我有一个活动,里面有一个
ImageView.我想要做的是能够用可绘制文件夹中的图像绘制用户触摸Imageview的位置.我已经读过最好的方法是使用Canvas,但我不知道我在哪里以及如何将onDraw方法与onTouchListener集成.这是我到目前为止:
public class Main extends Activity
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView textView = (TextView)findViewById(R.id.textView);
final ImageView image = (ImageView) findViewById(R.id.imageView2);
//Bitmap
Bitmap viewBitmap = Bitmap.createBitmap(image.getWidth(), image.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(viewBitmap);
image.draw(canvas);
image.setOnTouchListener(new View.OnTouchListener()
{
@Override
public boolean onTouch(View v, MotionEvent event)
{
textView.setText("Touch coordinates : " + String.valueOf(event.getX()) + "x" + String.valueOf(event.getY()));
return false;
}
});
}
}
所以我想要做的是当用户触摸ImageView时,图像将被准确地绘制在他触摸它的位置.
最佳答案 您将要继承ImageView以覆盖其onDraw()方法.通过这样做,您还可以在onTouchEvent()中进行自定义触摸处理,而不是附加侦听器.这不是一个完整的例子,但类似于以下内容:
public class CustomImageView extends ImageView {
private ArrayList<Point) mTouches;
private Bitmap mMarker;
//Java constructor
public CustomImageView(Context context) {
super(context);
init();
}
//XML constructor
public CustomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
mTouches = new ArrayList<Point>();
mMarker = BitmapFactory.decodeResource(context.getResources(), R.drawable.my_marker_image);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//Capture a reference to each touch for drawing
if(event.getAction() == MotionEvent.ACTION_DOWN) {
mTouches.add( new Point(event.getX(), event.getY()) );
return true;
}
return super.onTouchEvent(event);
}
@Override
protected void onDraw(Canvas c) {
//Let the image be drawn first
super.onDraw(c);
//Draw your custom points here
Paint paint = new Paint();
for(Point p : mTouches) {
c.drawBitmap(mMarker, p.x, p.y, paint);
}
}
}
HTH!