xamarin ios XibFree LinearLayout

本文详细介绍了如何利用XibFree框架创建自定义的UI布局,包括垂直线性布局、水平线性布局、按钮组件和图像视图的嵌套应用,展示了iOS应用程序界面设计的灵活性和强大功能。

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public override void LoadView()
{
    // This is a simple vertical LinearLayout.   ViewGroups are not implemented as UIViews - they're simply scaffolding for 
    // the layout of the contained NativeViews
    var layout = new LinearLayout(Orientation.Vertical)
    {
        Padding = new UIEdgeInsets(10,10,10,10),
        Gravity = Gravity.CenterVertical,
        SubViews = new View[] 
        {
            // A NativeView contains an iOS UIView
            new NativeView()
            {
                // This is the UIView
                View = new UIView(RectangleF.Empty)
                {
                    // Set properties here
                    BackgroundColor = UIColor.Red,
                },

                // This controls how it's laid out by its parent view group (in this case the outer linear layout)
                LayoutParameters = new LayoutParameters()
                {
                    Width = AutoSize.FillParent,
                    Height = 50,
                },
            },

            // Here we're nesting a horizontal linear layout inside the outer vertical linear layout
            new LinearLayout(Orientation.Horizontal)
            {
                // How to layout this linear layout within the outer one
                LayoutParameters = new LayoutParameters()
                {
                    Height = AutoSize.WrapContent,
                    Width = AutoSize.FillParent,
                },

                // Sub view collection
                SubViews = new View[]
                {
                    new NativeView()
                    {
                        // This time we're showing a UILabel
                        View = new UILabel(RectangleF.Empty)
                        {
                            BackgroundColor = UIColor.Purple,
                            Text="Hello World, this is a test to see if things wrap and measure correctly",
                            Lines = 0,
                            TextAlignment = UITextAlignment.Center,
                            TextColor = UIColor.White
                        },

                        LayoutParameters = new LayoutParameters()
                        {
                            Width = AutoSize.FillParent,
                            Height = AutoSize.WrapContent,      // Height calculated automatically based on text content!
                        },
                    },

                    new NativeView()
                    {
                        // Here we're hosting a button
                        View = new UIButton(UIButtonType.RoundedRect)
                        {
                        },
                        LayoutParameters = new LayoutParameters()
                        {
                            Width = AutoSize.WrapContent,               // Size of button determined by it's content
                            Height = AutoSize.WrapContent,
                            Gravity = Gravity.CenterVertical,
                            Margins = new UIEdgeInsets(0, 10, 0, 0),    // Put a margin on the left to separate it from the text

                        },
                        Init = v =>
                        {
                            // Because we can't set a button's title with a property, we use the Init property
                            // to execute some code.  Whatever action we assign to Init is simply executed immediately allowing
                            // us to to keep this code here with the rest of the layout definition
                            v.As<UIButton>().SetTitle("Hello", UIControlState.Normal);

                            // We can also setup an event handler
                            v.As<UIButton>().TouchUpInside += (sender,args) =>
                            {
                                new UIAlertView("Clicked", "", null, "OK").Show();
                            };
                        }
                    },
                }
            },
            new NativeView()
            {
                View = new UIImageView(UIImage.FromBundle("logo320.png"))
                {
                    ContentMode = UIViewContentMode.ScaleAspectFit,
                    //BackgroundColor = UIColor.White
                },
                LayoutParameters = new LayoutParameters()
                {
                    Width = AutoSize.FillParent,        // Overrall size determined by parent container width
                    Height = AutoSize.WrapContent,      // Height will be calculated by calling Measurer below
                    Margins = new UIEdgeInsets(10, 0, 0, 0)
                },
                Measurer = (v,s) =>
                {
                    // By supplying a custom measurer, we can do clever things like calculate a height for this
                    // image view that respects the aspect ratio of the image.  In this case the width is set
                    // to match the parent, whereas the height is wrapped.  To calculate the height, XibFree will
                    // call this function.
                    var iv = (UIImageView)v;
                    return new SizeF(s.Width, iv.Image.Size.Height * s.Width / iv.Image.Size.Width);
                },
            }
        },
    };

    // We've now defined our layout, to actually use it we simply create a UILayoutHost control and pass it the layout
    this.View = new XibFree.UILayoutHost(layout2);
    this.View.BackgroundColor=UIColor.Gray;

}

http://www.toptensoftware.com/xibfree/example_1

资源下载链接为: https://pan.quark.cn/s/9e7ef05254f8 行列式是线性代数的核心概念,在求解线性方程组、分析矩阵特性以及几何计算中都极为关键。本教程将讲解如何用C++实现行列式的计算,重点在于如何输出分数形式的结果。 行列式定义如下:对于n阶方阵A=(a_ij),其行列式由主对角线元素的乘积,按行或列的奇偶性赋予正负号后求和得到,记作det(A)。例如,2×2矩阵的行列式为det(A)=a11×a22-a12×a21,而更高阶矩阵的行列式可通过Laplace展开或Sarrus规则递归计算。 在C++中实现行列式计算时,首先需定义矩阵类或结构体,用二维数组存储矩阵元素,并实现初始化、加法、乘法、转置等操作。为支持分数形式输出,需引入分数类,包含分子和分母两个整数,并提供与整数、浮点数的转换以及加、减、乘、除等运算。C++中可借助std::pair表示分数,或自定义结构体并重载运算符。 计算行列式的函数实现上,3×3及以下矩阵可直接按定义计算,更大矩阵可采用Laplace展开或高斯 - 约旦消元法。Laplace展开是沿某行或列展开,将矩阵分解为多个小矩阵的行列式乘积,再递归计算。在处理分数输出时,需注意避免无限循环和除零错误,如在分数运算前先约简,确保分子分母互质,且所有计算基于整数进行,最后再转为浮点数,以避免浮点数误差。 为提升代码可读性和可维护性,建议采用面向对象编程,将矩阵类和分数类封装,每个类有明确功能和接口,便于后续扩展如矩阵求逆、计算特征值等功能。 总结C++实现行列式计算的关键步骤:一是定义矩阵类和分数类;二是实现矩阵基本操作;三是设计行列式计算函数;四是用分数类处理精确计算;五是编写测试用例验证程序正确性。通过这些步骤,可构建一个高效准确的行列式计算程序,支持分数形式计算,为C++编程和线性代数应用奠定基础。
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