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
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I am trying to create a simple paint application using Qt Creator. I want to have a rectangular area on QDialog in which I can draw an image using mouse. The image format will be QImage::Format_Mono (Black and white, pixel indexes are either 0 or 1). I will use pixel indexes for simple image processing purpose, which operates on simple 1 and 0 pixel values, so Format_Mono is essential.
Now the application does its job, but the image (painting area) is stuck at left top part (positioned at x=0 and y=0). I want to have rectangular image editor part at any x and y coordinates I want.
To create the image editor I defined a QImage in dialog.h
QImage image;
In constructor of the Dialog I have:
image = QImage(ui->label->size(), QImage::Format_Mono);
image.fill(Qt::black);
As you can see in above code, I have a QLabel named label in my user interface. I want to put the image editor part in that label (or do something similar).
I checked the QImage documentation, but could not find a function to change the position of the image. Or, it would also be good if I could find any other way to put the image (image editor) in QLabel.
What can I do to have that feature in my application?
EDIT: The created image editor part has the same size as the label (as it should be the case), but image editor (QImage) starts at x=0 and y=0 only.
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.
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.
Is it possible to make MathGL produce an image where the background is semi-transparent (like 50%) and the foreground elements are opaque?
How do I specify semi-transparent backgrounds in C++ for rendering-to-memory images?
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