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

水深无声 2024-02-21 11:38 74阅读 0赞

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

###  ###

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)
            }
        }
    }

![20b8eed226bf49fab11f48ce1d79931a.png][]

[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。![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/133994955][Android View_startDragAndDrop_Kotlin-CSDN_Android_Android DynamicGrid_Android DynamicGrid_DynamicGrid_github_https_github.com_askerov_DynamicGrid_view_android _favicon32.ico_https_blog.csdn.net_zhangphil_article_details_133994955]

[20b8eed226bf49fab11f48ce1d79931a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/21/bd0870e86d944bcd9b0f66b1e6e06b40.png
[favicon32.ico]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/21/949eb61434c14521bb354f274505a38e.png
[Android View_startDragAndDrop_Kotlin-CSDN_Android_Android DynamicGrid_Android DynamicGrid_DynamicGrid_github_https_github.com_askerov_DynamicGrid_view_android _favicon32.ico_https_blog.csdn.net_zhangphil_article_details_133994955]: https://blog.csdn.net/zhangphil/article/details/133994955