I'm looking for a way to add a solid border with Core Image. I have implement custom camera for taking pictures of rectangle shape documents. Now I am getting that documents four coordinates but problem to draw border on CIImage. Please help me.
CIImage *overlay = [CIImage imageWithColor:[CIColor colorWithRed:0 green:1 blue:0 alpha:0.6]];
overlay = [overlay imageByCroppingToRect:image.extent];
overlay = [overlay imageByApplyingFilter:#"CIPerspectiveTransformWithExtent" withInputParameters:#{#"inputExtent":[CIVector vectorWithCGRect:image.extent],#"inputTopLeft":[CIVector vectorWithCGPoint:topLeft],#"inputTopRight":[CIVector vectorWithCGPoint:topRight],#"inputBottomLeft":[CIVector vectorWithCGPoint:bottomLeft],#"inputBottomRight":[CIVector vectorWithCGPoint:bottomRight]}];
return [overlay imageByCompositingOverImage:image];
You can use this methods :
- (UIImage *)addBorderToImage:(UIImage *)image {
CGImageRef bgimage = [image CGImage];
float width = CGImageGetWidth(bgimage);
float height = CGImageGetHeight(bgimage);
// Create a temporary texture data buffer
void *data = malloc(width * height * 4);
// Draw image to buffer
CGContextRef ctx = CGBitmapContextCreate(data,
width,
height,
8,
width * 4,
CGImageGetColorSpace(image.CGImage),
kCGImageAlphaPremultipliedLast);
CGContextDrawImage(ctx, CGRectMake(0, 0, (CGFloat)width, (CGFloat)height), bgimage);
//Set the stroke (pen) color
CGContextSetStrokeColorWithColor(ctx, [UIColor greenColor].CGColor);
//Set the width of the pen mark
CGFloat borderWidth = (float)width*0.05;
CGContextSetLineWidth(ctx, borderWidth);
//Start at 0,0 and draw a square
CGContextMoveToPoint(ctx, 0.0, 0.0);
CGContextAddLineToPoint(ctx, 0.0, height);
CGContextAddLineToPoint(ctx, width, height);
CGContextAddLineToPoint(ctx, width, 0.0);
CGContextAddLineToPoint(ctx, 0.0, 0.0);
//Draw it
CGContextStrokePath(ctx);
// write it to a new image
CGImageRef cgimage = CGBitmapContextCreateImage(ctx);
UIImage *newImage = [UIImage imageWithCGImage:cgimage];
CFRelease(cgimage);
CGContextRelease(ctx);
// auto-released
return newImage;
}
Calling this method:
UIImage *updatedIMG = [self addBorderToImage:[[UIImage alloc] initWithCIImage:overlay]]
I'm trying to set the foreground/tintColor of a UISegmentedControl to a horizontal gradient. I want the gradient to extend across the control and appropriately adjust when each segment is clicked. See image below:
I've tried setting the tintColor using the stackoverflow solution found here, but using colorWithPattern doesn't seem to work when I change it to be horizontal:
Here's what I'm using now:
UIView* test2 = [[UIView alloc] initWithFrame:CGRectMake(10, 60, 200, 25)];
test2.backgroundColor = [self gradientFromColor:[UIColor redColor] toColor:[UIColor greenColor] withWidth:test2.frame.size.width];
[self.view addSubview:test2];
UISegmentedControl *test = [[UISegmentedControl alloc] initWithItems:#[#"one", #"two"]];
test.frame = CGRectMake(10, 100, 200, 25);
test.tintColor = [self gradientFromColor:[UIColor redColor] toColor:[UIColor greenColor] withWidth:test.frame.size.width];
[self.view addSubview:test];
...
- (UIColor*) gradientFromColor:(UIColor*)c1 toColor:(UIColor*)c2 withWidth:(int)width{
CGSize size = CGSizeMake(width, 1);
UIGraphicsBeginImageContextWithOptions(size, NO, 1);
CGContextRef context = UIGraphicsGetCurrentContext();
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
NSArray* colors = [NSArray arrayWithObjects:(id)c1.CGColor, (id)c2.CGColor, nil];
CGGradientRef gradient = CGGradientCreateWithColors(colorspace, (CFArrayRef)colors, NULL);
CGContextDrawLinearGradient(context, gradient, CGPointMake(0, 0), CGPointMake(width, 0), 0);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
CGGradientRelease(gradient);
CGColorSpaceRelease(colorspace);
UIGraphicsEndImageContext();
return [UIColor colorWithPatternImage:image];
}
I'm thinking I need to do some work with masking but I've been having trouble getting it to work.
CGRect rect = CGRectMake(0, 0, 100, 100);
float white[1] = {0.0f};
float gray[1] = {1.0f};
CGContextSetFillColorSpace(bitmap, colorSpace);
CGContextSetFillColorWithColor(bitmap, CGColorCreate(colorSpace, white));
CGContextClearRect(bitmap, rect);
CGContextSetFillColorWithColor(bitmap, CGColorCreate(colorSpace, gray));
CGContextFillEllipseInRect(bitmap, rect);
CGImageRef imgRef = CGBitmapContextCreateImage(bitmap);
UIImage *image = [[[UIImage alloc] initWithCGImage:imgRef] autorelease];
self.imageView.image = image;
CGContextRelease(bitmap);
CGColorSpaceRelease(colorSpace);
the code is above.it does't work as I expect.I'm not familar to iOS CoreGraphic framework.
See this syntax for CGColorCreate in apple Document
Example code is :
CGFloat components[]={r, g, b, 1.f};
drawColor=CGColorCreate(colorSpace, components);
CGColorSpaceRelease(colorSpace);
Note : You have to define r,g,b as your wish which are all CGFloat type..
I have a camera app to load photo into a device with mask. Everything is OK. When I try to use renderInContext to save the view to an image, I only see the image without any mask.
UIGraphicsBeginImageContext(contentView.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[contentView.layer renderInContext:context];
UIImage *outImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(outImage, self, #selector(image: didFinishSavingWithError: contextInfo:), context);
I have read some paper from Apple to say that renderInContext don't support mask and composition. I've made some search on the internet to get the information that UIView needed to draw as a context first and then use renderInContext to save the image.
Now my question is what method to do the job? What about drawRect, drawInRect, drawLayer, drawInContent, or other method. Can anyone give me a hint. Thanks a lots.
I started from here: http://chinkisingh.com/2013/03/03/draw-on-iphoneipad-screen-using-bezier-paths-core-graphics-ios-app-development/
I have a UIBezierPath and I wanted to apply a gradient to it and apply to an existing image, see if the following code helps
CGRect r = CGRectMake(0, 0, HEART_SIZE, HEART_SIZE);
UIBezierPath *heart = [Bezier heartShape:r]; //this is only in my case
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
UIColor *darkPink = [UIColor colorWithHue:0.915 saturation:1.000 brightness:0.941 alpha:1.000];
UIColor *lightPink = [UIColor colorWithHue:0.917 saturation:0.647 brightness:1.000 alpha:1.000];
NSArray *gradientColors = [NSArray arrayWithObjects:
(id)darkPink.CGColor,
(id)lightPink.CGColor,
(id)darkPink.CGColor, nil];
CGFloat gradientLocations[] = {0, 0.5, 1};
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)gradientColors, gradientLocations);
CGColorSpaceRelease(colorSpace);
UIGraphicsBeginImageContext(r.size);
heart.lineCapStyle = kCGLineCapRound;
heart.lineWidth = 10.0f;
[[UIColor blackColor] setStroke];
[[UIColor redColor] setFill];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
[heart stroke]; //removed the black stroke around
[heart fill];
CGContextAddPath(context, heart.CGPath);
CGContextClip(context);
CGContextDrawLinearGradient(context, gradient, CGPointMake(10, 10), CGPointMake(210, 210), kCGGradientDrawsAfterEndLocation); //check that gradient is drawn in the right place
CGGradientRelease(gradient);
UIImage *theRightImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I want to recreate a tab bar but I stumbled on this problem. As you can see in the images below my current (right image) selected tab bar item is a lot less crisp or sharper than the one from the UITabBar. Notice the small 1 point border around the icon in the left (which I don't know how to do) as well as the gradient inside the icon which is a lot noticeable in mine. I already thought of Core Graphics and Core Images Filters as possible approaches but can't seem to get that effect. I found an older thread which is part of what I want but the answer doesn't seem to work for me and requires a manual loop through the pixels of the image (which I don't know if it is to be desired). Can someone help me?
This is the code I'm currently using which, btw, you're welcome to correct some mistakes if you see any because I'm starting with Core Graphics:
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextSaveGState(context);
{
/* Adjust for different coordinate systems from UIKit and Core Graphics and center the image */
CGContextTranslateCTM(context, self.bounds.size.width/2.0 - self.image.size.width/2.0, self.bounds.size.height - self.bounds.size.height/2.0 + self.image.size.height/2.0);
CGContextScaleCTM(context, 1.0f, -1.0f);
CGRect rect = CGRectMake(0, 0, self.image.size.width, self.image.size.height);
/* Add a drop shadow */
UIColor *dropShadowColor = [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.8f];
CGContextSetShadowWithColor(context, CGSizeMake(0, 1), 5, dropShadowColor.CGColor);
/* Draw the original image */
CGContextDrawImage(context, rect, self.image.CGImage);
/* Clip to the original image, so that we only draw the shadows on the
inside of the image but nothing outside. */
CGContextClipToMask(context, rect, self.image.CGImage);
if(self.isSelected){
/* draw background image */
CGImageRef background = [UIImage imageNamed:#"UITabBarBlueGradient"].CGImage;
CGContextDrawImage(context, rect, background);
}
else{
/* draw background color to unselected items */
CGColorRef backgroundColor = [UIColor colorWithRed:95/255.0 green:95/255.0 blue:95/255.0 alpha:1].CGColor;
CGContextSetFillColorWithColor(context, backgroundColor);
CGContextFillRect(context, rect);
/* location of the gradient's colors */
CGFloat locations[] = { 0.0, 1.0 };
NSArray *colors = [NSArray arrayWithObjects:(id)[UIColor colorWithRed:1 green:1 blue:1 alpha:0].CGColor, (id)[UIColor colorWithRed:1 green:1 blue:1 alpha:0.6].CGColor, nil];
/* create the gradient with colors and locations */
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace,(__bridge CFArrayRef) colors, locations);
{
/* start and end points of the gradient */
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
/* draw gradient */
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
}
CGGradientRelease(gradient);
}
}
CGContextRestoreGState(context);
CGColorSpaceRelease(colorSpace);
}
I'm working on this too, an optimization you can probably make is instead of rendering the UIImage each time drawrect is called you can save off the UIImage objects in an ivar and just update a UIImageView.image property to display them.
I'm generating my image with the "shine" like this:
(plus_icon.png is a 30 x 30 image with a 4 px wide cross occupying the entire thing in black on a transparent background: which renders like in imageView 2 and 4 like this:
-(UIImage *)tabBarImage{
UIGraphicsBeginImageContext(CGSizeMake(60, 60));
UIImage *image = [UIImage imageNamed:#"plus_icon"];
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(ctx, [[UIColor clearColor] CGColor]);
CGContextFillRect(ctx, CGRectMake(0, 0, 60, 60));
CGRect imageRect = CGRectMake(15, 15, 30, 30);
CGContextDrawImage(ctx, imageRect, [image CGImage]);
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
-(UIImage *)sourceImage{
UIGraphicsBeginImageContext(CGSizeMake(60.0, 60.0));
CGContextRef context = UIGraphicsGetCurrentContext();
size_t num_locations = 2;
CGFloat locations[2] = { 0.3, 1.0 };
CGFloat components[8] = {NC(72), NC(122), NC(229), 1.0, NC(110), NC(202), NC(255), 1.0 };
CGColorSpaceRef cspace;
CGGradientRef gradient;
cspace = CGColorSpaceCreateDeviceRGB();
gradient = CGGradientCreateWithColorComponents (cspace, components, locations, num_locations);
CGPoint sPoint = CGPointMake(0.0, 15.0);
CGPoint ePoint = CGPointMake(0.0, 45.0);
CGContextDrawLinearGradient (context, gradient, sPoint, ePoint, kCGGradientDrawsBeforeStartLocation| kCGGradientDrawsAfterEndLocation);
CGGradientRelease(gradient);
CGColorSpaceRelease(cspace);
[self addShineToContext:context];
UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
-(void)addShineToContext:(CGContextRef) context{
CGContextSaveGState(context);
size_t num_locations = 2;
CGFloat locations[2] = { 0.3, 0.7};
CGFloat components[8] = {1.0, 1.0, 1.0, 0.8, 1.0, 1.0, 1.0, 0.0};//{0.82, 0.82, 0.82, 0.4, 0.92, 0.92, 0.92, .8 };
CGColorSpaceRef cspace;
CGGradientRef gradient;
cspace = CGColorSpaceCreateDeviceRGB();
gradient = CGGradientCreateWithColorComponents (cspace, components, locations, num_locations);
CGPoint sPoint = CGPointMake(25.0f, 15.0);
CGPoint ePoint = CGPointMake(35.0f, 44.0f);
[self addShineClip:context];
CGContextDrawLinearGradient(context, gradient, sPoint, ePoint, kCGGradientDrawsBeforeStartLocation);
// CGContextSetFillColorWithColor(context, [[UIColor redColor] CGColor]);
// CGContextFillRect(context, CGRectMake(15,15, 30, 30));
CGColorSpaceRelease(cspace);
CGGradientRelease(gradient);
CGContextRestoreGState(context);
}
-(void)addShineClip:(CGContextRef)context{
CGContextMoveToPoint(context, 15, 35);
CGContextAddQuadCurveToPoint(context, 25, 30, 45, 28);
CGContextAddLineToPoint(context, 45, 15);
CGContextAddLineToPoint(context, 15, 15);
CGContextClosePath(context);
CGContextClip(context);
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.imageView1.image = [self compositeOverSlate:[self drawTabBarOverSourceWithBlend:kCGBlendModeSourceIn]];
self.imageView2.image = [self compositeOverSlate:[self drawTabBarOverSourceWithBlend:kCGBlendModeDestinationIn]];
self.imageView3.image = [self compositeOverSlate:[self drawTabBarOverSourceWithBlend:kCGBlendModeSourceAtop]];
self.imageView4.image = [self compositeOverSlate:[self drawTabBarOverSourceWithBlend:kCGBlendModeDestinationAtop]];
}
-(UIImage *)compositeOverSlate:(UIImage *)image{
UIGraphicsBeginImageContext(image.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect imageRect = CGRectMake(0, 0, 0, 0);
imageRect.size = image.size;
CGContextSetFillColorWithColor(ctx, [[UIColor darkGrayColor] CGColor]);
CGContextFillRect(ctx, imageRect);
CGContextSetShadow(ctx, CGSizeMake(-1.0, 2.0), .5);
CGContextDrawImage(ctx, imageRect, [image CGImage]);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
-(UIImage *)drawTabBarOverSourceWithBlend:(CGBlendMode)blendMode{
UIGraphicsBeginImageContext(CGSizeMake(60,60));
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextDrawImage(ctx, CGRectMake(0, 0, 60.0, 60.0), [[self sourceImage] CGImage]);
CGContextSetBlendMode(ctx, blendMode);
CGContextDrawImage(ctx, CGRectMake(0, 0, 60.0, 60.0), [[self tabBarImage] CGImage]);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
but I don't have the border outline cracked yet, but will update if I do crack it.