I want to draw line on iPad using user points. How can I do that? Kindly reply if you know
For simple 2D graphics you'll want to use Quartz 2D.
This Stackoverflow question has some good examples, and apple provide full documentation here
Also - see this very similar question: How do I draw a line on the iPhone?
The accepted answer includes instructions and sample code.
Related
I'm building an iphone photo app. I don't know how to achieve this kind of effect on an image:
When the user drags a finger across the arrow, I want the image to be distorted accordingly. How can I achieve this? Is there any framework that makes this process simple?
Thank you.
No clue about iOS, but the look reminds me of a thin-plate spline warp. It's quite easy to implement in OpenGL, a quick Google search for example code returns plenty of hits.
From the sound of it I think your looking for the CoreImage framework. Look into the various distortion effects...in particular CIBumpDistortionLinear.
I don't have any code so check out this tutorial and read up on CoreImage.
i am developing an app, which display the curve colored like this and the length of it i can change (in code), but i don't know how to do that, can anybody help me:
Thank you !
Jerry Nixon posted a blog and walk through video on creating this exact same control.
It builds on a previous blog about building dials.
I want to create a area of similar colors when user touches into a point on imageview. Who knows library or technique to resolve problems for ios.
Original image link:
http://cannshine.com/images/1.jpg
After touched by user, link:
http://cannshine.com/images/2.jpg
Please helping, thanks!
It looks to me like you want to create a magic wand tool, correct? I can't help you come up with a way to handle this and I don't know of any libraries that can select a group of like-colored pixels based on tolerance, but there is this article here I found. It covers implementing a magic wand tool using Objective-C. I found it in the answer to this similar question on SO.
I'm following this guide: http://www.aishack.in/2010/08/sudoku-grabber-with-opencv/2/
and modifying to iOS 5.0.
I managed to find the largest contour (the sudoku "board"), however, it only locates the surrounding square, without the lines inside, as in the tutorial. can this be easily solved?
I'll try and find a way around it, but still would like to know. thanks!
I assume that you are using the camera right now. Try to load the image what is used in the tutorial and check if your implementation works on that image. Then you can continue with nice sudoku images from the web. You may also change the camera angle and distance from the sudoku when taking pictures to get a better, clearer view.
I am studying Core Graphics to make dynamic textures for my project.
A friend told me that i should use CGLayerCreate and CGContextDrawLayerAtPoint
to improve the texture of the brush app that i am building but i haven't found any book or tutorial that includes CGLayerCreate and CGContextDrawAtPoint.
can you guys tell what's the use of this two and how will able to code them?
also if you know any core graphics book that includes those please tell me, it'll surely help me.
thanks!
The Quartz 2D Programming Guide has a chapter that discusses CGLayer objects.
Your friend might be thinking of this use of layers, quoting that chapter:
Repeated drawing. For example, you might want to create a pattern that
consists of the same item drawn over and over. Draw the item to a
layer and then repeatedly draw the layer, as shown in Figure 12-1. Any
Quartz object that you draw repeatedly—including CGPath, CGShading,
and CGPDFPage objects—benefits from improved performance if you draw
it to a CGLayer. Note that a layer is not just for onscreen drawing;
you can use it for graphics contexts that aren’t screen-oriented, such
as a PDF graphics context.
There's also a very very simple example in the Quartz2DBasics sample app.