/*
* Copyright (C) 2012 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.v4.widget;
import android.content.Context;
import android.os.Build;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;
import android.widget.OverScroller;
import android.widget.Scroller;
/**
* Provides access to new {@link android.widget.Scroller Scroller} APIs when available.
*
* <p>This class provides a platform version-independent mechanism for obeying the
* current device's preferred scroll physics and fling behavior. It offers a subset of
* the APIs from Scroller or OverScroller.</p>
*/
public final class ScrollerCompat {
OverScroller mScroller;
private final boolean mIsIcsOrNewer;
public static ScrollerCompat create(Context context) {
return create(context, null);
}
public static ScrollerCompat create(Context context, Interpolator interpolator) {
return new ScrollerCompat(Build.VERSION.SDK_INT >= 14, context, interpolator);
}
/**
* Package protected constructor that allows to specify if API version is newer than ICS.
* It is useful for unit testing.
*/
ScrollerCompat(boolean isIcsOrNewer, Context context, Interpolator interpolator) {
mIsIcsOrNewer = isIcsOrNewer;
mScroller = interpolator != null ?
new OverScroller(context, interpolator) : new OverScroller(context);
}
/**
* Returns whether the scroller has finished scrolling.
*
* @return True if the scroller has finished scrolling, false otherwise.
*/
public boolean isFinished() {
return mScroller.isFinished();
}
/**
* Returns the current X offset in the scroll.
*
* @return The new X offset as an absolute distance from the origin.
*/
public int getCurrX() {
return mScroller.getCurrX();
}
/**
* Returns the current Y offset in the scroll.
*
* @return The new Y offset as an absolute distance from the origin.
*/
public int getCurrY() {
return mScroller.getCurrY();
}
/**
* @return The final X position for the scroll in progress, if known.
*/
public int getFinalX() {
return mScroller.getFinalX();
}
/**
* @return The final Y position for the scroll in progress, if known.
*/
public int getFinalY() {
return mScroller.getFinalY();
}
/**
* Returns the current velocity on platform versions that support it.
*
* <p>The device must support at least API level 14 (Ice Cream Sandwich).
* On older platform versions this method will return 0. This method should
* only be used as input for nonessential visual effects such as {@link EdgeEffectCompat}.</p>
*
* @return The original velocity less the deceleration. Result may be
* negative.
*/
public float getCurrVelocity() {
return mIsIcsOrNewer ? ScrollerCompatIcs.getCurrVelocity(mScroller) : 0;
}
/**
* Call this when you want to know the new location. If it returns true,
* the animation is not yet finished. loc will be altered to provide the
* new location.
*/
public boolean computeScrollOffset() {
return mScroller.computeScrollOffset();
}
/**
* Start scrolling by providing a starting point and the distance to travel.
* The scroll will use the default value of 250 milliseconds for the
* duration.
*
* @param startX Starting horizontal scroll offset in pixels. Positive
* numbers will scroll the content to the left.
* @param startY Starting vertical scroll offset in pixels. Positive numbers
* will scroll the content up.
* @param dx Horizontal distance to travel. Positive numbers will scroll the
* content to the left.
* @param dy Vertical distance to travel. Positive numbers will scroll the
* content up.
*/
public void startScroll(int startX, int startY, int dx, int dy) {
mScroller.startScroll(startX, startY, dx, dy);
}
/**
* Start scrolling by providing a starting point and the distance to travel.
*
* @param startX Starting horizontal scroll offset in pixels. Positive
* numbers will scroll the content to the left.
* @param startY Starting vertical scroll offset in pixels. Positive numbers
* will scroll the content up.
* @param dx Horizontal distance to travel. Positive numbers will scroll the
* content to the left.
* @param dy Vertical distance to travel. Positive numbers will scroll the
* content up.
* @param duration Duration of the scroll in milliseconds.
*/
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
mScroller.startScroll(startX, startY, dx, dy, duration);
}
/**
* Start scrolling based on a fling gesture. The distance travelled will
* depend on the initial velocity of the fling.
*
* @param startX Starting point of the scroll (X)
* @param startY Starting point of the scroll (Y)
* @param velocityX Initial velocity of the fling (X) measured in pixels per
* second.
* @param velocityY Initial velocity of the fling (Y) measured in pixels per
* second
* @param minX Minimum X value. The scroller will not scroll past this
* point.
* @param maxX Maximum X value. The scroller will not scroll past this
* point.
* @param minY Minimum Y value. The scroller will not scroll past this
* point.
* @param maxY Maximum Y value. The scroller will not scroll past this
* point.
*/
public void fling(int startX, int startY, int velocityX, int velocityY,
int minX, int maxX, int minY, int maxY) {
mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY);
}
/**
* Start scrolling based on a fling gesture. The distance travelled will
* depend on the initial velocity of the fling.
*
* @param startX Starting point of the scroll (X)
* @param startY Starting point of the scroll (Y)
* @param velocityX Initial velocity of the fling (X) measured in pixels per
* second.
* @param velocityY Initial velocity of the fling (Y) measured in pixels per
* second
* @param minX Minimum X value. The scroller will not scroll past this
* point.
* @param maxX Maximum X value. The scroller will not scroll past this
* point.
* @param minY Minimum Y value. The scroller will not scroll past this
* point.
* @param maxY Maximum Y value. The scroller will not scroll past this
* point.
* @param overX Overfling range. If > 0, horizontal overfling in either
* direction will be possible.
* @param overY Overfling range. If > 0, vertical overfling in either
* direction will be possible.
*/
public void fling(int startX, int startY, int velocityX, int velocityY,
int minX, int maxX, int minY, int maxY, int overX, int overY) {
mScroller.fling(startX, startY, velocityX, velocityY,
minX, maxX, minY, maxY, overX, overY);
}
/**
* Call this when you want to 'spring back' into a valid coordinate range.
*
* @param startX Starting X coordinate
* @param startY Starting Y coordinate
* @param minX Minimum valid X value
* @param maxX Maximum valid X value
* @param minY Minimum valid Y value
* @param maxY Maximum valid Y value
* @return true if a springback was initiated, false if startX and startY were
* already within the valid range.
*/
public boolean springBack(int startX, int startY, int minX, int maxX, int minY, int maxY) {
return mScroller.springBack(startX, startY, minX, maxX, minY, maxY);
}
/**
* Stops the animation. Aborting the animation causes the scroller to move to the final x and y
* position.
*/
public void abortAnimation() {
mScroller.abortAnimation();
}
/**
* Notify the scroller that we've reached a horizontal boundary.
* Normally the information to handle this will already be known
* when the animation is started, such as in a call to one of the
* fling functions. However there are cases where this cannot be known
* in advance. This function will transition the current motion and
* animate from startX to finalX as appropriate.
*
* @param startX Starting/current X position
* @param finalX Desired final X position
* @param overX Magnitude of overscroll allowed. This should be the maximum
* desired distance from finalX. Absolute value - must be positive.
*/
public void notifyHorizontalEdgeReached(int startX, int finalX, int overX) {
mScroller.notifyHorizontalEdgeReached(startX, finalX, overX);
}
/**
* Notify the scroller that we've reached a vertical boundary.
* Normally the information to handle this will already be known
* when the animation is started, such as in a call to one of the
* fling functions. However there are cases where this cannot be known
* in advance. This function will animate a parabolic motion from
* startY to finalY.
*
* @param startY Starting/current Y position
* @param finalY Desired final Y position
* @param overY Magnitude of overscroll allowed. This should be the maximum
* desired distance from finalY. Absolute value - must be positive.
*/
public void notifyVerticalEdgeReached(int startY, int finalY, int overY) {
mScroller.notifyVerticalEdgeReached(startY, finalY, overY);
}
/**
* Returns whether the current Scroller is currently returning to a valid position.
* Valid bounds were provided by the
* {@link #fling(int, int, int, int, int, int, int, int, int, int)} method.
*
* One should check this value before calling
* {@link #startScroll(int, int, int, int)} as the interpolation currently in progress
* to restore a valid position will then be stopped. The caller has to take into account
* the fact that the started scroll will start from an overscrolled position.
*
* @return true when the current position is overscrolled and in the process of
* interpolating back to a valid value.
*/
public boolean isOverScrolled() {
return mScroller.isOverScrolled();
}
}