我试图实现一个LinearLayout子类,它使用圆角绘制自己.从我的研究中,我设置setwillNotDraw(false)并覆盖onDraw()在画布中绘制一个圆角矩形：

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    int sc = canvas.saveLayer(0,getWidth(),getHeight(),drawPaint,Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
            | Canvas.FULL_COLOR_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG);
    canvas.drawRoundRect(bounds,mCornerRadius,roundPaint);
    canvas.restoretoCount(sc);
}

哪里：

drawPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
drawPaint.setColor(0xffffffff);
drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));

roundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
roundPaint.setColor(0xffffffff);

DST_IN在这里是正确的选择(根据APIDemos的例子),但是应该是透明的区域(圆角的)改为黑色背景,孩子的角落仍然可见.这是使用Android 4.2.2的galaxy Nexus的结果：

任何提示？

编辑：这是我想要实现的,对于拍摄的粗鲁感到遗憾:)

编辑2：我向GitHub添加了一个可运行的示例项目：https://github.com/venator85/RoundClippingLayout

谢谢

我正在创建一个 Windows 10 UWP应用程序,其中涉及BackgroundDownloader,这只适用于桌面而不是手机.

码：

var dl = new BackgroundDownloader();
    dl.CostPolicy = BackgroundTransferCostPolicy.Always;
    file = await localSoundsFolder.CreateFileAsync(name,CreationCollisionoption.ReplaceExisting);
    if (file != null)
    {
        var d = dl.CreateDownload(new Uri(uriTodownloadFrom,UriKind.RelativeOrAbsolute),file);
        d.Priority = BackgroundTransferPriority.High;

        var progressCallback = new Progress<DownloadOperation>(x => DownloadProgress(x,sc)); 
        try
        {
            await d.StartAsync().AsTask(cancellationToken.Token,progressCallback);
            //After this line it doesn't progress!
            CancellationTokenSource token = Utility.cancellationList[sc];
            if (token != null)
            {
                token.Cancel();
                Utility.cancellationList.Remove(sc);
                Debug.WriteLine("The sc has been removed from the download list");
            }
        }
        catch
        {
            return;
        }
    }


private static void DownloadProgress(DownloadOperation download,SoundClass sc)
{
    Debug.WriteLine("Callback");
    var value = download.Progress.BytesReceived * 100 / download.Progress.TotalBytesToReceive;
    Debug.WriteLine("The bytesReceived is {0} and total bytes is {1}",download.Progress.BytesReceived.ToString(),download.Progress.TotalBytesToReceive.ToString());
    new System.Threading.ManualResetEvent(false).WaitOne(10);
    sc.downloadProgress = value;
    if (download.Progress.Status == BackgroundTransferStatus.Completed || value >= 100)
    {
        Debug.WriteLine("DONE donwloading the file {0}",download.ResultFile.Name);
        Debug.WriteLine("The file name happened to be to be added was " + download.ResultFile.Name);
        string fileName = download.ResultFile.Name;
    }
}

行等待d.StartAsync().AsTask(cancellationToken.Token,progressCallback);该计划不进行.而且也没有错误.这不仅适用于手机在桌面上完美运行！我错过了什么？

BackgroundDownloader和我认为Windows UWP中的所有BackgroundTasks都难以使用它们. 您必须首先在当前解决方案中创建一个新的解决方案作为Windows运行时组件. 之后,您必须通过Package.AppxManifest链接它. 呃,不要忘记将运行时组件作为主项目的参考. 如果你做这些事情,希望它必须是有效的.但请确保您有一个RuntimeComponent并将其链接到您的项目中

我正在尝试创建一个自定义的NSWindow,所以我创建了一个带有适当的无边框窗口掩模并且可以工作.我提供自己的内容视图很好.但我想要做的是绘制圆角,也可以将子视图剪切到那些角落.这可能吗？

在我的内容视图中,我可以覆盖drawRect：并绘制一个带圆角的路径,但是当我向其添加子视图时,它们不会被剪裁.

我可以改为使我的内容视图支持图层并给它一个角半径(maskToBounds设置为YES)但是当我添加子视图时,它们仍然没有被我的圆角修剪.

有没有办法做到这一点？或者某种方式来绘制一个没有标题栏的NSWindow并且我可以完全控制绘图,并保持圆形的剪裁角落？

我能做的是提供我的NSWindow的自定义子类：

@implementation ELGRoundWindow

- (id)initWithContentRect:(NSRect)contentRect styleMask:(NSUInteger)aStyle backing:(NSbackingStoreType)bufferingType defer:(BOOL)flag
{
    self = [super initWithContentRect:contentRect styleMask:NSBorderlessWindowMask backing:bufferingType defer:flag];

    if ( self )
    {
        [self setStyleMask:NSBorderlessWindowMask];
        [self setopaque:NO];
        [self setBackgroundColor:[NSColor clearColor]];
    }

    return self;
}


- (void) setContentView:(NSView *)aView
{
    aView.wantsLayer            = YES;
    aView.layer.frame           = aView.frame;
    aView.layer.cornerRadius    = 20.0;
    aView.layer.masksToBounds   = YES;


    [super setContentView:aView];

}

@end

然后在IB中,我将我的内容视图的类更改为ELGRoundView：

@implementation ELGRoundView

- (void)drawRect:(NSRect)dirtyRect
{
    [[NSColor colorWithCalibratedRed:0.0 green:0.5 blue:1 alpha:1] set];
    NSRectFill(dirtyRect);
}

@end

我在内容视图中放置了另一个方形子视图,其中包含以下内容：

@implementation ELGSquareView

- (void)drawRect:(NSRect)dirtyRect
{
    [[NSColor colorWithCalibratedRed:0.0 green:0 blue:1 alpha:1] set];
    NSRectFill(dirtyRect);
}

@end

我结束了：