Android(安卓)露珠/水滴 拖拽 效果实现
16lz
2021-01-26
解释一下标题：
露珠拖拽/水滴拖拽：就是一个View不但能跟着手滑动。还能根据滑动速度，改变形状，像露珠或者水滴那样。
这里是效果实现的Demo
具体实现就是如下一个Java文件 DewdropView.java
package com.demo.dewdropdemo;import android.app.Activity;import android.content.res.Resources;import android.graphics.Canvas;import android.graphics.drawable.Drawable;import android.util.DisplayMetrics;import android.view.MotionEvent;import android.view.View;public class DewdropView extends View{ private final String TAG = "dewdrop"; //View的宽和高 private int width; private int height; //是否正在拖拽 private boolean isDraging = false; //手指触摸位置 private int touchPX; private int touchPY; //上一次统计的位置 private int mLastX = 0; private int mLastY = 0; //露珠效果大小 private final int rate = 2; //要绘制的图片资源 private Resources mRes; private Drawable mDrawable; //View的位置描述：Left、Top、Right、Bottom private int l,t,r,b; //手机屏幕尺寸 private int mScrrenWidth; private int mScrrenHeight; public DewdropView(Activity context) { super(context); // TODO Auto-generated constructor stub init(context); } /** * @title init * @author [email protected] * @description TODO 初始化 * @param context * @date 2013-11-05 4:03:05 PM */ private void init(Activity context){ mRes = context.getResources(); getScrrenSize(context); } /** * @title getScrrenSize * @author [email protected] * @description TODO 获得手机屏幕大小 * @param context * @date 2013-11-05 4:03:24 PM */ private void getScrrenSize(Activity context){ DisplayMetrics dm = new DisplayMetrics(); context.getWindowManager().getDefaultDisplay().getMetrics(dm); mScrrenWidth = dm.widthPixels; mScrrenHeight = dm.heightPixels; } /** * @title setSize * @author [email protected] * @description TODO 设置View的显示大小 * @param w * @param h * @date 2013-11-05 4:03:46 PM */ public void setSize(int w, int h){ if(w > mScrrenWidth){ w = mScrrenWidth; } if(h > mScrrenHeight){ h = mScrrenHeight; } width = w; height = h; r = l + width; b = t + height; validPos(); } /** * @title onDraging * @author [email protected] * @description TODO 拖拽事件处理 * @date 2013-11-05 4:08:56 PM */ private void onDraging(){ if(!isDraging){ return; } l = touchPX - width/2; t = touchPY - height/2; r = l + width; b = t + height; int speedX = getSpeedX(touchPX)*rate; mLastX = touchPX; int speedY = getSpeedY(touchPY)*rate; mLastY = touchPY; boolean isXValid = false; if(speedX > speedY){ isXValid = true; } if(isXValid){ t = t + speedY; b = b - speedY; l = l - speedX; r = r + speedX; }else{ t = t - speedY; b = b + speedY; l = l + speedX; r = r - speedX; } validPos(); layout(l, t, r, b); } /** * @title getSpeedX * @author [email protected] * @description TODO 获得X方向滑动速度 * @param x * @return * @date 2013-11-05 4:09:41 PM */ private int getSpeedX(int x){ if(mLastX == 0){ return 0; } return Math.abs(x - mLastX); } /** * @title getSpeedY * @author [email protected] * @description TODO 获得Y方向滑动速度 * @param y * @return * @date 2013-11-05 4:10:07 PM */ private int getSpeedY(int y){ if(mLastY == 0){ return 0; } return Math.abs(y - mLastY); } /** * @title setImageResource * @author [email protected] * @description TODO 要显示的图片资源 * @param id * @date 2013-11-05 4:10:28 PM */ public void setImageResource(int id){ if(mRes != null){ mDrawable = mRes.getDrawable(id); } } /** * @title validPos * @author [email protected] * @description TODO 使得View一直显示在屏幕之内 * @date 2013-11-04 8:19:51 PM */ private void validPos(){ if(l < 0){ l = 0; r = width; }else if(r > mScrrenWidth){ r = mScrrenWidth; l = r - width; } if(t < 0){ t = 0; b = height; }else if(b > mScrrenHeight){ b = mScrrenHeight; t = b - height; } } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); if(mDrawable == null) return; mDrawable.setBounds(0, 0, getWidth(), getHeight()); mDrawable.draw(canvas); } /** * @title touch * @author [email protected] * @description TODO 传递进来的touch事件处理 * @param event * @date 2013-11-05 4:11:20 PM */ public void touch(MotionEvent event) { // TODO Auto-generated method stub touchPX = (int)event.getX(); touchPY = (int)event.getY(); switch(event.getActionMasked()){ case MotionEvent.ACTION_DOWN: if(isInView()){ isDraging = true; } break; case MotionEvent.ACTION_UP: isDraging = false; if(isInView()){ reset(); } break; case MotionEvent.ACTION_MOVE: onDraging(); break; } } /** * @title isInView * @author [email protected] * @description TODO 判断点击位置是否在此View之上 * @return * @date 2013-11-04 8:17:30 PM */ private boolean isInView(){ if(touchPX > l && touchPX < r && touchPY > t && touchPY < b){ return true; } return false; } /** * @title reset * @author [email protected] * @description TODO 恢复图形正常大小和宽高比 * @date 2013-11-04 8:16:35 PM */ private void reset(){ l = touchPX - width/2; t = touchPY - height/2; r = l + width; b = t + height; validPos(); layout(l, t, r, b); }} 具体用法见 效果实现的Demo
更多相关文章
- Android(安卓)UI开发第八篇——ViewFlipper 左右滑动效果
- Android(安卓)自定义view 和 onMeasure方法介绍
- 动手学Android之九——列表没那么简单
- 使用ScrollView实现滚动效果
- 2014.04.22 ——— android listview header和左右滑动冲突
- UltimateRecyclerView发布，Android下新Listview的大杀器
- Android(安卓)仿微信对话列表滑动删除效果
- Android：使用canvas绘制饼状统计图（自动适应条目数量/大小）
- Android(安卓)新控件学习