如何在 GridLayout 中选择 child 类似于 GridView

Question

我想达到以下能力：

Select 每次长按 GridLayout 里面只有一个 child View。
单击视觉层次结构中的 GridLayout 或任何祖先 parent 将取消选中 child View 如果已经选中。

问题是当向 child View 注册 View.OnLongClickListener 回调时，parent GridLayout 和任何祖先注册的回调（View.OnClickListener 或 View.onTouchEvent) 在点击它们时调用。

如何在类似于 AdapterView.OnItemSelectedListener 或 AdapterView.OnItemLongClickListener 的 GridLayout 中选择一个 child 并解决上述问题？

Answer 1

使用以下代码：

int last_pos = -1;
GridLayout gridLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    gridLayout = (GridLayout) findViewById(R.id.gridLayout);
    int child_count = gridLayout.getChildCount();
    for(int i =0;i<child_count;i++){
        gridLayout.getChildAt(i).setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                //Deselect previous
                if(last_pos!=-1) gridLayout.getChildAt(last_pos).setSelected(false);
                //Select the one you clicked
                view.setSelected(true);
                last_pos = gridLayout.indexOfChild(view);
                return false;
            }
        });
    }
    //Remove focus if the parent is clicked
    gridLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            gridLayout.getChildAt(last_pos).setSelected(false);
        }
    });

Answer 2

如何将 "selected" 视图存储为全局变量，并在其焦点改变时将其删除？通过使用 focusable、focusableInTouchMode 和 onClick 听众，您可以获得正确的结果。我不确定这是最好的解决方案，但它确实有效。

您将需要：

A global View variable: the GridLayout's child long clicked, as selected.

(optional) A custom parent container as any ViewGroup: it will set the focusable listeners on all its children [*]. In my tests, I used a LinearLayout and a RelativeLayout.

[*] 如果您不使用可选的 parent 自定义 Class，则必须对所有设置 android:focusable="true" 和 android:focusableInTouchMode="true" children 属于 parent ViewGroup。您必须设置 OnClickListener 才能在单击 parent ViewGroup 时调用 removeViewSelected()。

Adding Click listeners for GridLayout children: which updates the selected view.

Implementing a Focus listener: which removes the selected view if it's losing focus.

它将处理 parent 和 child 层次结构上的所有焦点更改状态，请参阅输出：

我使用了以下模式：

CoordinatorLayout         --- simple root group
    ParentLayout          --- aka "parentlayout"
        Button            --- simple Button example
        GridLayout        --- aka "gridlayout"
    FloattingActionButton --- simple Button example

让我们在 Activity 中准备选定的 View 及其更新方法：

private View selectedView;

...
private void setViewSelected(View view) {
    removeViewSelected();

    selectedView = view;
    if (selectedView != null) {
        // change to a selected background for example
        selectedView.setBackgroundColor(
                ContextCompat.getColor(this, R.color.colorAccent));
    }
}

private View getViewSelected() {
    if (selectedView != null) {
        return selectedView;
    }
    return null;
}

private void removeViewSelected() {
    if (selectedView != null) {
        // reset the original background for example
        selectedView.setBackgroundResource(R.drawable.white_with_borders);
        selectedView = null;
    }
    // clear and reset the focus on the parent
    parentlayout.clearFocus();
    parentlayout.requestFocus();
}

在每个 GridLayout child 上，添加 Click 和 LongClick 侦听器以更新或删除所选视图。我的 TextView 是动态添加的，但您可以轻松创建 for-loop 来检索 children:

TextView tv = new TextView(this);
...
gridlayout.addView(tv);

tv.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        removeViewSelected();
    }
});

tv.setOnLongClickListener(new View.OnLongClickListener() {
    @Override
    public boolean onLongClick(View view) {
        setViewSelected(view);
        return true;
    }
});

在 parent 容器上设置 FocusChange 侦听器：

parentlayout.setOnFocusChangeListener(new View.OnFocusChangeListener() {
    @Override
    public void onFocusChange(View view, boolean hasFocus) {
        View viewSelected = getViewSelected();
        // if the selected view exists and it lost focus
        if (viewSelected != null && !viewSelected.hasFocus()) {
            // remove it
            removeViewSelected();
        }
    }
});

然后，可选的自定义 ViewGroup：它是可选的，因为您可以通过 XML 和 clickable 侦听器动态设置 focusable 状态，但它似乎更容易我。我使用以下自定义 Class 作为 parent 容器：

public class ParentLayout extends RelativeLayout implements View.OnClickListener {

    public ParentLayout(Context context) {
        super(context);
        init();
    }

    public ParentLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public ParentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    // handle focus and click states
    public void init() {
        setFocusable(true);
        setFocusableInTouchMode(true);
        setOnClickListener(this);
    }

    // when positioning all children within this 
    // layout, add their focusable state
    @Override
    protected void onLayout(boolean c, int l, int t, int r, int b) {
        super.onLayout(c, l, t, r, b);

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            child.setFocusable(true);
            child.setFocusableInTouchMode(true);
        }
        // now, even the Button has a focusable state
    }

    // handle the click events
    @Override
    public void onClick(View view) {
        // clear and set the focus on this viewgroup
        this.clearFocus();
        this.requestFocus();
        // now, the focus listener in Activity will handle
        // the focus change state when this layout is clicked
    }
}

例如，这是我使用的布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout ...>

    <com.app.ParentLayout
        android:id="@+id/parent_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_horizontal">

        <Button
            android:id="@+id/sample_button"
            android:layout_width="250dp"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_alignParentBottom="true"
            android:text="A Simple Button"
            android:layout_marginTop="20dp"
            android:layout_marginBottom="20dp"/>

        <android.support.v7.widget.GridLayout
            android:id="@+id/grid_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_centerHorizontal="true"
            android:layout_above="@id/sample_button" .../>
    </com.app.ParentLayout>

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

希望这会有所帮助。

如何在 GridLayout 中选择 child 类似于 GridView

How to get selected child in GridLayout similar to GridView

java

android

android-adapter

grid-layout

view-hierarchy