Inkscape: Copy Pasting PNG results in Black background for transparent areas - inkscape

In Inkscape, If I copy an Image from internet with a transparent background and paste it into Inkscape Canvas the portions where there is transparent turns out to be black.
But if I download the image and then import the image into inkscape from the file system it works great.
I there a way through which the pasted image can retain its transparency.

Related

How to draw transparent background image with Camlimages and Graphics

Yesterday I included all the modules of Camlimages Package into my project, I successfully draw images in my graphical window, but the png images (with transparent background) are not drawn with transparent background.
I will show you the image I have, and the result on the graphical window as well as the code.
let img = Png.load "./images/3mushrooms.png" [] in
Graphic_image.draw_image img 0 0

Image overlap with alphachannel doesn't work on QT

I've put two label of the same dimension overlapped on my GUI. On the first, that is on the back there is one image set by the pixmap of the label. The second label has another image set by pixmap that is trasparent in some pixel. During design i can see the back image via the front image. When I execute the program, the trasparent pixel of the second image are transformed into white pixel, so i cant see the back image. I'm using QT 5.10. The image are in .png format.
I've resolved putting autoFillBackground on and i've changed the color of window in palette putting a transparent color

C++ displaying an image with SDL2 with different formats than .bmp

I am trying to display an image in SDL2 and the only guide I found was a guide about how to display a .bmp image. What I would like to do is displaying an image or setting a temporary image as a background. For example if I press LEFT_KEY the program should proceed to the next image. Any relevant guides or any examples you can share? It is not needed to set the image as a background (stretched), my goal is to display an image and being able to scroll through other images by pressing a key.
Use SDL_Image:
https://www.libsdl.org/projects/SDL_image/
Example:
Loading PNGs with SDL_image

Qt rendering to offscreen display, copy to visible without overwritng the background

I am using Qt5.6, I have developed several widgets that render the content to an off-screen bitmap then copy the final image to the visible area.
I have an area on the visible display that shows a video feed, I want to copy the images over the video without overwriting the background and avoiding flicker.
I am currently creating the off-screen image using a 'QPixmap', I then create a painter using the Pixmap and draw as to the off-screen image. When the image is ready I then call the 'toImage' function to return a 'QImage' and then copy this to the visible display.
A lot of the widget contains lines and circles, a lot of which are not filled.
I've seen other posts not using a QPixmap, just using a 'QImage', should I be using a 'QPixmap' at all?
Question is how to copy the image from the off-screen area to the visible area without overwriting the background?
The key to transparency is that the overlay image has got an alpha channel. QPixmap uses the graphics format of the underlying graphics system which should include an alpha channel. For QImage, the format can be explicitly specified and it should be QImage::Format_ARGB32_Premultiplied, see [1]: http://doc.qt.io/qt-5/qimage.html#Format-enum
To get a a fully transparent QImage/QPixmap in the first place, call QPixmap/QImage::fill(QColor(0, 0, 0, 0)); before creating the QPainter.
The 4th parameter is the alpha channel which is 255 (full opacity) by default).
Unfortunately I can't give advice whether QPixmap or QImage is faster for your setup.
Provided the compositing operation with the videofeed considers the alpha-channel, this should solve your problem.

how to change the background colour of CImage object in mfc?

I have an windows app which contains some dialogs. the dialogs have been built using mfc. I am drawing some images (.png) on every dialog using CImage::Draw() method. I want to mention that I am not using any picture contol on the dialog to render these images instead I am loading them at runtime using some handle.till this everything is ok. now when the image is loaded the background of those images are coming as white. the images in the resource file does not have the white background. my question is how to change the background of these images while drawing them on the dialog? I want the background of the image similar to the color of default dialog which i am using.
One more question the .png images are not rendering well(the images are scattered) in the dialogs of windows server 2008 R2 machine. what could be the possible remedy for this?
any help will be appreciated.
Your PNG images are obviously not 32-bit. You need an alpha channel and a transparent background. Open your images in e.g. Paint.NET. I bet your background is white there too! Regarding the image quality, are you stretching your images on draw?
Edit: For 8-bit imagers, I believe a call to SetTransparentColor is required. For 32-bit images, perhaps this function will do: TransparentBlt