如何通过触摸android来拖动图像？

Question

如何通过触摸android来拖动图像？ 请帮我提供示例代码。

Answer 1

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;
            }
        });
    }
}

效果很好!!

Answer 2

你需要阅读有关手势的信息，特别是Scroll - 这是Android中的拖累 - 和Fling。

我向你推荐this教程。它正是你要找的。

Answer 3

在Android中没有直接的拖放方式。你必须写一些课程。查看Launcher项目中的DragController.java，DragLayer.java。