android 阻尼效果(图片下拉变大)
16lz
2021-01-24
效果图动态gif图就不上传了 论坛最大只能支持2M的图片 我也难得麻烦了
当然静态的图片还是要提供的不然亲们都不知道阻尼是个什么东东
其实这个也是一个仿Ios的效果啦
不知道这个是什么的东西 请记住专业术语——阻尼
废话不多说直接贴代码
老规矩直接复制到自己View
DampView.Java
package com.yt1.zuni;import android.content.Context;import android.graphics.Rect;import android.util.AttributeSet;import android.view.MotionEvent;import android.widget.ImageView;import android.widget.ScrollView;import android.widget.Scroller;/** * 阻尼效果的scrollview */public class DampView extends ScrollView { private static final int LEN = 0xc8; private static final int DURATION = 500; private static final int MAX_DY = 200; private Scroller mScroller; TouchTool tool; int left, top; float startX, startY, currentX, currentY; int imageViewH; int rootW, rootH; ImageView imageView; boolean scrollerType; public DampView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public DampView(Context context, AttributeSet attrs) { super(context, attrs); mScroller = new Scroller(context); } public DampView(Context context) { super(context); } public void setImageView(ImageView imageView) { this.imageView = imageView; } @Override protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { return 0; } private int[] li = new int[2]; private int[] li2 = new int[2]; private float lastLy; private boolean startIsTop = true; @Override public boolean dispatchTouchEvent(MotionEvent event) { super.dispatchTouchEvent(event); int action = event.getAction(); if (!mScroller.isFinished()) { return super.onTouchEvent(event); } currentX = event.getX(); currentY = event.getY(); imageView.getLocationInWindow(li); getLocationOnScreen(li2); imageView.getTop(); switch (action) { case MotionEvent.ACTION_DOWN: if (li[1] != li2[1]) {// 判断开始触摸时，imageview和窗口顶部对齐没 startIsTop = false; } left = imageView.getLeft(); top = imageView.getBottom(); rootW = getWidth(); rootH = getHeight(); imageViewH = imageView.getHeight(); startX = currentX; startY = currentY; tool = new TouchTool(imageView.getLeft(), imageView.getBottom(), imageView.getLeft(), imageView.getBottom() + LEN); break; case MotionEvent.ACTION_MOVE: if (!startIsTop && li[1] == li2[1]) { startY = currentY; startIsTop = true; } if (imageView.isShown() && imageView.getTop() >= 0) { if (tool != null) { int t = tool.getScrollY(currentY - startY); if (!scrollerType && currentY < lastLy && imageView.getHeight() > imageViewH) { scrollTo(0, 0); imageView.getLocationInWindow(li); getLocationOnScreen(li2); android.view.ViewGroup.LayoutParams params = imageView.getLayoutParams(); params.height = t; imageView.setLayoutParams(params); if (imageView.getHeight() == imageViewH && li[1] == li2[1]) { scrollerType = true; } if (startIsTop && li[1] != li2[1]) { startIsTop = false; } } if (t >= top && t <= imageView.getBottom() + LEN && li[1] == li2[1] && currentY > lastLy) { android.view.ViewGroup.LayoutParams params = imageView.getLayoutParams(); params.height = t; imageView.setLayoutParams(params); } } scrollerType = false; } lastLy = currentY; break; case MotionEvent.ACTION_UP: if (li[1] == li2[1]) { scrollerType = true; mScroller.startScroll(imageView.getLeft(), imageView.getBottom(), 0 - imageView.getLeft(), imageViewH - imageView.getBottom(), DURATION); invalidate(); } startIsTop = true; break; } return true; } @Override public void computeScroll() { super.computeScroll(); if (mScroller.computeScrollOffset()) { int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); imageView.layout(0, 0, x + imageView.getWidth(), y); invalidate(); if (!mScroller.isFinished() && scrollerType && y > MAX_DY) { android.view.ViewGroup.LayoutParams params = imageView.getLayoutParams(); params.height = y; imageView.setLayoutParams(params); } } } public class TouchTool { private int startX, startY; public TouchTool(int startX, int startY, int endX, int endY) { super(); this.startX = startX; this.startY = startY; } public int getScrollX(float dx) { int xx = (int) (startX + dx / 2.5F); return xx; } public int getScrollY(float dy) { int yy = (int) (startY + dy / 2.5F); return yy; } }}应用与布局文件: 不贴代码了 贴图 特别简单
代码配置(最后一步 也是最重要的一步) 提示:
1.布局里面一定要有ImageView 并设置android:scaleType="centerCrop" 图片放大后不失帧 2.DampView 实际上是一个ScrollView 所以里面只能有一个控件 最好的办法是在里面写一层Linearlayout 所有东西这些道里面就好更多相关文章
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