Why is this code setting artistImage to an image with 0 width and 0 height?
NSURL *artistImageURL = [NSURL URLWithString:#"http://userserve-ak.last.fm/serve/252/8581581.jpg"];
NSImage *artistImage = [[NSImage alloc] initWithContentsOfURL:artistImageURL];
As Ken wrote, the DPI is messed up in this image. If you want to force NSImage to set the real image size (ignoring the DPI), use the method described at http://borkware.com/quickies/one?topic=NSImage:
NSBitmapImageRep *rep = [[image representations] objectAtIndex: 0];
NSSize size = NSMakeSize([rep pixelsWide], [rep pixelsHigh]);
[image setSize: size];
NSImage does load this fine for me, but that particular image has corrupt metadata. Its resolution according to the exif data is 7.1999997999228071e-06 dpi.
NSImage respects the DPI info in the file, so if you try to draw the image at its natural size, you'll get something 2520000070 pixels across.
Last I checked, NSImage's -initWithContentsOfURL: only works with file URLs. You'll need to retrieve the URL first, and then use -initWithData:
It is more or less guaranteed that .representations contains NSImageRep* (of course not always NSBitmapImageRep). To be on a safe side for future extensions one can write something like code below. And it also takes into account multiple representation (like in some .icns and .tiff files).
#implementation NSImage (Extension)
- (void) makePixelSized {
NSSize max = NSZeroSize;
for (NSObject* o in self.representations) {
if ([o isKindOfClass: NSImageRep.class]) {
NSImageRep* r = (NSImageRep*)o;
if (r.pixelsWide != NSImageRepMatchesDevice && r.pixelsHigh != NSImageRepMatchesDevice) {
max.width = MAX(max.width, r.pixelsWide);
max.height = MAX(max.height, r.pixelsHigh);
}
}
}
if (max.width > 0 && max.height > 0) {
self.size = max;
}
}
#end
Related
I've done an exhaustive search on this and I know similar questions have been posted before about NSBitmapImageRep, but none of them seem specific to what I'm trying to do which is simply:
Read in an image from the desktop (but NOT display it)
Create an NSBitmap representation of that image
Iterate through the pixels to change some colours
Save the modified bitmap representation as a separate file
Since I've never worked with bitmaps before I thought I'd just try to create and save one first, and worry about modifying pixels later. That seemed really straightforward, but I just can't get it to work. Apart from the file saving aspect, most of the code is borrowed from another answer found on StackOverflow and shown below:
-(void)processBitmapImage:(NSString*)aFilepath
{
NSImage *theImage = [[NSImage alloc] initWithContentsOfFile:aFilepath];
if (theImage)
{
CGImageRef CGImage = [theImage CGImageForProposedRect:nil context:nil hints:nil];
NSBitmapImageRep *imageRep = [[NSBitmapImageRep alloc] initWithCGImage:CGImage];
NSInteger width = [imageRep pixelsWide];
NSInteger height = [imageRep pixelsHigh];
long rowBytes = [imageRep bytesPerRow];
// above matches the original size indicating NSBitmapImageRep was created successfully
printf("WIDE pix = %ld\n", width);
printf("HIGH pix = %ld\n", height);
printf("Row bytes = %ld\n", rowBytes);
// We'll worry about this part later...
/*
unsigned char* pixels = [imageRep bitmapData];
int row, col;
for (row=0; row < height; row++)
{
// etc ...
for (col=0; col < width; col++)
{
// etc...
}
}
*/
// So, let's see if we can just SAVE the (unmodified) bitmap first ...
NSData *pngData = [imageRep representationUsingType: NSPNGFileType properties: nil];
NSString *destinationStr = [self pathForDataFile];
BOOL returnVal = [pngData writeToFile:destinationStr atomically: NO];
NSLog(#"did we succeed?:%#", (returnVal ? #"YES": #"NO")); // the writeToFile call FAILS!
[imageRep release];
}
[theImage release];
}
While I like this code for its simplicity, another potential issue down the road might be that Apple docs advise us treat bitmaps returned with 'initWithCGImage' as read-only objects…
Can anyone please tell me where I'm going wrong with this code, and how I could modify it to work. While the overall concept looks okay to my non-expert eye, I suspect I'm making a dumb mistake and overlooking something quite basic. Thanks in advance :-)
That's a fairly roundabout way to create the NSBitmapImageRep. Try creating it like this:
NSBitmapImageRep* imageRep = [NSBitmapImageRep imageRepWithContentsOfFile:aFilepath];
Of course, the above does not give you ownership of the image rep object, so don't release it at the end.
To load icon images, I have the below code in one of the methods:
NSLog(#"icon path: %#", iconPath);
NSImage *iconImage = [[NSImage alloc] initWithContentsOfFile:iconPath];
return iconImage;
From the log output, it is clear that image resources are being opened from the correct location. I don't see errors. Yet, tif files that I open are shown to have empty NSSize (width=0, height=0) in debugger, and displayed on the screen as if I am pointing to some runaway memory segment.
Flags are mainly set to 0. The exceptions are colorMatchPreferred and multipleResolutionMatching set to 1.
Reps points to an array (NSArrayM *) containing two (2) bitmap representations (NSBitmapImageRep entries).
Please advise what am I doing wrong!
Thank you
//to get image original size use this code
NSArray * imageReps = [NSBitmapImageRep imageRepsWithContentsOfFile:fileUrl];
NSInteger width = 0;
NSInteger height = 0;
for (NSImageRep * imageRep in imageReps)
{
if ([imageRep pixelsWide] > width)
width = [imageRep pixelsWide];
if ([imageRep pixelsHigh] > height)
height = [imageRep pixelsHigh];
}
in my ios app i am listing out some data in scroll view. When a button is clicked the datas in the page are been generated in pdf file format. Following is the bit of code.
- (void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename{
// Creates a mutable data object for updating with binary data, like a byte array
NSMutableData *pdfData = [NSMutableData data];
// Points the pdf converter to the mutable data object and to the UIView to be converted
UIGraphicsBeginPDFContextToData(pdfData, aView.bounds, nil);
UIGraphicsBeginPDFPage();
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
// draws rect to the view and thus this is captured by UIGraphicsBeginPDFContextToData
[aView.layer renderInContext:pdfContext];
// remove PDF rendering context
UIGraphicsEndPDFContext();
// Retrieves the document directories from the iOS device
NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
NSString* documentDirectory = [documentDirectories objectAtIndex:0];
NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];
// instructs the mutable data object to write its context to a file on disk
[pdfData writeToFile:documentDirectoryFilename atomically:YES];
NSLog(#"documentDirectoryFileName: %#",documentDirectoryFilename);
}
From the above code, i am able to generate a pdf file, but i am facing the following issue.
If i have more than 50 data, in my app i am able to see only the first 10 data and to see the others i need to scroll them. In this case when the pdf file gets generated it is taking only the data of first 10 and not the others. How to get the other data too
renderInContext: will only render what you currently see - UIScrollView is smart and will only have the views in the hierarchy that you need right now. You need a for-loop to manually scroll and redraw. This might be tricky to get right, maybe call [aView layoutSubviews] manually after scrolling to force the scrollView to rearrange the subviews instantly.
as steipete said, you can use loop to renderIncontext
- You need to calculate num of loop
numOfLoop = webview.ScrollView.ContentSize.Height/weview.frame.size.height
use loop to renderInContext
for(int i = 0; i < numOfLopp; i ++)
1.UIGraphicsBeginPDFPage()
get current context
renderIncontext
This way run correct in my app but I am getting with BIG issue when the numOfLoop lager
- you will get slow to renderInContext
- Memory will be increase -> Close app
In this way, How can I remove/release context when I am in once loop ?
Other way, you can use https://github.com/iclems/iOS-htmltopdf/blob/master/NDHTMLtoPDF.h
to generate to PDF
#steipete, #all Hi i tried the below code it generate multipage PDF, but the visible area in view is repeated for all the pages. please add any further ideas to improve the result.
-(void)createPDFfromUIView:(UIWebView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
{
NSString *oldFilePath= [[NSBundle mainBundle] pathForResource:#"ABC" ofType:#"pdf"];
NSMutableData *pdfData = [NSMutableData data];
UIGraphicsBeginPDFContextToData(pdfData, aView.bounds, nil);
CFURLRef url = CFURLCreateWithFileSystemPath (NULL, (CFStringRef)oldFilePath, kCFURLPOSIXPathStyle, 0);
CGPDFDocumentRef templateDocument = CGPDFDocumentCreateWithURL(url);
CFRelease(url); size_t count = CGPDFDocumentGetNumberOfPages(templateDocument);
for (size_t pageNumber = 1; pageNumber <= count; pageNumber++)
{
UIGraphicsBeginPDFPage();
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
[aView.layer renderInContext:pdfContext];
}
CGPDFDocumentRelease(templateDocument);
// remove PDF rendering context UIGraphicsEndPDFContext();
// Retrieves the document directories from the iOS device
NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString* documentDirectory = [documentDirectories objectAtIndex:0];
NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];
[pdfData writeToFile:documentDirectoryFilename atomically:YES];
NSLog(#"documentDirectoryFileName: %#",documentDirectoryFilename);
}
Check ScrollViewToPDF example
It uses same scrollview's layer renderInContext but here PDF is created according to your requirement such as one page PDF or multiple page PDF
Note : It captures all visible as well as invisible part of scrollView
So, this is what I need :
Take an NSImage
Compress it as much as possible (loseless compress, no obvious drop in quality)
Save it back to disk
In the past, I tried using OptiPNG - as compiled binary (and getting results asynchronously) - which worked.
However, what if I don't want a terminal-like solution with external apps, but something more Cocoa-native?
Any ideas?
NSImage* image; // your NSImage
// With compression
NSData* data = [image
TIFFRepresentationUsingCompression:NSTIFFCompressionLZW
factor:0.5f]; // you can change factor between 0 and 1.0 for preferred compression rate
if (data != nil) {
NSBitmapImageRep* bitmap = [[NSBitmapImageRep alloc] initWithData:data];
if (bitmap != nil) {
NSData* bitmapData = [bitmap
representationUsingType:NSBitmapImageFileTypePNG
properties:#{}];
if (bitmapData != nil) {
[bitmapData
writeToFile:<file_path> //path where to save png
atomically:true];
}
}
}
Update: As mentioned in comments, this does not compress png.
However I have used this code in ShareExtension and it compress received screenshots well (from 1.1-1.5MB if save in plain to 0.4-0.7MB using representationUsingType) and without quality loss, just like OP asked.
My iPad app that I am creating has to be able to create the tiles for a 4096x2992 image that is generated earlier in my app..
4096x2992 image isn't very complex (what i'm testing with) and when written to file in png format is approximately 600kb...
On the simulator, this code seems to work fine however when I run the app in tighter memory conditions (on my iPad) the process quits because it ran out of memory...
I've been using the same code in the app previously what was working fine (was only creating tiles for 3072x2244 images however)...
Either I must be doing something stupidly wrong or my #autoreleasepool's aren't working as they should (i think i mentioned that im using ARC)... When running in instruments I can just see the memory used climb up until ~500mb where it then crashes!
I've analysed the code and it hasn't found a single memory leak related to this part of my app so I'm really confused on why this is crashing on me...
Just a little history on how my function gets called so you know whats happening... The app uses CoreGraphics to render a UIView (4096x2992) with some UIImageView's inside it then it sends that UIImage reference into my function buildFromImage: (below) where it begins cutting up/resizing the image to create my file...
Here is the buildFromImage: code... the memory issues are built up from within the main loop under NSLog(#"LOG ------------> Begin tile loop ");...
-(void)buildFromImage:(UIImage *)__image {
NSLog(#"LOG ------------> Begin Build ");
//if the __image is over 4096 width of 2992 height then we must resize it! (stop crashes ect)
if (__image.size.width > __image.size.height) {
if (__image.size.width > 4096) {
__image = [self resizeImage:__image toSize:CGSizeMake(4096, (__image.size.height * 4096 / __image.size.width))];
}
} else {
if (__image.size.height > 2992) {
__image = [self resizeImage:__image toSize:CGSizeMake((__image.size.width * 2992 / __image.size.height), 2992)];
}
}
//create preview image (if landscape, no more than 748 high... if portrait, no more than 1004 high) must keep scale
NSString *temp_archive_store = [[NSString alloc] initWithFormat:#"%#/%i-temp_imgdat.zip",NSTemporaryDirectory(),arc4random()];
NSString *temp_tile_store = [[NSString alloc] initWithFormat:#"%#/%i-temp_tilestore/",NSTemporaryDirectory(),arc4random()];
//create the temp dir for the tile store
[[NSFileManager defaultManager] createDirectoryAtPath:temp_tile_store withIntermediateDirectories:YES attributes:nil error:nil];
//create each tile and add it to the compressor once its made
//size of tile
CGSize tile_size = CGSizeMake(256, 256);
//the scales that we will be generating the tiles too
NSMutableArray *scales = [[NSMutableArray alloc] initWithObjects:[NSNumber numberWithInt:1000],[NSNumber numberWithInt:500],[NSNumber numberWithInt:250],[NSNumber numberWithInt:125], nil]; //scales to loop round over
NSLog(#"LOG ------------> Begin tile loop ");
#autoreleasepool {
//loop through the scales
for (NSNumber *scale in scales) {
//scale the image
UIImage *imageForScale = [self resizedImage:__image scale:[scale intValue]];
//calculate number of rows...
float rows = ceil(imageForScale.size.height/tile_size.height);
//calulate number of collumns
float cols = ceil(imageForScale.size.width/tile_size.width);
//loop through rows and cols
for (int row = 0; row < rows; row++) {
for (int col = 0; col < cols; col++) {
NSLog(#"LOG ------> Creating Tile (%i,%i,%i)",col,row,[scale intValue]);
//build name for tile...
NSString *tile_name = [NSString stringWithFormat:#"%#_%i_%i_%i.png",#"image",[scale intValue],col,row];
#autoreleasepool {
//build tile for this coordinate
UIImage *tile = [self tileForRow:row column:col size:tile_size image:imageForScale];
//convert image to png data
NSData *tile_data = UIImagePNGRepresentation(tile);
[tile_data writeToFile:[NSString stringWithFormat:#"%#%#",temp_tile_store,tile_name] atomically:YES];
}
}
}
}
}
}
Here are my resizing/cropping functions too as these could also be causing the issue..
-(UIImage *)resizeImage:(UIImage *)inImage toSize:(CGSize)scale {
#autoreleasepool {
CGImageRef inImageRef = [inImage CGImage];
CGColorSpaceRef clrRf = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(NULL, ceil(scale.width), ceil(scale.height), CGImageGetBitsPerComponent(inImageRef), CGImageGetBitsPerPixel(inImageRef)*ceil(scale.width), clrRf, kCGImageAlphaPremultipliedFirst );
CGColorSpaceRelease(clrRf);
CGContextDrawImage(ctx, CGRectMake(0, 0, scale.width, scale.height), inImageRef);
CGImageRef img = CGBitmapContextCreateImage(ctx);
UIImage *image = [[UIImage alloc] initWithCGImage:img scale:1 orientation:UIImageOrientationUp];
CGImageRelease(img);
CGContextRelease(ctx);
return image;
}
}
- (UIImage *)tileForRow: (int)row column: (int)col size: (CGSize)tileSize image: (UIImage*)inImage
{
#autoreleasepool {
//get the selected tile
CGRect subRect = CGRectMake(col*tileSize.width, row * tileSize.height, tileSize.width, tileSize.height);
CGImageRef inImageRef = [inImage CGImage];
CGImageRef tiledImage = CGImageCreateWithImageInRect(inImageRef, subRect);
UIImage *tileImage = [[UIImage alloc] initWithCGImage:tiledImage scale:1 orientation:UIImageOrientationUp];
CGImageRelease(tiledImage);
return tileImage;
}
}
Now I never use to be that good with memory management, so I did take the time to read up on it and also converted my project to ARC to see if that could address my issues (that was a while ago) but from the results i get after profiling it in instruments I must be doing something STUPIDLY wrong for the memory to leak as bad as it does but I just can't see what i'm doing wrong.
If anybody can point out anything I may be doing wrong it would be great!
Thanks
Liam
(let me know if you need more info)
I use "UIImage+Resize". Inside #autoreleasepool {} it works fine with ARC in a loop.
https://github.com/AliSoftware/UIImage-Resize
-(void)compress:(NSString *)fullPathToFile {
#autoreleasepool {
UIImage *fullImage = [[UIImage alloc] initWithContentsOfFile:fullPathToFile];
UIImage *compressedImage = [fullImage resizedImageByHeight:1024];
NSData *compressedData = UIImageJPEGRepresentation(compressedImage, 75.0);
[compressedData writeToFile:fullPathToFile atomically:NO];
}
}