Question

我需要以编程方式创建ListView并获取它的位图。我不需要在屏幕上绘制它，我只需要一个适配器并从其他屏幕准备好数据：

ListView listView1;
LinearLayout ll = new LinearLayout(applicationGlobalState.getActiveContext(QuickTestResultsActivity.class));
listView1 = new ListView(applicationGlobalState.getActiveContext(QuickTestResultsActivity.class));
ll.addView(listView1, LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.FILL_PARENT);

listView1.setBackgroundColor(R.color.orange);
ListAdapter adapter  = listView1.getAdapter();
int itemscount       = adapter.getCount();
int allitemsheight   = 0;
List<Bitmap> bmps    = new ArrayList<Bitmap>();
Bitmap bigbitmap = null;
try{
    for (int i = 0; i < itemscount; i++) {

        View childView = adapter.getView(i, null, listView1);
        childView.setBackgroundColor(R.color.orange);
        childView.measure(View.MeasureSpec.makeMeasureSpec(listView1.getWidth(), View.MeasureSpec.EXACTLY),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));

        childView.layout(0, 0, childView.getMeasuredWidth(), childView.getMeasuredHeight());
        childView.setDrawingCacheEnabled(true);
        childView.buildDrawingCache();
        bmps.add(childView.getDrawingCache());
        allitemsheight+=childView.getMeasuredHeight();
    }
    //////
    int m0 =listView1.getMeasuredWidth();
    int m = allitemsheight;

    //bigbitmap    = Bitmap.createBitmap(listView1.getMeasuredWidth(), allitemsheight, Bitmap.Config.ARGB_8888);
    bigbitmap    = Bitmap.createBitmap(800, allitemsheight, Bitmap.Config.ARGB_8888);
    Canvas bigcanvas    = new Canvas(bigbitmap);

    Paint paint = new Paint();
    int iHeight = 0;

    for (int i = 0; i < bmps.size(); i++) {
        Bitmap bmp = bmps.get(i);
        bigcanvas.drawBitmap(bmp, 0, iHeight, paint);
        iHeight+=bmp.getHeight();

        bmp.recycle();
        bmp=null;
    }

}catch(Exception e){Log.e("¬","",e);}

Bitmap bmp = bigbitmap;
FileOutputStream fos = new FileOutputStream("/data/data/co.uk.orange.application/app_temp_results/aps" +(System.currentTimeMillis()/1000)+".png", true);
applicationGlobalState.wifiScreenshotPath="/data/data/co.uk.orange.application/app_temp_results/aps" +(System.currentTimeMillis()/1000)+".png";
bmp.compress(CompressFormat.PNG, 75, fos);
bmp.recycle();

给我一个例外：“bmps.get（i）”为null;

01-04 19:08:49.843: ERROR/¬(1549): java.lang.NullPointerException
    at android.graphics.Canvas.throwIfRecycled(Canvas.java:954)
    at android.graphics.Canvas.drawBitmap(Canvas.java:980)
    at co.uk.orange.application.asynctasks.WifiAPPicture.getDrawingBitmap(WifiAPPicture.java:121)
    at co.uk.orange.application.asynctasks.WifiAPPicture.onCreate(WifiAPPicture.java:82)
    at co.uk.orange.application.asynctasks.WifiAPsTestAsyncTask.doInBackground(WifiAPsTestAsyncTask.java:100)
    at co.uk.orange.application.asynctasks.WifiAPsTestAsyncTask.doInBackground(WifiAPsTestAsyncTask.java:20)
    at android.os.AsyncTask$2.call(AsyncTask.java:185)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
    at java.lang.Thread.run(Thread.java:1096)

以编程方式创建listview并获取它的android位图

0 个答案: