I am doing an photo editor apllication..
i came to know that we can create jpeg using canvas(any UIElement)
i am taking a proxy(smaller size) image while in editing mode.
i am not getting how to save the original image by replacing proxy without rendering the original image on screen.
Thanks and regards
Before saving change the canvas size to original width height
say canvas.updatelayout()
convert UIElement to writeable bitmap
Scale down the image to previous width and height
Related
I am trying to display image using BitmapImage for some time and it worked.I have changed the image and it stopped working.
For Bitmapimage I was using this code:
`ms.Seek(0, SeekOrigin.Begin); // ms is memory stream
BitmapImage b = new BitmapImage();
b.SetSource(ms);
image.ImageSource = b;`
I have ran into piece of code where it was checking if the length of the bytes[] ==14400
if(bytes.length == 14400)
{
var bmp = new WriteableBitmap(width, height);
Buffer.BlockCopy(buffer, 0, bmp.Pixels, 0, buffer.Length);
}
I want to know when to use WriteableBitmap and BitmapImage .
From iProgrammer:
Bitmaps are generally implemented as immutable objects. What this means is that once you create a bitmap you can't make any changes to it. You can manipulate bitmaps by creating new versions, which then immediately become immutable....
The WriteableBitmap, as its name suggests, isn't immutable and you can get at its individual pixels and manipulate them as much as you want. This is the ideal way to work when you need dynamic bitmaps.
iProgrammer - WriteableBitmap
From MSDN:
"Use the WriteableBitmap class to update and render a bitmap on a per-frame basis..." MSDN - WriteableBitmap Class
The Examples section of the MSDN article also shows how to update a WritableBitmap image when responding to mouse events. The code in the example erases pixels of the image by setting the pixel's ARGB values to 0 when the mouse's right button is down. The code also shows how to update individual pixels in the image where the mouse's left button is down. Essentially the code shows a rudimentary pixel image editor.
The point, however, is that you can't change image data when using regular bitmap - you have to use WritableBitmap instead. You can, however, render both if you wish.
I am generating tiles from very large images to use with leaflet. I have a working solution that uses System.Drawing.Bitmap and loads the image from file. I already have the image in memory as a BitmapImage however, and would like to reuse it for memory purposes since these images can be very large. But I can not find a good way of doing this with BitmapImage.
What I basically need is something equivalent of
GraphicsHandle.DrawImage(sourceImage, destinationRect, sourceRect, GraphicsUnit.Pixel);
I need to crop and resize a part of the image, and draw this onto another image in a specified location and then save this to file. What is the best way of doing this using BitmapImage?
I want to convert a xaml canvas to a png image using c#. I used RenderTargetBitmap as described in the second post here. It works quite well if the xaml that's meant to be converted is displayed in a window or a page and you can actually see it on screen. But if the window is closed or hidden or the canvas isn't a child of a window / page / frame, a blank image will be generated. Does anyone know why this happens or how to make it work?
I can't be sure but it may be that WPF is saving time by not rendering anything that isn't currently on screen, therefore when you grab the bitmap from the render target for that object, it hasn't been rendered and so it is blank.
I would suggest putting it on screen for the duration of your capture and then remove it. If the object is small it may even appear and disappear in no more than a flicker.
I'm trying to save a Visual object, which has a transparent background, to a bitmap using RenderTargetBitmap...
public static RenderTargetBitmap RenderToBitmap(this Visual Source, int Width, int Height)
{
var Result = new RenderTargetBitmap(Width, Height, 96, 96, PixelFormats.Default);
Result.Render(Source);
return Result;
}
It works, but the transparent pixels are rendered with black color.
What the simplest way to change these transparent pixels to another color?
If you are saving the image as a JPG, transparent will appear black since JPG does not support transparent channel AFAIK. Possible solution: save as a PNG, or paint with a reasonable background color.
I haven't tested this, but in theory it should work.
Use the CopyPixels() method to extract all the pixel data from your RenderTargetBitmap to an array.
Then query the Alpha channel of all those pixels and where they are equal to 0x00 (fully transparent), set the color to whatever you'd like in the background. If you want to be more elegant, you'd have to do the "color math" to properly set the colors in semi-transparent pixels.
Finally, after you have an adjusted array of pixels, create a new BitmapSource from them.
To save that to disk, you'll probably have to create an Image in memory and set its Source to your new Bitmapsource and run your RenderToBitmap again.
Hope it helps.
EDIT:
After posting this, I had
another thought that may be easier.
If you take a clone or snapshot of the
visual element you're trying to save
and put it into a new in-memory panel
(such as a grid or a canvas), you
could simply change the background of
the panel to be the color you want.
Then you'd use the panel as your
source for RenderTargetBitmap.
I capture an image using the photo or camera task and I want to resize the image to say example 480x240 from the captured size of around 2592x1944.
how do I do this ?
thanks
You can pass the JPEG stream you get from the Completed event to the PictureDecoder.DecodeJpeg method. The second and the third parameters define the size. You will get a WriteableBitmap that can be manipulated further and saved back to the MediaLibrary. See this blog post for some example.