423 lines
13 KiB
Java
423 lines
13 KiB
Java
/*
|
|
* Copyright (C) 2006 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.widget;
|
|
|
|
import android.content.Context;
|
|
import android.hardware.SensorManager;
|
|
import android.view.ViewConfiguration;
|
|
import android.view.animation.AnimationUtils;
|
|
import android.view.animation.Interpolator;
|
|
|
|
|
|
/**
|
|
* This class encapsulates scrolling. The duration of the scroll
|
|
* can be passed in the constructor and specifies the maximum time that
|
|
* the scrolling animation should take. Past this time, the scrolling is
|
|
* automatically moved to its final stage and computeScrollOffset()
|
|
* will always return false to indicate that scrolling is over.
|
|
*/
|
|
public class Scroller {
|
|
private int mMode;
|
|
|
|
private int mStartX;
|
|
private int mStartY;
|
|
private int mFinalX;
|
|
private int mFinalY;
|
|
|
|
private int mMinX;
|
|
private int mMaxX;
|
|
private int mMinY;
|
|
private int mMaxY;
|
|
|
|
private int mCurrX;
|
|
private int mCurrY;
|
|
private long mStartTime;
|
|
private int mDuration;
|
|
private float mDurationReciprocal;
|
|
private float mDeltaX;
|
|
private float mDeltaY;
|
|
private boolean mFinished;
|
|
private Interpolator mInterpolator;
|
|
|
|
private float mCoeffX = 0.0f;
|
|
private float mCoeffY = 1.0f;
|
|
private float mVelocity;
|
|
|
|
private static final int DEFAULT_DURATION = 250;
|
|
private static final int SCROLL_MODE = 0;
|
|
private static final int FLING_MODE = 1;
|
|
|
|
private final float mDeceleration;
|
|
|
|
private static float sViscousFluidScale;
|
|
private static float sViscousFluidNormalize;
|
|
|
|
static {
|
|
// This controls the viscous fluid effect (how much of it)
|
|
sViscousFluidScale = 8.0f;
|
|
// must be set to 1.0 (used in viscousFluid())
|
|
sViscousFluidNormalize = 1.0f;
|
|
sViscousFluidNormalize = 1.0f / viscousFluid(1.0f);
|
|
}
|
|
|
|
/**
|
|
* Create a Scroller with the default duration and interpolator.
|
|
*/
|
|
public Scroller(Context context) {
|
|
this(context, null);
|
|
}
|
|
|
|
/**
|
|
* Create a Scroller with the specified interpolator. If the interpolator is
|
|
* null, the default (viscous) interpolator will be used.
|
|
*/
|
|
public Scroller(Context context, Interpolator interpolator) {
|
|
mFinished = true;
|
|
mInterpolator = interpolator;
|
|
float ppi = context.getResources().getDisplayMetrics().density * 160.0f;
|
|
mDeceleration = SensorManager.GRAVITY_EARTH // g (m/s^2)
|
|
* 39.37f // inch/meter
|
|
* ppi // pixels per inch
|
|
* ViewConfiguration.getScrollFriction();
|
|
}
|
|
|
|
/**
|
|
*
|
|
* Returns whether the scroller has finished scrolling.
|
|
*
|
|
* @return True if the scroller has finished scrolling, false otherwise.
|
|
*/
|
|
public final boolean isFinished() {
|
|
return mFinished;
|
|
}
|
|
|
|
/**
|
|
* Force the finished field to a particular value.
|
|
*
|
|
* @param finished The new finished value.
|
|
*/
|
|
public final void forceFinished(boolean finished) {
|
|
mFinished = finished;
|
|
}
|
|
|
|
/**
|
|
* Returns how long the scroll event will take, in milliseconds.
|
|
*
|
|
* @return The duration of the scroll in milliseconds.
|
|
*/
|
|
public final int getDuration() {
|
|
return mDuration;
|
|
}
|
|
|
|
/**
|
|
* Returns the current X offset in the scroll.
|
|
*
|
|
* @return The new X offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getCurrX() {
|
|
return mCurrX;
|
|
}
|
|
|
|
/**
|
|
* Returns the current Y offset in the scroll.
|
|
*
|
|
* @return The new Y offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getCurrY() {
|
|
return mCurrY;
|
|
}
|
|
|
|
/**
|
|
* @hide
|
|
* Returns the current velocity.
|
|
*
|
|
* @return The original velocity less the deceleration. Result may be
|
|
* negative.
|
|
*/
|
|
public float getCurrVelocity() {
|
|
return mVelocity - mDeceleration * timePassed() / 2000.0f;
|
|
}
|
|
|
|
/**
|
|
* Returns the start X offset in the scroll.
|
|
*
|
|
* @return The start X offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getStartX() {
|
|
return mStartX;
|
|
}
|
|
|
|
/**
|
|
* Returns the start Y offset in the scroll.
|
|
*
|
|
* @return The start Y offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getStartY() {
|
|
return mStartY;
|
|
}
|
|
|
|
/**
|
|
* Returns where the scroll will end. Valid only for "fling" scrolls.
|
|
*
|
|
* @return The final X offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getFinalX() {
|
|
return mFinalX;
|
|
}
|
|
|
|
/**
|
|
* Returns where the scroll will end. Valid only for "fling" scrolls.
|
|
*
|
|
* @return The final Y offset as an absolute distance from the origin.
|
|
*/
|
|
public final int getFinalY() {
|
|
return mFinalY;
|
|
}
|
|
|
|
/**
|
|
* 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() {
|
|
if (mFinished) {
|
|
return false;
|
|
}
|
|
|
|
int timePassed = (int)(AnimationUtils.currentAnimationTimeMillis() - mStartTime);
|
|
|
|
if (timePassed < mDuration) {
|
|
switch (mMode) {
|
|
case SCROLL_MODE:
|
|
float x = (float)timePassed * mDurationReciprocal;
|
|
|
|
if (mInterpolator == null)
|
|
x = viscousFluid(x);
|
|
else
|
|
x = mInterpolator.getInterpolation(x);
|
|
|
|
mCurrX = mStartX + Math.round(x * mDeltaX);
|
|
mCurrY = mStartY + Math.round(x * mDeltaY);
|
|
break;
|
|
case FLING_MODE:
|
|
float timePassedSeconds = timePassed / 1000.0f;
|
|
float distance = (mVelocity * timePassedSeconds)
|
|
- (mDeceleration * timePassedSeconds * timePassedSeconds / 2.0f);
|
|
|
|
mCurrX = mStartX + Math.round(distance * mCoeffX);
|
|
// Pin to mMinX <= mCurrX <= mMaxX
|
|
mCurrX = Math.min(mCurrX, mMaxX);
|
|
mCurrX = Math.max(mCurrX, mMinX);
|
|
|
|
mCurrY = mStartY + Math.round(distance * mCoeffY);
|
|
// Pin to mMinY <= mCurrY <= mMaxY
|
|
mCurrY = Math.min(mCurrY, mMaxY);
|
|
mCurrY = Math.max(mCurrY, mMinY);
|
|
|
|
if (mCurrX == mFinalX && mCurrY == mFinalY) {
|
|
mFinished = true;
|
|
}
|
|
|
|
break;
|
|
}
|
|
}
|
|
else {
|
|
mCurrX = mFinalX;
|
|
mCurrY = mFinalY;
|
|
mFinished = true;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* 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) {
|
|
startScroll(startX, startY, dx, dy, DEFAULT_DURATION);
|
|
}
|
|
|
|
/**
|
|
* 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) {
|
|
mMode = SCROLL_MODE;
|
|
mFinished = false;
|
|
mDuration = duration;
|
|
mStartTime = AnimationUtils.currentAnimationTimeMillis();
|
|
mStartX = startX;
|
|
mStartY = startY;
|
|
mFinalX = startX + dx;
|
|
mFinalY = startY + dy;
|
|
mDeltaX = dx;
|
|
mDeltaY = dy;
|
|
mDurationReciprocal = 1.0f / (float) mDuration;
|
|
}
|
|
|
|
/**
|
|
* 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) {
|
|
mMode = FLING_MODE;
|
|
mFinished = false;
|
|
|
|
float velocity = (float)Math.hypot(velocityX, velocityY);
|
|
|
|
mVelocity = velocity;
|
|
mDuration = (int) (1000 * velocity / mDeceleration); // Duration is in
|
|
// milliseconds
|
|
mStartTime = AnimationUtils.currentAnimationTimeMillis();
|
|
mStartX = startX;
|
|
mStartY = startY;
|
|
|
|
mCoeffX = velocity == 0 ? 1.0f : velocityX / velocity;
|
|
mCoeffY = velocity == 0 ? 1.0f : velocityY / velocity;
|
|
|
|
int totalDistance = (int) ((velocity * velocity) / (2 * mDeceleration));
|
|
|
|
mMinX = minX;
|
|
mMaxX = maxX;
|
|
mMinY = minY;
|
|
mMaxY = maxY;
|
|
|
|
|
|
mFinalX = startX + Math.round(totalDistance * mCoeffX);
|
|
// Pin to mMinX <= mFinalX <= mMaxX
|
|
mFinalX = Math.min(mFinalX, mMaxX);
|
|
mFinalX = Math.max(mFinalX, mMinX);
|
|
|
|
mFinalY = startY + Math.round(totalDistance * mCoeffY);
|
|
// Pin to mMinY <= mFinalY <= mMaxY
|
|
mFinalY = Math.min(mFinalY, mMaxY);
|
|
mFinalY = Math.max(mFinalY, mMinY);
|
|
}
|
|
|
|
static float viscousFluid(float x)
|
|
{
|
|
x *= sViscousFluidScale;
|
|
if (x < 1.0f) {
|
|
x -= (1.0f - (float)Math.exp(-x));
|
|
} else {
|
|
float start = 0.36787944117f; // 1/e == exp(-1)
|
|
x = 1.0f - (float)Math.exp(1.0f - x);
|
|
x = start + x * (1.0f - start);
|
|
}
|
|
x *= sViscousFluidNormalize;
|
|
return x;
|
|
}
|
|
|
|
/**
|
|
* Stops the animation. Contrary to {@link #forceFinished(boolean)},
|
|
* aborting the animating cause the scroller to move to the final x and y
|
|
* position
|
|
*
|
|
* @see #forceFinished(boolean)
|
|
*/
|
|
public void abortAnimation() {
|
|
mCurrX = mFinalX;
|
|
mCurrY = mFinalY;
|
|
mFinished = true;
|
|
}
|
|
|
|
/**
|
|
* Extend the scroll animation. This allows a running animation to scroll
|
|
* further and longer, when used with {@link #setFinalX(int)} or {@link #setFinalY(int)}.
|
|
*
|
|
* @param extend Additional time to scroll in milliseconds.
|
|
* @see #setFinalX(int)
|
|
* @see #setFinalY(int)
|
|
*/
|
|
public void extendDuration(int extend) {
|
|
int passed = timePassed();
|
|
mDuration = passed + extend;
|
|
mDurationReciprocal = 1.0f / (float)mDuration;
|
|
mFinished = false;
|
|
}
|
|
|
|
/**
|
|
* Returns the time elapsed since the beginning of the scrolling.
|
|
*
|
|
* @return The elapsed time in milliseconds.
|
|
*/
|
|
public int timePassed() {
|
|
return (int)(AnimationUtils.currentAnimationTimeMillis() - mStartTime);
|
|
}
|
|
|
|
/**
|
|
* Sets the final position (X) for this scroller.
|
|
*
|
|
* @param newX The new X offset as an absolute distance from the origin.
|
|
* @see #extendDuration(int)
|
|
* @see #setFinalY(int)
|
|
*/
|
|
public void setFinalX(int newX) {
|
|
mFinalX = newX;
|
|
mDeltaX = mFinalX - mStartX;
|
|
mFinished = false;
|
|
}
|
|
|
|
/**
|
|
* Sets the final position (Y) for this scroller.
|
|
*
|
|
* @param newY The new Y offset as an absolute distance from the origin.
|
|
* @see #extendDuration(int)
|
|
* @see #setFinalX(int)
|
|
*/
|
|
public void setFinalY(int newY) {
|
|
mFinalY = newY;
|
|
mDeltaY = mFinalY - mStartY;
|
|
mFinished = false;
|
|
}
|
|
}
|