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elwig/Elwig/Helpers/Printing/PdfPrintDocument.cs
Lorenz Stechauner 751246537e
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Printing: Replace PdfiumViewer with native pdfium.dll binary
2026-02-17 17:22:33 +01:00

103 lines
4.0 KiB
C#

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Printing;
using System.Runtime.InteropServices;
namespace Elwig.Helpers.Printing {
public class PdfPrintDocument : PrintDocument {
private readonly IntPtr _handle;
private readonly int _pageCount;
private readonly double _dpi;
private int _currentPage;
public PdfPrintDocument(string path, string? password = null, double dpi = 300.0) :
base() {
_handle = PdfiumNative.FPDF_LoadDocument(path, password);
_pageCount = PdfiumNative.FPDF_GetPageCount(_handle);
_dpi = dpi;
}
protected override void Dispose(bool disposing) {
PdfiumNative.FPDF_CloseDocument(_handle);
base.Dispose(disposing);
}
protected override void OnBeginPrint(PrintEventArgs evt) {
_currentPage = (PrinterSettings.FromPage != 0) ? (PrinterSettings.FromPage - 1) : 0;
base.OnBeginPrint(evt);
}
protected override void OnPrintPage(PrintPageEventArgs evt) {
if (_currentPage < _pageCount) {
IntPtr page = PdfiumNative.FPDF_LoadPage(_handle, _currentPage);
double width = PdfiumNative.FPDF_GetPageWidth(page);
double height = PdfiumNative.FPDF_GetPageHeight(page);
int pixelWidth = (int)(width / 72.0 * _dpi);
int pixelHeight = (int)(height / 72.0 * _dpi);
IntPtr bitmap = PdfiumNative.FPDFBitmap_Create(pixelWidth, pixelHeight, 1);
PdfiumNative.FPDF_RenderPageBitmap(bitmap, page, 0, 0, pixelWidth, pixelHeight, 0, 0);
IntPtr buffer = PdfiumNative.FPDFBitmap_GetBuffer(bitmap);
int stride = PdfiumNative.FPDFBitmap_GetStride(bitmap);
using (var bmp = new Bitmap(pixelWidth, pixelHeight, stride, PixelFormat.Format32bppArgb, buffer)) {
evt.Graphics?.DrawImage(bmp, evt.PageBounds);
}
_currentPage++;
PdfiumNative.FPDFBitmap_Destroy(bitmap);
PdfiumNative.FPDF_ClosePage(page);
}
evt.HasMorePages = _currentPage < ((PrinterSettings.ToPage == 0) ? _pageCount : Math.Min(PrinterSettings.ToPage, _pageCount));
base.OnPrintPage(evt);
}
}
internal partial class PdfiumNative {
[LibraryImport("pdfium.dll")]
public static partial void FPDF_InitLibrary();
[LibraryImport("pdfium.dll")]
public static partial void FPDF_DestroyLibrary();
[LibraryImport("pdfium.dll", StringMarshalling = StringMarshalling.Utf8)]
public static partial IntPtr FPDF_LoadDocument(string filePath, string? password);
[LibraryImport("pdfium.dll")]
public static partial void FPDF_CloseDocument(IntPtr document);
[LibraryImport("pdfium.dll")]
public static partial int FPDF_GetPageCount(IntPtr document);
[LibraryImport("pdfium.dll")]
public static partial IntPtr FPDF_LoadPage(IntPtr document, int pageIndex);
[LibraryImport("pdfium.dll")]
public static partial void FPDF_ClosePage(IntPtr page);
[LibraryImport("pdfium.dll")]
public static partial double FPDF_GetPageWidth(IntPtr page);
[LibraryImport("pdfium.dll")]
public static partial double FPDF_GetPageHeight(IntPtr page);
[LibraryImport("pdfium.dll")]
public static partial IntPtr FPDFBitmap_Create(int width, int height, int alpha);
[LibraryImport("pdfium.dll")]
public static partial void FPDFBitmap_Destroy(IntPtr bitmap);
[LibraryImport("pdfium.dll")]
public static partial IntPtr FPDFBitmap_GetBuffer(IntPtr bitmap);
[LibraryImport("pdfium.dll")]
public static partial int FPDFBitmap_GetStride(IntPtr bitmap);
[LibraryImport("pdfium.dll")]
public static partial void FPDF_RenderPageBitmap(IntPtr bitmap, IntPtr page, int start_x, int start_y, int size_x, int size_y, int rotate, int flags);
}
}