Develop Reference

What can cause problems with displaying text from Image when I save it to .tiff?

Here is code, what I use to save Image to .tiff file:
var encoder = new TiffBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create((myImage.Source as DrawingImage).ToBitmapSource()));
using FileStream stream = new FileStream(filePath, FileMode.Create);
encoder.Save(stream);
Here is extension for DrawingImage, which converts DrawingImage to BitmapSource:
public static class DrawingImageExtension
{
public static BitmapSource ToBitmapSource(this DrawingImage source)
{
var drawingVisual = new DrawingVisual();
DrawingContext drawingContext = drawingVisual.RenderOpen();
drawingContext.DrawImage(source, new Rect(new Point(0, 0), new Size(source.Width, source.Height)));
drawingContext.Close();
var bmp = new RenderTargetBitmap((int)source.Width, (int)source.Height, 96, 96, PixelFormats.Pbgra32);
bmp.Render(drawingVisual);
return bmp;
}
}
It works, but when I try to save a large image, part of the text stops being displayed. I add the text to the picture as follows:
private GlyphRunDrawing GetGlyphVertex(string str)
{
var emSize = 10;
var glyphIndices = new ushort[str.Length];
var advanceWidths = new double[str.Length];
double strWidth = 0, strHeight = 0;
for (int i = 0; i < str.Length; i++)
{
var glyphIndex = font.CharacterToGlyphMap[str[i]];
glyphIndices[i] = glyphIndex;
advanceWidths[i] = font.AdvanceWidths[glyphIndex] * emSize;
strWidth += advanceWidths[i];
if (i == 0) strHeight = font.AdvanceHeights[glyphIndex] * emSize;
}
var baselineOrigin = new Point(...); //It doesn't matter
var glyphRun = new GlyphRun(
font, 0, false, emSize,
glyphIndices, baselineOrigin, advanceWidths,
null, null, null, null, null, null);
return new GlyphRunDrawing(textColor, glyphRun);
}
Then I just add this GlyphRunDrawing to common DrawingGroup.
Here is the part of the big picture with which the problem arises:
From some point until the end of the image, the text stops being displayed. With smaller pictures, everything works correctly. What could be the problem?

Create snapshot of a non-shown UserControl

I want to take a snapshot of my UserControl, which has not been shown yet.
That's my code:
public Screenshot(MyViewModel viewModel)
{
if (viewModel == null)
return;
// Create a TabControl, where View is hosted in
var visualTab = new TabControl();
visualTab.Width = FrameworkAdjustments.VisualSize.Width;
visualTab.Height = FrameworkAdjustments.VisualSize.Height;
visualTab.TabStripPlacement = Dock.Left;
// Tabs should only be shown, if there are more than one 'SubView'
Visibility tabVisibility = Visibility.Collapsed;
if (viewModel.SubViews.Count > 1)
tabVisibility = Visibility.Visible;
foreach (var subView in viewModel.SubViews)
{
var tab = new TabItem();
tab.Header = subView.TranslatedId; // multilanguage header
tab.Visibility = tabVisibility;
if (subView.Id == viewModel.ActiveSubView.Id)
{
tab.IsSelected = true;
// Without the following line my UI works, but my TabControl is empty.
tab.Content = ViewManager.GetViewById(subView.Id);
// ViewManager.GetViewById(subView.Id); returns a UserControl
}
tab.Measure(FrameworkAdjustments.VisualSize);
tab.Arrange(new Rect(FrameworkAdjustments.VisualSize));
visualTab.Items.Add(tab);
}
_ContentCtrl = new ContentControl() { Width = FrameworkAdjustments.VisualSize.Width, Height = FrameworkAdjustments.VisualSize.Height };
_ContentCtrl.Content = visualTab;
_ContentCtrl.Measure(FrameworkAdjustments.VisualSize);
_ContentCtrl.Arrange(new Rect(FrameworkAdjustments.VisualSize));
RenderTargetBitmap bmp = new RenderTargetBitmap((int)FrameworkAdjustments.VisualSize.Width, (int)FrameworkAdjustments.VisualSize.Height, 96, 96, PixelFormats.Pbgra32);
bmp.Render(_ContentCtrl);
this.ItemBrush = new ImageBrush(bmp);
}
This code runs for each 'MyViewModel' when I start my App.
'MyViewModel' contains a List of 'SubViews' which are the content of the Tabs and they contain a 'FunctionKeyBar' which's buttons can be activated by using 'F1' to 'F12'. But after creating my screenshot I can't use the F1 to F12 anymore. Also there are other problems, like switch language.
Is there an other way to create a snapshot of a control which has not came into view?
Thanks for all replys.
Greetings Benny

Approach : Set Margin to negative to keep it hidden, Add the control to the Grid / any other container.
Follow these steps :
1) Create a Task to create and add your ContentControl to the Grid.
2) Call user-define CaptureScreen () function.
3) Visibility must not be Hidden/Collapsed. Margin can be negative to hide the control.
In this example, I have done this in a Button.Click.
async private void Button_Click(object sender, RoutedEventArgs e)
{
Task<ContentControl> t = AddContentControl();
ContentControl ctrl = await t;
RenderTargetBitmap bmp = CaptureScreen(ctrl, 5000, 5000);
Img.Source = bmp;
}
/* Add the ContentControl to the Grid, and keep it hidden using neg. Margin */
private Task<ContentControl> AddContentControl()
{
Task<ContentControl> task = Task.Factory.StartNew(() =>
{
ContentControl ctrl = null;
Dispatcher.Invoke(() =>
{
ctrl = new ContentControl() { Content = "Not shown", Width = 100, Height = 25, Margin = new Thickness(-8888, 53, 0, 0) };
Grd.Children.Add(ctrl);
});
return ctrl;
});
return task;
}
/* Important , wont work with Visibility.Collapse or Hidden */
private static RenderTargetBitmap CaptureScreen(Visual target, double dpiX, double dpiY)
{
if (target == null)
{
return null;
}
Rect bounds = VisualTreeHelper.GetDescendantBounds(target);
RenderTargetBitmap rtb = new RenderTargetBitmap((int)(bounds.Width * dpiX / 96.0),
(int)(bounds.Height * dpiY / 96.0),
dpiX,
dpiY,
PixelFormats.Pbgra32);
DrawingVisual dv = new DrawingVisual();
using (DrawingContext ctx = dv.RenderOpen())
{
VisualBrush vb = new VisualBrush(target);
ctx.DrawRectangle(vb, null, new Rect(new Point(), bounds.Size));
}
rtb.Render(dv);
return rtb;
}

Now I found a solution, thanks to AnjumSKan.
I took his code and changed it a little bit. As I said, I need to create the snapshot on application startup or culture changed and I have more than one view. in my Function AddContentControl, I add the Content to my TabControl which has negative Margin. Add the end I call HiddenTab.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Render, new Action(CreateSnapshotOnRender));
('HiddenTab' is my TabControl which is not shown to user). This calls a function called CreateSnapshotOnRender, where I call AnjumSKhan's CaptureScreen-method from. After that I call again the function AddContentControl with my next content. This looks as following:
private void CreateScreenshotOnRender()
{
HiddenTab.Measure(ViewSize);
HiddenTab.Arrange(new Rect(ViewSize));
var snapshot = CaptureScreen(HiddenTab, dpiX, dpiY);
/* Do anything with snapshot */
_Index++; // counter to know thich view is next
CreateAllScreenshots();
}
Thanks again to AnjumSKan, because you lead me to this. Thats why I marked your Answer as the correct one.

Blur effect on image: different result before and after saving

I have a bug in my image editor with the blur tool.
When I select the rectangle to set the blur effect, and when I apply, result is a bit different see:
To create the "Before" I do:
var blurredImage = ExtractImageToBlur(); // extract the selected area from image
BlurredImageRectangle.Fill = new ImageBrush(blurredImage);
var effect = new BlurEffect();
effect.KernelType = KernelType.Gaussian;
effect.RenderingBias = RenderingBias.Quality;
effect.Radius = m_blurValue;
BlurredImageRectangle.Effect = effect;
To create the "After", I do:
var blurredImage = ExtractImageToBlur(); // extract the selected area from image
Rectangle rectangleToRender = new Rectangle();
rectangleToRender.Fill = new ImageBrush(blurredImage);
var effect = new BlurEffect();
effect.KernelType = KernelType.Gaussian;
effect.RenderingBias = RenderingBias.Quality;
effect.Radius = m_blurValue;
rectangleToRender.Effect = effect;
Size size = new Size(croppedImg.PixelWidth, croppedImg.PixelHeight);
rectangleToRender.Measure(size);
rectangleToRender.Arrange(new Rect(size));
var render = new RenderTargetBitmap(croppedImg.PixelWidth, croppedImg.PixelHeight, 96, 96, PixelFormats.Pbgra32);
render.Render(rectangleToRender);
// Merge the source with the blurred section
DrawingVisual drawingVisual = new DrawingVisual();
using (DrawingContext context = drawingVisual.RenderOpen())
{
int left = (int)(Canvas.GetLeft(BlurredImageRectangle) * WidthRatio);
int top = (int)(Canvas.GetTop(BlurredImageRectangle) * HeightRatio);
context.DrawImage(Source, new Rect(0, 0, Source.PixelWidth, Source.PixelHeight));
context.DrawImage(render, new Rect(left, top, croppedImg.PixelWidth, croppedImg.PixelHeight));
}
var bitmap = new RenderTargetBitmap(Source.PixelWidth, Source.PixelHeight, 96, 96, PixelFormats.Pbgra32);
bitmap.Render(drawingVisual);
And when I play with the blur radius, its sometimes a lot more different from both images.
Why its not the same?

Found the problem.
When I was drawing the rectangle on the screen, I applied the blur effect on the pixels on the screen.
When I hit save, the blur effect is applied on the pixel on the image on disk.
Huge difference.

Take a screenshot of a WPF window with the predefined image size without losing quality

When I take a screenshot of a current WPF window, the image resolution is that of my monitor (if the app is maximized), which is ok. However, if I was to print that image to a much bigger format, the image would look blurry. I found the way to capture the current window, and save it as a png file, but it's not doing the trick. The image is saved with the resolution I set, but the actual wpf window takes only a small portion of the saved image. Example is taken from:
http://blogs.msdn.com/b/saveenr/archive/2008/09/18/wpf-xaml-saving-a-window-or-canvas-as-a-png-bitmap.aspx
var screen = System.Windows.Application.Current.Windows.OfType<Window>().SingleOrDefault(x => x.IsActive);
var rtb = new RenderTargetBitmap(4000, 4000, 96, 96, PixelFormats.Pbgra32);
rtb.Render(screen);
var enc = new System.Windows.Media.Imaging.PngBitmapEncoder();
enc.Frames.Add(System.Windows.Media.Imaging.BitmapFrame.Create(rtb));
using (var stm = System.IO.File.Create("ScreenShot.png"))
{
enc.Save(stm);
using (Image img = Image.FromStream(stm))
{
Rectangle dest = new Rectangle(0, 0, 6000, 4000);
using (Graphics imgG = Graphics.FromImage(img))
{
imgG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
imgG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
imgG.DrawImage(img, dest);
}
img.Save("NewScreenShot.png");
}
}
So basically, I'd like to capture the screenshot with the resolution of 4000 x 4000, if that's possible, without losing quality.
The above code produces an image of 4000 x 4000, however the screenshot only takes a small portion of it, its original resolution.

To scale your image, you can use a DrawingVisual and a ScaleTransform :
var w = 4000;
var h = 4000;
var screen = System.Windows.Application.Current.Windows.OfType<Window>().SingleOrDefault(x => x.IsActive);
var visual = new DrawingVisual();
using (var context = visual.RenderOpen())
{
context.DrawRectangle(new VisualBrush(screen),
null,
new Rect(new Point(), new Size(screen.Width, screen.Height)));
}
visual.Transform = new ScaleTransform(w / screen.ActualWidth, h / screen.ActualHeight);
var rtb = new RenderTargetBitmap(w, h, 96, 96, PixelFormats.Pbgra32);
rtb.Render(visual);
var enc = new PngBitmapEncoder();
enc.Frames.Add(BitmapFrame.Create(rtb));
using (var stm = File.Create("ScreenShot.png"))
{
enc.Save(stm);
}

How do I print an Image from a Uri?

I am attempting to print a JPEG file that I reference using a Uri object and am having some difficulties. I found that while the image was printing, it was cropped slightly and was flipped and mirrored. I'm guessing that the crop was caused by a size not being set properly but have no idea why it's being flipped and rotated. Assuming that this was a natural oddity, I attempted to resolve the issue by applying a transform to the drawingContext object but this results a blank page being printed. Here is my code:
public void Print(List<Uri> ListToBePrinted)
{
XpsDocumentWriter writer =
PrintQueue.CreateXpsDocumentWriter(this.SelectedPrinter.PrintQueue);
PrintCapabilities printerCapabilities =
this.SelectedPrinter.PrintQueue.GetPrintCapabilities();
Size PageSize =
new Size(printerCapabilities.PageImageableArea.ExtentWidth,
printerCapabilities.PageImageableArea.ExtentHeight);
foreach (Uri aUri in ListToBePrinted)
{
BitmapImage anImage = new BitmapImage(aUri);
//create new visual which would be initialized by image
DrawingVisual drawingVisual = new DrawingVisual();
//create a drawing context so that image can be rendered to print
DrawingContext drawingContext = drawingVisual.RenderOpen();
// Flips along X and Y axis (flips and mirrors)
drawingContext.PushTransform(new ScaleTransform(-1, -1));
drawingContext.DrawImage(anImage, new Rect(PageSize));
drawingContext.Close();
writer.Write(drawingVisual);
}
}
Any help would be greatly appreciated - thank you!

Here's what I ended up with:
public void Print(List<Uri> ListToBePrinted)
{
XpsDocumentWriter writer =
PrintQueue.CreateXpsDocumentWriter(this.SelectedPrinter.PrintQueue);
PrintCapabilities printerCapabilities =
this.SelectedPrinter.PrintQueue.GetPrintCapabilities();
Size PrintableImageSize =
new Size(printerCapabilities.PageImageableArea.ExtentWidth,
printerCapabilities.PageImageableArea.ExtentHeight);
foreach (Uri aUri in ListToBePrinted)
{
DrawingVisual drawVisual = new DrawingVisual();
ImageBrush imageBrush = new ImageBrush();
imageBrush.ImageSource = new BitmapImage(aUri);
imageBrush.Stretch = Stretch.Fill;
imageBrush.TileMode = TileMode.None;
imageBrush.AlignmentX = AlignmentX.Center;
imageBrush.AlignmentY = AlignmentY.Center;
using (DrawingContext drawingContext = drawVisual.RenderOpen())
{
// Flips along X and Y axis (flips and mirrors)
drawingContext.PushTransform(new ScaleTransform(-1, 1, PrintableImageSize.Width / 2, PrintableImageSize.Height / 2));
drawingContext.PushTransform(new RotateTransform(180, PrintableImageSize.Width / 2, PrintableImageSize.Height / 2)); // Rotates 180 degree
drawingContext.DrawRectangle(imageBrush, null, new Rect(25, -25, PrintableImageSize.Width, PrintableImageSize.Height));
}
writer.Write(drawVisual);
}
}
The image is a little fuzzy but is certainly acceptable. I'm still not sure why my image needed to be flipped or mirrored.

Could you do something like:
BitmapImage anImage = new BitmapImage(aUri);
Image image = new Image();
image.BeginInit();
image.Source = anImage;
image.EndInit();
image.Measure(PageSize);
image.InvalidateVisual();
Then just print the Image object since it derives from Visual...
You need to call InvalidateVisual so that OnRender will be called, if you didn't it would result in a blank image...