我有一些想要打印的图片。这些图像可以有不同的格式,从不同的DPI到不同的格式(JPEG,PNG等)
现在我所做的就是将图像加载到我的应用程序中并尝试 转换dpi说96.但是在这个过程中我得到一个OutOfMemoryException,我不知道如何继续。
Private Sub PrintImage(Optional providedPrintDialog As PrintDialog = Nothing)
Dim objPrintDialog As PrintDialog
If providedPrintDialog IsNot Nothing Then
objPrintDialog = providedPrintDialog
Else
objPrintDialog = New PrintDialog()
End If
Dim myPanel As New StackPanel
myPanel.Margin = New Thickness(15)
Dim myImage As New Controls.Image
Dim tempBitmapImage = ConvertBitmapToXDPI(Me.SelectedFileViewModel.File.GetPath, 96)
Dim tempBitmapImageWidth As Integer = CInt(objPrintDialog.PrintableAreaWidth)
' A4 max width = 793
If tempBitmapImage.Width > tempBitmapImageWidth Then
myImage.Stretch = System.Windows.Media.Stretch.Uniform
Else
myImage.Stretch = System.Windows.Media.Stretch.None
End If
myImage.Source = tempBitmapImage
myPanel.Children.Add(myImage)
myPanel.Measure(New System.Windows.Size(objPrintDialog.PrintableAreaWidth, objPrintDialog.PrintableAreaHeight))
myPanel.Arrange(New Rect(New System.Windows.Point(0, 0), myPanel.DesiredSize))
objPrintDialog.PrintVisual(myPanel, "Billede") ' <- OutOfMemoryException thrown here
End Sub
Private Function ConvertBitmapToXDPI(path As String, newDpi As Integer) As BitmapSource
Using bitmap As Bitmap = DirectCast(System.Drawing.Image.FromFile(path), Bitmap)
Dim bitmapData = bitmap.LockBits(New System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), System.Drawing.Imaging.ImageLockMode.[ReadOnly], bitmap.PixelFormat)
Dim bmSource = BitmapSource.Create(
bitmapData.Width,
bitmapData.Height, 96, 96, PixelFormats.Bgr24, Nothing,
bitmapData.Scan0,
bitmapData.Stride * bitmapData.Height,
bitmapData.Stride)
bitmap.UnlockBits(bitmapData)
Return bmSource
End Using
End Function
答案 0 :(得分:4)
无需进行任何DPI转换。只需创建一个DrawingVisual并使用适当的大小绘制BitmapImage:
Dim image As New BitmapImage()
image.BeginInit()
image.CacheOption = BitmapCacheOption.OnLoad
image.UriSource = New Uri(path)
image.EndInit()
image.Freeze()
Dim size As New Size()
If image.Width < printDialog.PrintableAreaWidth Then
size.Width = image.Width
size.Height = image.Height
Else
size.Width = printDialog.PrintableAreaWidth
size.Height = size.Width / image.Width * image.Height
End If
Dim visual As New DrawingVisual()
Using dc As DrawingContext = visual.RenderOpen()
dc.DrawImage(image, New Rect(size))
End Using
printDialog.PrintVisual(visual, "Billede")