Android之监听View的两个指头是放大和缩小
16lz
2021-01-26
我们有时需要对view进行手势监听,通过两个手指开始距离和结束距离,来判断放大缩小,下面是实现代码,所有View通用。
private double nLenStart = 0;//监听 WebView所用手势@Override public boolean onTouch(View v, MotionEvent event) { int nCnt = event.getPointerCount(); int n = event.getAction(); if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_POINTER_DOWN && 2 == nCnt)//2表示两个手指 { for (int i = 0; i < nCnt; i++) { float x = event.getX(i); float y = event.getY(i); Point pt = new Point((int) x, (int) y); } int xlen = Math.abs((int) event.getX(0) - (int) event.getX(1)); int ylen = Math.abs((int) event.getY(0) - (int) event.getY(1)); nLenStart = Math.sqrt((double) xlen * xlen + (double) ylen * ylen); } else if ((event.getAction() & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_POINTER_UP && 2 == nCnt) { for (int i = 0; i < nCnt; i++) { float x = event.getX(i); float y = event.getY(i); Point pt = new Point((int) x, (int) y); } int xlen = Math.abs((int) event.getX(0) - (int) event.getX(1)); int ylen = Math.abs((int) event.getY(0) - (int) event.getY(1)); double nLenEnd = Math.sqrt((double) xlen * xlen + (double) ylen * ylen); if (nLenEnd > nLenStart)//通过两个手指开始距离和结束距离,来判断放大缩小 { Toast.makeText(getApplicationContext(), "放大", Toast.LENGTH_SHORT).show(); tv_web_danGe.getSettings().setTextSize(WebSettings.TextSize.LARGER); tv_web_danGe.reload(); tv_web_danGe.loadDataWithBaseURL(null, getHtmlData(content),"text/html","UTF-8",null);//显示WebView } else { Toast.makeText(getApplicationContext(), "缩小", Toast.LENGTH_SHORT).show(); tv_web_danGe.getSettings().setTextSize(WebSettings.TextSize.NORMAL); tv_web_danGe.reload(); tv_web_danGe.loadDataWithBaseURL(null, getHtmlData(content),"text/html","UTF-8",null);//显示WebView } } return false; }
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