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 * This ordering change may affect layout, if this container 151 * uses an order-dependent layout scheme (e.g., LinearLayout). Prior 152 * to {@link android.os.Build.VERSION_CODES#KITKAT} this 153 * method should be followed by calls to {@link #requestLayout()} and 154 * {@link View#invalidate()} on this parent to force the parent to redraw 155 * with the new child ordering. 156 * 157 * @param child The child to bring to the top of the z order 158 */ 159 public void bringChildToFront(View child); 160 161 /** 162 * Tells the parent that a new focusable view has become available. This is 163 * to handle transitions from the case where there are no focusable views to 164 * the case where the first focusable view appears. 165 * 166 * @param v The view that has become newly focusable 167 */ 168 public void focusableViewAvailable(View v); 169 170 /** 171 * Bring up a context menu for the specified view or its ancestors. 172 * 173 * <p>In most cases, a subclass does not need to override this. However, if 174 * the subclass is added directly to the window manager (for example, 175 * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)}) 176 * then it should override this and show the context menu.</p> 177 * 178 * @param originalView The source view where the context menu was first invoked 179 * @return true if a context menu was displayed 180 */ 181 public boolean showContextMenuForChild(View originalView); 182 183 /** 184 * Have the parent populate the specified context menu if it has anything to 185 * add (and then recurse on its parent). 186 * 187 * @param menu The menu to populate 188 */ 189 public void createContextMenu(ContextMenu menu); 190 191 /** 192 * Start an action mode for the specified view. 193 * 194 * <p>In most cases, a subclass does not need to override this. However, if the 195 * subclass is added directly to the window manager (for example, 196 * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)}) 197 * then it should override this and start the action mode.</p> 198 * 199 * @param originalView The source view where the action mode was first invoked 200 * @param callback The callback that will handle lifecycle events for the action mode 201 * @return The new action mode if it was started, null otherwise 202 */ 203 public ActionMode startActionModeForChild(View originalView, ActionMode.Callback callback); 204 205 /** 206 * This method is called on the parent when a child's drawable state 207 * has changed. 208 * 209 * @param child The child whose drawable state has changed. 210 */ 211 public void childDrawableStateChanged(View child); 212 213 /** 214 * Called when a child does not want this parent and its ancestors to 215 * intercept touch events with 216 * {@link ViewGroup#onInterceptTouchEvent(MotionEvent)}. 217 * 218 * <p>This parent should pass this call onto its parents. This parent must obey 219 * this request for the duration of the touch (that is, only clear the flag 220 * after this parent has received an up or a cancel.</p> 221 * 222 * @param disallowIntercept True if the child does not want the parent to 223 * intercept touch events. 224 */ 225 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept); 226 227 /** 228 * Called when a child of this group wants a particular rectangle to be 229 * positioned onto the screen. {@link ViewGroup}s overriding this can trust 230 * that: 231 * <ul> 232 * <li>child will be a direct child of this group</li> 233 * <li>rectangle will be in the child's coordinates</li> 234 * </ul> 235 * 236 * <p>{@link ViewGroup}s overriding this should uphold the contract:</p> 237 * <ul> 238 * <li>nothing will change if the rectangle is already visible</li> 239 * <li>the view port will be scrolled only just enough to make the 240 * rectangle visible</li> 241 * <ul> 242 * 243 * @param child The direct child making the request. 244 * @param rectangle The rectangle in the child's coordinates the child 245 * wishes to be on the screen. 246 * @param immediate True to forbid animated or delayed scrolling, 247 * false otherwise 248 * @return Whether the group scrolled to handle the operation 249 */ 250 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 251 boolean immediate); 252 253 /** 254 * Called by a child to request from its parent to send an {@link AccessibilityEvent}. 255 * The child has already populated a record for itself in the event and is delegating 256 * to its parent to send the event. The parent can optionally add a record for itself. 257 * <p> 258 * Note: An accessibility event is fired by an individual view which populates the 259 * event with a record for its state and requests from its parent to perform 260 * the sending. The parent can optionally add a record for itself before 261 * dispatching the request to its parent. A parent can also choose not to 262 * respect the request for sending the event. The accessibility event is sent 263 * by the topmost view in the view tree.</p> 264 * 265 * @param child The child which requests sending the event. 266 * @param event The event to be sent. 267 * @return True if the event was sent. 268 */ 269 public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event); 270 271 /** 272 * Called when a child view now has or no longer is tracking transient state. 273 * 274 * <p>"Transient state" is any state that a View might hold that is not expected to 275 * be reflected in the data model that the View currently presents. This state only 276 * affects the presentation to the user within the View itself, such as the current 277 * state of animations in progress or the state of a text selection operation.</p> 278 * 279 * <p>Transient state is useful for hinting to other components of the View system 280 * that a particular view is tracking something complex but encapsulated. 281 * A <code>ListView</code> for example may acknowledge that list item Views 282 * with transient state should be preserved within their position or stable item ID 283 * instead of treating that view as trivially replaceable by the backing adapter. 284 * This allows adapter implementations to be simpler instead of needing to track 285 * the state of item view animations in progress such that they could be restored 286 * in the event of an unexpected recycling and rebinding of attached item views.</p> 287 * 288 * <p>This method is called on a parent view when a child view or a view within 289 * its subtree begins or ends tracking of internal transient state.</p> 290 * 291 * @param child Child view whose state has changed 292 * @param hasTransientState true if this child has transient state 293 */ 294 public void childHasTransientStateChanged(View child, boolean hasTransientState); 295 296 /** 297 * Ask that a new dispatch of {@link View#fitSystemWindows(Rect) 298 * View.fitSystemWindows(Rect)} be performed. 299 */ 300 public void requestFitSystemWindows(); 301 302 /** 303 * Gets the parent of a given View for accessibility. Since some Views are not 304 * exposed to the accessibility layer the parent for accessibility is not 305 * necessarily the direct parent of the View, rather it is a predecessor. 306 * 307 * @return The parent or <code>null</code> if no such is found. 308 */ 309 public ViewParent getParentForAccessibility(); 310 311 /** 312 * Notifies a view parent that the accessibility state of one of its 313 * descendants has changed and that the structure of the subtree is 314 * different. 315 * @param child The direct child whose subtree has changed. 316 * @param source The descendant view that changed. 317 * @param changeType A bit mask of the types of changes that occurred. One 318 * or more of: 319 * <ul> 320 * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_CONTENT_DESCRIPTION} 321 * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_SUBTREE} 322 * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_TEXT} 323 * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_UNDEFINED} 324 * </ul> 325 */ 326 public void notifySubtreeAccessibilityStateChanged(View child, View source, int changeType); 327 328 /** 329 * Tells if this view parent can resolve the layout direction. 330 * See {@link View#setLayoutDirection(int)} 331 * 332 * @return True if this view parent can resolve the layout direction. 333 */ 334 public boolean canResolveLayoutDirection(); 335 336 /** 337 * Tells if this view parent layout direction is resolved. 338 * See {@link View#setLayoutDirection(int)} 339 * 340 * @return True if this view parent layout direction is resolved. 341 */ 342 public boolean isLayoutDirectionResolved(); 343 344 /** 345 * Return this view parent layout direction. See {@link View#getLayoutDirection()} 346 * 347 * @return {@link View#LAYOUT_DIRECTION_RTL} if the layout direction is RTL or returns 348 * {@link View#LAYOUT_DIRECTION_LTR} if the layout direction is not RTL. 349 */ 350 public int getLayoutDirection(); 351 352 /** 353 * Tells if this view parent can resolve the text direction. 354 * See {@link View#setTextDirection(int)} 355 * 356 * @return True if this view parent can resolve the text direction. 357 */ 358 public boolean canResolveTextDirection(); 359 360 /** 361 * Tells if this view parent text direction is resolved. 362 * See {@link View#setTextDirection(int)} 363 * 364 * @return True if this view parent text direction is resolved. 365 */ 366 public boolean isTextDirectionResolved(); 367 368 /** 369 * Return this view parent text direction. See {@link View#getTextDirection()} 370 * 371 * @return the resolved text direction. Returns one of: 372 * 373 * {@link View#TEXT_DIRECTION_FIRST_STRONG} 374 * {@link View#TEXT_DIRECTION_ANY_RTL}, 375 * {@link View#TEXT_DIRECTION_LTR}, 376 * {@link View#TEXT_DIRECTION_RTL}, 377 * {@link View#TEXT_DIRECTION_LOCALE} 378 */ 379 public int getTextDirection(); 380 381 /** 382 * Tells if this view parent can resolve the text alignment. 383 * See {@link View#setTextAlignment(int)} 384 * 385 * @return True if this view parent can resolve the text alignment. 386 */ 387 public boolean canResolveTextAlignment(); 388 389 /** 390 * Tells if this view parent text alignment is resolved. 391 * See {@link View#setTextAlignment(int)} 392 * 393 * @return True if this view parent text alignment is resolved. 394 */ 395 public boolean isTextAlignmentResolved(); 396 397 /** 398 * Return this view parent text alignment. See {@link android.view.View#getTextAlignment()} 399 * 400 * @return the resolved text alignment. Returns one of: 401 * 402 * {@link View#TEXT_ALIGNMENT_GRAVITY}, 403 * {@link View#TEXT_ALIGNMENT_CENTER}, 404 * {@link View#TEXT_ALIGNMENT_TEXT_START}, 405 * {@link View#TEXT_ALIGNMENT_TEXT_END}, 406 * {@link View#TEXT_ALIGNMENT_VIEW_START}, 407 * {@link View#TEXT_ALIGNMENT_VIEW_END} 408 */ 409 public int getTextAlignment(); 410 } 411
