android - 使用 AppBarLayout 的 CoordinatorLayout 自定义行为

Question

我正在尝试实现与 Telegram 类似的行为，在设置页面上，即有一个 CircleImage，当向上滚动到顶部栏标题的左侧，向下滚动到中间展开的 AppBarLayout。

我的工作基于这个例子:

https://github.com/saulmm/CoordinatorBehaviorExample

但在这种情况下，原始编码器正在重新创建 Topbar 两次。我不想那样做，顶栏的默认行为是我需要的，而且我想利用汉堡菜单和开箱即用的选项菜单。

这是我的 View 层次结构:

DrawerLayout
  |
  |---CoordinatorLayout
       |--AppBarLayout
       |    |-CollapsingToolbarLayout
       |        |-ImageView (backdrop image)
       |        |-Toolbar
       |--NestedScrollView
       |--ImageView (circleimage avatar)

如您所见，我无法将工具栏布局设为 CircleImage 的兄弟，因此无法在 layoutDependsOn 方法上将它们绑定(bind)在一起。我尝试根据 github 存储库上的代码绑定(bind)到 AppBarLayout，但老实说，我无法理解原始代码中发生的事情。

Answer 1

我的行为与扫罗的行为方式大致相同。最大的不同是我喜欢将一个不可见的 View (如 Space)放在我希望圆形图像结束的位置，然后使用该 View 的边界来确定如何移动和调整圆形图像的大小。

public class CollapsingImageBehavior extends CoordinatorLayout.Behavior<View> {

    private final static int X = 0;
    private final static int Y = 1;
    private final static int WIDTH = 2;
    private final static int HEIGHT = 3;

    private int mTargetId;

    private int[] mView;

    private int[] mTarget;

    public CollapsingImageBehavior() {
    }

    public CollapsingImageBehavior(Context context, AttributeSet attrs) {

        if (attrs != null) {
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CollapsingImageBehavior);
            mTargetId = a.getResourceId(R.styleable.CollapsingImageBehavior_collapsedTarget, 0);
            a.recycle();
        }

        if (mTargetId == 0) {
            throw new IllegalStateException("collapsedTarget attribute not specified on view for behavior");
        }
    }

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

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

        setup(parent, child);

        AppBarLayout appBarLayout = (AppBarLayout) dependency;

        int range = appBarLayout.getTotalScrollRange();
        float factor = -appBarLayout.getY() / range;

        int left = mView[X] + (int) (factor * (mTarget[X] - mView[X]));
        int top = mView[Y] + (int) (factor * (mTarget[Y] - mView[Y]));
        int width = mView[WIDTH] + (int) (factor * (mTarget[WIDTH] - mView[WIDTH]));
        int height = mView[HEIGHT] + (int) (factor * (mTarget[HEIGHT] - mView[HEIGHT]));

        CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
        lp.width = width;
        lp.height = height;
        child.setLayoutParams(lp);
        child.setX(left);
        child.setY(top);

        return true;
    }

    private void setup(CoordinatorLayout parent, View child) {

        if (mView != null) return;

        mView = new int[4];
        mTarget = new int[4];

        mView[X] = (int) child.getX();
        mView[Y] = (int) child.getY();
        mView[WIDTH] = child.getWidth();
        mView[HEIGHT] = child.getHeight();

        View target = parent.findViewById(mTargetId);
        if (target == null) {
            throw new IllegalStateException("target view not found");
        }

        mTarget[WIDTH] += target.getWidth();
        mTarget[HEIGHT] += target.getHeight();

        View view = target;
        while (view != parent) {
            mTarget[X] += (int) view.getX();
            mTarget[Y] += (int) view.getY();
            view = (View) view.getParent();
        }

    }
}

这是布局。我发现的一件重要的事情是，圆形 ImageView 需要设置一个高程，以便它在折叠模式下放置在工具栏的顶部，否则它将位于工具栏的后面并且不显示。

<?xml version="1.0" encoding="utf-8"?>
<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:id="@+id/coordinator_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.krislarson.customcoordinatorlayoutbehavior.ScrollingActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:fitsSystemWindows="true"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/toolbar_layout"
            android:layout_width="match_parent"
            android:layout_height="280dp"
            android:minHeight="108dp"
            android:fitsSystemWindows="true"
            app:title="Abby"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleGravity="center_horizontal"
            app:expandedTitleMarginTop="140dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <ImageView
                android:id="@+id/background"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:src="@drawable/sunset"
                app:layout_collapseMode="parallax"
                android:scaleType="centerCrop"/>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/AppTheme.PopupOverlay">

                <Space
                    android:id="@+id/circle_collapsed_target"
                    android:layout_width="40dp"
                    android:layout_height="40dp"/>

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


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

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

    <include layout="@layout/content_scrolling"/>

    <de.hdodenhof.circleimageview.CircleImageView
        android:id="@+id/circle_image_view"
        android:layout_width="120dp"
        android:layout_height="120dp"
        android:src="@drawable/abby"
        android:layout_marginTop="220dp"
        android:layout_gravity="top|center_horizontal"
        android:elevation="8dp"
        app:border_color="@android:color/black"
        app:border_width="2dp"
        app:collapsedTarget="@id/circle_collapsed_target"
        app:layout_behavior="com.krislarson.customcoordinatorlayoutbehavior.CollapsingImageBehavior"/>

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

您可以在 https://github.com/klarson2/CustomCoordinatorLayoutBehavior 查看整个演示项目