我正在构建Xamarin Forms应用程序，该应用程序必须能够通过iPad上的Airprint在标签打印机上打印名称标签，但是在从真实设备上打印时，图像空白。标签是一个相当简单的HTML字符串，其中嵌入了base64编码的图像：
<html style="height: 100%">
<body style="height: 100%; margin: 0">
<div style="height: 100%; display: flex; flex-direction: column; justify-content: space-between">
<div style="display: flex; justify-content: space-between">
<span style="font-size: x-large">VISITOR</span>
<span><img src='data:image/jpeg;base64,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' /></span>
</div>
<div style="display:flex; flex-direction: column; align-items: center">
<span style="font-size: larger; font-weight: 600">[VisitorName]</span>
<span>[VisitorCompany]</span>
</div>
<div style="display: flex; justify-content: space-between">
<div style="display: flex; flex-direction: column">
<span>DATE OF VISIT</span>
<span>[CheckinTime]</span>
</div>
<div style="display: flex; flex-direction: column; align-items: flex-end">
<span>HOST</span>
<span>[HostName]</span>
</div>
</div>
</div>
</body>
</html>
我的初始实现在iOS模拟器上运行良好，但是在实际设备上，图像没有被打印（只是空白）：
private static void PrintToPrinter(string label, UIPrinter selectedPrinter)
{
var printInfo = UIPrintInfo.PrintInfo;
printInfo.JobName = "My Job";
printInfo.OutputType = UIPrintInfoOutputType.General;
printInfo.Orientation = UIPrintInfoOrientation.Landscape;
var htmlFormatter = new UIMarkupTextPrintFormatter(label);
var printer = UIPrintInteractionController.SharedPrintController;
printer.PrintInfo = printInfo;
printer.PrintFormatter = htmlFormatter;
printer.PrintToPrinter(selectedPrinter, (printInteractionController, completed, error) =>
{
if (!completed && error != null)
{
Console.WriteLine($"Error: {error.LocalizedDescription ?? ""}");
}
});
printInfo.Dispose();
htmlFormatter.Dispose();
}
我读到其他人有图像无法打印的问题，因为渲染显然是异步发生的：https://stackoverflow.com/a/40320983
因此，我的下一个尝试是将标记加载到Web视图中，但是我不确定如何等待标记完全加载，因此这是我的幼稚尝试。它永远不会超越while循环：
private static void PrintToPrinter(string label, UIPrinter selectedPrinter)
{
WkWebViewRenderer renderer = new WkWebViewRenderer();
renderer.LoadHtml(label, null);
while (renderer.IsLoading)
{
Thread.Sleep(100);
}
var printInfo = UIPrintInfo.PrintInfo;
printInfo.JobName = "My Job";
printInfo.OutputType = UIPrintInfoOutputType.General;
printInfo.Orientation = UIPrintInfoOrientation.Landscape;
var printer = UIPrintInteractionController.SharedPrintController;
printer.PrintInfo = printInfo;
printer.PrintFormatter = renderer.ViewPrintFormatter;
printer.PrintToPrinter(selectedPrinter, (printInteractionController, completed, error) =>
{
if (!completed && error != null)
{
Console.WriteLine($"Error: {error.LocalizedDescription ?? ""}");
}
});
printInfo.Dispose();
renderer.Dispose();
}
然后我尝试实例化一个WebView，但这只会打印一个空白页/标签：
private static void PrintToPrinter(string label, UIPrinter selectedPrinter)
{
var view = new WebView
{
Source = new HtmlWebViewSource { Html = label }
};
var renderer = Platform.CreateRenderer(view);
var printInfo = UIPrintInfo.PrintInfo;
printInfo.JobName = "My Job";
printInfo.OutputType = UIPrintInfoOutputType.General;
printInfo.Orientation = UIPrintInfoOrientation.Landscape;
var printer = UIPrintInteractionController.SharedPrintController;
printer.PrintInfo = printInfo;
printer.PrintFormatter = renderer.NativeView.ViewPrintFormatter;
printer.PrintToPrinter(selectedPrinter, (printInteractionController, completed, error) =>
{
if (!completed && error != null)
{
Console.WriteLine($"Error: {error.LocalizedDescription ?? ""}");
}
});
printInfo.Dispose();
renderer.Dispose();
}
[尝试找到一种等待视图加载的方法，我尝试了此方法，但是从未调用过Navigated事件：
private static void PrintToPrinter(string label, UIPrinter selectedPrinter)
{
var view = new WebView();
view.Navigated += (sender, e) =>
{
var renderer = Platform.CreateRenderer(view);
var printInfo = UIPrintInfo.PrintInfo;
printInfo.JobName = "My Job";
printInfo.OutputType = UIPrintInfoOutputType.General;
printInfo.Orientation = UIPrintInfoOrientation.Landscape;
var printer = UIPrintInteractionController.SharedPrintController;
printer.PrintInfo = printInfo;
printer.PrintFormatter = renderer.NativeView.ViewPrintFormatter;
printer.PrintToPrinter(selectedPrinter, (printInteractionController, completed, error) =>
{
if (!completed && error != null)
{
Console.WriteLine($"Error: {error.LocalizedDescription ?? ""}");
}
});
printInfo.Dispose();
renderer.Dispose();
};
view.Source = new HtmlWebViewSource { Html = label };
}
我不确定还可以尝试什么，但是我愿意接受任何建议。
我非常想这样做，但这太难了。最终将其内置于Forms9Patch-MIT许可的open source project。