c# - 大图像上的 ImageResizer 溢出错误开始按比例缩小

Question

使用版本 4.2.5

我有一个允许用户上传 PDF 的应用程序，然后将其光栅化为图像流（使用 HiQPDF），然后我使用 ImageResizer 将其缩小。

在 PDF 的打印尺寸非常大的情况下，光栅化的结果图像非常大（30,000 像素 x 75,000 像素），因此 Image.Build() 失败并出现以下错误。

HiQPDF 在光栅化期间没有任何大小缩放选项，所以我有点卡住了。关于是否有办法解决此错误的任何想法？

Overflow error.

堆栈跟踪：

at System.Drawing.Graphics.CheckErrorStatus(Int32 status)
   at System.Drawing.Graphics.DrawImage(Image image, PointF[] destPoints, RectangleF srcRect, GraphicsUnit srcUnit, ImageAttributes imageAttr, DrawImageAbort callback, Int32 callbackData)
   at System.Drawing.Graphics.DrawImage(Image image, PointF[] destPoints, RectangleF srcRect, GraphicsUnit srcUnit, ImageAttributes imageAttr)
   at ImageResizer.ImageBuilder.InternalGraphicsDrawImage(ImageState state, Bitmap dest, Bitmap source, PointF[] targetArea, RectangleF sourceArea, Single[][] colorMatrix)
   at ImageResizer.ImageBuilder.RenderImage(ImageState s)
   at ImageResizer.ImageBuilder.Render(ImageState s)
   at ImageResizer.ImageBuilder.Process(ImageState s)
   at ImageResizer.ImageBuilder.BuildJobBitmapToBitmap(ImageJob job, Bitmap source, Boolean transparencySupported)
   at ImageResizer.ImageBuilder.BuildJobBitmapToStream(ImageJob job, Bitmap source, Stream dest)
   at ImageResizer.ImageBuilder.BuildJob(ImageJob job)
   at ImageResizer.ImageBuilder.BuildInternal(ImageJob job)
   at ImageResizer.ImageBuilder.BuildInQueue(ImageJob job, Boolean useSemaphore, Int32 maxQueuingMilliseconds, CancellationToken cancel)
   at ImageResizer.ImageBuilder.Build(ImageJob job)

相关代码：

string strInstructions = $"maxwidth={maxWidthPixels};maxheight={maxHeightPixels};format=jpg;mode=max;";
strInstructions += "quality=" + ImageSaveQuality + ";";

using (var updatedImageFileStream = new MemoryStream())
{
    ImageJob imageJob = new ImageJob(origFileStream, updatedImageFileStream,
        new Instructions(strInstructions)
    );
    imageJob.Build();

Answer 1

您可能已经达到了基于 System.Drawing 的系统的上限。

我建议改用 ImageResizer 替换Imageflow.NET。它还应该生成压缩更好的文件。

string strInstructions = $"maxwidth={maxWidthPixels};maxheight={maxHeightPixels};format=jpg;mode=max;";
strInstructions += "quality=" + ImageSaveQuality + ";";
    
using var buildJob = new ImageJob();
var jobResult = await buildJob.BuildCommandString(
            new StreamSource(originalStream, true),
            new StreamDestination(destStream, true), strInstructions)
        .SetSecurityOptions(new SecurityOptions()
            .SetMaxDecodeSize(new FrameSizeLimit(80000, 80000, 80000))
            .SetMaxEncodeSize(new FrameSizeLimit(80000, 80000, 80000))
            .SetMaxFrameSize(new FrameSizeLimit(80000, 80000, 80000)))
        .Finish()
        .InProcessAsync();