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