android - 在 Canvas 上移动位图

Question

我有一个 imageView、 Canvas 和一个按钮..当我单击按钮时，会在 Canvas 上绘制位图

我想使用我的 onTouch 移动该位图(将位图拖到 Canvas 上的任何位置)。

       s.setOnItemClickListener(new OnItemClickListener() {
           public void onItemClick(AdapterView<?> parent,
                   View v, int position, long id) {
            Bitmap workingBitmap = Bitmap.createBitmap(currentBitmap);
            workingBitmap = Bitmap.createBitmap(workingBitmap); 
            Canvas c = new Canvas(workingBitmap);
            brightBitmap = BitmapFactory.decodeResource(getResources(), sIds.mSmileyIds[position], null); 
            brightBitmap = Bitmap.createScaledBitmap(brightBitmap, 100, 100, false);
            chosenSmiley = brightBitmap;
                if (chosenSmiley != null) {
                    try {
                    c.drawBitmap(chosenSmiley, posX, posY, null);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
                iv.setImageBitmap(workingBitmap);
               }

        public boolean onTouchEvent(MotionEvent event) {
            int eventaction = event.getAction();

            switch (eventaction) {
                case MotionEvent.ACTION_DOWN: 
                    // finger touches the screen
                    break;

                case MotionEvent.ACTION_MOVE:
                    // finger moves on the screen
                    lastX = (int) event.getX();
                    lastY = (int) event.getY();
                    Log.e("my xname", lastX + " Coords of lastX");
                    Log.e("my xname", lastY + " Coords of lastY");
                    brightBitmap = Bitmap.createScaledBitmap(brightBitmap, lastX, lastY, false);
                    break;

                case MotionEvent.ACTION_UP:   
                    // finger leaves the screen
                    break;
            }

            // tell the system that we handled the event and no further processing is required
            return true; 
        }   

       });

这是我当前的代码，位图是在 0,0 上创建的，但我不能拖动它等等 ..

Answer 1

 public class MainActivity extends Activity
{
  @Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    DrawingView dv = new DrawingView(this);
    setContentView(dv);
}

class DrawingView extends View{
Bitmap bitmap;

float x,y;

public DrawingView(Context context)
{
 super(context);
 bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher);
}


public boolean onTouchEvent(MotionEvent event)
{

 switch(event.getAction())
    {
   case MotionEvent.ACTION_DOWN: {

   }
   break;

   case MotionEvent.ACTION_MOVE: 
   {
      x=(int)event.getX();
      y=(int)event.getY();

 invalidate();
 }

 break;
   case MotionEvent.ACTION_UP: 

       x=(int)event.getX();
       y=(int)event.getY();
       System.out.println(".................."+x+"......"+y); //x= 345 y=530 
       invalidate();
    break; 
   }
  return true;
 }

 @Override
 public void onDraw(Canvas canvas)
 {
 Paint paint = new Paint();
 paint.setStyle(Paint.Style.FILL);
 paint.setColor(Color.CYAN);
 canvas.drawBitmap(bitmap, x, y, paint);  //originally bitmap draw at x=o and y=0
 }
 }
 }

星形位图绘制在x=0 和y=0 处；在拖动 x 和 y 时发生变化，因此调用 inavlidate 来刷新 drate。在触摸时在拖动位置 x 和 y 处绘制位图并调用 invalidate 刷新绘制。

在 x=0 y=0 处绘制的位图。拖放//x= 345 y=530。附上生成的快照。

您需要确保您的图像看起来不会在屏幕边缘处超出屏幕范围检查 x 是否在屏幕宽度 - 位图宽度内并且 y 是否小于屏幕高度 - 位图高度。我没有在代码中包含这些条件。

编辑:

      setContentView(R.layout.main);    
      LinearLayout ll = (LinearLayout) findViewById(R.id.ll);
      DrawingView dv= new DrawingView(this);
      ll.addView(dv);