垂直滚动时的工具栏梯度颜色

Question

进入我的工具栏，该工具栏以颜色为蓝色...当我滚动10％的colapsing工具栏时，它会保留更多黑色，20％的黑色……100％的后背。。

有人有任何IDEIA我该怎么做？

我正在使用此代码，但是它只从蓝色跳到黑色...

        appBar.addOnOffsetChangedListener(new AppBarStateChangeListener() {
        @Override
        public void onStateChanged(AppBarLayout appBarLayout, State state) {
            if (state == State.COLLAPSED) {
                btCollapseCards.setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.ic_keyboard_arrow_down_white_24dp));
                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
                    toolbarLayout.setBackgroundDrawable(ContextCompat.getDrawable(getActivity(), R.drawable.background_gradient_black));
                    llCardTitle.setBackgroundDrawable(ContextCompat.getDrawable(getActivity(), R.drawable.background_gradient_black));
                } else {
                    toolbarLayout.setBackground(ContextCompat.getDrawable(getActivity(), R.drawable.background_gradient_black));
                    llCardTitle.setBackground(ContextCompat.getDrawable(getActivity(), R.drawable.background_gradient_black));
                }
            } else if (state == State.EXPANDED) {
                btCollapseCards.setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.ic_keyboard_arrow_up_white_24dp));
                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
                    toolbarLayout.setBackgroundDrawable(ContextCompat.getDrawable(getActivity(), R.color.colorPrimary));
                    llCardTitle.setBackgroundDrawable(ContextCompat.getDrawable(getActivity(), R.color.colorPrimary));
                } else {
                    toolbarLayout.setBackground(ContextCompat.getDrawable(getActivity(), R.color.colorPrimary));
                    llCardTitle.setBackground(ContextCompat.getDrawable(getActivity(), R.color.colorPrimary));
                }
            }

                int toolBarHeight = toolbar.getMeasuredHeight();
            int appBarHeight = appBarLayout.getMeasuredHeight();
            Float f = ((((float) appBarHeight - toolBarHeight) + verticalOffset) / ( (float) appBarHeight - toolBarHeight)) * 255;
            viewBackground.getBackground().setAlpha(255 - Math.round(f));
        }
    });

请帮助我...

编辑＃01

插入此代码，在滚动时产生了想要的效果...但是当我向下滚动时，不要获得相同的效果。

                int toolBarHeight = toolbar.getMeasuredHeight();
            int appBarHeight = appBarLayout.getMeasuredHeight();
            Float f = ((((float) appBarHeight - toolBarHeight) + verticalOffset) / ( (float) appBarHeight - toolBarHeight)) * 255;
            viewBackground.getBackground().setAlpha(255 - Math.round(f));

Answer 1

尝试此示例

activity_main.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <ImageView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                android:background="@drawable/profile_pic"
                android:id="@+id/profile_id"
                app:layout_collapseMode="parallax" />

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin" />
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>
    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/abc_search_url_text_normal"/>
    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#ffe5e5e5"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:layout_marginTop="10dp">
            <include layout="@layout/card_layout" />
            <include layout="@layout/card_layout" />
            <include layout="@layout/card_layout" />
        </LinearLayout>

    </android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>

card_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="10dp"
   >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="12dp">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Lorem ipsum"
            android:textSize="20sp"/>
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/text_content"
            android:textSize="18sp"/>
    </LinearLayout>
</android.support.v7.widget.CardView>

mainActivity.java

public class MainActivity extends AppCompatActivity {
    private CollapsingToolbarLayout collapsingToolbarLayout = null;
    TabLayout tabs;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        collapsingToolbarLayout = (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
        collapsingToolbarLayout.setTitle(getResources().getString(R.string.user_name));
        tabs = (TabLayout) findViewById(R.id.tabs);
        dynamicToolbarColor();
        toolbarTextAppernce();
    }

    private void dynamicToolbarColor() {
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.profile_pic);
        Palette.from(bitmap).generate(new Palette.PaletteAsyncListener() {
            @Override
            public void onGenerated(Palette palette) {
                collapsingToolbarLayout.setContentScrimColor(palette.getMutedColor(R.attr.colorPrimary));
                collapsingToolbarLayout.setStatusBarScrimColor(palette.getMutedColor(R.attr.colorPrimaryDark));
//                tabs.setBackgroundColor(palette.getMutedColor(R.attr.colorPrimary));
            }
        });
    }

    private void toolbarTextAppernce() {
        collapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.collapsedappbar);
        collapsingToolbarLayout.setExpandedTitleTextAppearance(R.style.expandedappbar);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        return super.onOptionsItemSelected(item);
    }

}

build.gradle

apply plugin: 'com.android.application'
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"
    defaultConfig {
        applicationId "com.tutorialsbuzz.collapsingtoolbardemo"
        minSdkVersion 7
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:23.0.1'
    compile 'com.android.support:design:23.0.1'
    compile 'com.android.support:cardview-v7:23.0.1'
    compile 'com.android.support:palette-v7:22.2.0'
}