Android 中view.getDrawingCache()生

在做分享的时候出现一个问题是渐变色出现色块，查到的原因是TextView或者Button，IMageView等获取当前的控件生成的图片RGB是565，但是使用LInearLayout包一层获取外面一层的控件就会生成一个RGB8888的图片。
代码如下：

   public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final View view = View.inflate(this, R.layout.activity_main, null);
    TextView textView = view.findViewById(R.id.textview1);
    TextView button = view.findViewById(R.id.button);
    LinearLayout textView2 = view.findViewById(R.id.textview2);
    ImageView imageview = view.findViewById(R.id.imageview);
    DisplayMetrics metric = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metric);
    int width = metric.widthPixels;     // 屏幕宽度（像素）
    final int height = metric.heightPixels;   // 屏幕高度（像素）
    ImageUtils.layoutView(view, width, height);
    Bitmap bitmap = ImageUtils.viewSaveToBitmap(textView, button, textView2, imageview);
}}




  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.wenxin.test.MainActivity">
<TextView
    android:id="@+id/textview1"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:background="@drawable/bg" />
<View
    android:layout_width="match_parent"
    android:layout_height="3dp"
    android:background="#ffffff" />
<TextView
    android:id="@+id/button"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:background="@drawable/bg" />
<View
    android:layout_width="match_parent"
    android:layout_height="3dp"
    android:background="#ffffff" />
<LinearLayout
    android:id="@+id/textview2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="30dp"
        android:background="@drawable/bg" />
</LinearLayout>
<View
    android:layout_width="match_parent"
    android:layout_height="3dp"
    android:background="#ffffff" />
<ImageView
    android:id="@+id/imageview"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:background="@drawable/bg" />
 </LinearLayout>



public class ImageUtils {
//然后View和其内部的子View都具有了实际大小，也就是完成了布局，相当与添加到了界面上。接着就可以创建位图并在上面绘制了：
public static void layoutView(View v, int width, int height) {
    // 整个View的大小 参数是左上角 和右下角的坐标
    int measuredWidth = View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY);
    int measuredHeight = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);
    /** 当然，measure完后，并不会实际改变View的尺寸，需要调用View.layout方法去进行布局。
     * 按示例调用layout函数后，View的大小将会变成你想要设置成的大小。
     */
    v.measure(measuredWidth, measuredHeight);
    v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
}
/**
 * @param view1
 * @param view2
 * @param view3
 * @param view4
 * @return
 */
public static Bitmap viewSaveToBitmap(View view1, View view2, View view3, View view4) {
    /**
     * View组件显示的内容可以通过cache机制保存为bitmap
     * 我们要获取它的cache先要通过setDrawingCacheEnable方法把cache开启，
     * 然后再调用getDrawingCache方法就可 以获得view的cache图片了
     * 。buildDrawingCache方法可以不用调用，因为调用getDrawingCache方法时，
     * 若果 cache没有建立，系统会自动调用buildDrawingCache方法生成cache。
     * 若果要更新cache, 必须要调用destoryDrawingCache方法把旧的cache销毁，才能建立新的。
     */
    // 把一个View转换成图片
    Bitmap view1Bmp = loadBitmapFromView(view1);
    Bitmap view2Bmp = loadBitmapFromView(view2);
    Bitmap view3Bmp = loadBitmapFromView(view3);
    Bitmap view4Bmp = loadBitmapFromView(view4);
    Bitmap bitmap = toConformBitmap(view1Bmp, view2Bmp, view3Bmp, view4Bmp);
    // 得到新的图片
    view1.destroyDrawingCache();
    view2.destroyDrawingCache();
    view3.destroyDrawingCache();
    view4.destroyDrawingCache();
    return bitmap;
}

/**
 * 根据view生成图片
 *
 * @param view
 * @return
 */
public static Bitmap loadBitmapFromView(View view) {
    final boolean drawingCacheEnabled = true;
    view.setDrawingCacheEnabled(drawingCacheEnabled);
    view.buildDrawingCache(drawingCacheEnabled);
    Bitmap drawingCache = view.getDrawingCache();
    if (drawingCache != null) {
        Bitmap.Config cfg = drawingCache.getConfig();
        Log.d("测试", "cache.getConfig() = " + cfg);
    }
    Bitmap bitmap;
    if (drawingCache != null) {
        bitmap = Bitmap.createBitmap(drawingCache);
        view.setDrawingCacheEnabled(false);
    } else {
        bitmap = null;
    }
    return bitmap;
}

/**
 * 合并图片
 *
 * @param head   图片头
 * @param bitmap 图片
 * @return 新图片
 */
public static Bitmap toConformBitmap(Bitmap head, Bitmap bitmap, Bitmap bitmap1, Bitmap foot) {
    if (head == null || bitmap == null) {
        return null;
    }
    int bitmapWidth = bitmap.getWidth();
    int headHeight = head.getHeight();
    int bitmapHeight = bitmap.getHeight();
    int footHeight = foot.getHeight();
    int bitmap1Height = bitmap1.getHeight();
    //生成四个图片合并大小的Bitmap
    Bitmap newbmp = Bitmap.createBitmap(bitmapWidth, headHeight + bitmapHeight + bitmap1Height + footHeight, bitmap.getConfig());
    Canvas cv = new Canvas(newbmp);
    cv.drawBitmap(head, 0, 0, null);// 在 0，0坐标开始画入headBitmap
    cv.drawBitmap(bitmap, 0, headHeight, null);
    cv.drawBitmap(bitmap1, 0, headHeight + bitmapHeight, null);
    cv.drawBitmap(foot, 0, headHeight + bitmapHeight + bitmap1Height, null);
    //回收
    head.recycle();
    bitmap.recycle();
    bitmap1.recycle();
    foot.recycle();
    return newbmp;
} }

打印的日志是：
11-05 17:57:33.682 4261-4261/? D/测试: cache.getConfig() = ARGB_565
11-05 17:57:33.694 4261-4261/? D/测试: cache.getConfig() = ARGB_565
11-05 17:57:33.725 4261-4261/? D/测试: cache.getConfig() = ARGB_8888
11-05 17:57:33.736 4261-4261/? D/测试: cache.getConfig() = ARGB_565