In my app I have custom gradients I use to stylize all instances of UIBarButtonItem, accomplished by creating a gradient, clipping the gradient with a rounded rectangle Bezier path, then creating a resizable UIImage, like so:
CGRect rect = CGRectMake(0, 0, 44, 44);
CGSize size = rect.size;
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
size_t gradientNumberOfLocations = 2;
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
CGContextRef btncontext = UIGraphicsGetCurrentContext();
CGFloat btngradientLocations[2] = { 0.2, 1.0 };
CGFloat btngradientComponents[8] = { 0.10, 0.10, 0.10, 1.0, 0.05, 0.05, 0.05, 1.0 };
CGGradientRef btngradient = CGGradientCreateWithColorComponents (colorspace, btngradientComponents, btngradientLocations, gradientNumberOfLocations);
UIBezierPath * path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:4.0f];
[path addClip];
CGContextDrawLinearGradient(btncontext, btngradient, CGPointMake(0, 0), CGPointMake(0, size.height), 0);
UIImage *btnimage = UIGraphicsGetImageFromCurrentImageContext();
CGGradientRelease(btngradient);
UIGraphicsEndImageContext();
CGColorSpaceRelease(colorspace);
UIImage *navButton = [btnimage resizableImageWithCapInsets:UIEdgeInsetsMake(22.0, 8.0, 22.0, 8.0)];
[[UIBarButtonItem appearance] setBackgroundImage:navButton forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
This works just fine, and I am developing a similar method to stylize the back button via -setBackButtonBackgroundImage, however I have a question:
I would like to know if anyone has knows a proper way to create a UIBezierPath object that represents the outline of the back button, such that I can create a gradient and programmatically clip the gradient to a back button shape (just like in the example) without having to use a PNG or some such resource.
Any help is appreciated, thank you.
Related
I want to make eraser functionality in my image editing application
If i set eraser opacity with 0.5 then where i move the eraser that portion of image reduce the opacity with eraser opacity
i tried below code for that but no success on this
UIImage *img_BG = self.imgEdit;
CGSize size = img_BG.size;
CGRect area_BG = CGRectMake(0, 0, size.width, size.height);
UIImageView imgvw = (UIImageView *)self.contentView;
CGFloat ox = (img_BG.size.width * self.touchStart.x) / imgvw.frame.size.width;
CGFloat oy = (img_BG.size.height * self.touchStart.y) / imgvw.frame.size.height;
CGFloat nx = (img_BG.size.width * currentPoint.x) / imgvw.frame.size.width;
CGFloat ny = (img_BG.size.height * currentPoint.y) / imgvw.frame.size.height;
CGColorRef strokeColor = [UIColor whiteColor].CGColor;
UIGraphicsBeginImageContext(img_BG.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[img_BG drawInRect:area_BG];;
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, self.actualSizeEraser);
if (self.erraserMode == ZDEraserModeRestore) {
CGContextSetStrokeColorWithColor(context, [UIColor colorWithPatternImage:self.imgOriginal].CGColor);
}
else {
CGContextSetStrokeColorWithColor(context, strokeColor);
CGContextSetBlendMode(context, kCGBlendModeClear);
}
CGContextBeginPath(context);
CGContextMoveToPoint(context, ox, oy);
CGContextAddLineToPoint(context, nx, ny);
CGContextStrokePath(context);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
And One more thing i want to set that when i select eraser and move on then edge of edge of erased line will be soft like some blur effect
How i can achieve this?
If anyone provide solution with swift code that is also acceptable
I'm trying to change the color of an area of my UIImage with CGContext then create a new image from the current state. The original image has the correct orientation but after this, the image turns side ways.
CGRect imageRect = CGRectMake(0, 0, originalImage.size.width, originalImage.size.height);
UIGraphicsBeginImageContextWithOptions(originalImage.size, false, originalImage.scale);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGContextDrawImage(context, imageRect, originalImage.CGImage);
CGContextSetRGBFillColor(context, 255.0f, 255.0f, 255.0f, 1.0f);
CGContextFillRect(context, CGRectMake(5,5,100,100));
CGContextRotateCTM (context, radians(270));
CGContextRestoreGState(context);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
It's a very easy question.
Because iOS system has 3 different Coordinate System.
UIKit － y axis direction is down
Core Graphics(Quartz) － y axis direction is up
OpenGL ES － y axis direction is up
The originalImage is create by UIKit and the target image is create by Core Graphics, so it should be upside-down.
If you want get the correct image, you can use:
UIImageView* imageV = [[UIImageView alloc] initWithFrame:CGRectMake(100,100, 100, 100)];
imageV.layer.borderColor = [UIColor redColor].CGColor;
imageV.layer.borderWidth = 1;
imageV.image = img;
imageV.layer.transform = CATransform3DRotate(imageV.layer.transform, M_PI, 1.0f, 0.0f, 0.0f);
[self.view addSubview:imageV];
Hope it can help you.
How can I fill the non-transparent areas of a PNG UIImage with a linear gradient? I'd like to reuse a PNG shape for MKAnnotationViews, but change the gradient per annotation's properties.
To use an image as a mask for a gradient (i.e. to have a gradient in the shape of the non-transparent pixels of your image), you can:
create a simple view with a gradient (you can either create a simple UIView and use the addGradientLayerToView shown below to give it a gradient or you can create the gradient PNG in advance and add it to your bundle).
apply your PNG as a mask to that gradient view:
UIImage *mask = [UIImage imageNamed:#"mask.png"];
CALayer *maskLayer = [CALayer layer];
maskLayer.frame = CGRectMake(0, 0, mask.size.width, mask.size.height);
maskLayer.contents = (id)[mask CGImage];
gradientViewToMask.layer.mask = maskLayer;
To apply a gradient to the transparent pixels, you can either:
Create a new image with a gradient:
- (UIImage *)imageWithGradient:(UIImage *)image
{
UIGraphicsBeginImageContextWithOptions(image.size, NO, 1.0);
CGContextRef context = UIGraphicsGetCurrentContext();
size_t locationCount = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 0.0, 0.8, 0.8, 1.0, // Start color
0.9, 0.9, 0.9, 1.0 }; // End color
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents (colorspace, components, locations, locationCount):
CGPoint startPoint = CGPointMake(0.0, 0.0);
CGPoint endPoint = CGPointMake(0.0, image.size.height);
CGContextDrawLinearGradient (context, gradient, startPoint, endPoint, 0);
CGContextTranslateCTM(context, 0, image.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0.0, 0.0, image.size.width, image.size.height), [image CGImage]);
UIImage *gradientImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGGradientRelease(gradient);
CGColorSpaceRelease(colorspace);
return gradientImage;
}
You can also add a CAGradientLayer to a view and then add the UIImageView as a subview of that view.
- (void)addGradientLayerToView:(UIView *)view
{
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = view.bounds;
gradient.colors = #[(id)[[UIColor colorWithRed:0.0 green:0.8 blue:0.8 alpha:1.0] CGColor],
(id)[[UIColor colorWithRed:0.9 green:0.9 blue:0.9 alpha:1.0] CGColor]];
[view.layer insertSublayer:gradient atIndex:0];
}
Note, you have to #import <QuartzCore/QuartzCore.h> as well as add the QuartzCore framework to your project.
I ended up hacking together some bits of Rob's code and an extension to UIImage I found at http://coffeeshopped.com/2010/09/iphone-how-to-dynamically-color-a-uiimage
+ (UIImage *)imageNamed:(NSString *)name withGradient:(CGGradientRef)gradient
{
// load the image
UIImage *img = [UIImage imageNamed:name];
// begin a new image context, to draw our colored image onto
UIGraphicsBeginImageContextWithOptions(img.size, NO, [[UIScreen mainScreen] scale]);
// get a reference to that context we created
CGContextRef context = UIGraphicsGetCurrentContext();
// translate/flip the graphics context (for transforming from CG* coords to UI* coords
CGContextTranslateCTM(context, 0, img.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// set the blend mode to overlay, and the original image
CGContextSetBlendMode(context, kCGBlendModeOverlay);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
// set a mask that matches the shape of the image, then draw (overlay) a colored rectangle
CGContextClipToMask(context, rect, img.CGImage);
CGContextAddRect(context, rect);
//gradient
CGPoint startPoint = CGPointMake(0.0, img.size.height);
CGPoint endPoint = CGPointMake(0.0, 0.0);
CGContextDrawLinearGradient (context, gradient, startPoint, endPoint, 0);
// generate a new UIImage from the graphics context we drew onto
UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGGradientRelease(gradient);
//return the color-burned image
return coloredImg;
}
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.
I've got a problem with an custom UIBarButtonItem. When I create an custom UIBarButtonItem via
[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:#"FilterIcon.png"] style:UIBarButtonItemStyleBordered target:self action:#selector(filterTouched:)];
the resulting button does not have the "embossed" look, that the system items achieve by placing a semi-transparent black shadow behind their icons.
On the left you see the "Organize" system bar button item, rightthe result of the code from above.
Creating the shadow in the resource is futile, because iOS/Cocoa only used the mask of the image and discards any color information.
Interestingly, if I create the bar button item in the Interface-Builder it looks fine. However, in the context of my problem, I need to create the button item in code.
There is Objective-C version of James Furey's script.
- (UIImage *)applyToolbarButtonStyling:(UIImage *)oldImage {
float shadowOffset = 1;
float shadowOpacity = .54;
CGRect imageRect = CGRectMake(0, 0, oldImage.size.width, oldImage.size.height);
CGRect shadowRect = CGRectMake(0, shadowOffset, oldImage.size.width, oldImage.size.height);
CGRect newRect = CGRectUnion(imageRect, shadowRect);
UIGraphicsBeginImageContextWithOptions(newRect.size, NO, oldImage.scale);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -(newRect.size.height));
CGContextSaveGState(ctx);
CGContextClipToMask(ctx, shadowRect, oldImage.CGImage);
CGContextSetFillColorWithColor(ctx, [UIColor colorWithWhite:0 alpha:shadowOpacity].CGColor);
CGContextFillRect(ctx, shadowRect);
CGContextRestoreGState(ctx);
CGContextClipToMask(ctx, imageRect, oldImage.CGImage);
CGContextSetFillColorWithColor(ctx, [UIColor colorWithWhite:1 alpha:1].CGColor);
CGContextFillRect(ctx, imageRect);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I think the reason this occurs is covered by these answers to another question:
https://stackoverflow.com/a/3476424/1210490
https://stackoverflow.com/a/6528603/1210490
UIBarButtonItems behave differently depending on where you programmatically attach them. If you attach them to a toolbar, they'll become white "embossed" icons. If you attach them to a navigation bar, they won't.
I've spent the last few hours writing a function to apply toolbar UIBarButtonItem styling to UIImages. It's written in C# for MonoTouch, but I'm sure you'll be able to tweak it to Obj-C no problemo...
UIImage ApplyToolbarButtonStyling(UIImage oldImage)
{
float shadowOffset = 1f;
float shadowOpacity = .54f;
RectangleF imageRect = new RectangleF(PointF.Empty, oldImage.Size);
RectangleF shadowRect = new RectangleF(new PointF(0, shadowOffset), oldImage.Size);
RectangleF newRect = RectangleF.Union(imageRect, shadowRect);
UIGraphics.BeginImageContextWithOptions(newRect.Size, false, oldImage.CurrentScale);
CGContext ctxt = UIGraphics.GetCurrentContext();
ctxt.ScaleCTM(1f, -1f);
ctxt.TranslateCTM(0, -newRect.Size.Height);
ctxt.SaveState();
ctxt.ClipToMask(shadowRect, oldImage.CGImage);
ctxt.SetFillColor(UIColor.FromWhiteAlpha(0f, shadowOpacity).CGColor);
ctxt.FillRect(shadowRect);
ctxt.RestoreState();
ctxt.ClipToMask(imageRect, oldImage.CGImage);
ctxt.SetFillColor(UIColor.FromWhiteAlpha(1f, 1f).CGColor);
ctxt.FillRect(imageRect);
UIImage newImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return newImage;
}
So, a UIBarButtonItem that used to look like this:
Created instead with the function above, like this:
UIBarButtonItem barButtonItem = new UIBarButtonItem(ApplyToolbarButtonStyling(UIImage.FromFile("MusicIcon.png")), UIBarButtonItemStyle.Plain, delegate {});
Would now look like this:
Hope this helps someone in the future.
Take note of the shadow offset in James Furey's script.
I've made the following experience:
float shadowOffset = 1.0f // for a UIBarButtonItem in UINavigationItem
float shadowOffset = 0.0f // for a UIBarButtonItem in UIToolBar
This was observed with iOS 6.1 SDK.
(Now obsolete under iOS 7)