PDFsharp在图形下绘制文本 [英] PDFsharp draws text under graphics

问题描述

我正在使用PDFsharp从头开始生成PDF文档。我正在尝试在渐变填充矩形的顶部写入文本。生成文档后，渐变显示在文本顶部，使文本完全隐藏。

  using（var document = new PdfDocument （））
 {
 var page = document.AddPage（）; 
 var graphics = XGraphics.FromPdfPage（page，XGraphicsPdfPageOptions.Append）; 
 graphics.SmoothingMode = XSmoothingMode.HighQuality; 
 
 var bounds = new XRect（graphics.PageOrigin，graphics.PageSize）; 
 graphics.DrawRectangle（
 new XLinearGradientBrush（
界限，
 XColor.FromKnownColor（XKnownColor.Red），
 XColor.FromKnownColor（XKnownColor.White），
 XLinearGradientMode.ForwardDiagonal），
 bounds）; 
 graphics.DrawString（
Hello World！，
 new XFont（Arial，20），
 XBrushes.Black，
 bounds.Center，
 XStringFormats.Center）; 
 
 document.Save（test.pdf）; 
 document.Close（）; 
} 
  

如何使文字在矩形顶部呈现？

我发现后面绘制的任何图像都会显示在矩形的顶部。这只是隐藏在后面的文本。

解决方案

试试这样：

< pre $ 使用（var document = new PdfDocument（））
{
var page = document.AddPage（）;
var graphics = XGraphics.FromPdfPage（page，XGraphicsPdfPageOptions.Append）;
graphics.SmoothingMode = XSmoothingMode.HighQuality;

var bounds = new XRect（graphics.PageOrigin，graphics.PageSize）;
var state = graphics.Save（）;
graphics.DrawRectangle（
new XLinearGradientBrush（
界限，
XColor.FromKnownColor（XKnownColor.Red），
XColor.FromKnownColor（XKnownColor.White），
XLinearGradientMode.ForwardDiagonal），
bounds）;
graphics.Restore（state）;
graphics.DrawString（
Hello World！，
new XFont（Arial，20），
XBrushes.Black，
bounds.Center，
XStringFormats.Center）;

document.Save（test.pdf）;
document.Close（）;
}


不幸的是，根据此论坛帖子。
解决方法是：保存和还原 XGraphics 操作之间的对象状态。

I am using PDFsharp to generate a PDF document from scratch. I am trying to write text on top of a gradient filled rectangle. After generating the document, the gradient appears on top of the text rendering the text completely hidden.

using (var document = new PdfDocument())
{
    var page = document.AddPage();
    var graphics = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
    graphics.SmoothingMode = XSmoothingMode.HighQuality;

    var bounds = new XRect(graphics.PageOrigin, graphics.PageSize);
    graphics.DrawRectangle(
        new XLinearGradientBrush(
            bounds,
            XColor.FromKnownColor(XKnownColor.Red),
            XColor.FromKnownColor(XKnownColor.White),
            XLinearGradientMode.ForwardDiagonal),
        bounds);
    graphics.DrawString(
        "Hello World!",
        new XFont("Arial", 20),
        XBrushes.Black,
        bounds.Center,
        XStringFormats.Center);

    document.Save("test.pdf");
    document.Close();
}

How can I make the text render on top of the rectangle?

I find that any images I draw later will appear on top of the rectangle. It’s only text that hides behind.

解决方案

Try it like this:

using (var document = new PdfDocument())
{
    var page = document.AddPage();
    var graphics = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
    graphics.SmoothingMode = XSmoothingMode.HighQuality;

    var bounds = new XRect(graphics.PageOrigin, graphics.PageSize);
    var state = graphics.Save();
    graphics.DrawRectangle(
        new XLinearGradientBrush(
            bounds,
            XColor.FromKnownColor(XKnownColor.Red),
            XColor.FromKnownColor(XKnownColor.White),
            XLinearGradientMode.ForwardDiagonal),
        bounds);
    graphics.Restore(state);
    graphics.DrawString(
        "Hello World!",
        new XFont("Arial", 20),
        XBrushes.Black,
        bounds.Center,
        XStringFormats.Center);

    document.Save("test.pdf");
    document.Close();
}

Unfortunately, there is a bug in the library's code according to this forum post. The workaround is to Save and Restore the XGraphics object's state between operations.

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