小编Sud*_*dha的帖子

我想在按下时删除按钮背景颜色,并且喜欢具有透明背景,因为我使用图像作为背景.
鼠标悬停时能够通过以下代码删除边框:

btn.BorderThickness = new Thickness(0,0,0,0);
btn.Padding = new Thickness(0, 0, 0, 0);

并通过设置:

btn.Background = new Windows.UI.Xaml.Media.SolidColorBrush(Windows.UI.Colors.Transparent);

但是我点击它时无法删除背景,它显示的是灰色背景.
任何建议将不胜感激.

我需要实现的是，在将屏幕从纵向更改为横向时向现有页面添加布局。我设法使用void OnSizeAllocated(double width, double height)检测方向变化。但我无法在此事件上添加布局。

我的示例 C# 代码是

   public class MyLayoutView : ContentPage
   {
      StackLayout portraitcontent = null;
      StackLayout landscapecontent = null;
      StackLayout footer = null;

   public MyLayoutView ()
    {

    portraitcontent = new StackLayout ();
    landscapecontent = new StackLayout ();
    footer = new StackLayout ();

    this.Padding = new Thickness(0, Device.OnPlatform(20, 0, 0), 0, 0);
    this.BackgroundColor = Color.FromHex ("#ffffff");
    this.Content = new StackLayout
        {
            Children =
            {
                portraitcontent ,
                landscapecontent ,
                footer 
            }
            };
         }
   }

OnSizeAllocated 方法

   protected …

将Xamarin Forms更新为1.3.1版本后,我收到以下错误.
也试过更新Xamarin.Forms.Labs to 1.2.1 pre2,它也没有帮助.

[MonoDroid] UNHANDLED EXCEPTION:
[MonoDroid] System.NullReferenceException: Object reference not set to an instance of an object
[MonoDroid] at Xamarin.Forms.Platform.Android.FormsApplicationActivity.OnDestroy () <IL 0x0002d, 0x000d8>
[MonoDroid] at Xamarin.Forms.Labs.Droid.XFormsApplicationDroid.OnDestroy () [0x0001f] in c:\Users\rmarinho\Documents\GitHub\Xamarin-Forms-Labs\src\Xamarin.Forms.Labs\Xamarin.Forms.Labs.Droid\XFormsApp.cs:61
[MonoDroid] at Android.App.Activity.n_OnDestroy (intptr,intptr) [0x00009] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.20-series/ba9bbbdd/source/monodroid/src/Mono.Android/platforms/android-17/src/generated/Android.App.Activity.cs:2524
[MonoDroid] at (wrapper dynamic-method) object.e36a43a7-84b6-4476-8a62-6959a3b43e6a (intptr,intptr) <IL 0x00011, 0x0003b>

有关如何解决此错误的任何帮助？

我一直在尝试用xamarin表单录制音频,没有直接的方法可以做到这一点所以我试图通过自定义渲染实现它,我已经从这里按照示例.

// AVAudioRecorder创作

        //set up the NSObject Array of values that will be combined with the keys to make the NSDictionary
        NSObject[] values = new NSObject[]
        {
            NSNumber.FromFloat (16000.0f), //Sample Rate
            NSNumber.FromInt32 ((int)AudioToolbox.AudioFormatType.MPEG4AAC), //AVFormat
            NSNumber.FromInt32 (1), //Channels
            NSNumber.FromInt32 (16), //PCMBitDepth  
            NSNumber.FromBoolean (false), //IsBigEndianKey
            NSNumber.FromBoolean (false) //IsFloatKey
        };

        //Set up the NSObject Array of keys that will be combined with the values to make the NSDictionary
        NSObject[] keys = new NSObject[]
        {
            AVAudioSettings.AVSampleRateKey,
            AVAudioSettings.AVFormatIDKey,
            AVAudioSettings.AVNumberOfChannelsKey,
            AVAudioSettings.AVLinearPCMBitDepthKey,
            AVAudioSettings.AVLinearPCMIsBigEndianKey,
            AVAudioSettings.AVLinearPCMIsFloatKey
        }; …