/*
* Copyright (C) 2014 The AppCan Open Source Project.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package org.zywx.wbpalmstar.engine;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;
public class EGallery extends ViewGroup {
static final int F_TOUCH_STATE_REST = 0;
static final int F_TOUCH_STATE_SCROLLING = 1;
static final int SNAP_VELOCITY = 600;
private int mTouchState;
private int mTouchSlop;
private float mLastMotionX;
private int mCurChild;
private Scroller mScroller;
private VelocityTracker mVelocityTracker;
public EGallery(Context context) {
this(context, null);
}
public EGallery(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public EGallery(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (changed) {
int childLeft = 0;
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
int childWidth = child.getMeasuredWidth();
child.layout(childLeft, 0, childLeft + childWidth, child.getMeasuredHeight());
childLeft += childWidth;
}
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("can only run at EXACTLY mode!");
}
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("can only run at EXACTLY mode!");
}
int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
scrollTo(mCurChild * width, 0);
}
private void backToLeftOrRight() {
int width = getWidth();
int scrollX = getScrollX();
int destChild = (scrollX + width / 2) / width;
scrollToChild(destChild);
}
private void scrollToChild(int which) {
which = max(0, min(which, getChildCount() - 1));
int width = getWidth();
int scrollX = getScrollX();
if (scrollX != (which * width)) {
int delta = which * width - scrollX;
mScroller.startScroll(scrollX, 0, delta, 0, abs(delta) * 2);
mCurChild = which;
postInvalidate();
}
}
public void setDisplayedChild(int which) {
int size = getChildCount();
if (which >= size) {
return;
}
which = max(0, min(which, getChildCount() - 1));
int duration = 300;
int count = which - mCurChild;
int c = abs(count);
duration = (int) ((duration * c) * 0.8);
int dist = count * getWidth();
int sx = getScrollX();
mScroller.startScroll(sx, 0, dist, 0, duration);
postInvalidate();
mCurChild = which;
//scrollTo(dist, 0);
}
public int getDisplayedChild() {
return mCurChild;
}
public View getCurrentView() {
return getChildAt(mCurChild);
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
int cx = mScroller.getCurrX();
// int cy = mScroller.getCurrY();
int cy = 0;
scrollTo(cx, cy);
postInvalidate();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
int action = event.getAction();
float x = event.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
scrollBy(deltaX, 0);
break;
case MotionEvent.ACTION_UP:
VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
if (velocityX > SNAP_VELOCITY && mCurChild > 0) {
scrollToChild(mCurChild - 1);
} else if (velocityX < -SNAP_VELOCITY && mCurChild < getChildCount() - 1) {
scrollToChild(mCurChild + 1);
} else {
backToLeftOrRight();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
mTouchState = F_TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = F_TOUCH_STATE_REST;
break;
}
return true;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != F_TOUCH_STATE_REST)) {
return true;
}
float x = ev.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
mLastMotionX = x;
mTouchState = mScroller.isFinished() ? F_TOUCH_STATE_REST : F_TOUCH_STATE_SCROLLING;
break;
case MotionEvent.ACTION_MOVE:
int xDiff = (int) abs(mLastMotionX - x);
if (xDiff > mTouchSlop) {
mTouchState = F_TOUCH_STATE_SCROLLING;
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
mTouchState = F_TOUCH_STATE_REST;
break;
}
return mTouchState != F_TOUCH_STATE_REST;
}
private int max(int a, int b) {
return a > b ? a : b;
}
private int min(int a, int b) {
return a < b ? a : b;
}
private int abs(int a) {
return a >= 0 ? a : -a;
}
private float abs(float f) {
int bits = Float.floatToIntBits(f);
bits &= 0x7fffffff;
return Float.intBitsToFloat(bits);
}
}