I'm completely newbie to Qt
i want to create a 800X600 window that just show some circle and be able to manipulate pixels of the form. there is no interaction between user and form(no click, no dblclick,...) it just shows some circles with one color and lines with different pixel colors(each line may have different pixel colors)
also i want to be able to change the coordination system, i mean change it from top-left to the center of the window. could anyone help me do that with some sample code?
thanks in advance for your reply.
Please try downloading the Qt Creator (IDE), then reading through the tutorials. There's a whole host of very useful information provided for free, including a lot of the code samples you are looking for.
The following examples might also be of particular interest:
Animation Framework Examples
Graphics View Examples
Painting Examples
Related
I need access to the coordinates of individual strokes of a PKDrawing in PencilKit. Is there any way I can get access to that? Currently, my only idea is to try and decode the opaque data representation we get from PKDrawing.
As Ben has said, there doesn't seem to be any way to access stroke-level data in PencilKit at this time. This seems like a pretty rudimentary feature so hopefully Apple will add it next WWDC. Fingers crossed.
LetsBuildThatApp's YouTube tutorial is a good starting point if you just want basic drawing capabilities and are not too concerned about drawing quality or latency. I ran into issues when I tried to add the ability to vary the stroke width with pen pressure. I was never able to get it to transition smoothly between stroke segments of different widths - it always 'jumped' jarringly from one width to the next. Maybe there's a way to fix that, but I wasn't able to.
I suspect that currently, the only way to draw low-latency high-quality images with Apple Pencil is to write a drawing engine from scratch in Metal or OpenCL. It's strange it has taken Apple so long since the release of Apple Pencil to get a comprehensive drawing framework out. Fingers crossed that changes at WWDC 2020.
Edit: Apple announced substantial updates to PencilKit at WWDC20, including access to stroke data and functions to programatically draw strokes.
I was was looking for the same thing and from this comment https://stackoverflow.com/a/57565661/8891611 and my own searching of the documentation, it seems what you're asking for doesn't exist. If you do discover a way to decode the opaque data please update this thread on how so.
If you aren't necessarily set on PencilKit, you could manually code your drawing functions which is easier than it sounds. In this tutorial: https://youtu.be/E2NTCmEsdSE?t=504 I have timestamped where he shows that he has access to all the points on the lines he is creating.
And another potential solution could be to use both, by have a mapping between your PencilKit drawing and the points found from the technique in this tutorial.
For the strokes, you can access the property .renderBounds that gives you the dimensions of the rectangle where the stroke is into.
Please tell me how to solve this problem.
Where to start and which way to go.
I have an image with some buttons :
How can i detect coordinates of blue round button for example?
The difficulty lies in the fact that these are not application buttons, but just a picture on the desktop.
I understand that this is a vast and complex question, but tell me at least the right way.
It will be useful to many people.
The first thing I can imagine is to do a desktop screen, and then try to detect pixels with blue color.
You don't need to do manual image detection because Apple's vision framework already does this. You can use it to detect rectangular regions, detect text, or recognize and image within an image, depending on your needs.
See Detecting Objects in Still Images
I am working on a project where I have to render 4 different sides of a 3D object at the same time on the screen. The output should have 4 different camera outputs rendering the front side, left side, right side and back side of the 3d object.
I found that a gaming engine like Unity may help to do something like this. However, I have just started using Unity and can't figure out how to do it.
Here is the link for some examples. This is how I want the output to look like
Well first of all, welcome to Stackoverflow. And you are right, Unity is an excellent IDE to achieve what you described.
As stated in the FAQ and here, I'm going to give you an answer I deem fitting to your question. I can post the code here in about 30 minutes which does exactly what you asked for, but then we'd miss the point of learning to program and posting at StackOverflow in general. I'll show you the way on how to start on this project, but then you'll have to try yourself. If you have any troubles after trying some more, we can help you with specific problems, provided you have researched some before and show us what you tried.
As to your question, it's relative easy to do so. First create your object in the scene, then drag and place four different Camera-objects in the screen. Using the Camera's Normalized View Port Rect (Four values that indicate where on the screen this camera view will be drawn, in Screen Coordinates (values 0-1)), you can then split up the view to show the feed of each Camera.
This ofcourse happens in a script. You can read here about Scripting in Unity. Even if you are an expert in programming, that link is worth a read when you are new to Unity.
Good luck.
I have a database of images of one person who is using his hands to show various words and phrases in sign language. The background is white and the only thing changing is the shape of the person's hands and their locations. Now in my gui in matlab, I want the user to be able to choose another image from the same person that was taken at another time doing a sign but wearing the same clothes and then the program will have to compare this against the images in the database and show the most similar. Obviously I can't do pixel by pixel comparison as the images were taken by a hand held mobile camera and slight movement has been inevitable so I should try and locate the hands in the images and compare their shapes. I have no idea how to go about this? I have to say I am new to image processing toolbox in matlab.
Your help is much appreciated
I am doing a phD in computer vision, and I can tell you that it is an unsolved problem. (even in your simple framewrok, with white background)
If you are interested, you might read some works about it ar MIT:
http://people.csail.mit.edu/rywang/handtracking/
or at Oxford:
http://www.robots.ox.ac.uk/~vgg/research/sign_language/index.html
http://www.robots.ox.ac.uk/~vgg/research/hands/index.html
I disagree with you. Such a project can achieve results quickly.
This becomes a problem as soon as the project has to deal with "real life".
Using a single camera, and a completely known background; Opencv provides a simple way to extract hand shape in a image (in about 20 lines of code). You will find plenty of source on the web (have a look at calcbackproj).
After that, what you will have to do is to play with shape, and search for characteristic points.
Begin with some simple signs (example : a circle and a V). How would you recognize one from the other?
There are thousands of papers on sign language; just read the older one to simple ideas flowing :)
HI all ,what i want is to map the images.Suppose i have two images of persons,one is of fat person and another is of weak person,Now i want to match their faces ,eyes.I want to increase or decrease the face size eye size of one image according to another.As you can see in adobe photoshop you can make the face fat,make it squueze.I want to do the image manuplation in this.These types of operations i want to implement.I don't know from where to start.
Pleas guide and help me.Can i perform all this with core graphics if so then how
Any reference,tutorial address ,sample code ........appreciated.
You are probably going to have to deal with some sort of edge detection and face recognition algorithms, at the very least, if this is to be accomplished automatically. Otherwise, if the user is going to be resizing one image to match the other, this will require simple resizing operations driven by perhaps user pinch & gestures.
UPDATE:
For manual resizing:
Download the source code for the great book Cool iPhone Projects. One of the projects is called 'Touching'. This project contains code that accomplishes what you need: pinch and zoom functionality.