位图图形VS WinForm控件图形 [英] Bitmap Graphics vs WinForm Control Graphics

问题描述

我只是用 Pdfium 的.NET端口命名的 PdfiumViewer 。这只是工作得很好，一旦呈现在WinForm控件但是当我尝试以使其在位图显示在WPF窗口（甚至是保存到磁盘）呈现的文本有问题。

I'm just using a .NET port of Pdfium named PdfiumViewer. It just works very well once rendered in the WinForm controls but when I try to render it on a Bitmap to show in the WPF windows (or even saving to disk) the rendered text has problem.

var pdfDoc = PdfiumViewer.PdfDocument.Load(FileName);
int width = (int)(this.ActualWidth - 30) / 2;
int height = (int)this.ActualHeight - 30;            

var bitmap = new System.Drawing.Bitmap(width, height);

var g = System.Drawing.Graphics.FromImage(bitmap);

g.FillRegion(System.Drawing.Brushes.White, new System.Drawing.Region(
    new System.Drawing.RectangleF(0, 0, width, height)));

pdfDoc.Render(1, g, g.DpiX, g.DpiY, new System.Drawing.Rectangle(0, 0, width, height), false);

// Neither of these are readable
image.Source = BitmapHelper.ToBitmapSource(bitmap);
bitmap.Save("test.bmp");

// Directly rendering to a System.Windows.Forms.Panel control works well
var controlGraphics = panel.CreateGraphics(); 
pdfDoc.Render(1, controlGraphics, controlGraphics.DpiX, controlGraphics.DpiY,
    new System.Drawing.Rectangle(0, 0, width, height), false);

这是引人注目的说，我测试了图形对象上几乎每一个可能的选项包括<$c$c>TextContrast,<$c$c>TextRenderingHint,<$c$c>SmoothingMode,<$c$c>PixelOffsetMode, ...

It's notable to say that I tested almost every possible options on the Graphics object including TextContrast,TextRenderingHint,SmoothingMode,PixelOffsetMode, ...

哪些配置我失踪，导致这个位图对象？

Which configurations I'm missing on the Bitmap object that cause this?

编辑2

很多搜索@BoeseB，并提到后，我只是发现Pdfium通过提供第二渲染方法渲染设备句柄和位图不同的<一个href=\"http://tickets.foxitsoftware.com/support/usermanuals/DLL311/group___f_p_d_f_v_i_e_w.html#ga78e560fce2c6efa038afd4ab64526baa\"相对=nofollow> FPDF_RenderPageBitmap ，目前我挣扎到其本机BGRA位图格式转换为托管位图。

After lots of searching and as @BoeseB mentioned I just found that Pdfium render device handle and bitmaps differently by providing a second render method FPDF_RenderPageBitmap and currently I'm struggling to convert its native BGRA bitmap format to managed Bitmap.

修改

TextRenderingHint 的不同模式

也试过 Application.SetCompatibleTextRenderingDefault（假），没有明显的区别。

Also tried Application.SetCompatibleTextRenderingDefault(false) with no noticeable difference.

推荐答案

这难道不是你的问题的？
看看最近修复它。
正如你所看到的，库所有者COMMITED PdfiumViewer的新版本。现在，你可以写这样的：

Isn't it your issue ? Look recent fix for it. As you can see, repository owner commited newer version of PdfiumViewer. Now you can write this way:

var pdfDoc = PdfDocument.Load(@"mydoc.pdf");
var pageImage = pdfDoc.Render(pageNum, width, height, dpiX, dpiY, isForPrinting);
pageImage.Save("test.png", ImageFormat.Png);

// to display it on WPF canvas
BitmapSource source = ImageToBitmapSource(pageImage);
canvas.DrawImage(source, rect);     // canvas is instance of DrawingContext

下面是转换图像到一个的ImageSource流行的做法

Here is a popular approach to convert Image to ImageSource

BitmapSource ImageToBitmapSource(System.Drawing.Image image)
{
    using(MemoryStream memory = new MemoryStream())
    {
        image.Save(memory, ImageFormat.Bmp);
        memory.Position = 0;
        var source = new BitmapImage();
        source.BeginInit();
        source.StreamSource = memory;
        source.CacheOption = BitmapCacheOption.OnLoad;
        source.EndInit();

        return source;
    }
}

这篇关于位图图形VS WinForm控件图形的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！