具有自定义行为的 CollapsingToolbarLayout

Question

我正在关注这个流行的link 的协调器行为，遵循这个post。
我想要一个期望的行为，图像应该浮动到右侧而不是左侧，为此，我修改了

AvatarImageBehavior.java -> maybeInitProperties() method ->

如下：

if (mFinalXPosition == 0)
            mFinalXPosition= getScreenWidth()-70;

现在我希望工具栏固定在顶部，只有图像可以移动并粘在上面。
据我了解，只有 Behavior 文件负责此转换。
我尝试了太多东西，但没有得到正确的方法/回电继续。
欢迎任何解决方案/方法/不同的示例。

Answer 1

所以，第一你应该做的事情是调整布局文件 - 通过删除 layout_anchor 属性使 Toolbar 固定在顶部。

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:ignore="RtlHardcoded"
    >

    <android.support.design.widget.AppBarLayout
        android:id="@+id/main.appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        >

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/main.collapsing"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|exitUntilCollapsed|snap"
            >

            <ImageView
                android:id="@+id/main.imageview.placeholder"
                android:layout_width="match_parent"
                android:layout_height="300dp"
                android:scaleType="centerCrop"
                android:src="@drawable/quila2"
                android:tint="#11000000"
                app:layout_collapseMode="parallax"
                app:layout_collapseParallaxMultiplier="0.9"
                />

        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>


    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="none"
        app:behavior_overlapTop="24dp"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        >

        <android.support.v7.widget.CardView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="8dp"
            app:cardElevation="8dp"
            app:contentPadding="16dp"
            >

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:lineSpacingExtra="8dp"
                android:text="@string/lorem"
                android:textSize="18sp"
                />
        </android.support.v7.widget.CardView>


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

    <android.support.v7.widget.Toolbar
        android:id="@+id/main.toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/primary"
        app:theme="@style/ThemeOverlay.AppCompat.Dark"
        app:title="">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal">
            <TextView
                android:id="@+id/main.textview.title"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_marginLeft="8dp"
                android:gravity="center_vertical"
                android:text="@string/quila_name2"
                android:textColor="@android:color/white"
                android:textSize="20sp"/>

        </LinearLayout>
    </android.support.v7.widget.Toolbar>

    <de.hdodenhof.circleimageview.CircleImageView
        android:layout_width="@dimen/image_width"
        android:layout_height="@dimen/image_width"
        android:layout_gravity="center_horizontal"
        android:src="@drawable/quila"
        app:border_color="@android:color/white"
        app:border_width="2dp"
        app:finalHeight="@dimen/image_final_width"
        app:layout_behavior="saulmm.myapplication.AvatarImageBehavior"
        />
</android.support.design.widget.CoordinatorLayout>

注意，我还删除了 main.framelayout.title 部分，因为我认为它也是 Toolbar 的一部分。而且我还删除了onOffsetChanged() 以及MainActivity 中所有与它相关的方法，并使我们的Toolbar 标题始终可见。

其次，当然，您应该在AvatarImageBehavior 类中进行更改。这里主要的是现在你的ImageView 依赖于NestedScrollView 而不是Toolbar。但是由于我们不再依赖Toolbar，我们仍然需要它来定义mFinalYPosition，所以我也添加了查找Toolbar 的方法。这是行为：

public class AvatarImageBehavior extends CoordinatorLayout.Behavior<CircleImageView> {

    private final static float MIN_AVATAR_PERCENTAGE_SIZE   = 0.3f;
    private final static int EXTRA_FINAL_AVATAR_PADDING     = 80;

    private final static String TAG = "behavior";
    private Context mContext;

    private float mCustomFinalYPosition;
    private float mCustomStartXPosition;
    private float mCustomStartToolbarPosition;
    private float mCustomStartHeight;
    private float mCustomFinalHeight;

    private float mAvatarMaxSize;
    private float mStartPosition;
    private int mStartXPosition;
    private float mStartToolbarPosition;
    private int mStartYPosition;
    private int mFinalYPosition;
    private int mStartHeight;
    private int mFinalXPosition;
    private float mChangeBehaviorPoint;

    public AvatarImageBehavior(Context context, AttributeSet attrs) {
        mContext = context;

        if (attrs != null) {
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AvatarImageBehavior);
            mCustomFinalYPosition = a.getDimension(R.styleable.AvatarImageBehavior_finalYPosition, 0);
            mCustomStartXPosition = a.getDimension(R.styleable.AvatarImageBehavior_startXPosition, 0);
            mCustomStartToolbarPosition = a.getDimension(R.styleable.AvatarImageBehavior_startToolbarPosition, 0);
            mCustomStartHeight = a.getDimension(R.styleable.AvatarImageBehavior_startHeight, 0);
            mCustomFinalHeight = a.getDimension(R.styleable.AvatarImageBehavior_finalHeight, 0);

            a.recycle();
        }

        init();
    }

    private void init() {
        bindDimensions();
    }

    private void bindDimensions() {
        mAvatarMaxSize = mContext.getResources().getDimension(R.dimen.image_width);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, CircleImageView child, View dependency) {
        return dependency instanceof NestedScrollView;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, CircleImageView child, View dependency) {
        maybeInitProperties(parent, child, dependency);

        final int maxScrollDistance = (int) (mStartToolbarPosition);
        float expandedPercentageFactor = dependency.getY() / maxScrollDistance;

        if (expandedPercentageFactor < mChangeBehaviorPoint) {
            float heightFactor = (mChangeBehaviorPoint - expandedPercentageFactor) / mChangeBehaviorPoint;

            float distanceXToSubtract = ((mStartXPosition - mFinalXPosition)
                    * heightFactor) + (child.getHeight()/2);
            float distanceYToSubtract = ((mStartYPosition - mFinalYPosition)
                    * (1f - expandedPercentageFactor)) + (child.getHeight()/2);

            child.setX(mStartXPosition - distanceXToSubtract);
            child.setY(mStartYPosition - distanceYToSubtract);

            float heightToSubtract = ((mStartHeight - mCustomFinalHeight) * heightFactor);

            CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
            lp.width = (int) (mStartHeight - heightToSubtract);
            lp.height = (int) (mStartHeight - heightToSubtract);
            child.setLayoutParams(lp);
        } else {
            float distanceYToSubtract = ((mStartYPosition - mFinalYPosition)
                    * (1f - expandedPercentageFactor)) + (mStartHeight/2);

            child.setX(mStartXPosition - child.getWidth()/2);
            child.setY(mStartYPosition - distanceYToSubtract);

            CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
            lp.width = (int) (mStartHeight);
            lp.height = (int) (mStartHeight);
            child.setLayoutParams(lp);
        }
        return true;
    }

    private void maybeInitProperties(CoordinatorLayout parent, CircleImageView child, View dependency) {
        if (mStartYPosition == 0)
            mStartYPosition = (int) (dependency.getY());

        View toolbar = tryFindToolbarInLayout(parent);

        if (mFinalYPosition == 0 && toolbar != null) {
            mFinalYPosition = (toolbar.getHeight() / 2);
        }

        if (mStartHeight == 0)
            mStartHeight = child.getHeight();

        if (mStartXPosition == 0)
            mStartXPosition = (int) (child.getX() + (child.getWidth() / 2));

        if (mFinalXPosition == 0)
            mFinalXPosition = dependency.getContext().getResources().getDisplayMetrics().widthPixels - mContext.getResources().getDimensionPixelOffset(R.dimen.abc_action_bar_content_inset_material)
                    - ((int) mCustomFinalHeight / 2);

        if (mStartToolbarPosition == 0)
            mStartToolbarPosition = dependency.getY();

        if (mChangeBehaviorPoint == 0 && toolbar != null) {
            mChangeBehaviorPoint = (child.getHeight() - mCustomFinalHeight) / (mStartYPosition - mFinalYPosition - toolbar.getHeight());
        }
    }

    private View tryFindToolbarInLayout(CoordinatorLayout parent) {
        for (int i = 0; i < parent.getChildCount(); i++) {
            View child = parent.getChildAt(i);
            if (child instanceof Toolbar)
                return child;
        }
        return null;
    }

    public int getStatusBarHeight() {
        int result = 0;
        int resourceId = mContext.getResources().getIdentifier("status_bar_height", "dimen", "android");

        if (resourceId > 0) {
            result = mContext.getResources().getDimensionPixelSize(resourceId);
        }
        return result;
    }
} 

这是我设法做到的：