I have the following problem - I have two high resolution images that are 300dpi. I want to create new image from the two high-res images. I am using the following code:
I generate the new image like this:
NSString *fileName = #"imageOne.jpeg";
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDirectory = [path objectAtIndex:0];
NSString *imgPathWithFileName = [documentDirectory stringByAppendingPathComponent:fileName];
// [UIImagePNGRepresentation(finalImage) writeToFile:imgPathWithFileName atomically:YES];
[UIImageJPEGRepresentation(imageOne, 1) writeToFile:imgPathWithFileName atomically:YES];
NSLog (#"Success!");
The problem is that the new image is 72dpi. Why is that, when the images that compose the new one, are 300dpi each? How to create the image with 300dpi, any ideas?
Related
My scenario goes in this way. At the start of application a list of images will be downloaded from server & once downloaded all images will be converted into the static images and onwards will be using those static images everywhere in application. I think in android this thing can be achieved using BITMAP. (Not confirm).
Currently i'm using SDWEBIMAGE library for downloading and caching images. But i don't want to use this library anymore. I just want to download all images once and then everywhere i want to add below code snippet for displaying downloaded images.
[ImageView setImage:[UIImage imageNamed:#"DownloadedImageName"]];
Is there any way to get this thing done in ios?
You have to download each Image and save it into "Documents" Directory, and then whenever you need them use that.
For saving image into documents directory, use code like this:
- (IBAction)saveImage:(UIImage*)img {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:#"savedImage.png"];
NSData *imageData = UIImagePNGRepresentation(img);
[imageData writeToFile:savedImagePath atomically:NO];
}
And for getting and show image on imageview, use this code:
- (UIImage*)getImage
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent:#"savedImage.png"];
UIImage *img = [UIImage imageWithContentsOfFile:getImagePath];
return img;
}
[UIImage imageNamed:] method is only for getting images that already exist in your app bundle. So if you have dynamic content that is downloaded from internet, you cannot use this method. Rather, create your own method to load the images from sandbox Documents folder.
I am writing an app which downloads image from my server and stores them locally for offline viewing. The codes I use to store the image locally are shown below. Apart from storing the image, I am also able to read the image from the path (which I stored separately).
However when I re-run my code from Xcode to the iPhone (without uninstalling the app from the phone), the stored image file would be missing. Is this expected? Would I face similar issue when my app has been released on App Store and when the user updates the app? Is there a way to keep the file persistent when I re-run them when I update some codes in Xcode?
NSData *imageData = UIImageJPEGRepresentation(image, 1.0);
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *imagePath =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"file.jpeg",]];
if (![imageData writeToFile:imagePath atomically:YES])
{
// Handling when there is an error
NSLog(#"Failed to store file at path %#",imagePath);
stored.text = #"";
}
else
{ // Handling when write is successful
NSLog(#"Imaged stored path is %#",imagePath);
stored.text = imagePath;
}
[imageView setImage:image];
The code to read the image is shown below:
NSString *imagePathToRead = stored.text;
NSLog(#"Retrieve image from %#",imagePathToRead);
UIImage *image = [UIImage imageWithContentsOfFile:imagePathToRead];
[imageView setImage:image];
I am posting the answer here from rmaddy which solved the issue I was facing. I am posting here so that others can benefit if they are facing similar issue.
For the storing portion:
The stored.text should never store the full path:
stored.text = imagePath;
Instead I should store #"file.jpeg" only.
For the Read portion:
I should always regenerate the full path below when I wanted to read the path instead of the code below:
NSString *imagePathToRead = stored.text;
The corrected codes are:
NSString *imagePathToRead = stored.text;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *imagePath =[documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:imagePathToRead]];
NSLog(#"Retrieve image from %#",imagePath);
UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
This solved the issue and the image is able to be read even though the app is re-installed through Xcode.
So I have an image saved from the camera roll or camera and have a saved the directory and image name to reference back to. When I go back to where I want that image to show it won't. It's just a blank image view.
I seem like it should be straight forward and I have done my own research, but no answer seems to be working for me.
Below is the image path and the code I am using to try and show the image. What am I doing wrong here?
/Users/*****/Library/Developer/CoreSimulator/Devices/FA19C634-C029-4518-BAE1-E7CC601FB9C2/data/Containers/Data/Application/72B5C82B-A8FB-451D-A6DC-DF2C3F3ED12D/Documents/Profile Pics/CYKGXryEDj-1.jpg
self.imageView.image = [UIImage imageWithContentsOfFile:profileImg];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory
NSString *filePath = [documentsPath stringByAppendingPathComponent:#"image.png"]; //Add the file name
NSData *pngData = [NSData dataWithContentsOfFile:filePath];
UIImage *image = [UIImage imageWithData:pngData];
I did only one time using AVFoundation framework -
I was saving images as data and showing them by using imageWithData method. hope this will help you.
On my iPhone app, I'm saving pictures associated with an event via this code:
[pngData writeToFile:filePath atomically:YES]; //Write the file
self.thisTransaction.picPath = filePath;
Later I retrieve and display the photo with this code:
UIImage * image = [UIImage imageWithContentsOfFile:thisTransaction.picPath];
Works great on my iPad (I don't have an iPhone).
However, if I update the app by connecting the iPad to my MB Pro after an Xcode code modification not involving the above lines, then disconnect and run it independently, the picture at the expected picPath is not retrieved. All other data associated with thisTransaction in Core Data is intact and unchanged, but the expected picture doesn't appear on the device after the update.
Can someone please tell me where I'm going wrong?
Edit to clarify file path construction
pngData = UIImagePNGRepresentation(capturedImage.scaledImage);
NSLog(#"1 The size of pngData should be %lu",(unsigned long)pngData.length);
//Save the image someplace, and add the path to this transaction's picPath attribute
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory
int timestamp = [[NSDate date] timeIntervalSince1970];
NSString *timeTag = [NSString stringWithFormat:#"%d",timestamp];
filePath = [documentsPath stringByAppendingPathComponent:timeTag]; //Add the file name
NSLog(#"1 The picture was saved at %#",filePath);
The console log shows this filePath:
/Users/YoursTruly/Library/Developer/CoreSimulator/Devices/65FB33E1-03A7-430D-894D-0C1893E03120/data/Containers/Data/Application/EB9B9523-003E-4613-8C34-4E91B3357F5A/Documents/1433624434
The issue you are having is that the location of an app's sandbox can change over time. Typically this happens when an app is updated. So the worst thing you can do is persist absolute file paths.
What you need to do is persist just the part of the path relative to the base path (the "Documents" folder in this case).
Then when you want to reload the file again, append the persisted relative path to the current value of the "Documents" folder.
So your code needs to be something like this:
Save the file:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory
int timestamp = [[NSDate date] timeIntervalSince1970];
NSString *timeTag = [NSString stringWithFormat:#"%d",timestamp];
filePath = [documentsPath stringByAppendingPathComponent:timeTag]; //Add the file name
[pngData writeToFile:filePath atomically:YES]; //Write the file
self.thisTransaction.picPath = timeTag; // not filePath
Load the file:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory
NSString *filePath = [documentsPath stringByAppendingPathComponent:thisTransaction.picPath];
UIImage *image = [UIImage imageWithContentsOfFile:filePath];
Usually it's the other way around, you use the path to display the image. I was wondering if you can get the path if you already have the image.
if you already have the image i.e. have added the file to your resources, you can use this to get the file path;
NSString *string = [[NSBundle mainBundle] pathForResource:#"IMAGE_FILE_NAME" ofType:#"jpg"]; // or ofType:#"png", etc.
I don't believe it is possible to get it directly from UIImage.
Best way is to save the image in a directory, then you will have the file path.
//image is your UIImage;
if (image != nil)
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:
#"test.png" ];
NSData* data = UIImagePNGRepresentation(image);
[data writeToFile:path atomically:YES];
}
path will be your filepath.
Once a UIImage is created, the image data is loaded into memory and no longer connected to the file on disk. As such, the file can be deleted or modified without consequence to the UIImage and there is no way of getting the source path from a UIImage.