I am developing an application for viewing images.
I used the example of PhotoScroller Apple to implement this application.
In my application I want to be able to draw on the image.
I had the idea to put a UIView on top with transparent background and draw the lines via touch events. This solution has become very slow because the generated images are very large, around 3700x2000 pixels.
I also tried a solution with the example of Apple GLPaint that uses OpenGL, but it has a size limitation of 2048x2048 pixels.
Anyone have any idea or example of how I implement this?
I think you should try and tile your image.
One option is using CATiledLayer. Have a look at this short tutorial.
Or you could try and use CGContextDrawTiledImage to get your stuff done. Possibly this post from S.O. could help you getting started.
Related
So I have a programming project that I have to do for my school. What I have to do is setup a 2 player dice game. I could have gone the easy way and just display the number of the 2 die, but I was thinking of using images that I made in photoshop instead. However, the problem is that I do not know how to change images in an efficient way.
My first option is using the visibility tag on several images laid on top of eachother and change it accordingly as such
image1.visible = false
image2.visible = true
However, I do not think that is very efficient. Images also do not support changing the image with code from my research.
Secondly, I could use a PictureBox instead, which do support changing the image as the program is running. However, it does not support transparency, and the die images are transparent. Plus it gives me the invalid image file error, I guess due to the transparency in the gif files.
There is also the cheap workaround of me making the background of the images the same as the form background.
So is there a more efficient way I am missing out? I know that the cheap workaround would be the best option for this case, but I would like to have this knowledge for future use like semi-transparent pixels that blend in and such.
And before you ask, no, I cannot use another programming language as visual basic 6 is what my school teaches. Thankfully they are changing it soon, but I am stuck with this for now.
Turns out you CAN change the pictures of Images, while keeping transparency and stretch. I am going to properly show it:
Image1.Picture = LoadPicture("YOURPATHHERE.gif")
This is what I get for believing what I've seen on some forum.
Also, the error of invalid image file was due to the images being corrupted for some reason.
I am creating a simple photo catalogue application for macOS to see whether the latest APIs can significantly improve performance of loading directories with large numbers of images.
So far it looks pretty promising and loading around 600 45MB RAW image thumbnails using QLThumbnailGenerator and CGImageSourceCreateWithURL is super fast allowing thumbnail images and image metadata to be displayed almost instantly.
Displaying these images in a NSCollectionView using a CALayer in the NSCollectionViewItem's view also appears to be extremely fast and scrolling is very smooth.
I did find that QLThumbnailGeneratorseems to start failing after a few hundred images and starts returning error code 108 if I call the api in a continuous loop - I fixed that by calling CGImageSourceCopyPropertiesAtIndex immediately after the thumbnail generator api call - so maybe there is a timing issue or not enough file handles or something if the api is called to quickly and for too long.
However I am still having trouble rendering a full sized image to the display - here I am using a NSScrollView with a layer backed NSView documentView. Everything is super fast until the following call:
view.layer.contents = cgImage
And at this point the entire main thread hangs until the image has loaded - and this may take a few seconds.
Once it has loaded it's fine and zooming in and out by changing the documentView frame size is very fast - scrolling around the full size image is also super smooth without any of the typical hiccups.
Is there a way of loading these images without causing the UI to freeze ?
I've seen the recent WWDC2020 session where they demonstrate similar scrolling of large numbers of images but I haven't been able to find anything useful on loading large images other than CATiledLayer - but it's not really clear if that is the right answer for this problem.
The old Apple sample RawExpose seemed to be an option but most of that code is deprecated and it seems one has to use MetalKit not instead of GLKit - unfortunately there is no example of using MetaKit with Core Image that I can find.
FYI - I tried using some the new SwiftUI CollectionView and List but they seem to be significantly slower than AppKit and I found some of the collection view items never render - of course these could just be bugs in the macOS 11 beta.
OK - well I finally figured it out and it's complicated but simple. It's complicated because there are so many options to choose from and so many outdated sample apps to look at. In any event I think I have solved most if not all the issues related to using metal backed CALayers and rendering realtime updates of the images as CIFilter adjustments are applied. There are many pieces to the puzzle and happy to share if anyone is looking for help.
Some key pointers:
I am using CAMetalLayer and NSView
I override the CAMetalLayer.display(layer:) method and call the layer.setNeedsDisplay() when the user slides an adjustment slider.
I chain together all the CIFilters, including the RAW filter created with CIFilter(imageUrl:)
Most importantly I use the RAW filters scaleFactor parameter to size the image - encountered major performance issues using any other method to resize the image for the views size
Don't expect high performance if the image is zoomed right in - 50% is seems to be the limit for 45megapixel RAW imaged from Nikon D850.
A short video of the result is here https://youtu.be/5wp0CIWAoIM
I am working on a Xamarin App compatible with all devices. I have a general question related to images. I am using Location Mark Image Icons to provide locations available on the Map. My issue is, Image has a white background which is also showing along with its background. I want to show only the Image.
Is this related to the designer to provide the image without background? Or as a developer, I can do something on it.
Xamarin.Forms doesn't delete your white background. What you need to do is following a small tutorial on how to use Adobe Photoshop for example and export your images as png, you might even consider which png type you need, there's 3 types of png:
png8
png24
png32
I won't be going deep in explaining each one of them, but you need to know that they all support transparency and could have a transparent background, however, you might notice some differences between them on the edges.
For example, png8 will give a small white border while png24 will not show that.
You can check this for example: https://helpx.adobe.com/photoshop-elements/using/optimizing-images-png-24-format.html
No, you can't do anything about it using Xamarin.Forms. You need to modify the image and remove the background (using Adobe Photoshop, etc.) and make sure to save it as .png.
If its simple white background you want to remove, You can utilise simple [MakeTransparent][1] method ofBitMap.
But this will remove all white coloured pixel. So IF your logo also contains white color, better you contact your designer.
I am trying to curve and round the image but I am not able to do it perfectly. I have tried to create an .amd file and set it as the background but this is not working perfectly. Is there any other way through which I can make the image round as well as curved on a Blackberry - 10.?
I am getting an image as a response from the server like below:
I want something like the following images.Images are not static they are dynamic it's comes from web service.
I have checked the links from the BlackBerry forums also but did not get a proper solution. If anyone knows then please let me know.
To put rounded corners on an image I would use the the Nine Slice feature described in the API. Using a drawing program crreate a small square example of the frame. Using the nine slice system to scale it to the size of your image and lay it over your image.
The same procedure will work for cicularly vignetting images. Depending on howmany sizes you want you may have to draw them on the fly or have several sizes and scale to other sizes.
Hello I am building a social network similar to facebook and I really need some help on how to handle the images in my website. I would like to know how sites like facebook manage the resizing of their images. An example would be looking at someones photo album. The length and width are not just simply changed. They are done in a more professional way to make the image still look clear and not stretched. Do they use a special tool for this. Another example would be profile pics when they are loaded to your message wall. Your friends profile pics are centered and cropped accordingly and then re sized. How do they go about doing this. Any help would be greatly appreciated.
They resize proportionally with an imaging library like GD, Imagick or others.
The presentation in the gray area is just that, presentation so HTML and CSS.
They stretch the images proportionally so that they don't look wrong; if you make the image 37.5% wider... you also make it 37.5% taller.
If we knew what language you are familiar with, we could probably suggest something to help with this.