用C#编写代码以获取已安装或选定打印机的最大dpi

Question

我希望能够获取已安装或所选打印机的最大Dpi。我已经尝试过：

PrinterSettings ps = new PrinterSettings();
        MessageBox.Show(ps.PrinterResolutions.ToString());

我得到的输出是：System.Drawing.Printing.PrinterSettings+PreinterResolutionCollection（期望的输出是600x600）。

- user1533870

Answer 1

使用LINQ:

PrinterSettings ps = new PrinterSettings();
var maxResolution = ps.PrinterResolutions.OfType<PrinterResolution>()
                                         .OrderByDescending(r => r.X)
                                         .ThenByDescending(r => r.Y)
                                         .First();
MessageBox.Show(String.Format("{0}x{1}", maxResolution.X, maxResolution.Y));

- tukaef

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显示错误：错误 4 'System.Drawing.Printing.PrinterSettings.PrinterResolutionCollection' 不包含定义为 'OrderByDescending' 的成员，也没有找到接受类型为 'System.Drawing.Printing.PrinterSettings.PrinterResolutionCollection' 的第一个参数的扩展方法 'OrderByDescending'（是否缺少 using 指令或程序集引用？）。 - user1533870

@Dhaval 请确保你拥有指令 using System.Linq;。 - tukaef

@Dhaval 我也编辑了我的答案，使其可以与 PrinterResolutions 实现的非泛型 IEnumerable 一起使用。 - tukaef

Answer 2

打印机分辨率是一个集合，您需要通过迭代来读取所有可用的分辨率，类似于：

foreach (string installedPrinter in PrinterSettings.InstalledPrinters)
{
    var ps = new PrinterSettings { PrinterName = installedPrinter };
    var maxResolution = ps.PrinterResolutions.Cast<PrinterResolution>().OrderByDescending(pr => pr.X).First();
    Console.WriteLine("{0}: {1}x{2}", installedPrinter, maxResolution.X, maxResolution.Y);
}

或者显示所有打印机及其 PrinterResolutions

foreach (string installedPrinter in PrinterSettings.InstalledPrinters)
{
    var ps = new PrinterSettings { PrinterName = installedPrinter };
    foreach (PrinterResolution printerResolution in ps.PrinterResolutions)
    {
        var tpl = printerResolution.Kind == PrinterResolutionKind.Custom ? "{0}: {1} ({2}x{3})" : "{0}: {1}";
        Console.WriteLine(tpl, installedPrinter, printerResolution.Kind, printerResolution.X, printerResolution.Y);
    }       
}

- David

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给Dve：我尝试过那个方法，但它显示的输出是[PrinterResolution High]，[PrinterResolution Medium]，[PrinterResolution Low]，[PrinterResolution Draft]。但我想要的答案是600x600（即我的打印机规格中的最大dpi）。 - user1533870

我得到了三个答案。第三个是佳能iP1300 -1x-1。什么是-1x-1？你能解释一下吗？ - user1533870

@Dhaval 只有当 PrinterResolutionKind == custom 时才返回分辨率。请参见此处：http://msdn.microsoft.com/zh-cn/library/system.drawing.printing.printersettings.printerresolutions(v=vs.100).aspx - David

Answer 3

这是我使用的 (.NET 2.0，所以没有 Linq)

public static int CompareResolutions(System.Drawing.Printing.PrinterResolution y, System.Drawing.Printing.PrinterResolution x)
{
    if (x.X*x.Y > y.X*y.Y) 
        return 1;
    else if (x.X * x.Y < y.X * y.Y) 
        return -1;

    return 0;
}


public static System.Drawing.Printing.PrinterResolution GetMaxResolution(System.Drawing.Printing.PrintDocument pd)
{
    return GetMaxResolution(pd.PrinterSettings);
}

public static System.Drawing.Printing.PrinterResolution GetMaxResolution(System.Drawing.Printing.PrinterSettings ps)
{
    System.Drawing.Printing.PrinterResolution prMax = null;

    System.Collections.Generic.List<System.Drawing.Printing.PrinterResolution> ls = new System.Collections.Generic.List<System.Drawing.Printing.PrinterResolution>();
    for (int i = 0; i < ps.PrinterResolutions.Count; ++i)
    {
        System.Drawing.Printing.PrinterResolution pres = ps.PrinterResolutions[i];
        ls.Add(pres);
    } // Next i

    ls.Sort(CompareResolutions);

    if (ls.Count > 0)
        prMax = ls[0];

    ls.Clear();
    ls = null;

    return prMax;
}

- Stefan Steiger

Answer 4

看起来PrinterResolutions是一个集合，你正在尝试将其转换为字符串值。

- Derek

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那么如何获得所需的输出，即600x600（我的打印机规格中的最大dpi）？ - user1533870