I have two images that need to be overlaid over one another, and they are both png images (since I need to be able to make them transparent). However, when I load them into a UIImage view in my xib file, neither of them display at all! When I try using the jpg format of the same images it works fine, but because jpg doesn't support transparency, the overlay effect I need is lost. How can I get the png images to actually display in the window?
This is the kind of task that is easier to do from code than from Interface "Crappy" Builder:
CGRect imageFrame = CGRectMake(x, y, width, height);
UIImage *image1 = // however you obtain your 1st image
UIImage *image2 = // however you obtain your 2nd image
UIImageView *imgView1 = [[UIImageView alloc] initWithImage:image1];
// Adjust the alpha of the view
imgView1.alpha = 1.0f; // This is most advisably 1.0 (always)
imgView1.backgroundColor = [UIColor clearColor];
imgView1.frame = imageFrame;
UIImageView *imgView2 = [[UIImageView alloc] initWithImage:image2];
// Adjust the alpha of the view
imgView1.alpha = 0.5f; // or whatever you find practical
imgView1.backgroundColor = [UIColor clearColor];
imgView2.frame = imageFrame;
// Assume a view controller
[self.view addSubview:imgView1];
[self.view addSUbview:imgView2]; // add the image view later which you wanna be on the top of the other one
// If non-ARC environment, we need to take care of the percious RAM
[imgView1 release];
[imgView2 release];
Try to open your png images in a photo editor like photoshop or pixelmator and save it again as NOT interlaced (in the save options of png).
Related
hello I built this tableview using the InterfaceBuilder and storyboard I used custom for the style of the cell and content prototype of the table view, this is the image:
custom tableview
but now I need to redo everything programmatically I tried insert an imageview in the cell using this code
UIImageView *imgView = [[UIImageView alloc] initWithFrame:
CGRectMake(300, 0, 80, 80)];
imgView.image = [UIImage imageNamed:#"esquina_estrella.png"];
cell.imageView.image = imgView.image;`
but the image stays static unresponsive to CGRectMake thanks for you help
Use this code to the Cell:
// Make your frame origin 0,0 as below done.
UIImageView *imgView = [[UIImageView alloc] initWithFrame:
CGRectMake(0, 0, 80, 80)];
imgView.image = [UIImage imageNamed:#"esquina_estrella.png"];
[cell addSubview:imgView];
[imgView release];
imgView = nil;
Add
imgView.clipsToBounds = YES;
To limit display of the image to the frame of the image view.
Also, you are adding the image of the image view to the cell's image view, which is a different object, without using your image view and its frame. You actually do not need an image view if you are just using the image. What you want is
cell.imageView = imgView;
or
[cell.contentView addSubview:imgView];
The latter will be preferable if you want to place it exactly and add more image views as in your screen shot.
I seem to have a curious bug involving renderInContext.
I am working on a "scrapbook" app which allows people to freely arrange text, colored squares and photos within a scrapbookView. Note that users can add both photos from a built-in collection of photos (loaded via imageNamed:) and photos from their asset library.
My code creates both PDFs and thumbnails as needed from the scrapbook view and all its subviews by first creating a PDFContext (for PDFs) or an ImageContext (for thumbnail images), then calling renderInContext on scrapBookView.layer.
In general, the code works, with one exception which I will describe. When I am creating a PDF, both built-in images and asset library images are correctly included in the rendered PDF. However, when I am creating a thumbnail, the built-in images appear, but the asset library images don't correctly appear. I know the imageView is there because elsewhere I set its background color to light gray but the image itself is absent.
I suspect that there may be an asynchronous element to loading the images into image views, and the image doesn't get there fast enough when its an asset library image being rendered into an ImageContext.
Is this possible? If not, why would renderInContext work fine in a PDFContext but not so well in an ImageContext?
And more to the point, how can I get my asset library images included in my thumbnails.
Both the pdf representation and the thumbnail are created via methods in scrapbookView. The code is as follows:
To create pdfs:
-(NSData*) pdfRepresentation
{
//== create a pdf context
NSMutableData* result = [[NSMutableData alloc] init];
UIGraphicsBeginPDFContextToData(result, self.bounds, nil);
UIGraphicsBeginPDFPage();
//== draw this view into it
[self.layer renderInContext: UIGraphicsGetCurrentContext()]; // works for asset library images
//== add a rectangular frame also
CGContextRef pdf = UIGraphicsGetCurrentContext();
CGContextAddRect(pdf, self.bounds);
[[UIColor lightGrayColor] setStroke];
CGContextStrokePath(pdf);
//== clean up and return the results
UIGraphicsEndPDFContext();
return [result copy];
}
To create the thumbnail:
-(UIImage*) thumbnailRepresentation
{
//== create a large bitmapped image context
CGFloat minSpan = MIN(self.bounds.size.height, self.bounds.size.width);
CGSize imageSize = CGSizeMake(minSpan, minSpan);
UIGraphicsBeginImageContextWithOptions(imageSize, YES, 0.0);
//== draw the current view into the bitmap context
self.backgroundColor = [UIColor whiteColor];
[self.layer renderInContext: UIGraphicsGetCurrentContext()]; // doesn't work for asset library images
self.backgroundColor = [UIColor clearColor];
//== get the preliminary results
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//== create a smaller image from this image
CGFloat thumbnailWidth = 40.0;
CGFloat scaleFactor = thumbnailWidth / minSpan;
UIImage* result = [UIImage imageWithCGImage:[image CGImage] scale:scaleFactor orientation:UIImageOrientationUp];
return result;
}
// btw - seems wasteful to create such a large intermediate image
Any help would be appreciated.
i have this method i use to load many images to scroll view, but when the images load from the url my scroll view is stuck and i can't understand how to load them in the background so the user will not feel it.
this method will call few times (8) in "for" cycle.
- (void)loadPhotosToLeftscroll{
//getting image information from JSON
NSMutableDictionary *photoDict;
photoDict = [leftPhotoArray lastObject];
//getting the photo
NSString *photoPath = [photoDict objectForKey:#"photos_path"];
NSLog(#"photo Path:%#",photoPath);
NSData * imageData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:photoPath]];
UIImage *image = [UIImage imageWithData:imageData];
// use the image how you like, say, as your button background
//calculating the hight of next photo
UIImageView *leftImage = [leftBlockScroll.subviews lastObject];
//allocating photoView
UIImageView *photoView = [[UIImageView alloc]initWithFrame:CGRectMake(5 , leftImage.frame.origin.y + leftImage.frame.size.height+5, image.size.width/2, image.size.height/2 )];
photoView.userInteractionEnabled=YES;
[photoView.layer setMasksToBounds:YES];
[photoView.layer setCornerRadius:3];
//getting items list
NSDictionary *sh_items = [photoDict objectForKey:#"items"];
//adding image button
UIButton *imageOverButton = [UIButton buttonWithType:UIButtonTypeCustom];
imageOverButton.frame = CGRectMake(0, 0, photoView.frame.size.width, photoView.frame.size.height);
[imageOverButton addTarget:self action:#selector(LeftimagePressed:) forControlEvents:UIControlEventTouchUpInside];
[imageOverButton setTag:[leftPhotoArray count]-1];
[photoView addSubview:imageOverButton];
//adding sh button to imageView
[self addThe_sh_signs:sh_items To_ImageView:photoView];
//subViewing the image to the scrollView
[self insert_Image:image toImageView:photoView in_Scroll:leftBlockScroll];
//calclulating the position of next imageView in scroll.
nextLeftPhotoHight = photoView.frame.size.height + photoView.frame.origin.y + 5;
//calculating the hight of the highest scroll view in both.
leftBlockScroll.contentSize = CGSizeMake(160, [self theSizeOfScrollViewHight]);
rightBlocScroll.contentSize = CGSizeMake(160, [self theSizeOfScrollViewHight]);
isLoadindContant = NO;
[self.view reloadInputViews];
[leftBlockScroll reloadInputViews];
}
please do not send me to some link that trying to explain how to use the asynchronous.
Try to explain according the method you see here.
Im here for any question, that you need to ask to help me.
You will have to do it asynchronously in a proper way. I do not think there is any way around that. I subclassed an UIImageView object and placed many instances of it within the cells of a talbe (in your case within the scroll view). The subclass objects are initialized with an url and load their image asynchronously (with some caching so that the image is not loaded every time).
This tutorial helped me much in the beginning:
http://www.markj.net/iphone-asynchronous-table-image/
You will just have to adopt that to your scroll view. The underlaying principle remains the same.
I have a 16x16 pixel image that I want to display in an UIImageView. So far, no problem, however 16x16 is a bit small so I want to resize the image view to 32x32 and thus also scale the image up.
But I can't get it to work, it always shows the image with 16x16, no matter what I try. I googled a lot, and found many snippets here on Stack Overflow, but its still doesn't work.
Here is my code so far:
[[cell.imageView layer] setMagnificationFilter:kCAFilterNearest];
[cell.imageView setAutoresizingMask:UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight];
[cell.imageView setClipsToBounds:NO];
[cell.imageView setFrame:CGRectMake(0, 0, 32, 32)];
[cell.imageView setBounds:CGRectMake(0, 0, 32, 32)];
[cell.imageView setImage:image];
I don't want to create a new 32x32 pixel image because I already have some memory problems on older devices and creating two images instead of having just one looks like a very bad approach to me (the images can be perfectly scaled and it doesn't matter if they lose quality).
I have successfully made it using CGAffineTransformMakeScale!
cell.imageView.image = cellImage;
//self.rowWidth is the desired Width
//self.rowHeight is the desired height
CGFloat widthScale = self.rowWidth / cellImage.size.width;
CGFloat heightScale = self.rowHeight / cellImage.size.height;
//this line will do it!
cell.imageView.transform = CGAffineTransformMakeScale(widthScale, heightScale);
I think you need to set the contentMode:
cell.imageView.contentMode = UIViewContentModeScaleAspectFit;
In context:
UIImage *image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"slashdot" ofType:#"png"]];
imageView = [[UIImageView alloc] initWithImage:image];
[imageView setBackgroundColor:[UIColor greenColor]];
[imageView setFrame:CGRectMake(x,y,32,32)];
imageView.contentMode = UIViewContentModeScaleAspectFit;
[self.view addSubview:imageView];
Note: I've set a background colour so you can debug the on-screen boundaries of the UIImageView. Also x and y are arbitrary integer coordinates.
Using CGAffineTransformMakeScele as #ahmed said is valid and do not seems to be duck type solution at al! For instance, if you have a large image and put it into a UITableViewCell (say the image is 2x larger than the one that fits into a table cell. If you scale by 0.9 you don't see any result. Only if you scale by less than 0.5 (because 0.5*2.0 = 1.0 that is the size of the cell). So it seems that inside the api, apple is doing exactly that.
You need to override the layoutSubviews method. By default, it's resizing the imageview based on the cell height size.
-(void)layoutSubviews
{
[super layoutSubviews];
self.imageView.frame = CGRectMake(self.imageView.frame.origin.x,
self.imageView.frame.origin.y,
MY_ICON_SIZE,
MY_ICON_SIZE);
}
You'll probably want to recalculate the origin as well so it's vertically centered.
I use the same big images in a tableView and detailView.
Need to make imageView filled in 40x40 when an imags is showed in tableView, but stretched on a half of a screen. I played with several properties but have no positive result:
[cell.imageView setBounds:CGRectMake(0, 0, 50, 50)];
[cell.imageView setClipsToBounds:NO];
[cell.imageView setFrame:CGRectMake(0, 0, 50, 50)];
[cell.imageView setContentMode:UIViewContentModeScaleAspectFill];
I am using SDK 3.0 with build in "Cell Objects in Predefined Styles".
I put Ben's code as an extension in my NS-Extensions file so that I can tell any image to make a thumbnail of itself, as in:
UIImage *bigImage = [UIImage imageNamed:#"yourImage.png"];
UIImage *thumb = [bigImage makeThumbnailOfSize:CGSizeMake(50,50)];
Here is .h file:
#interface UIImage (PhoenixMaster)
- (UIImage *) makeThumbnailOfSize:(CGSize)size;
#end
and then in the NS-Extensions.m file:
#implementation UIImage (PhoenixMaster)
- (UIImage *) makeThumbnailOfSize:(CGSize)size
{
UIGraphicsBeginImageContextWithOptions(size, NO, UIScreen.mainScreen.scale);
// draw scaled image into thumbnail context
[self drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newThumbnail = UIGraphicsGetImageFromCurrentImageContext();
// pop the context
UIGraphicsEndImageContext();
if(newThumbnail == nil)
NSLog(#"could not scale image");
return newThumbnail;
}
#end
I cache a thumbnail version since using large images scaled down on the fly uses too much memory.
Here's my thumbnail code:
- (UIImage *)thumbnailOfSize:(CGSize)size {
if( self.previewThumbnail )
return self.previewThumbnail; // returned cached thumbnail
UIGraphicsBeginImageContext(size);
// draw scaled image into thumbnail context
[self.preview drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newThumbnail = UIGraphicsGetImageFromCurrentImageContext();
// pop the context
UIGraphicsEndImageContext();
if(newThumbnail == nil)
NSLog(#"could not scale image");
self.previewThumbnail = newThumbnail;
return self.previewThumbnail;
}
Just make sure you properly clear the cached thumbnail if you change your original image (self.preview in my case).
I have mine wrapped in a UIView and use this code:
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.autoresizingMask = UIViewAutoresizingFlexibleWidth |UIViewAutoresizingFlexibleHeight;
[self addSubview:imageView];
imageView.frame = self.bounds;
(self is the wrapper UIView, with the dimensions I want - I use AsyncImageView).
I thought Ben Lachman's suggestion of generating thumbnails in advance rather than on the fly was smart, so I adapted his code so it could handle a whole array and to make it more portable (no hard-coded property names).
- (NSArray *)arrayOfThumbnailsOfSize:(CGSize)size fromArray:(NSArray*)original {
NSMutableArray *temp = [NSMutableArray arrayWithCapacity:[original count]];
for(UIImage *image in original){
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0,0,size.width,size.height)];
UIImage *thumb = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[temp addObject:thumb];
}
return [NSArray arrayWithArray:temp];
}
you might be able to use this?
yourTableViewController.rowImage = [UIImage imageNamed:#"yourImage.png"];
and/or
cell.image = yourTableViewController.rowImage;
and if your images are already 40x40 then you shouldn't have to worry about setting bounds and stuff... but, i'm also new to this, so, i wouldn't know, haven't played around with Table View row/cell images much
hope this helps.
I was able to make this work using interface builder and a tableviewcell. You can set the "Mode" properties for an image view to "Aspect Fit". I'm not sure how to do this programatically.
Try setting UIImageView.autoresizesSubviews and/or UIImageView.contentStretch.