Android 初学者想要创造阻力&；投递申请

我是Android开发新手，但熟悉编程。我已经学习了一些基础知识，例如片段、OnClickListeners等。作为我的第一个android项目，我想创建一个应用程序，其中

我可以将形状拖放到背景图像上（下图）

将图像另存为JPEG格式并保存到手机

有人能告诉我实现这一点需要了解哪些概念和小部件，并为我提供合适的教程吗？最好是视频

给你。 1.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/toplinear"
        android:layout_width="fill_parent"
        android:layout_height="170dp"
        android:layout_marginBottom="10dp" >

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

    </LinearLayout>

    <LinearLayout
        android:id="@+id/bottomlinear"
        android:layout_width="fill_parent"
        android:layout_height="170dp"
         >

        <TextView
            android:id="@+id/text"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:text="Drag the image and drop it here..." />

    </LinearLayout>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="invisible"
        android:id="@+id/save"
        android:text="Save as file"/>

</GridLayout>

5.AndroidManifest.xml添加以下权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

6.输出将如下所示

---

。这就是您要找的吗？您好，这真的很好，但我希望找到一个解释所有这些代码的教程。如果这个示例也解决了您的问题，您能接受答案吗？

<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <stroke
        android:width="2dp"
        android:color="#FFFF0000" />

    <gradient
        android:angle="225"
        android:endColor="#DD2ECCFA"
        android:startColor="#DD000000" />

    <corners
        android:bottomLeftRadius="7dp"
        android:bottomRightRadius="7dp"
        android:topLeftRadius="7dp"
        android:topRightRadius="7dp" />

</shape>

public class MainActivity extends AppCompatActivity {

    private ImageView myImage;
    private static final String IMAGEVIEW_TAG = "The Android Logo";
    Button btn;
    File file,f;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        myImage = (ImageView)findViewById(R.id.image);
        // Sets the tag
        myImage.setTag(IMAGEVIEW_TAG);
        btn = (Button)findViewById(R.id.save);

        // set the listener to the dragging data
        myImage.setOnTouchListener(new MyClickListener());

        findViewById(R.id.toplinear).setOnDragListener(new MyDragListener());
        findViewById(R.id.bottomlinear).setOnDragListener(new MyDragListener());

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                LinearLayout content = (LinearLayout)findViewById(R.id.bottomlinear);
                content.setDrawingCacheEnabled(true);
                Bitmap bitmap = content.getDrawingCache();


                if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
                {
                    file =new File(android.os.Environment.getExternalStorageDirectory(),"TTImages_cache");
                    if(!file.exists())
                    {
                        file.mkdirs();

                    }
                    f = new File(file.getAbsolutePath()+file.separator+ "filename"+".png");
                    Toast.makeText(getApplicationContext(),"File saved successfully",Toast.LENGTH_SHORT).show();
                }

                try {
                    FileOutputStream ostream = new FileOutputStream(f);
                    bitmap.compress(Bitmap.CompressFormat.PNG, 10, ostream);
                    ostream.close();
                }catch (Exception e){
                    e.printStackTrace();
                    //Toast.makeText(getApplicationContext(),"Failed",Toast.LENGTH_SHORT).show();
                }
            }
        });

    }

    private final class MyClickListener implements View.OnTouchListener {


        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {
            ClipData.Item item = new ClipData.Item((CharSequence)view.getTag());

            String[] mimeTypes = { ClipDescription.MIMETYPE_TEXT_PLAIN };
            ClipData data = new ClipData(view.getTag().toString(), mimeTypes, item);
            View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);

            view.startDrag( data, //data to be dragged
                    shadowBuilder, //drag shadow
                    view, //local data about the drag and drop operation
                    0   //no needed flags
            );


            view.setVisibility(View.INVISIBLE);
            return true;
        }

    }

    class MyDragListener implements View.OnDragListener {
        Drawable normalShape = getResources().getDrawable(R.drawable.shapes);
        Drawable targetShape = getResources().getDrawable(R.drawable.shape_drop_target);

        @Override
        public boolean onDrag(View v, DragEvent event) {

            // Handles each of the expected events
            switch (event.getAction()) {

                //signal for the start of a drag and drop operation.
                case DragEvent.ACTION_DRAG_STARTED:
                    // do nothing
                    break;

                //the drag point has entered the bounding box of the View
                case DragEvent.ACTION_DRAG_ENTERED:
                    v.setBackground(targetShape);   //change the shape of the view
                    break;

                //the user has moved the drag shadow outside the bounding box of the View
                case DragEvent.ACTION_DRAG_EXITED:
                    v.setBackground(normalShape);   //change the shape of the view back to normal
                    break;

                //drag shadow has been released,the drag point is within the bounding box of the View
                case DragEvent.ACTION_DROP:
                    // if the view is the bottomlinear, we accept the drag item
                    if(v == findViewById(R.id.bottomlinear)) {
                        View view = (View) event.getLocalState();
                        ViewGroup viewgroup = (ViewGroup) view.getParent();
                        viewgroup.removeView(view);

                        //change the text
                        TextView text = (TextView) v.findViewById(R.id.text);
                        text.setText("The item is dropped");

                        LinearLayout containView = (LinearLayout) v;
                        containView.addView(view);
                        btn.setVisibility(View.VISIBLE);
                        view.setVisibility(View.VISIBLE);
                    } else {
                        View view = (View) event.getLocalState();
                        view.setVisibility(View.VISIBLE);
                        Context context = getApplicationContext();
                        Toast.makeText(context, "You can't drop the image here",
                                Toast.LENGTH_LONG).show();
                        break;
                    }
                    break;

                //the drag and drop operation has concluded.
                case DragEvent.ACTION_DRAG_ENDED:
                    v.setBackground(normalShape);   //go back to normal shape

                default:
                    break;
            }
            return true;
        }
    }
}

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />