I am trying to make a simple Crop functionality with Swift. I am trying with CGImageCreateWithImageInRect function - which works perfectly but produce inferior quality. Am I missing something ?
func retriveCroppedImage(){
let yratio: CGFloat = imgviewrect.size.height / chosenImage.size.height
let xratio: CGFloat = imgviewrect.size.width / chosenImage.size.width
var cliprect = CGRectMake(centerpoint.x - vWidth/2, centerpoint.y - vHeight/2, vWidth, vHeight)
print("cliprect top \(cliprect.size)")
cliprect.size.height = cliprect.size.height / xratio;
cliprect.size.width = cliprect.size.width / xratio;
cliprect.origin.x = cliprect.origin.x / xratio + imgviewrect.origin.x / xratio
cliprect.origin.y = cliprect.origin.y / yratio - imgviewrect.origin.y / xratio
print("cliprect On Image \(cliprect)")
let imageRef = CGImageCreateWithImageInRect(chosenImage.CGImage, cliprect )
croppedImg = UIImage(CGImage: imageRef!, scale: UIScreen.mainScreen().scale, orientation: chosenImage.imageOrientation)
print("Operation complete");
}
Screen shots : Main VC
after cropping I get Cropped Image
After trying all the options - I found accidentally I set Alpha in Image View on the story board. There was nothing wrong with the CGImageCreateWithImageInRect function. Now my cropping app is working as desired. But thank you all for the suggestions.
Related
I was able to identify squares from a images using VNDetectRectanglesRequest. Now I want those rectangles to store as separate images (UIImage or cgImage). Below is what I tried.
let rectanglesDetection = VNDetectRectanglesRequest { request, error in
rectangles = request.results as! [VNRectangleObservation]
rectangles.sort{$0.boundingBox.origin.y > $1.boundingBox.origin.y}
for rectangle in rectangles {
let rect = rectangle.boundingBox
let imageRef = cgImage.cropping(to: rect)
let image = UIImage(cgImage: imageRef!, scale: image!.scale, orientation: image!.imageOrientation)
checkBoxImages.append(image)
}
Can anybody point out what's wrong or what should be the best approach?
Update 1
At this stage, I'm testing with an image that I added to the assets.
With this image I get 7 rectangles as observations as each for each cell and one for the table margin.
My task is to identify the text inside in each rectangle and my approach is to send VNRecognizeTextRequest for each rectangle that has been identified. My real scenario is little complicated than this but I want to at least achieve this before going forward.
Update 2
for rectangle in rectangles {
let trueX = rectangle.boundingBox.minX * image!.size.width
let trueY = rectangle.boundingBox.minY * image!.size.height
let width = rectangle.boundingBox.width * image!.size.width
let height = rectangle.boundingBox.height * image!.size.height
print("x = " , trueX , " y = " , trueY , " width = " , width , " height = " , height)
let cropZone = CGRect(x: trueX, y: trueY, width: width, height: height)
guard let cutImageRef: CGImage = image?.cgImage?.cropping(to:cropZone)
else {
return
}
let croppedImage: UIImage = UIImage(cgImage: cutImageRef)
croppedImages.append(croppedImage)
}
My image width and height is
width = 406.0 height = 368.0
I've taken my debug interface for you to get a proper understand.
As #Lasse mentioned, this is my actual issue with screenshots.
This is just a guess since you didn't state what the actual problem is, but probably you're getting a zero-sized image for each VNRectangleObservation.
The reason is: Vision uses a normalized coordinate space from 0.0 to 1.0 with lower left origin.
So in order to get the correct rectangle of your original image, you need to convert the rect from Normalized Space to Image Space. Luckily there is VNImageRectForNormalizedRect(::_:) to do just that.
While using TPPDF library, when a high-quality image is loaded inside a pdf, the image turns blurry.
I tried all the possible methods.
Here is my Code:
let coverImage = PDFImage(image: UIImage(named: "Banner")!, quality: 1, options: [.resize])
//To find proportional width and height
let imageWidth: CGFloat = coverImage.image.size.width
let imageHeight: CGFloat = coverImage.image.size.height
let targetHeight: CGFloat = imageHeight/imageWidth
print("PdfWidth", pdf.layout.width)
print("PdfHeight", pdf.layout.height)
print("TargetHeight", pdf.layout.width*targetHeight)
print("ImageWidth", coverImage.image.size.width)
print("ImageHeight", coverImage.image.size.height)
coverImage.size = CGSize(width: pdf.layout.width, height: pdf.layout.width*targetHeight)
print("size", coverImage.size)
pdf.addImage(.contentCenter, image: coverImage)
log, I get is:
PdfWidth 595.0
PdfHeight 842.0
TargetHeight 44.5
ImageWidth 595.0
ImageHeight 44.5
size (595.0, 44.5)
I also tried to add a high-resolution image of 8000x600, but still, the image is blurry.
I have a UIScrollView which contains a UIImage. On top of that is a box that the user can move the image, so that that portion is cropped.
This screenshot explains it better:
So they can scroll the image around until the portion they want is inside that box.
I then want to be able to crop the scrollView/UIImage to exactly that size and store the cropped image.
It shouldn't be very hard but I've spent ages trying screenshots, UIGraphicsContext, etc. and cant seem to get anything to work.
Thanks for the help.
I finally figured out how to get it to work. Here is the code:
func croppedImage() -> UIImage {
let cropSize = CGSize(width: 280, height: 280)
let scale = (imageView.image?.size.height)! / imageView.frame.height
let cropSizeScaled = CGSize(width: cropSize.width * scale, height: cropSize.height * scale)
if #available(iOS 10.0, *) {
let r = UIGraphicsImageRenderer(size: cropSizeScaled)
let x = -scrollView.contentOffset.x * scale
let y = -scrollView.contentOffset.y * scale
return r.image { _ in
imageView.image!.draw(at: CGPoint(x: x, y: y))
}
} else {
return UIImage()
}
}
So it first calculates the scale of the imageView and the actual image.
Then it creates a CGSize of that crop box as shown in the photo. However, the width and height must be scaled by the scale factor. (e.g. 280 * 6.5)
You must check if the phone is running iOS 10.0 for UIGraphicsImageRender - if not, it won't work.
Initialise this with the crop box size.
The image must then be offset, and this is calculated by getting the scrollView's content offset, negating it, and multiplying by the scale factor.
Then return the image drawn at that point!
I am trying to create a simple crop feature that takes into effect device screen-density and zoom-scale
I basically modeled it after the code in this tutorial:
https://www.youtube.com/watch?v=hz9pMw4Y2Lk
func cropImage(sender:AnyObject!) { //triggered by a button
let myScale = UIScreen.mainScreen().scale
var height = self.scrollView.bounds.height
var width = self.scrollView.bounds.width
UIGraphicsBeginImageContextWithOptions(CGSizeMake(width, height), true, myScale)
let offset = scrollView.contentOffset
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), -offset.x, -offset.y)
scrollView.layer.renderInContext(UIGraphicsGetCurrentContext())
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
//i would like to check here if target image is >300x300px
if image.size.width > 300 && image.size.height > 300{
println("image correct")
println(image.size)
} else {
println("nope")
println(image.size)
}
}
So far I will always end up having an image that is bounds.height/width -which means that on a 320 device incl. a 8xp leading/trailing gap, the user might never be able to create a "correct image".
I understand why it happens, but I do not understand where I should be multiplying with device-scale factor and/or zoom-factor of the UIScrollView.
For example having a camera picture imported at ScrollView zoom-scale 0.0 - i want to keep it at ~8MP'ish.
I have been trying to rotate an image for a couple days now, but the best I get is still a black image.
I suspect it may have something to do with the point I'm rotating around but I'm not sure. I say that because I tried the whole solution proposed here and translated in Xamarin terms, but that didn't work.
Here's my code:
public void Rotate (string sourceFile, bool isCCW){
using (UIImage sourceImage = UIImage.FromFile(sourceFile))
{
var sourceSize = sourceImage.Size;
UIGraphics.BeginImageContextWithOptions(new CGSize(sourceSize.Height, sourceSize.Width), true, 1.0f);
CGContext bitmap = UIGraphics.GetCurrentContext();
// rotating before DrawImage didn't work, just got the image cropped inside a rotated frame
// bitmap.RotateCTM((float)(isCCW ? Math.PI / 2 : -Math.PI / 2));
// swapped Width and Height because the image is rotated
bitmap.DrawImage(new CGRect(0, 0, sourceSize.Height, sourceSize.Width), sourceImage.CGImage);
// rotating after causes the resulting image to be just black
bitmap.RotateCTM((float)(isCCW ? Math.PI / 2 : -Math.PI / 2));
var resultImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
if (targetFile.ToLower().EndsWith("png"))
resultImage.AsPNG().Save(sourceFile, true);
else
resultImage.AsJPEG().Save(sourceFile, true);
}
}
It looks like you want to take a UIImage, and then rotate it either 90 clockwise or 90 degrees counter clockwise. You can actually do this with just a few lines of code:
public void RotateImage(ref UIImage imageToRotate, bool isCCW)
{
var imageRotation = isCCW ? UIImageOrientation.Right : UIImageOrientation.Left;
imageToRotate = UIImage.FromImage(imageToRotate.CGImage, imageToRotate.CurrentScale, imageRotation);
}
We use UIImage.FromImage() that accepts 3 parameters. The first is a CGImage, from which we can get from the UIImage you're trying to rotate. The 2nd parameter is the scale of the image. The 3rd parameter is the important one. We can rotate it using UIImageOrientation.Right (90 degrees CCW) or UIImageOrientation.Left (90 degrees CW). You can check out the Apple documentation for the meaning of the other UIImageOrientation constants:
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIImage_Class/index.html#//apple_ref/c/tdef/UIImageOrientation
UPDATE:
Note that the code above only changes EXIF flags and calling it twice doesn't rotate the image 180deg.
Add this code to make the result cumulative:
UIGraphics.BeginImageContextWithOptions(new CGSize((float)h, (float)w), true, 1.0f);
imageToRotate.Draw(new CGRect(0, 0, (float)h, (float)w));
var resultImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
imageToRotate = resultImage;