using Android.App; using Android.Widget; using Android.OS; using Android.Content; using Android.Runtime; using Android.Net; using Microsoft.International.Converters.PinYinConverter; using System; using System.Text; using Android.Webkit; using Android.Views; using System.Collections.Generic; namespace android_filepiker_demo_test { [Activity(Label = "android_filepiker_demo_test", MainLauncher = true, Icon = "@drawable/icon")] public class MainActivity : Activity { public class WebViewTouchParameter { public double Distance { get; set; } public int FontSize { get; set; } public int MinFontSize { get; set; } public int MaxFontSize { get; set; } } public delegate void FontSizeChanged(int fontSize); protected override void OnCreate(Bundle bundle) { base.OnCreate(bundle); SetContentView(Resource.Layout.Main); var button1 = FindViewById<Button>(Resource.Id.button1); button1.Click += Button1_Click; var web1 = FindViewById<WebView>(Resource.Id.web1); web1.Touch += Web1_Touch; web1.LoadData("<html><body style='font-size:12px;'><h1>abcde</h1></body></html>", "text/html", "utf-8"); } private void Web1_Touch(object sender, Android.Views.View.TouchEventArgs e) { WebViewTouchHandler(e, new WebViewTouchParameter { MinFontSize = 12, MaxFontSize = 50 }, delegate(int fontSize) { var web1 = FindViewById<WebView>(Resource.Id.web1); web1.LoadDataWithBaseURL(null, "<html><body style='font-size:" + fontSize + "px;'><h1>" + fontSize + "px,abcde</h1></body></html>", "text/html", "utf-8", null); }); } private void Button1_Click(object sender, System.EventArgs e) { } } }
private void WebViewTouchHandler(Android.Views.View.TouchEventArgs e, WebViewTouchParameter p, FontSizeChanged fsc) { var ev = e.Event; var action = ev.Action; switch (action) { case MotionEventActions.Pointer2Down: { System.Diagnostics.Debug.Print("Pointer2Down"); p.Distance = Math.Abs(Math.Sqrt(Math.Pow(ev.GetX(0) - ev.GetX(1), 2) + Math.Pow(ev.GetY(0) - ev.GetY(1), 2))); break; } case MotionEventActions.Move: { if (e.Event.PointerCount == 2) { var distance = Math.Abs(Math.Sqrt(Math.Pow(ev.GetX(0) - ev.GetX(1), 2) + Math.Pow(ev.GetY(0) - ev.GetY(1), 2))); p.FontSize += (int)((distance - p.Distance) / 7); if (p.FontSize > p.MaxFontSize) p.FontSize = p.MaxFontSize; if (p.FontSize < p.MinFontSize) p.FontSize = p.MinFontSize; if (fsc != null && Math.Abs(distance - p.Distance) > 7) fsc(p.FontSize); p.Distance = distance; } break; } case MotionEventActions.Up: { break; } case MotionEventActions.Cancel: { break; } case MotionEventActions.Pointer2Up: { break; } } }
此代码经过测试，可以稳定实现放大缩小。代码衔接调用处参数可能需要调试，最新优化调试后，我只更新了最后一段核心代码段。