Android View拖拽/拖放DragAndDrop自定义View.DragShadowBuilder，Kotlin（2）

Kotlin 复制代码

import android.graphics.Canvas
import android.graphics.Point
import android.graphics.drawable.ColorDrawable
import android.os.Bundle
import android.util.Log
import android.view.DragEvent
import android.view.View
import android.view.View.OnDragListener
import android.view.View.OnLongClickListener
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import androidx.core.content.ContextCompat

class MainActivity : AppCompatActivity() {
    private val TAG = "fly"

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val imageView = findViewById<ImageView>(R.id.image)

        imageView.setOnLongClickListener(object : OnLongClickListener {
            //长按事件触发拖拽
            override fun onLongClick(v: View?): Boolean {
                Log.d(TAG, "onLongClick")

                val builder = MyDragShadowBuilder(imageView)
                imageView.startDragAndDrop(
                    null,
                    builder,
                    null,
                    0
                )

                return true
            }
        })

        imageView.setOnDragListener(object : OnDragListener {
            override fun onDrag(v: View?, event: DragEvent?): Boolean {
                when (event?.action) {
                    DragEvent.ACTION_DRAG_STARTED -> Log.d(TAG, "DragEvent.ACTION_DRAG_STARTED")
                    DragEvent.ACTION_DRAG_ENTERED -> Log.d(TAG, "DragEvent.ACTION_DRAG_ENTERED")
                    DragEvent.ACTION_DRAG_ENDED -> Log.d(TAG, "DragEvent.ACTION_DRAG_ENDED")
                }

                return true
            }
        })
    }

    class MyDragShadowBuilder(private var imageView: ImageView) : View.DragShadowBuilder() {
        //自定义绘制一个拖放时显示的阴影色块
        private val shadow = ColorDrawable(
            ContextCompat.getColor(
                imageView.context,
                android.R.color.holo_green_light
            )
        )

        override fun onProvideShadowMetrics(outShadowSize: Point?, outShadowTouchPoint: Point?) {
            val width: Int = imageView.width * 2
            val height: Int = imageView.height * 2

            shadow.setBounds(0, 0, width, height)

            //拖动图像的宽和高
            outShadowSize?.set(width, height)

            //手指在拖动图像的位置 中点
            outShadowTouchPoint?.set(width / 2, height / 2)
        }

        override fun onDrawShadow(canvas: Canvas) {
            shadow.draw(canvas)
        }
    }
}

Android View拖拽startDragAndDrop，Kotlin-CSDN博客一个Android手势缩放图片的工具类；Android DynamicGrid：拖曳交换位置Android DynamicGrid是一个第三方开源项目，DynamicGrid在github上的项目主页是：https://github.com/askerov/DynamicGrid它实现在一个网格布局内，拖曳任意子view实现动态的交换位置，这很类似手机的桌面，手机桌面的图标，均可自由拖曳实现摆放位置的交换，如动图所示：_android 拖拽交换位置。但是还有一些遗漏问题尚未解决：垂直方向的拖曳。https://blog.csdn.net/zhangphil/article/details/133994955