Question

我正在尝试了解有关MonoTouch的更多信息，因此我尝试使用Quartz2D绘图。我想创建一个示例，我以编程方式绘制n矩形。问题是只绘制了第一个。我认为第二个被第一个删除/清除/覆盖。

这是我的代码：

SingleViewMTViewController.cs

public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        PointF locationOne = new PointF (5, 5);
        PointF locationTwo = new PointF (5, 100);
        SizeF size = new SizeF (120, 40);

        DraggableRectangle tView = new DraggableRectangle (locationOne, size, UIColor.Yellow);
        DraggableRectangle tView2 = new DraggableRectangle (locationTwo, size, UIColor.Brown);

        DraggableRectangle[] views = new DraggableRectangle[2];
        views [0] = tView;
        views [1] = tView2;

        View.AddSubviews (views);
    }

DraggableRectangle.cs

public class DraggableRectangle : UIView
{
    private CGPath path;
    private PointF _targetLocation;
    private SizeF _size;
    private UIColor _fillColor = UIColor.Brown;

    public DraggableRectangle (PointF targetLocation, SizeF size)
    {
        _targetLocation = targetLocation;
        _size = size;

        RectangleF frameRect = new RectangleF (_targetLocation.X, _targetLocation.Y, _size.Width, _size.Height);
        this.Frame = frameRect;
        this.BackgroundColor = UIColor.Clear; //without this, nothing is drawn
    }

    public DraggableRectangle (PointF targetLocation, SizeF size, UIColor fillColor):this(targetLocation,size)
    {
        _fillColor = fillColor;
    }

    public override void Draw (RectangleF rect)
    {
        //base.Draw (rect);
        //works without base-call?

        //get graphics context
        using (CGContext gctx = UIGraphics.GetCurrentContext ()) {

            //set up drawing attributes
            _fillColor.SetFill ();

            //create geometry
            path = new CGPath ();

            path.AddRect (new RectangleF (_targetLocation.X, _targetLocation.Y, _size.Width, _size.Height));

            path.CloseSubpath ();

            //add geometry to graphics context and draw it
            gctx.AddPath (path);        
            gctx.DrawPath (CGPathDrawingMode.FillStroke);   
        }       
    }

使用MonoTouch绘制独立矩形有更好的方法吗？或者可以请某人解释一下，我做错了什么？

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Answer 1

实际上，两个矩形都是绘制的。问题是您的_targetLocation.Y值。您要为视图的Frame及其矩形设置相同的 Y 值，并使用Draw方法绘制。

所以基本上，你的矩形是在视图边界之外绘制的。你的“棕色”视图的高度是40pt，而它的矩形是在Y = 100（在其可见部分下方）绘制的。

您必须区分这些值，因为视图的位置始终相对于其父坐标。

编辑：一个伪代码示例。

以下一行：

path.AddRect (new RectangleF (_targetLocation.X, _targetLocation.Y, _size.Width, _size.Height));

应该是这样的：

    path.AddRect (new RectangleF ({Frame.Width >= something >= 0}, 
{Frame.Height >= something >= 0}, width, height);

编辑＃2：

如果我更改路径的矩形，请使用以下命令：

path.AddRect (new RectangleF (0f, 0f, _size.Width, _size.Height));

这是我得到的......

Two rects

使用MonoTouch以编程方式绘制矩形

1 个答案: