I'm creating a custom view that renders a PDF to its bounds rectangle .
I have pasted the code below :
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context, self.bounds);
CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
CGFloat scale = MIN(self.bounds.size.width / pageRect.size.width, self.bounds.size.height / pageRect.size.height);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextScaleCTM(context, scale, scale);
CGContextDrawPDFPage(context, self.page);
CGContextRestoreGState(context);
My question is , if I use the above code in the drawRect method it just gives me a black rectangle . If I use it in the drawLayer: inContext: method it works fine . What could be the reason ?
PS : When using it drawRect I use the method UIGraphicsGetCurrentContext() to get the current graphics context .
This code actually works fine for me ..
Add breakpoint and check it hits the -drawrect method
CGContextRef context = UIGraphicsGetCurrentContext();
NSString *filePath = [[NSBundle mainBundle]
pathForResource:#"Trial" ofType:#"pdf"];
NSURL *url = [[NSURL alloc] initFileURLWithPath:filePath];
CGPDFDocumentRef document = [self openDocument:(CFURLRef)url];
[url release];
CGPDFPageRef docPageRef =CGPDFDocumentGetPage(document, 1);
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context, self.bounds);
CGRect pageRect = CGPDFPageGetBoxRect(docPageRef, kCGPDFMediaBox);
CGFloat scale = MIN(self.bounds.size.width / pageRect.size.width, self.bounds.size.height / pageRect.size.height);
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextScaleCTM(context, scale, scale);
CGContextDrawPDFPage(context, docPageRef);
CGContextRestoreGState(context);
I used this in my drawrect and it worked fine.
Check all the references are getting the value that you are providing to the drawrect
check this
Related
I want to draw lines in a UIView with based the UIView's height. (i.e) line height should be equal to the UIView's height. For that i'm using the following code.
- (void)testDraw :(void(^)(UIImage *image, UIImage *selectedImage))done
{
CGSize imageSize = CGSizeMake(1000, self.bounds.size.height);
//Begin the animation by checking the screen is retina / ordinary
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)])
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0f);
else
UIGraphicsBeginImageContext(imageSize);
CGContextRef context = UIGraphicsGetCurrentContext();
for (NSInteger intSample=0; intSample < 1000; intSample++) {
if(intSample % self.samplesPerSecond == 0){
//draw separator line
[self drawLine:context fromPoint:CGPointMake(intSample, 0) toPoint:CGPointMake(intSample, self.frame.size.height) color:self.lineColor lineWidth:2.0];
}
}
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
CGRect drawRect = CGRectMake(0, 0, image.size.width, self.frame.size.height);
[self.progressColor set];
UIRectFillUsingBlendMode(drawRect, kCGBlendModeSourceAtop);
UIImage *tintedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
done(image, tintedImage);
}
//Draw the line based on the value received
- (void) drawLine:(CGContextRef) context fromPoint:(CGPoint) fromPoint toPoint:(CGPoint) toPoint color:(UIColor*) color lineWidth:(float) lineWidth{
CGContextBeginPath(context);
//add the lines with sizes that u want
CGContextSetAlpha(context,1.0);
CGContextSetLineWidth(context, lineWidth);
CGContextSetStrokeColorWithColor(context, [color CGColor]);
CGContextMoveToPoint(context, fromPoint.x, fromPoint.y);
CGContextAddLineToPoint(context, toPoint.x, toPoint.y);
CGContextStrokePath(context);
}
When i execute the above code with it working fine in 3.5 inch display, It's working fine. But when i run the same code in 4-inch the line height is not increasing based on the UIView. The lines are not working as like auto layouts.
Thanks in advance, Can anyone give your suggestion to fix this issue.
In objective-c, I make a circle shape programmatically by following codes:
+(UIImage *)makeRoundedImage:(CGSize) size backgroundColor:(UIColor *) backgroundColor cornerRadius:(int) cornerRadius
{
UIImage* bgImage = [self imageWithColor:backgroundColor andSize:size];;
CALayer *imageLayer = [CALayer layer];
imageLayer.frame = CGRectMake(0, 0, size.width, size.height);
imageLayer.contents = (id) bgImage.CGImage;
imageLayer.masksToBounds = YES;
imageLayer.cornerRadius = cornerRadius;
UIGraphicsBeginImageContext(bgImage.size);
[imageLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return roundedImage;
}
The imageWithColor method is as following:
+(UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size
{
//quick fix, or pop up CG invalid context 0x0 bug
if(size.width == 0) size.width = 1;
if(size.height == 0) size.height = 1;
//---quick fix
UIImage *img = nil;
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
color.CGColor);
CGContextFillRect(context, rect);
img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Then I used it to create a pure color circle shape image, but what I found is the circle image is not perfect rounded. As an example, please see following code:
CGSize size = CGSizeMake(diameter, diameter);
int r = ceil((float)diameter/2.0);
UIImage *imageNormal = [self makeRoundedImage:size backgroundColor:backgroundColor cornerRadius:r];
[slider setThumbImage:imageNormal forState:UIControlStateNormal];
First I created a circle image, then I set the image as the thumb to a UISlider. But what shown is as the picture shown below:
You can see the circle is not an exact circle. I'm thinking probably it caused by the screen resolution issue? Because if I use an image resource for the thumb, I need add #2x. Anybody know the reason? Thanx in advance.
updated on 8th Aug 2015.
Further to this question and the answer from #Noah Witherspoon, I found the blurry edge issue has been solved. But still, the circle looks like being cut. I used the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f, radius*2.0f);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rect);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
And the circle looks like:
You can see the edge has been cut.
I changed the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f+4, radius*2.0f+4);
CGRect rectmin = CGRectMake(2.0f, 2.0f, radius*2, radius*2);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rectmin);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
You can see the circle looks better(The top edge and the bottom edge):
I made the fill rect size smaller, and the edge looks better, but I don't think it's a nice solution. Still, does anybody know why this happen?
From your screenshot it looks like you do actually have a circular image, but its scale is wrong—it’s not Retina—so it looks blurry and not-circular. The key thing is that instead of using UIGraphicsBeginImageContext which defaults to a scale of 1.0 (as compared to your screen, which is at a scale of 2.0 or 3.0), you should be using UIGraphicsBeginImageContextWithOptions. Also, you don’t need to make a layer or a view to draw a circle in an image context.
+ (UIImage *)makeCircleImageWithDiameter:(CGFloat)diameter color:(UIColor *)color {
UIGraphicsBeginImageContextWithOptions(CGSizeMake(diameter, diameter), NO, 0 /* scale (0 means “use the current screen’s scale”) */);
[color setFill];
CGContextFillEllipseInRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, diameter, diameter));
UIImage *image = UIGraphicsGetImageFromCurrentContext();
UIGraphicsEndImageContext();
return image;
}
If you want to get a circle every time try this:
- (UIImage *)makeCircularImage:(CGSize)size backgroundColor:(UIColor *)backgroundColor {
CGSize squareSize = CGSizeMake((size.width > size.height) ? size.width : size.height,
(size.width > size.height) ? size.width : size.height);
UIView *circleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, squareSize.width, squareSize.height)];
circleView.layer.cornerRadius = circleView.frame.size.height * 0.5f;
circleView.backgroundColor = backgroundColor;
circleView.opaque = NO;
UIGraphicsBeginImageContextWithOptions(circleView.bounds.size, circleView.opaque, 0.0);
[circleView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
I have UITableView with static cells in 4 sections done in Storyboard. However, I want to change the separator color for one section ([UIColor clearColor]). How can I do that??? Is it actually possible?
I can set the separatorColor to clearColor for the entire table, but not only for one specific section.
Screenshot of table view section:
AFAIK there is no method for this. But you can put a background image to the cell which has a separator at the bottom and set separatorstyle to UITableViewCellSeparatorStyleNone. So you have your own separator in every cell.
Maybe you can achieve your goal by setting the header text for the section to an empty string.
One approach would to create your own UIView subclass and do your own custom drawing in drawRect:. You would take this view and add it as the backgroundView of your table view cell. Something like this:
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
// Drawing code
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 1.0);
// Draw black line
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGFloat components[] = {0.0, 0.0, 0.0, 0.3};
CGColorRef blackColor = CGColorCreate(colorspace, components);
CGContextSetStrokeColorWithColor(context, blackColor);
CGContextMoveToPoint(context, 0, rect.size.height - 1.5);
CGContextAddLineToPoint(context, rect.size.width, rect.size.height - 1.5);
CGContextStrokePath(context);
CGColorRelease(blackColor);
// Draw white bottom line
CGFloat whiteComponents[] = {1.0, 1.0, 1.0, 0.75f};
CGColorRef whiteColor = CGColorCreate(colorspace, whiteComponents);
CGContextSetStrokeColorWithColor(context, whiteColor);
CGContextMoveToPoint(context, 0, rect.size.height - 0.5);
CGContextAddLineToPoint(context, rect.size.width, rect.size.height - 0.5);
CGContextStrokePath(context);
CGColorRelease(whiteColor);
// Draw top white line
CGFloat whiteTransparentComponents[] = {1.0, 1.0, 1.0, 0.45};
CGColorRef whiteTransparentColor = CGColorCreate(colorspace, whiteTransparentComponents);
CGContextSetStrokeColorWithColor(context, whiteTransparentColor);
CGContextMoveToPoint(context, 0, 0.5);
CGContextAddLineToPoint(context, rect.size.width, 0.5);
CGContextStrokePath(context);
CGColorRelease(whiteTransparentColor);
CGColorSpaceRelease(colorspace);
}
Is there any way to provide this kind of effect in a UITextView? If not, then how can I achieve this effect?
Having the same requirement, I created a UIView subclass that draws text with a drop cap. The text is drawn using core text, and as #CodaFi suggested the drop cap is drawn in a separate core text frame.
The full implementation of the class: https://gist.github.com/4596476
The meat of it looks something like this:
- (void)drawRect:(CGRect)rect {
// Create attributed strings
NSAttributedString *bodyText = [[NSAttributedString alloc] initWithString:[self.text substringWithRange:NSMakeRange(1, self.text.length -1)] attributes:_bodyAttributes];
NSAttributedString *capText = [[NSAttributedString alloc] initWithString:[[self.text substringWithRange:NSMakeRange(0, 1)] uppercaseString] attributes:_capAttributes];
CGRect capFrame = CGRectMake(0, 0, [capText size].width, [capText size].height);
// Set up graphics context
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// Create type frames
CGMutablePathRef bodyPath = CGPathCreateMutable();
CGAffineTransform transform = CGAffineTransformTranslate(CGAffineTransformMakeScale(1, -1), 0, -self.bounds.size.height);
CGPathMoveToPoint(bodyPath, &transform, CGRectGetMaxX(capFrame), 0);
CGPathAddLineToPoint(bodyPath, &transform, self.bounds.size.width, 0);
CGPathAddLineToPoint(bodyPath, &transform, self.bounds.size.width, self.bounds.size.height);
CGPathAddLineToPoint(bodyPath, &transform, 0, self.bounds.size.height);
CGPathAddLineToPoint(bodyPath, &transform, 0, CGRectGetMaxY(capFrame));
CGPathAddLineToPoint(bodyPath, &transform, CGRectGetMaxX(capFrame), CGRectGetMaxY(capFrame));
CGPathCloseSubpath(bodyPath);
CGMutablePathRef capPath = CGPathCreateMutable();
CGPathAddRect(capPath, &transform, CGRectMake(0, 0, capFrame.size.width+10, capFrame.size.height+10));
// Draw text
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef) bodyText);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), bodyPath, NULL);
CFRelease(framesetter);
CTFrameDraw(frame, context);
CFRelease(frame);
framesetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)capText);
frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), capPath, NULL);
CFRelease(framesetter);
CTFrameDraw(frame, context);
CFRelease(frame);
}
The gist of it is you create two paths, one rectangle to contain the drop cap, and a rectangle with a notch removed for the rest of the text. The full implementation on gist allows you to control the fonts, spacing around the drop cap, and content inset of the whole view using properties.
It does not implement most of the features of a UITextView (only the features I needed) so it may not be a full solution.
Hope that helps!
I'm trying to crate a simple Mac paint application. On iOS I used UIGraphicsGetImageFromCurrentImageContext to update a UIImageView's image when touchesMoved. I'm now trying to active the same thing but on a Mac app, I want to do:
myNSImageView.image = UIGraphicsGetImageFromCurrentImageContext();
But that function does only exist on cocoa-touch and not within the cocoa framework, any tips on where/if I can find a similar function in Cocoa?
Thanks.
Update
Some additional code for completeness.
- (void)mouseDragged:(NSEvent *)event
{
NSInteger width = canvasView.frame.size.width;
NSInteger height = canvasView.frame.size.height;
NSGraphicsContext * graphicsContext = [NSGraphicsContext currentContext];
CGContextRef contextRef = (CGContextRef) [graphicsContext graphicsPort];
CGContextRef imageContextRef = CGBitmapContextCreate(0, width, height, 8, width*4, [NSColorSpace genericRGBColorSpace].CGColorSpace, kCGImageAlphaPremultipliedFirst);
NSPoint currentPoint = [event locationInWindow];
CGContextSetRGBStrokeColor(contextRef, 49.0/255.0, 147.0/255.0, 239.0/255.0, 1.0);
CGContextSetLineWidth(contextRef, 1.0);
CGContextBeginPath(contextRef);
CGContextMoveToPoint(contextRef, lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(contextRef, currentPoint.x, currentPoint.y);
CGContextDrawPath(contextRef,kCGPathStroke);
CGImageRef imageRef = CGBitmapContextCreateImage(imageContextRef);
NSImage* image = [[NSImage alloc] initWithCGImage:imageRef size:NSMakeSize(width, height)];
canvasView.image = image;
CFRelease(imageRef);
CFRelease(imageContextRef);
lastPoint = currentPoint;
}
The result I'm getting now that the painting works fine in the upper part of the view, but bot the rest. Like on this image (the red part should be the canvasView):
NSInteger width = 1024;
NSInteger height = 768;
CGContextRef contextRef = CGBitmapContextCreate(0, width, height, 8, width*4, [NSColorSpace genericRGBColorSpace].CGColorSpace, kCGImageAlphaPremultipliedFirst);
CGContextSetRGBStrokeColor(contextRef, 49.0/255.0, 147.0/255.0, 239.0/255.0, 1.0);
CGContextFillRect(contextRef, CGRectMake(0.0f, 0.0f, width, height));
CGImageRef imageRef = CGBitmapContextCreateImage(contextRef);
NSImage* image = [[NSImage alloc] initWithCGImage:imageRef size:NSMakeSize(width, height)];
CFRelease(imageRef);
CFRelease(contextRef);
NSGraphicsContext * graphicsContext = [NSGraphicsContext currentContext];
CGContextRef contextRef = (CGContextRef) [graphicsContext graphicsPort];
CGContextRef imageContextRef = CGBitmapContextCreate(0, width, height, 8, width*4, [NSColorSpace genericRGBColorSpace].CGColorSpace, kCGImageAlphaPremultipliedFirst);
You're assuming, first off, that there is a current context, and then you create a separate context.
CGContextSetRGBStrokeColor(contextRef, 49.0/255.0, 147.0/255.0, 239.0/255.0, 1.0);
CGContextSetLineWidth(contextRef, 1.0);
(etc.)
And then you draw into the context you assume exists, not the context you created.
CGImageRef imageRef = CGBitmapContextCreateImage(imageContextRef);
And then you create an image from the context you created and never drew into.
Cut out the attempt to get [NSGraphicsContext currentContext] and its graphics port. You can't assume that there is a current context outside of drawRect:, anyway. Instead, draw into the context you created.