Canvas 顶部的按钮

Question

我正在尝试将一个按钮放在一个视图之上，我将其与 Canvas 一起使用，但无法解决。

有什么想法吗？我到处都看了（这似乎是一个常见的问题）但没有找到任何解决方案。

谢谢，

public class MyActivity extends Activity {

private RandomShapeView mDrawingArea;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);

    mDrawingArea = (RandomShapeView) findViewById(R.id.drawing_area);
    mDrawingArea.setBackgroundColor(Color.GREEN);

}

}

查看Class

public class RandomShapeView extends View {

Paint paint;

public RandomShapeView(Context context) {
    super(context);

    paint = new Paint();
    paint.setColor(Color.BLACK);

}

@Override
protected void onDraw(Canvas canvas) {

}

}

布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MyActivity">

<Button
    android:id="@+id/button"
    android:text="@string/hello_world"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<View
    class="com.examples.danilofernandes.canvasonrelativelayout.RandomShapeView"
    android:id="@+id/drawing_area"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"/>


</RelativeLayout>

Answer 1

Z 顺序隐含在元素在 XML 中出现的顺序中。换个地方，应该没问题。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MyActivity">

    <com.examples.danilofernandes.canvasonrelativelayout.RandomShapeView
        android:id="@+id/drawing_area"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>

    <Button
        android:id="@+id/button"
        android:text="@string/hello_world"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>

Canvas 顶部的按钮

Button on top of a Canvas

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