为什么我的卡片视图没有被绘制到 canvas？

Question

我正在尝试将卡片视图绘制到其 canvas 的 pdf 上。不幸的是，没有绘制卡片视图。但是绘制了一些测试文本。为什么我的carview没有画出来？

代码：

        // start a page
        PdfDocument.Page page = document.startPage(pageInfo);
        Canvas c = page.getCanvas();

        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(1000, 50);
        CardView card = new CardView(this);
        card.setLayoutParams(params);
        card.setRadius(4f);
        Bitmap cardBitmap = Utils.loadBitmapFromView(card);

        c.drawText("tessssssttt", 30, 30, p);
        c.drawBitmap(cardBitmap, new Rect(0,0,1000,50), new Rect(5, 50, 995, 100), p);

        document.finishPage(page);

查看位图：

public static Bitmap loadBitmapFromView(View v) {
    Bitmap b = Bitmap.createBitmap(v.getLayoutParams().width, v.getLayoutParams().height, Bitmap.Config.ARGB_8888);
    Canvas c = new Canvas(b);
    v.layout(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
    v.draw(c);
    return b;
}

Answer 1

以下代码将 CardView 绘制为位图。
但是阴影没有画出来

public class MainActivity extends AppCompatActivity {

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

        View view = getLayoutInflater().inflate(R.layout.card_view, null, false);
        Bitmap bitmap = loadBitmapFromView(view, 500, 500);

        //This is sample code. So I print the bitmap to ImageView, not to PDF.
        ImageView imageView = (ImageView) findViewById(R.id.image);
        imageView.setImageBitmap(bitmap);
    }

    public static Bitmap loadBitmapFromView(View v, int width, int height) {
        v.setMinimumWidth(width);
        v.setMinimumHeight(height);
        v.measure(
                View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY),
                View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.EXACTLY)
        );
        v.layout(0, 0, width, height);
        v.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

        Bitmap b = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(b);
        v.draw(c);
        return b;
    }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
        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"
        tools:context=".MainActivity">

    <ImageView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

</FrameLayout>

card_view.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:background="#33000000">

    <android.support.v7.widget.CardView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

        <TextView
                android:layout_width="100dp"
                android:layout_height="100dp"
                android:gravity="center"
                android:text="This is sample."/>

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

</FrameLayout>

为什么我的卡片视图没有被绘制到 canvas？

Why is my cardview not being drawn onto canvas?

android

android-canvas

android-view