view.getDrawingCache()仅在Samsung Galaxy note 8.0中返回null？

Question

**注意:(对于书呆子)请勿将其标记为重复的问题.

1. 是的,我知道它是什么NullPointerException.
2. 是的我尝试view.getDrawingCache从Stackoverflow返回null答案.

我正在尝试单独为平板电脑开发绘图应用程序.我创建了一个用于绘图的自定义视图.自定义视图包含在内部ScrollView以使用户滚动图像(如果它太大).

activity_drawing.xml

 <RelativeLayout
            android:id="@+id/container"
            android:layout_marginLeft="@dimen/activity_correction_answer_horizontal_margin"
            android:layout_marginRight="@dimen/activity_correction_answer_horizontal_margin"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <in.com.hourglass.views.ImageScroll   
                android:layout_centerInParent="true"
                android:id="@+id/image_scroll"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <FrameLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content">

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

                    <in.com.hourglass.views.DrawView
                        android:id="@+id/draw_view"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content" />
                </FrameLayout>
            </in.com.hourglass.views.ImageScroll>
  </RelativeLayout> 

因此,当完成视图上的绘图时,用户可以保存图像并进行思考Canvas.

我正在调整图像大小并将其附加到自定义视图Bitmap,并将它们保存为单个图像.整个过程很好用三星平板电脑10.1.

但是当我尝试在较低屏幕设备samsung Note 8.0中测试相同的时候.view.getDrawingCache()给我一个空的Bitmap.

我已经调试并检查了自定义视图的宽度和高度,它们指定了宽度和高度的scrollview,并且customview中也有一个位图.

我Bitmap尽可能地重用以减少app堆内存使用量.

我知道,我必须对此警告采取措施:

W/View: View too large to fit into drawing cache, needs 4380332 bytes, only 4096000 available

错误日志:

E/AndroidRuntime: FATAL EXCEPTION: main
Process: in.com.hourglassPID: 10456
java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.Bitmap.getWidth()' on a null object reference
at android.graphics.Bitmap.createBitmap(Bitmap.java:614)
at in.com.hourglass.views.DrawView.getCorrectedBitmapWithoutResizing(DrawView.java:449)
at in.com.hourglass.activities.DrawingActivity.saveAnswerSheet(DrawingActivity.java:842)
at in.com.hourglass.activities.DrawingActivity.navigateNext(DrawingActivity.java:426)
at in.com.hourglass.activities.DrawingActivity.access$500(DrawingActivity.java:89)
at in.com.hourglass.activities.DrawingActivity$ToolIconClick.onClick(DrawingActivity.java:362)
at android.view.View.performClick(View.java:4789)
at android.view.View$PerformClick.run(View.java:19881)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5294)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

代码用于获取调整大小的位图

       public class DrawView extends View {

        public void setBitmap(Bitmap bitmap) {
            this.bitmap = bitmap;
            invalidate();
        }
  @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int width = MeasureSpec.getSize(widthMeasureSpec);
        int height = MeasureSpec.getSize(heightMeasureSpec);
        setMeasuredDimension(width, height);
    }




          public Bitmap getResizedBitmap(int originial_width, int original_height) {
                this.setDrawingCacheEnabled(true);
                Bitmap bitmap = Bitmap.createBitmap(this.getDrawingCache());
                 return  Bitmap.createScaledBitmap(bitmap,originial_width_answersheet,original_height_answersheet,false);
            }
        }

链接我提到并且不成功,

Android View.getDrawingCache返回null,仅返回null

getDrawingCache启用滚动时,调用返回null

等等..

Answer 1

根据你的解释,似乎大型图像不是由代码绘制的,所以为此,请使用下面的代码它是工作,

我还没有测试过,但我认为这会对你有所帮助

   public static Bitmap loadLargeBitmapFromView(View v) 
   {
      Bitmap b = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.ARGB_8888);

      Canvas c = new Canvas(b);
      v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);
      v.draw(c);
      return b;
   } 

编辑您的方法如下

     public Bitmap getResizedBitmap(int originial_width, int original_height) {
                this.setDrawingCacheEnabled(true);
     Bitmap bitmap = null;
    if(this.getDrawingCache()==null)
        {
      bitmap = loadLargeBitmapFromView(this);
     }
    else
    {
     bitmap = Bitmap.createBitmap(this.getDrawingCache());
       }

   return  Bitmap.createScaledBitmap(bitmap,originial_width_answersheet,original_height_answersheet,false);
            }