Android uses gestures to drag images

In this example, Android uses gestures to drag and drop images. The running effect is as follows:

 

 

The Code is as follows:

Package com. android. drag;

Import android. app. Activity;
Import android. content. Context;
Import android. graphics. Canvas;
Import android. graphics. Color;
Import android. graphics. Paint;
Import android. OS. Bundle;
Import android. util. DisplayMetrics;
Import android. view. MotionEvent;
Import android. view. View;

/**
* Android uses gestures to drag images.
* @ Author Administrator
*
*/
Public class DragActivity extends Activity {
/** Called when the activity is first created .*/
@ Override
Public void onCreate (Bundle savedInstanceState ){
Super. onCreate (savedInstanceState );
// SetContentView (R. layout. main );
View view = new ImageDragView (this );

SetContentView (view );
}

Class ImageDragView extends View {

Private float x1;
Private float y1;
Private float x2;
Private float y2;

Public ImageDragView (Context context ){
Super (context );
// TODO Auto-generated constructor stub
}

@ Override
Public boolean onTouchEvent (MotionEvent event ){
// TODO Auto-generated method stub

Float size = event. getSize ();

Int szi = (int) size;
Int dxi = szi> 12;
Int dyit = (1 <12)-1 );
Int dyi = szi & dyit;

DisplayMetrics metrics = getResources (). getDisplayMetrics ();

Float dx = metrics. widthPixels * dxi/(float) dyit;
Float dy = metrics. heightPixels * dyi/(float) dyit;

X1 = event. getX ();
Y1 = event. getY ();

X2 = x1 + dx;
Y2 = y1 + dy;

Invalidate ();

Return true;
}

@ Override
Protected void onDraw (Canvas canvas ){
// TODO Auto-generated method stub
Super. onDraw (canvas );

Float r = (float) Math. sqrt (x1-x2) * (x1-x2) + (y1-y2)
* (Y1-y2)/2;
R = 100> = r? 100: r;

Paint paint = new Paint ();
Paint. setColor (Color. RED );
Canvas. drawCircle (x1, y1, r, paint );
}
}

}

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Complete. Pai_^