Java tutorial
/* * Copyright (C) 2017 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.support.transition; import android.graphics.Rect; import android.support.v4.view.ViewCompat; import android.view.Gravity; import android.view.View; import android.view.ViewGroup; /** * A <code>TransitionPropagation</code> that propagates based on the distance to the side * and, orthogonally, the distance to epicenter. If the transitioning View is visible in * the start of the transition, then it will transition sooner when closer to the side and * later when farther. If the view is not visible in the start of the transition, then * it will transition later when closer to the side and sooner when farther from the edge. * This is the default TransitionPropagation used with {@link android.transition.Slide}. */ public class SidePropagation extends VisibilityPropagation { private float mPropagationSpeed = 3.0f; private int mSide = Gravity.BOTTOM; /** * Sets the side that is used to calculate the transition propagation. If the transitioning * View is visible in the start of the transition, then it will transition sooner when * closer to the side and later when farther. If the view is not visible in the start of * the transition, then it will transition later when closer to the side and sooner when * farther from the edge. The default is {@link Gravity#BOTTOM}. * * @param side The side that is used to calculate the transition propagation. Must be one of * {@link Gravity#LEFT}, {@link Gravity#TOP}, {@link Gravity#RIGHT}, * {@link Gravity#BOTTOM}, {@link Gravity#START}, or {@link Gravity#END}. */ public void setSide(@Slide.GravityFlag int side) { mSide = side; } /** * Sets the speed at which transition propagation happens, relative to the duration of the * Transition. A <code>propagationSpeed</code> of 1 means that a View centered at the side * set in {@link #setSide(int)} and View centered at the opposite edge will have a difference * in start delay of approximately the duration of the Transition. A speed of 2 means the * start delay difference will be approximately half of the duration of the transition. A * value of 0 is illegal, but negative values will invert the propagation. * * @param propagationSpeed The speed at which propagation occurs, relative to the duration * of the transition. A speed of 4 means it works 4 times as fast * as the duration of the transition. May not be 0. */ public void setPropagationSpeed(float propagationSpeed) { if (propagationSpeed == 0) { throw new IllegalArgumentException("propagationSpeed may not be 0"); } mPropagationSpeed = propagationSpeed; } @Override public long getStartDelay(ViewGroup sceneRoot, Transition transition, TransitionValues startValues, TransitionValues endValues) { if (startValues == null && endValues == null) { return 0; } int directionMultiplier = 1; Rect epicenter = transition.getEpicenter(); TransitionValues positionValues; if (endValues == null || getViewVisibility(startValues) == View.VISIBLE) { positionValues = startValues; directionMultiplier = -1; } else { positionValues = endValues; } int viewCenterX = getViewX(positionValues); int viewCenterY = getViewY(positionValues); int[] loc = new int[2]; sceneRoot.getLocationOnScreen(loc); int left = loc[0] + Math.round(sceneRoot.getTranslationX()); int top = loc[1] + Math.round(sceneRoot.getTranslationY()); int right = left + sceneRoot.getWidth(); int bottom = top + sceneRoot.getHeight(); int epicenterX; int epicenterY; if (epicenter != null) { epicenterX = epicenter.centerX(); epicenterY = epicenter.centerY(); } else { epicenterX = (left + right) / 2; epicenterY = (top + bottom) / 2; } float distance = distance(sceneRoot, viewCenterX, viewCenterY, epicenterX, epicenterY, left, top, right, bottom); float maxDistance = getMaxDistance(sceneRoot); float distanceFraction = distance / maxDistance; long duration = transition.getDuration(); if (duration < 0) { duration = 300; } return Math.round(duration * directionMultiplier / mPropagationSpeed * distanceFraction); } private int distance(View sceneRoot, int viewX, int viewY, int epicenterX, int epicenterY, int left, int top, int right, int bottom) { final int side; if (mSide == Gravity.START) { final boolean isRtl = ViewCompat.getLayoutDirection(sceneRoot) == ViewCompat.LAYOUT_DIRECTION_RTL; side = isRtl ? Gravity.RIGHT : Gravity.LEFT; } else if (mSide == Gravity.END) { final boolean isRtl = ViewCompat.getLayoutDirection(sceneRoot) == ViewCompat.LAYOUT_DIRECTION_RTL; side = isRtl ? Gravity.LEFT : Gravity.RIGHT; } else { side = mSide; } int distance = 0; switch (side) { case Gravity.LEFT: distance = right - viewX + Math.abs(epicenterY - viewY); break; case Gravity.TOP: distance = bottom - viewY + Math.abs(epicenterX - viewX); break; case Gravity.RIGHT: distance = viewX - left + Math.abs(epicenterY - viewY); break; case Gravity.BOTTOM: distance = viewY - top + Math.abs(epicenterX - viewX); break; } return distance; } private int getMaxDistance(ViewGroup sceneRoot) { switch (mSide) { case Gravity.LEFT: case Gravity.RIGHT: case Gravity.START: case Gravity.END: return sceneRoot.getWidth(); default: return sceneRoot.getHeight(); } } }