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最近在做項目中遇到一個滑動需要改變狀態(tài)欄的back圖標
如果只是必全局那就簡單了

GIF.gif

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

直接在Application引用的Style里加一句這個就可以了
可需求又不能改全部的，并且項目中用到的是 android.support.v7.widget.Toolbar在調一單個Activity布局也不行。設置樣式也行不通。
后面就直接在代碼里設置了
toolbar.setNavigationIcon(R.drawable.bt_title_back_selector);

然后就是監(jiān)聽滑動改變back icon了

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);
}

上面代碼直接復制使用，也是從別處拷過來的，驗證可以使用

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

                    //展開狀態(tài)
                    toolbar.setNavigationIcon(R.drawable.bt_title_back_selector);

                }else if(state == State.COLLAPSED){
                    //折疊狀態(tài)
                    toolbar.setNavigationIcon(android.support.v7.appcompat.R.drawable.abc_ic_ab_back_material);
                }else {
                    //中間狀態(tài)
                    toolbar.setNavigationIcon(android.support.v7.appcompat.R.drawable.abc_ic_ab_back_material);

                }
            }
        });

然后就是對android.support.design.widget.AppBarLayout這個控件設置監(jiān)聽了
因為android.support.design.widget.CollapsingToolbarLayout外層是 android.support.design.widget.AppBarLayout所以設置的監(jiān)聽是它了。然后在相應的監(jiān)聽里你可以為所欲為了。

上面代碼只是記錄，防以后工作中會使用到。