Use Pdfium-allocated buffers for correctness and simplicity

#178
cyanfish · Aug 31, 2023 · 8edee06 · 8edee06
1 parent 15b732a
commit 8edee06
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Showing 3 changed files with 23 additions and 31 deletions.
diff --git a/NAPS2.Sdk/Pdf/Pdfium/PdfBitmap.cs b/NAPS2.Sdk/Pdf/Pdfium/PdfBitmap.cs
@@ -5,16 +5,19 @@ internal class PdfBitmap : NativePdfiumObject
     public const uint BLACK = 0;
     public const uint WHITE = uint.MaxValue;
 
-    public static PdfBitmap CreateFromPointerBgr(int width, int height, IntPtr scan0, int stride)
+    public static PdfBitmap CreateFromPointerBgr(int width, int height, IntPtr scan0, int stride) =>
+        CreateFromPointer(width, height, scan0, stride, PdfiumNativeLibrary.FPDFBitmap_BGR);
+
+    public static PdfBitmap CreateFromPointer(int width, int height, IntPtr scan0, int stride, int format)
     {
         return new PdfBitmap(
-            Native.FPDFBitmap_CreateEx(width, height, PdfiumNativeLibrary.FPDFBitmap_BGR, scan0, stride));
+            Native.FPDFBitmap_CreateEx(width, height, format, scan0, stride));
     }
 
-    public static PdfBitmap CreateFromPointer(int width, int height, IntPtr scan0, int stride, int format)
+    public static PdfBitmap Create(int width, int height, int format)
     {
         return new PdfBitmap(
-            Native.FPDFBitmap_CreateEx(width, height, format, scan0, stride));
+            Native.FPDFBitmap_CreateEx(width, height, format, IntPtr.Zero, 0));
     }
 
     internal PdfBitmap(IntPtr handle) : base(handle)

diff --git a/NAPS2.Sdk/Pdf/PdfiumImageExtractor.cs b/NAPS2.Sdk/Pdf/PdfiumImageExtractor.cs
@@ -78,26 +78,21 @@ private static IMemoryImage RenderPdfPageToNewImage(ImageContext imageContext, P
         return CopyPdfBitmapToNewImage(imageContext, pdfBitmap, metadata);
     }
 
-    private static unsafe PdfBitmap RenderPdfPageToBitmap(PdfPage page, PdfImageMetadata imageMetadata)
+    private static PdfBitmap RenderPdfPageToBitmap(PdfPage page, PdfImageMetadata imageMetadata)
     {
         var w = imageMetadata.Width;
         var h = imageMetadata.Height;
-        var (subPixelType, format) = imageMetadata.BitsPerPixel switch
+        var format = imageMetadata.BitsPerPixel switch
         {
-            1 or 8 => (SubPixelType.Gray, PdfiumNativeLibrary.FPDFBitmap_Gray),
-            24 => (SubPixelType.Bgr, PdfiumNativeLibrary.FPDFBitmap_BGR),
-            32 => (SubPixelType.Bgra, PdfiumNativeLibrary.FPDFBitmap_BGRA),
+            1 or 8 => PdfiumNativeLibrary.FPDFBitmap_Gray,
+            24 => PdfiumNativeLibrary.FPDFBitmap_BGR,
+            32 => PdfiumNativeLibrary.FPDFBitmap_BGRA,
             _ => throw new ArgumentException()
         };
-        var pixelInfo = new PixelInfo(w, h, subPixelType);
-        var buffer = new byte[pixelInfo.Length];
-        fixed (byte* ptr = buffer)
-        {
-            var pdfiumBitmap = PdfBitmap.CreateFromPointer(w, h, (IntPtr) ptr, pixelInfo.Stride, format);
-            pdfiumBitmap.FillRect(0, 0, w, h, PdfBitmap.WHITE);
-            pdfiumBitmap.RenderPage(page, 0, 0, w, h);
-            return pdfiumBitmap;
-        }
+        var pdfiumBitmap = PdfBitmap.Create(w, h, format);
+        pdfiumBitmap.FillRect(0, 0, w, h, PdfBitmap.WHITE);
+        pdfiumBitmap.RenderPage(page, 0, 0, w, h);
+        return pdfiumBitmap;
     }
 
     private static IMemoryImage CopyPdfBitmapToNewImage(ImageContext imageContext, PdfBitmap pdfBitmap,

diff --git a/NAPS2.Sdk/Pdf/PdfiumPdfRenderer.cs b/NAPS2.Sdk/Pdf/PdfiumPdfRenderer.cs
@@ -74,21 +74,15 @@ public unsafe IMemoryImage RenderPageToNewImage(ImageContext imageContext, PdfPa
         var bitmap = imageContext.Create(widthInPx, heightInPx, ImagePixelFormat.RGB24);
         bitmap.SetResolution(xDpi, yDpi);
 
-        // As Pdfium only supports BGR, to be general we need to store it in an intermediate buffer,
-        // then use a copy operation to get the data to our output image (which might be BGR or RGB).
-        var pixelInfo = new PixelInfo(widthInPx, heightInPx, SubPixelType.Bgr);
-        var buffer = new byte[pixelInfo.Length];
-        fixed (byte* ptr = buffer)
-        {
-            using var pdfiumBitmap =
-                PdfBitmap.CreateFromPointerBgr(widthInPx, heightInPx, (IntPtr) ptr, pixelInfo.Stride);
-            pdfiumBitmap.FillRect(0, 0, widthInPx, heightInPx, PdfBitmap.WHITE);
-            pdfiumBitmap.RenderPage(page, 0, 0, widthInPx, heightInPx);
+        using var pdfiumBitmap =
+            PdfBitmap.Create(widthInPx, heightInPx, PdfiumNativeLibrary.FPDFBitmap_BGR);
+        pdfiumBitmap.FillRect(0, 0, widthInPx, heightInPx, PdfBitmap.WHITE);
+        pdfiumBitmap.RenderPage(page, 0, 0, widthInPx, heightInPx);
 
-            new CopyBitwiseImageOp().Perform(buffer, pixelInfo, bitmap);
+        var pixelInfo = new PixelInfo(pdfiumBitmap.Width, pdfiumBitmap.Height, SubPixelType.Bgr, pdfiumBitmap.Stride);
+        new CopyBitwiseImageOp().Perform(pdfiumBitmap.Buffer, pixelInfo, bitmap);
 
-            return bitmap;
-        }
+        return bitmap;
     }
 
     /// <summary>