CollapsingToolbarLayout滑动状态监听

请参照来源链接

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最近在做项目中遇到一个滑动需要改变状态栏的back图标
如果只是必全局那就简单了

GIF.gif

<!--<item name="android:homeAsUpIndicator">@drawable/bt_title_back_selector</item>-->

直接在Application引用的Style里加一句这个就可以了
可需求又不能改全部的，并且项目中用到的是 android.support.v7.widget.Toolbar在调一单个Activity布局也不行。设置样式也行不通。
后面就直接在代码里设置了
toolbar.setNavigationIcon(R.drawable.bt_title_back_selector);

然后就是监听滑动改变back icon了

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public abstract class AppBarStateChangeListener implements AppBarLayout.OnOffsetChangedListener {
    public enum State {
        EXPANDED,
        COLLAPSED,
        IDLE
    }

    private State mCurrentState = State.IDLE;

    @Override
    public final void onOffsetChanged(AppBarLayout appBarLayout, int i) {
        if (i == 0) {
            if (mCurrentState != State.EXPANDED) {
                onStateChanged(appBarLayout, State.EXPANDED);
            }
            mCurrentState = State.EXPANDED;
        } else if (Math.abs(i) >= appBarLayout.getTotalScrollRange()) {
            if (mCurrentState != State.COLLAPSED) {
                onStateChanged(appBarLayout, State.COLLAPSED);
            }
            mCurrentState = State.COLLAPSED;
        } else {
            if (mCurrentState != State.IDLE) {
                onStateChanged(appBarLayout, State.IDLE);
            }
            mCurrentState = State.IDLE;
        }
    }

    public abstract void onStateChanged(AppBarLayout appBarLayout, State state);
}

上面代码直接复制使用，也是从别处拷过来的，验证可以使用

appBarLayout.addOnOffsetChangedListener(new AppBarStateChangeListener() {
            @Override
            public void onStateChanged(AppBarLayout appBarLayout, State state) {
                if( state == State.EXPANDED ) {

                    //展开状态
                    toolbar.setNavigationIcon(R.drawable.bt_title_back_selector);

                }else if(state == State.COLLAPSED){
                    //折叠状态
                    toolbar.setNavigationIcon(android.support.v7.appcompat.R.drawable.abc_ic_ab_back_material);
                }else {
                    //中间状态
                    toolbar.setNavigationIcon(android.support.v7.appcompat.R.drawable.abc_ic_ab_back_material);

                }
            }
        });

然后就是对android.support.design.widget.AppBarLayout这个控件设置监听了
因为android.support.design.widget.CollapsingToolbarLayout外层是 android.support.design.widget.AppBarLayout所以设置的监听是它了。然后在相应的监听里你可以为所欲为了。

上面代码只是记录，防以后工作中会使用到。