QuickLook/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfPageExtension.cs

// Copyright © 2017-2025 QL-Win Contributors
//
// This file is part of QuickLook program.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using PdfiumViewer;
using QuickLook.Common.ExtensionMethods;
using QuickLook.Common.Helpers;
using System;
using System.Drawing;
using System.Windows.Media.Imaging;

namespace QuickLook.Plugin.PDFViewer;

internal static class PdfPageExtension
{
    private static int _renderCount;
    private static readonly object LockObj = new object();

    public static BitmapSource RenderThumbnail(this PdfDocumentWrapper doc, int page)
    {
        lock (LockObj)
        {
            if (_renderCount++ == 50)
            {
                doc.Refresh();
                _renderCount = 0;
            }
        }

        var size = doc.PdfDocument.PageSizes[page];
        var factorX = 60d / size.Width;
        var factorY = 120d / size.Height;

        return doc.Render(page, Math.Min(factorX, factorY), false);
    }

    public static BitmapSource Render(this PdfDocumentWrapper doc, int page, double factor, bool fixDpi = true)
    {
        var scale = DisplayDeviceHelper.GetCurrentScaleFactor();
        var dpiX = fixDpi ? scale.Horizontal * DisplayDeviceHelper.DefaultDpi : 96;
        var dpiY = fixDpi ? scale.Vertical * DisplayDeviceHelper.DefaultDpi : 96;

        Bitmap bitmap;

        lock (LockObj)
        {
            var size = doc.PdfDocument.PageSizes[page];
            var realWidth = (int)Math.Round(size.Width * scale.Horizontal * factor);
            var realHeight = (int)Math.Round(size.Height * scale.Vertical * factor);

            bitmap = doc.PdfDocument.Render(page, realWidth, realHeight, dpiX, dpiY, PdfRotation.Rotate0,
                PdfRenderFlags.LimitImageCacheSize | PdfRenderFlags.LcdText | PdfRenderFlags.Annotations |
                PdfRenderFlags.ForPrinting, true) as Bitmap;
        }

        var bs = bitmap?.ToBitmapSource();
        bitmap?.Dispose();

        bs?.Freeze();
        return bs;
    }
}