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BobLdBobLd
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Do not convert PdfPig images to Png and use SKImage instead of SKBitmap
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3 files changed

+265
-23
lines changed

3 files changed

+265
-23
lines changed

‎UglyToad.PdfPig.Rendering.Skia/Helpers/SkiaExtensions.cs

Lines changed: 0 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,6 @@
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using System;
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using SkiaSharp;
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using UglyToad.PdfPig.Content;
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using UglyToad.PdfPig.Core;
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using UglyToad.PdfPig.Graphics.Colors;
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using UglyToad.PdfPig.Graphics.Core;
@@ -338,23 +337,5 @@ public static void ApplySMask(this SKBitmap image, SKBitmap smask)
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scaled.Dispose();
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}
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*/
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public static ReadOnlySpan<byte> GetImageBytes(this IPdfImage pdfImage)
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{
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// Try get png bytes
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if (pdfImage.TryGetPng(out byte[]? bytes) && bytes?.Length > 0)
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{
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return bytes;
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}
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// Fallback to bytes
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if (pdfImage.TryGetBytesAsMemory(out var bytesL) && bytesL.Length > 0)
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{
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return bytesL.Span;
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}
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// Fallback to raw bytes
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return pdfImage.RawBytes;
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}
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}
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}

‎UglyToad.PdfPig.Rendering.Skia/Helpers/SkiaImageExtensions.cs

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,261 @@
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// Copyright 2024 BobLd
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//
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// Licensed under the Apache License, Version 2.0 (the "License").
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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using System;
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using System.Runtime.InteropServices;
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using SkiaSharp;
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using UglyToad.PdfPig.Content;
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using UglyToad.PdfPig.Core;
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using UglyToad.PdfPig.Graphics.Colors;
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using UglyToad.PdfPig.Images;
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namespace UglyToad.PdfPig.Rendering.Skia.Helpers
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{
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internal static class SkiaImageExtensions
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{
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// https://stackoverflow.com/questions/50312937/skiasharp-tiff-support#50370515
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private static bool TryGenerate(this IPdfImage image, out SKImage bitmap)
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{
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bitmap = null;
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var hasValidDetails = image.ColorSpaceDetails != null && !(image.ColorSpaceDetails is UnsupportedColorSpaceDetails);
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var isColorSpaceSupported = hasValidDetails && image.ColorSpaceDetails!.BaseType != ColorSpace.Pattern;
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if (!isColorSpaceSupported || !image.TryGetBytesAsMemory(out var imageMemory))
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{
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return false;
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}
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var bytesPure = imageMemory.Span;
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try
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{
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bytesPure = ColorSpaceDetailsByteConverter.Convert(image.ColorSpaceDetails!, bytesPure,
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image.BitsPerComponent, image.WidthInSamples, image.HeightInSamples);
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var numberOfComponents = image.ColorSpaceDetails!.BaseNumberOfColorComponents;
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var is3Byte = numberOfComponents == 3;
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var requiredSize = (image.WidthInSamples * image.HeightInSamples * numberOfComponents);
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var actualSize = bytesPure.Length;
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var isCorrectlySized = bytesPure.Length == requiredSize ||
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// Spec, p. 37: "...error if the stream contains too much data, with the exception that
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// there may be an extra end-of-line marker..."
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(actualSize == requiredSize + 1 && bytesPure[actualSize - 1] == ReadHelper.AsciiLineFeed) ||
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(actualSize == requiredSize + 1 && bytesPure[actualSize - 1] == ReadHelper.AsciiCarriageReturn) ||
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// The combination of a CARRIAGE RETURN followed immediately by a LINE FEED is treated as one EOL marker.
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(actualSize == requiredSize + 2 &&
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bytesPure[actualSize - 2] == ReadHelper.AsciiCarriageReturn &&
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bytesPure[actualSize - 1] == ReadHelper.AsciiLineFeed);
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if (!isCorrectlySized)
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{
67+
return false;
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}
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if (numberOfComponents == 1)
71+
{
72+
return TryGetGray8Bitmap(image.WidthInSamples, image.HeightInSamples, bytesPure, out bitmap);
73+
}
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var info = new SKImageInfo(image.WidthInSamples, image.HeightInSamples, SKColorType.Rgba8888);
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// create the buffer that will hold the pixels
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bool hasAlphaChannel = true;
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var bpp = hasAlphaChannel ? 4 : 3;
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var length = (image.HeightInSamples * image.WidthInSamples * bpp) + image.HeightInSamples;
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var raster = new byte[length];
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var builder = ImageBuilder.Create(raster, image.WidthInSamples, image.HeightInSamples, hasAlphaChannel);
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// get a pointer to the buffer, and give it to the bitmap
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var ptr = GCHandle.Alloc(raster, GCHandleType.Pinned);
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using (SKPixmap pixmap = new SKPixmap(info, ptr.AddrOfPinnedObject(), info.RowBytes))
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{
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bitmap = SKImage.FromPixels(pixmap, (addr, ctx) => ptr.Free());
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}
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byte alpha = byte.MaxValue;
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if (image.ColorSpaceDetails.BaseType == ColorSpace.DeviceCMYK || numberOfComponents == 4)
97+
{
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int i = 0;
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for (int col = 0; col < image.HeightInSamples; col++)
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{
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for (int row = 0; row < image.WidthInSamples; row++)
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{
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/*
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* Where CMYK in 0..1
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* R = 255 × (1-C) × (1-K)
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* G = 255 × (1-M) × (1-K)
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* B = 255 × (1-Y) × (1-K)
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*/
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double c = (bytesPure[i++] / 255d);
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double m = (bytesPure[i++] / 255d);
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double y = (bytesPure[i++] / 255d);
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double k = (bytesPure[i++] / 255d);
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var r = (byte)(255 * (1 - c) * (1 - k));
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var g = (byte)(255 * (1 - m) * (1 - k));
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var b = (byte)(255 * (1 - y) * (1 - k));
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builder.SetPixel(r, g, b, alpha, row, col);
119+
}
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}
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return true;
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}
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if (is3Byte)
125+
{
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int i = 0;
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for (int col = 0; col < image.HeightInSamples; col++)
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{
129+
for (int row = 0; row < image.WidthInSamples; row++)
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{
131+
builder.SetPixel(bytesPure[i++], bytesPure[i++], bytesPure[i++], alpha, row, col);
132+
}
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}
134+
return true;
135+
}
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throw new Exception($"Could not process image with ColorSpace={image.ColorSpaceDetails.BaseType}, numberOfComponents={numberOfComponents}.");
138+
}
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catch
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{
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// ignored.
142+
}
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bitmap?.Dispose();
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return false;
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}
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private static bool TryGetGray8Bitmap(int width, int height, ReadOnlySpan<byte> bytesPure, out SKImage? bitmap)
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{
150+
bitmap = null;
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152+
try
153+
{
154+
bitmap = SKImage.FromPixelCopy(new SKImageInfo(width, height, SKColorType.Gray8), bytesPure);
155+
return true;
156+
}
157+
catch (Exception)
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{
159+
// ignored.
160+
}
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162+
bitmap?.Dispose();
163+
return false;
164+
}
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166+
private sealed class ImageBuilder
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{
168+
private readonly byte[] rawData;
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private readonly bool hasAlphaChannel;
170+
private readonly int width;
171+
private readonly int height;
172+
private readonly int bytesPerPixel;
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174+
/// <summary>
175+
/// Create a builder for a PNG with the given width and size.
176+
/// </summary>
177+
public static ImageBuilder Create(byte[] rawData, int width, int height, bool hasAlphaChannel)
178+
{
179+
var bpp = hasAlphaChannel ? 4 : 3;
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181+
var length = (height * width * bpp) + height;
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183+
if (rawData.Length != length)
184+
{
185+
throw new ArgumentOutOfRangeException(nameof(rawData.Length), "TestBuilder.Create");
186+
}
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188+
return new ImageBuilder(rawData, hasAlphaChannel, width, height, bpp);
189+
}
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191+
private ImageBuilder(byte[] rawData, bool hasAlphaChannel, int width, int height, int bytesPerPixel)
192+
{
193+
this.rawData = rawData;
194+
this.hasAlphaChannel = hasAlphaChannel;
195+
this.width = width;
196+
this.height = height;
197+
this.bytesPerPixel = bytesPerPixel;
198+
}
199+
200+
/// <summary>
201+
/// Set the pixel value for the given column (x) and row (y).
202+
/// </summary>
203+
public void SetPixel(byte r, byte g, byte b, byte a, int x, int y)
204+
{
205+
var start = (y * (width * bytesPerPixel)) + (x * bytesPerPixel);
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207+
rawData[start++] = r;
208+
rawData[start++] = g;
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rawData[start++] = b;
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211+
if (hasAlphaChannel)
212+
{
213+
rawData[start] = a;
214+
}
215+
}
216+
}
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218+
public static SKImage GetSKImage(this IPdfImage pdfImage)
219+
{
220+
// Try get png bytes
221+
if (pdfImage.TryGenerate(out var bitmap))
222+
{
223+
return bitmap;
224+
}
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// Fallback to bytes
227+
if (pdfImage.TryGetBytesAsMemory(out var bytesL) && bytesL.Length > 0)
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{
229+
try
230+
{
231+
return SKImage.FromEncodedData(bytesL.Span);
232+
}
233+
catch (Exception)
234+
{
235+
// ignore
236+
}
237+
}
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// Fallback to raw bytes
240+
return SKImage.FromEncodedData(pdfImage.RawBytes);
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}
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public static ReadOnlySpan<byte> GetImageBytes(this IPdfImage pdfImage)
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{
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// Try get png bytes
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if (pdfImage.TryGetPng(out byte[]? bytes) && bytes?.Length > 0)
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{
248+
return bytes;
249+
}
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251+
// Fallback to bytes
252+
if (pdfImage.TryGetBytesAsMemory(out var bytesL) && bytesL.Length > 0)
253+
{
254+
return bytesL.Span;
255+
}
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// Fallback to raw bytes
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return pdfImage.RawBytes;
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}
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}
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}

‎UglyToad.PdfPig.Rendering.Skia/SkiaStreamProcessor.Image.cs

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -52,9 +52,9 @@ private void RenderImage(IPdfImage image)
5252
if (CurrentTransformationMatrix.A > 0 && CurrentTransformationMatrix.D > 0)
5353
{
5454
// No transformation to do
55-
using (var bitmap = SKBitmap.Decode(image.GetImageBytes()))
55+
using (var bitmap = image.GetSKImage())
5656
{
57-
_canvas.DrawBitmap(bitmap, destRect, _paintCache.GetAntialiasing());
57+
_canvas.DrawImage(bitmap, destRect, _paintCache.GetAntialiasing());
5858
}
5959
}
6060
else
@@ -63,11 +63,11 @@ private void RenderImage(IPdfImage image)
6363
Math.Sign(CurrentTransformationMatrix.A),
6464
Math.Sign(CurrentTransformationMatrix.D));
6565

66-
using (var bitmap = SKBitmap.Decode(image.GetImageBytes()))
66+
using (var bitmap = image.GetSKImage())
6767
using (new SKAutoCanvasRestore(_canvas, true))
6868
{
6969
_canvas.SetMatrix(matrix);
70-
_canvas.DrawBitmap(bitmap, matrix.MapRect(destRect), _paintCache.GetAntialiasing());
70+
_canvas.DrawImage(bitmap, matrix.MapRect(destRect), _paintCache.GetAntialiasing());
7171
}
7272
}
7373

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