I am trying to draw the numbers into circle shape.
But I did not succeed. I have tried some tutorials which are available but could not succeed.
We haven't fixed the numbers to show in circle. Numbers are dynamic.
I am attaching snapshot below so that I could clear what I am really trying to do.
Help would be appreciated.
You could use David's suggestion of placing labels by translating and rotating them. That would be easiest, but would involve a fair amount of overhead.
Alternatively you could use CoreText to draw your text along a CGPath that's a circle. Erica Sadun's excellent "iOS Developer Cookbook" series includes a recipe that shows how to wrap text along a curved path using Core Text. I don't remember which volume it's in however.
A third option would be to use Nick Lockwood's excellent iCarousel framework to create a circular carousel out of the numbers you're using. It is very flexible and you should be able to adjust the settings to get a look very similar to the control you've posted.
Related
Let's say you have some flutter widget, for example, a TabBar. It is rendered in a rectangular box. I need it to be rendered in an arc so that the text and the underline follow part of a circle (or better still, a bezier curve).
How can that be achieved?
This illustrates what I am trying to achieve - bent TabBar widget:
Please note that in this case, the TabBar bends following and an arc (edge of a circle). This is what I need immediately. However, in the future, I might need bending that follows the edge of an eclipse so a solution that allows it would be preferable.
Also, a solution that works for different widgets is preferred.
IMPORTANT: I do NOT want to clip a curved shape of the widget. The entire area of the widget should stay visible. Instead, I need to bend the content of the widget (=bend its render image).
Apologies for the bold font but without it, people will keep posting answers about how to clip a widget which is trivial in comparison and useless for my problem.
An answer "this is currently not supported by Flutter" from authority (e.g. high reputation in Flutter tag or Flutter a team member) will also be accepted.
One approach: Use a CustomPaint to draw lines/areas/etc freely
You can use a CustomPaint to draw whatever curved lines, areas, etc freely. Therefore, you can definitely achieve your goal - since they are nothing but curved lines, areas with curved edges, rotated texts, etc.
That will take a bit of work, but if you encapsulate it well enough, it is not that hard to implement. For example, draw a Path with filled red area, then draw a white arc, then draw several texts with calculated rotations, etc. Sounds like you can do that within maybe hundreds of lines. If you find difficulty implementing this please comment and I will explain.
Another approach: Hack Canvas such that the call to drawLine becomes indeed calls to drawPath, etc.
You may do the following to allow bend/crook for any widget (and their combination, of course), but this may need a bit of engineering. You can make your own Canvas, say, class BendCanvas implements Canvas {}. The BendCanvas.drawLine, for example, has an implementation of Canvas.drawPath with a curved path cooresponding to the input "line". Similar things hold for drawing rectangles, etc. Then you need to hack Flutter's painting logic, such that it takes in your own BendCanvas instead of the original canvas. This is a universal solution, and it is much more efficient (less code) if you plan to have a lot of bend UI; but if only on bend TabBar, maybe use the first approach.
As for the bend text
In the two approaches above, we have mainly described how you draw the bended rectangle (i.e. draw an arbitrary shaped widget). As for bending text, see: https://github.com/flutter/flutter/issues/16477 , which is still an open issue.
Remarks
It is not possible using transformations. As explained in the comments, you already see Transform does not work - it is affine or perspective, which, by definition, will not bend. Then what about other transforms? After some research there seems to be none. Then, what about looking under the scene. We know Flutter uses Skia under it to draw the UI with high performance, then let us search through Skia. However, it does not provide any transformations like bending. So there seems no use.
P.S. I am not that high reputation in Flutter tag, but I did answer >100 Flutter questions (including some dig-into-source-code style ones), and have developed >100k lines of Flutter code in the production app.
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.
I need to create an ellipse with a width of 52 pixels and a height of 47 pixels. Using the Chipmunk engine, I've found that you can create circles with a certain radius, as well as polygons. I'm new to working with Chipmunk, and the documentation for the engine is quite brief.
How do I create ellipses in Chipmunk? I'm currently working with iPhones, using Objective-c and cocos2d.
I know it may seem useless to go in these details but I need to create it as precise as possible.
Thank you!
The recommendation from Chipmunk's author, slembcke, seems to be “approximate it using a polygon”. See this forum post.
If a polygon approximation isn't good enough, you will have to modify Chipmunk to add a new ellipse shape type, because it doesn't have support for ellipses. And adding support for ellipses is probably a significant amount of work.
You can also use PhysicsEditor to design any shape.
If you already have an image of an ellipse, then you can use that image to allow PhysicsEditor to trace the borders of the image. Either way this is a lot easier than actually programming the shape.
I'd like to allow a user to add a shape (which would just be a UIImage) onto some sort of canvas, then move and resize it on the screen but I'm not sure how to go about this. Ideally I'd like the basics of a drawing app which can use images from a user's device. Each shape would have an associated position, size and z-index.
The only thing I'm unsure of is how I'd create a bounding box (the one with four blue dots to allow resizing/moving). I have experience with UIKit, and would prefer to keep the majority of the app in this for the time being, but I get the feeling this type of thing might be better suited to Cocos2D or a similar framework.
If anyone has any pointers/open source code I can dig through it would be hugely appreciated.
I think you should look into CALayer, or even CAShapeLayer. I'm just starting to play with them, but I'm pretty sure you can easily get the functionality you want with either. Draw the border in the layer's drawLayer:inContext:. Check out the Quartz2d Guide path drawing section for the functions you need.
This might be trivial for some of you, but I have two screenshots from the Lose It! app in which I'm curious how two different screens were put together.
The first:
That middle graph which shows the statistics chart. Is that a custom image being drawn on top of with Core Graphics / Quartz to achieve the desired numbers? Is the yellow line that's being dynamically allocated all the work of Quartz?
And second:
This one might be a bit easier, but the whole bar which looks like a native UIKit widget, which contains [Budget, Food, Exercise, Net, Under]. There appears to be a drop shadow above it. Are they doing a drop shadow on the UINavigationBar? Is the menu below it just a UIImage that a designer was able to craft to look like the UINavigationBar?
If there's a blog out there which teaches UI tricks such as these, I'd love to read more.
1) Yes, it's likely a view that uses the chart as a background and then uses core graphics to render the line,
2) This could be a single view divided into four sections. Each section has two lines of text drawn with different colors. It's possible that each section may be a view that encapsulates this behavior.
I'm not aware of any blog that teaches these "tricks". It's really a case of understanding what functionality is available and then using it creatively to develop your UI.
For example we know it's possible to;
Draw images at different sizes/positions.
Draw text in different fonts, sizes, colors, alignment
Draw primitives
Really, when you have those you can create pretty much anything.
I think there's an SDK sample that demonstrates using custom views to create a fancy timezone style applications. That might be one worth checking out.
Update: found it, it's here.