ContextMenu menu); 184 185 /** 186 * Start an action mode for the specified view. 187 * 188 * <p>In most cases, a subclass does not need to override this. However, if the 189 * subclass is added directly to the window manager (for example, 190 * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)}) 191 * then it should override this and start the action mode.</p> 192 * 193 * @param originalView The source view where the action mode was first invoked 194 * @param callback The callback that will handle lifecycle events for the action mode 195 * @return The new action mode if it was started, null otherwise 196 */ 197 public ActionMode startActionModeForChild(View originalView, ActionMode.Callback callback); 198 199 /** 200 * This method is called on the parent when a child's drawable state 201 * has changed. 202 * 203 * @param child The child whose drawable state has changed. 204 */ 205 public void childDrawableStateChanged(View child); 206 207 /** 208 * Called when a child does not want this parent and its ancestors to 209 * intercept touch events with 210 * {@link ViewGroup#onInterceptTouchEvent(MotionEvent)}. 211 * 212 * <p>This parent should pass this call onto its parents. This parent must obey 213 * this request for the duration of the touch (that is, only clear the flag 214 * after this parent has received an up or a cancel.</p> 215 * 216 * @param disallowIntercept True if the child does not want the parent to 217 * intercept touch events. 218 */ 219 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept); 220 221 /** 222 * Called when a child of this group wants a particular rectangle to be 223 * positioned onto the screen. {@link ViewGroup}s overriding this can trust 224 * that: 225 * <ul> 226 * <li>child will be a direct child of this group</li> 227 * <li>rectangle will be in the child's coordinates</li> 228 * </ul> 229 * 230 * <p>{@link ViewGroup}s overriding this should uphold the contract:</p> 231 * <ul> 232 * <li>nothing will change if the rectangle is already visible</li> 233 * <li>the view port will be scrolled only just enough to make the 234 * rectangle visible</li> 235 * <ul> 236 * 237 * @param child The direct child making the request. 238 * @param rectangle The rectangle in the child's coordinates the child 239 * wishes to be on the screen. 240 * @param immediate True to forbid animated or delayed scrolling, 241 * false otherwise 242 * @return Whether the group scrolled to handle the operation 243 */ 244 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 245 boolean immediate); 246 247 /** 248 * Called by a child to request from its parent to send an {@link AccessibilityEvent}. 249 * The child has already populated a record for itself in the event and is delegating 250 * to its parent to send the event. The parent can optionally add a record for itself. 251 * <p> 252 * Note: An accessibility event is fired by an individual view which populates the 253 * event with a record for its state and requests from its parent to perform 254 * the sending. The parent can optionally add a record for itself before 255 * dispatching the request to its parent. A parent can also choose not to 256 * respect the request for sending the event. The accessibility event is sent 257 * by the topmost view in the view tree.</p> 258 * 259 * @param child The child which requests sending the event. 260 * @param event The event to be sent. 261 * @return True if the event was sent. 262 */ 263 public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event); 264 } 265
