I'm trying to convert a PDF to a UIImage, but I'm getting all sorts of weird errors. I'm not doing the conversion in a drawRect method because I'm not displaying the graphics to the screen. Any ideas how I can make this work?
The code I'm trying is this:
CGPDFPageRef page = [self getPage:pageIndex];
CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
float pdfScale = 1024.0/pageRect.size.height;
pageRect.size = CGSizeMake(pageRect.size.width*pdfScale, pageRect.size.height*pdfScale);
UIGraphicsBeginImageContext(pageRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context,pageRect);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, pageRect.size.height);
CGContextScaleCTM(context, pdfScale,-pdfScale);
CGContextDrawPDFPage(context, page);
CGContextRestoreGState(context);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Related
I'm currently using this code to color a white UIImage with a desired color. But after treatment, it appears that the image (embedded in a UIImageView with the good size of the original image) lost its quality.
+ (UIImage *)imageNamed:(NSString *)name withColor:(UIColor *)theColor
{
UIImage *baseImage = [UIImage imageNamed:name];
UIGraphicsBeginImageContext(baseImage.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect area = CGRectMake(0, 0, baseImage.size.width, baseImage.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSaveGState(ctx);
CGContextClipToMask(ctx, area, baseImage.CGImage);
[theColor set];
CGContextFillRect(ctx, area);
CGContextRestoreGState(ctx);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextDrawImage(ctx, area, baseImage.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Any suggestion on how to fix this issue ?
iam doing one application.In that Im using one imageview with image and add one view with sone clear holes.Means through that holes we can see the background image.So my problem is i want to capture that total screen (imageview with this holes view).Iam using below code but it's not working.
- (UIImage*)captureView:(UIView *)yourView {
CGRect rect = [[UIScreen mainScreen] bounds];
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[yourView.layer renderInContext:context];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
but it's not working.
This IS how we do:
UIGraphicsBeginImageContextWithOptions(yourView.bounds.size, yourView.opaque, 0.0);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *LastImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Try this to take your screeShoT
-(UIImage*)getScreenShot
{
CGSize screenSize = [[UIScreen mainScreen] applicationFrame].size;
//CGSize screenSize = CGSizeMake(1024, 768);
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(nil, screenSize.width, 416, 8, 4*(int)screenSize.width, colorSpaceRef, kCGImageAlphaPremultipliedLast);
CGContextTranslateCTM(ctx, 0.0, screenSize.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
[(CALayer*)self.yourView.layer renderInContext:ctx];
CGImageRef cgImage = CGBitmapContextCreateImage(ctx);
UIImage *image = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
CGContextRelease(ctx);
return image;
}
I have this code, which creates an image, and then adds some effects to it and sizes it down to make largeThumbnail.
UIImage *originalImage = [UIImage imageWithData:self.originalImage];
thumbnail = createLargeThumbnailFromImage(originalImage);
NSLog(#"thumbnail: %f", thumbnail.size.height);
NSData *thumbnailData = UIImageJPEGRepresentation(thumbnail, 1.0);
Later on:
UIImage *image = [UIImage imageWithData:self.largeThumbnail];
NSLog(#"thumbnail 2: %f", image.size.height);
NSLog returns:
thumbnail: 289.000000
thumbnail 2: 578.000000
As you can see, when it converts the image back from data, it makes it 2x the size. Any ideas why this may be happening?
Large thumbnail code:
UIImage *createLargeThumbnailFromImage(UIImage *image) {
UIImage *resizedImage;
resizedImage = [image imageScaledToFitSize:LARGE_THUMBNAIL_SIZE];
CGRect largeThumbnailRect = CGRectMake(0, 0, resizedImage.size.width, resizedImage.size.height);
UIGraphicsBeginImageContextWithOptions(resizedImage.size, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
//Image
CGContextTranslateCTM(context, 0, resizedImage.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, largeThumbnailRect, resizedImage.CGImage);
//Border
CGContextSaveGState(context);
CGRect innerRect = rectForRectWithInset(largeThumbnailRect, 1.5);
CGMutablePathRef borderPath = createRoundedRectForRect(innerRect, 0);
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextSetLineWidth(context, 3);
CGContextAddPath(context, borderPath);
CGContextStrokePath(context);
CGContextRestoreGState(context);
UIImage *thumbnail = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return thumbnail;
}
Try replacing the part where you load the second image:
UIImage *image = [UIImage imageWithData:self.largeThumbnail];
with this one:
UIImage *jpegImage = [UIImage imageWithData:self.largeThumbnail];
UIImage *image = [UIImage imageWithCGImage:jpegImage.CGImage scale:originalImage.scale orientation:jpegImage.imageOrientation];
What happens here is that the image scale is not set, so you get double image dimensions.
I haven't been able to find one single example on the internets that teaches me how to create a circle on the fly and then use this circle to clip an UIImage.
Here's my code, unfortunately it doesn't give me desired results.
//create a graphics context
UIGraphicsBeginImageContext(CGSizeMake(243, 243));
CGContextRef context = UIGraphicsGetCurrentContext();
//create my object in this context
CGContextAddEllipseInRect(context, CGRectMake(0, 0, 243, 243));
CGContextSetFillColor(context, CGColorGetComponents([[UIColor whiteColor] CGColor]));
CGContextFillPath(context);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
//create an uiimage from the ellipse
//Get the drawing image
CGImageRef maskImage = [image CGImage];
// Get the mask from the image
CGImageRef maskRef = CGImageMaskCreate(CGImageGetWidth(maskImage)
, CGImageGetHeight(maskImage)
, CGImageGetBitsPerComponent(maskImage)
, CGImageGetBitsPerPixel(maskImage)
, CGImageGetBytesPerRow(maskImage)
, CGImageGetDataProvider(maskImage)
, NULL
, false);
//finally clip the context to the mask.
CGContextClipToMask( context , CGRectMake(0, 0, 243, 243) , maskRef );
//draw the image
[firstPieceView.image drawInRect:CGRectMake(0, 0, 320, 480)];
// [firstPieceView drawRect:CGRectMake(0, 0, 320, 480)];
//extract a new image
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
NSLog(#"self.firstPieceView is %#", NSStringFromCGRect(self.firstPieceView.frame));
UIGraphicsEndImageContext();
self.firstPieceView.image = outputImage;
I would appreciate any directions.
I suspect you need to rephrase your question better.
There's plenty of example code for whatever you're trying to do out there.
Here's how you could implement a custom UIView subclass to clip am image to an ellipse:
- (void)drawInRect:(CGRect)rect {
UIImage image;// set/get from somewhere
CGImageRef imageRef = [image CGImageRef];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddEllipseInRect(context, self.bounds);
CGContextClip(context);
CGContextDrawImage(context, self.bounds, imageRef);
}
caveat emptor
Edit (a day later, free time produces):
- (void)drawRect:(CGRect)rect {
// we're ignoring rect and drawing the whole view
CGImageRef imageRef = [_image CGImage]; // ivar: UIImage *_image;
CGContextRef context = UIGraphicsGetCurrentContext();
// set the background to black
[[UIColor blackColor] setFill];
CGContextFillRect(context, self.bounds);
// modify the context coordinates,
// UIKit and CoreGraphics are oriented differently
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0, CGRectGetHeight(rect));
CGContextScaleCTM(context, 1, -1);
// add clipping path to the context, then execute the clip
// this is in effect for all drawing until GState restored
CGContextAddEllipseInRect(context, self.bounds);
CGContextClip(context);
// stretch the image to be the size of the view
CGContextDrawImage(context, self.bounds, imageRef);
CGContextRestoreGState(context);
}
I have a method that return an UIImage from a CGPDFPageRef. You can specify a width for the image.
The problem is that when pdfScale is > 1, a white border appears in the image. So the PDF is always drawn at scale 1 with a border instead of a bigger scale. Smaller scales are OK.
I've tried to change the type of PDFBox but that doesn't seems to change anything and the documentation is not really clear.
Does somebody sees the error?
- (UIImage*) PDFImageForWidth:(CGFloat) width {
CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
CGFloat pdfScale = width/pageRect.size.width;
pageRect.size = CGSizeMake(pageRect.size.width*pdfScale, pageRect.size.height*pdfScale);
pageRect.origin = CGPointZero;
UIGraphicsBeginImageContext(pageRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context, pageRect);
CGContextTranslateCTM(context, 0.0, pageRect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextConcatCTM(context, CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, pageRect, 0, true));
CGContextDrawPDFPage(context, page);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
The problem was that CGPDFPageGetDrawingTransform doesn't scale the PDF when scale > 1. You have to do it yourself.
Also, the method is thread safe now.
- (UIImage*) PDFImageForWidth:(CGFloat) width {
CGRect smallPageRect = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
CGFloat pdfScale = width/smallPageRect.size.width;
CGRect pageRect;
pageRect.size = CGSizeMake(smallPageRect.size.width*pdfScale, smallPageRect.size.height*pdfScale);
pageRect.origin = CGPointZero;
__block CGContextRef context;
dispatch_sync(dispatch_get_main_queue(), ^{
UIGraphicsBeginImageContext(pageRect.size);
context = UIGraphicsGetCurrentContext();
});
if (context != nil) {
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context, pageRect);
CGContextTranslateCTM(context, 0.0, pageRect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGAffineTransform transform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, pageRect, 0, true);
if (pdfScale > 1) {
transform = CGAffineTransformScale(transform, pdfScale, pdfScale);
transform.tx = 0;
transform.ty = 0;
}
CGContextConcatCTM(context, transform);
CGContextDrawPDFPage(context, page);
__block UIImage* image;
dispatch_sync(dispatch_get_main_queue(), ^{
image = [UIGraphicsGetImageFromCurrentImageContext() retain];
UIGraphicsEndImageContext();
});
return [image autorelease];
}
else return nil;
}
I was having the same problem and the answer before did help me in some parts but it didn't solve the whole problem.
This is the how I solved my problem.
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context
{
NSLog(#"pdfQuartzViewViewController - drawLayer");
CGPDFDocumentRef myDocumentRef = CGPDFDocumentCreateWithURL((CFURLRef)[NSURL fileURLWithPath:self.strFilename]);
CGPDFPageRef pageReference = CGPDFDocumentGetPage(myDocumentRef, 1);
CGContextSetRGBFillColor(context, 1.0f, 1.0f, 1.0f, 1.0f); // White
CGContextFillRect(context, CGContextGetClipBoundingBox(context)); // Fill
CGContextTranslateCTM(context, 0.0f, layer.bounds.size.height);
// Scaling the pdf page a little big bigger than the view so we can cover the white borders on the page
CGContextScaleCTM(context, 1.0015f, -1.0015f);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(pageReference, kCGPDFCropBox, layer.bounds, 0, true);
pdfTransform.tx = pdfTransform.tx - 0.25f;
pdfTransform.ty = pdfTransform.ty - 0.40f;
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, pageReference); // Render the PDF page into the context
CGPDFDocumentRelease(myDocumentRef);
myDocumentRef = NULL;
}
Here there is a good link where you can find more information about it. The post explains how to use all this methods.
http://iphonedevelopment.blogspot.ch/2008/10/demystifying-cgaffinetransform.html