How can set Image and PDF size in UWP C#-CodePudding

I am trying to generate a pdf in my project where I converted Image into Pdf and Image generated from Layout. Generated image size is very large and also There are not received good quality. Please Help me to solve this.

I am using this code in program.

 RenderTargetBitmap renderTargetBitmapimg = new RenderTargetBitmap();

            var mainlayoutHeight = pageStackPanel.ActualHeight;
            var mainlayoutWidth = pageStackPanel.ActualWidth;
            int mlHeight = Convert.ToInt32(mainlayoutHeight);
            int mlWidth = Convert.ToInt32(mainlayoutWidth);


            
            await renderTargetBitmapimg.RenderAsync(pageStackPanel, mlWidth, mlHeight);
            
            ///SAVE IMAGE IN FOLDER 
            var pixelBufferimg = await renderTargetBitmapimg.GetPixelsAsync();
            var pixels = pixelBufferimg.ToArray();
            var displayInformation = DisplayInformation.GetForCurrentView();
            var storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.PicturesLibrary);

            StorageFolder projectFolder = await storageFolder.CreateFolderAsync("TestImage", CreationCollisionOption.OpenIfExists);
            var file = await projectFolder.CreateFileAsync(jpgFilename, CreationCollisionOption.GenerateUniqueName);

            using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
            {
                var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);
                encoder.SetPixelData(BitmapPixelFormat.Bgra8,
                                     BitmapAlphaMode.Premultiplied,
                                    (uint)renderTargetBitmapimg.PixelWidth,
                                    (uint)renderTargetBitmapimg.PixelHeight,
                                    200, 200,
                                    pixels);

                await encoder.FlushAsync();
                StorageFile prescriptionJpgFile = await projectFolder.GetFileAsync(jpgFilename);
                await stream.FlushAsync();
                stream.Seek(0);
                stream.Dispose();
                renderTargetBitmapimg = null;

CodePudding user response：

The answer is no, you can't set the size of the generated image file. But you could try to resize it to reduce its physical size by giving a specific width and height. You could use BitmapEncoder class to encode the original image, change the BitmapInterpolationMode of the image. The code looks like this:

    //open file as stream
        using (IRandomAccessStream fileStream = await imagefile.OpenAsync(FileAccessMode.ReadWrite))
        {
            var decoder = await BitmapDecoder.CreateAsync(fileStream);

            var resizedStream = new InMemoryRandomAccessStream();

            BitmapEncoder encoder = await BitmapEncoder.CreateForTranscodingAsync(resizedStream, decoder);
            double widthRatio = (double)reqWidth / decoder.PixelWidth;
            double heightRatio = (double)reqHeight / decoder.PixelHeight;

            double scaleRatio = Math.Min(widthRatio, heightRatio);

            if (reqWidth == 0)
                scaleRatio = heightRatio;

            if (reqHeight == 0)
                scaleRatio = widthRatio;

            uint aspectHeight = (uint)Math.Floor(decoder.PixelHeight * scaleRatio);
            uint aspectWidth = (uint)Math.Floor(decoder.PixelWidth * scaleRatio);

            encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Linear;

            encoder.BitmapTransform.ScaledHeight = aspectHeight;
            encoder.BitmapTransform.ScaledWidth = aspectWidth;

            await encoder.FlushAsync();
            resizedStream.Seek(0);
            var outBuffer = new byte[resizedStream.Size];
            await resizedStream.ReadAsync(outBuffer.AsBuffer(), (uint)resizedStream.Size, InputStreamOptions.None);


            StorageFolder storageFolder = ApplicationData.Current.LocalFolder;
            Debug.WriteLine(storageFolder.Path);
            StorageFile sampleFile = await storageFolder.CreateFileAsync("testfile.pdf", CreationCollisionOption.ReplaceExisting);
            await FileIO.WriteBytesAsync(sampleFile, outBuffer);

        }

For more information, you could check this document:How to Compress image and change its Size.

Another suggestion is that you could just use the UWP print API to generate the PDF file. You could take a look at the Print Helper of Windows Community Toolkit. You could choose not to print but save it as a PDF file.