package com.marshalchen.common.uimodule.parallaxscroll;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ScrollView;
import com.marshalchen.ultimateandroiduicomponent.R;
import java.util.ArrayList;
public class ParallaxScrollView extends ScrollView {
private static final int DEFAULT_PARALLAX_VIEWS = 1;
private static final float DEFAULT_INNER_PARALLAX_FACTOR = 1.9F;
private static final float DEFAULT_PARALLAX_FACTOR = 1.9F;
private int numOfParallaxViews = DEFAULT_PARALLAX_VIEWS;
private float innerParallaxFactor = DEFAULT_PARALLAX_FACTOR;
private float parallaxFactor = DEFAULT_PARALLAX_FACTOR;
private ArrayList<ParallaxedView> parallaxedViews = new ArrayList<ParallaxedView>();
public ParallaxScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs);
}
public ParallaxScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}
public ParallaxScrollView(Context context) {
super(context);
}
protected void init(Context context, AttributeSet attrs) {
TypedArray typeArray = context.obtainStyledAttributes(attrs, R.styleable.ParallaxScroll);
this.parallaxFactor = typeArray.getFloat(R.styleable.ParallaxScroll_parallax_factor, DEFAULT_PARALLAX_FACTOR);
this.innerParallaxFactor = typeArray.getFloat(R.styleable.ParallaxScroll_inner_parallax_factor, DEFAULT_INNER_PARALLAX_FACTOR);
this.numOfParallaxViews = typeArray.getInt(R.styleable.ParallaxScroll_parallax_views_num, DEFAULT_PARALLAX_VIEWS);
typeArray.recycle();
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
makeViewsParallax();
}
private void makeViewsParallax() {
if (getChildCount() > 0 && getChildAt(0) instanceof ViewGroup) {
ViewGroup viewsHolder = (ViewGroup) getChildAt(0);
int numOfParallaxViews = Math.min(this.numOfParallaxViews, viewsHolder.getChildCount());
for (int i = 0; i < numOfParallaxViews; i++) {
ParallaxedView parallaxedView = new ScrollViewParallaxedItem(viewsHolder.getChildAt(i));
parallaxedViews.add(parallaxedView);
}
}
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
float factor = parallaxFactor;
for (ParallaxedView parallaxedView : parallaxedViews) {
parallaxedView.setOffset((float)t / factor);
factor *= innerParallaxFactor;
}
}
protected class ScrollViewParallaxedItem extends ParallaxedView{
public ScrollViewParallaxedItem(View view) {
super(view);
}
@Override
protected void translatePreICS(View view, float offset) {
view.offsetTopAndBottom((int)offset - lastOffset);
lastOffset = (int)offset;
}
}
}