如何在安卓系统中通过触摸来拖动一张图片?请提供一个示例代码帮助我。
package com.examples.Touchmoveimage;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout.LayoutParams;
public class Touchmoveimage extends Activity {
int windowwidth;
int windowheight;
private LayoutParams layoutParams;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
windowwidth = getWindowManager().getDefaultDisplay().getWidth();
windowheight = getWindowManager().getDefaultDisplay().getHeight();
final ImageView balls = (ImageView) findViewById(R.id.ball);
balls.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
LayoutParams layoutParams = (LayoutParams) balls.getLayoutParams();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
int x_cord = (int) event.getRawX();
int y_cord = (int) event.getRawY();
if (x_cord > windowwidth) {
x_cord = windowwidth;
}
if (y_cord > windowheight) {
y_cord = windowheight;
}
layoutParams.leftMargin = x_cord - 25;
layoutParams.topMargin = y_cord - 75;
balls.setLayoutParams(layoutParams);
break;
default:
break;
}
return true;
}
});
}
}
运行良好!
您需要了解手势,尤其是滚动手势(在Android中称为拖动)和快速滑动手势。
我向您推荐这个教程:链接。它正是您所寻找的内容。
在Android中没有直接的方法来实现拖放操作。您需要编写一些类。请查看Launcher项目中的DragController.java和DragLayer.java。