I need to draw a rect filled with color and its border...
the rect is filled with color properly but the outside border is partially drawn, just the right side of the rect is drawn!
The generated UIImage is going to be used in a UITableViewCell's imageView.
- (UIImage *)legendItemWithColor:(UIColor *)color
{
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect outside = CGRectMake(128, 128, 128, 128);
CGRect legend = CGRectInset(outside, 1, 1);
NSLog(#"Outside: %#", NSStringFromCGRect(outside));
NSLog(#"Legend: %#", NSStringFromCGRect(legend));
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillRect(context, legend);
CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);
CGContextStrokeRect(context, outside);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIGraphicsPopContext();
return img;
}
The problem is when you pass self.view.frame.size to UIGraphicsBeginImageContext() and then use drawn rectangle in array, it is downscaled and the border is obfuscated. Try to pass only the size you need so, i.e. CGSizeMake(2*128+128+2,2*128+128+2). Then it displays ok
Related
I would like to change the color of an image that I have placed as a button in my navBar. The code I am using to create the image/button is:
UIImage *btnGoImage = [UIImage imageNamed:#"settings_cog.png"];
UIButton *btnGoPre = [UIButton buttonWithType:UIButtonTypeCustom];
btnGoPre.bounds = CGRectMake( 0, 0, 30, 30 );
[btnGoPre setImage:btnGoImage forState:UIControlStateNormal];
[btnGoPre addTarget:self action:#selector(loginAction)
forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *btnGo = [[UIBarButtonItem alloc] initWithCustomView:btnGoPre];
If I wanted to change the image to red (it is currently gray). How would I do this? Thanks!
this is the method that will help to change the color of your image you need to pass the image and color as your input variables and it will return the output image
-(UIImage *)imageNamed:(NSString *)name withColor:(UIColor *)color
{
// load the image
UIImage *img = [UIImage imageNamed:name];
// begin a new image context, to draw our colored image onto
UIGraphicsBeginImageContext(img.size);
// get a reference to that context we created
CGContextRef context = UIGraphicsGetCurrentContext();
// set the fill color
[color setFill];
// 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 color burn, and the original image
CGContextSetBlendMode(context, kCGBlendModeColorBurn);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, rect, img.CGImage);
// set a mask that matches the shape of the image, then draw (color burn) a colored rectangle
CGContextClipToMask(context, rect, img.CGImage);
CGContextAddRect(context, rect);
CGContextDrawPath(context,kCGPathFill);
// generate a new UIImage from the graphics context we drew onto
UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//return the color-burned image
return coloredImg;
}
and here is the example how you can call this method
yourImageView.image = [self imageNamed:#"yourImageName" withColor:[UIColor orangeColor]];
Try a UIBarButtonItem class tintColor property.
I have this code, to draw some text inside a (so far) simple button:
UIImage *buttonImage(CGRect bounds, UIColor *fillColor, NSString *title) {
UIGraphicsBeginImageContextWithOptions(bounds.size, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, fillColor.CGColor);
CGContextFillRect(context, bounds);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
[title drawInRect:bounds withFont:PanelButtonFont];
UIGraphicsEndImageContext();
return image;
}
The problematic part is the drawInRect. It's simply not drawing my text. The font is correct, and I've tested this with normal font code there, so it's not that. I think perhaps it doesn't realise that I want it to draw it onto the image that it's producing?
Just change the order and get the image after you draw the text:
UIImage *buttonImage(CGRect bounds, UIColor *fillColor, NSString *title) {
UIGraphicsBeginImageContextWithOptions(bounds.size, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, fillColor.CGColor);
CGContextFillRect(context, bounds);
CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
[title drawInRect:bounds withFont:PanelButtonFont];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
Can I know how to have the emboss effect as the text "Reminders" as shown on the picture?
It looks like the text are embedded?
Thanks
UPDATE FOR iOS 7.0
In iOS 7.0, Apple added a new attribute, NSTextEffectAttributeName, for attributed strings. If your deployment target is iOS 7.0 or later, you can set this attribute to NSTextEffectLetterpressStyle to draw an attributed string in an embossed style.
ORIGINAL
I can't say for certain how Apple draws the embossed text. It looks to me like they fill the string glyphs with a reddish color, then apply a shadow around the interior edges of the glyphs, and also apply a very faint shadow along the top outside edges of the glyphs. I tried it out and here's what it looks like:
On top is my rendering. Below that is a simple UILabel with shadow as Chris suggested in his answer. I put a screen shot of the Reminders app in the background.
Here's my code.
First, you need a function that creates an image mask of your string. You'll use the mask to draw the string itself, and then to draw a shadow that only appears around the inside edges of the string. This image just has an alpha channel and no RGB channels.
- (UIImage *)maskWithString:(NSString *)string font:(UIFont *)font size:(CGSize)size
{
CGRect rect = { CGPointZero, size };
CGFloat scale = [UIScreen mainScreen].scale;
CGColorSpaceRef grayscale = CGColorSpaceCreateDeviceGray();
CGContextRef gc = CGBitmapContextCreate(NULL, size.width * scale, size.height * scale, 8, size.width * scale, grayscale, kCGImageAlphaOnly);
CGContextScaleCTM(gc, scale, scale);
CGColorSpaceRelease(grayscale);
UIGraphicsPushContext(gc); {
[[UIColor whiteColor] setFill];
[string drawInRect:rect withFont:font];
} UIGraphicsPopContext();
CGImageRef cgImage = CGBitmapContextCreateImage(gc);
CGContextRelease(gc);
UIImage *image = [UIImage imageWithCGImage:cgImage scale:scale orientation:UIImageOrientationDownMirrored];
CGImageRelease(cgImage);
return image;
}
Second, you need a function that inverts that mask. You'll use this to make CoreGraphics draw a shadow around the inside edges of the string. This needs to be a full RGBA image. (iOS doesn't seem to support grayscale+alpha images.)
- (UIImage *)invertedMaskWithMask:(UIImage *)mask
{
CGRect rect = { CGPointZero, mask.size };
UIGraphicsBeginImageContextWithOptions(rect.size, NO, mask.scale); {
[[UIColor blackColor] setFill];
UIRectFill(rect);
CGContextClipToMask(UIGraphicsGetCurrentContext(), rect, mask.CGImage);
CGContextClearRect(UIGraphicsGetCurrentContext(), rect);
}
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
You can use those in a function that draws the string in red and applies a shadow to its interior edges.
-(UIImage *)imageWithInteriorShadowAndString:(NSString *)string font:(UIFont *)font textColor:(UIColor *)textColor size:(CGSize)size
{
CGRect rect = { CGPointZero, size };
UIImage *mask = [self maskWithString:string font:font size:rect.size];
UIImage *invertedMask = [self invertedMaskWithMask:mask];
UIImage *image;
UIGraphicsBeginImageContextWithOptions(rect.size, NO, [UIScreen mainScreen].scale); {
CGContextRef gc = UIGraphicsGetCurrentContext();
// Clip to the mask that only allows drawing inside the string's image.
CGContextClipToMask(gc, rect, mask.CGImage);
// We apply the mask twice because we're going to draw through it twice.
// Only applying it once would make the edges too sharp.
CGContextClipToMask(gc, rect, mask.CGImage);
mask = nil; // done with mask; let ARC free it
// Draw the red text.
[textColor setFill];
CGContextFillRect(gc, rect);
// Draw the interior shadow.
CGContextSetShadowWithColor(gc, CGSizeZero, 1.6, [UIColor colorWithWhite:.3 alpha:1].CGColor);
[invertedMask drawAtPoint:CGPointZero];
invertedMask = nil; // done with invertedMask; let ARC free it
image = UIGraphicsGetImageFromCurrentImageContext();
}
UIGraphicsEndImageContext();
return image;
}
Next you need a function that takes an image and returns a copy with a faint upward shadow.
- (UIImage *)imageWithUpwardShadowAndImage:(UIImage *)image
{
UIGraphicsBeginImageContextWithOptions(image.size, NO, image.scale); {
CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, -1), 1, [UIColor colorWithWhite:0 alpha:.15].CGColor);
[image drawAtPoint:CGPointZero];
}
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultImage;
}
Finally, you can combine those functions to create an embossed image of your string. I put my final image into a UIImageView for easy testing.
- (void)viewDidLoad
{
[super viewDidLoad];
CGRect rect = self.imageView.bounds;
NSString *string = #"Reminders";
UIFont *font = [UIFont systemFontOfSize:33];
UIImage *interiorShadowImage = [self imageWithInteriorShadowAndString:string
font:font
textColor:[UIColor colorWithHue:0 saturation:.9 brightness:.7 alpha:1]
size:rect.size];
UIImage *finalImage = [self imageWithUpwardShadowAndImage:interiorShadowImage];
self.imageView.image = finalImage;
}
That just looks like a shadow around the text. You set it in IB in the same area where you set the text color - pick an appropriate color for the shadow and set how you want the shadow offset (in the example you posted, it looks like they set the shadow color to the same color as the text and offset it 0 horizontal and -1 vertical (which means one pixel up).
In code, the properties are set like this (assuming you have already set up a UILabel named, appropriately, "label":
label.shadowColor = [UIColor blackColor]; // Choose your color here - in the example
// posted, they probably chose a similar color
// to the text color and then set the alpha
// down around 0.7 or so so the shadow would be
// faint.
label.shadowOffset = CGSizeMake(0,-1); // First parameter is horizontal, second is vertical
You can configure your effect on the basis of this example
I need to darken a UIImageView when it gets touched, almost exactly like icons on the springboard (home screen).
Should I be added UIView with a 0.5 alpha and black background. This seems clumsy. Should I be using Layers or something (CALayers).
I would let a UIImageView handle the actual drawing of the image, but toggle the image to one that's been darkened in advance. Here's some code I've used to generate darkened images with alpha maintained:
+ (UIImage *)darkenImage:(UIImage *)image toLevel:(CGFloat)level
{
// Create a temporary view to act as a darkening layer
CGRect frame = CGRectMake(0.0, 0.0, image.size.width, image.size.height);
UIView *tempView = [[UIView alloc] initWithFrame:frame];
tempView.backgroundColor = [UIColor blackColor];
tempView.alpha = level;
// Draw the image into a new graphics context
UIGraphicsBeginImageContext(frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[image drawInRect:frame];
// Flip the context vertically so we can draw the dark layer via a mask that
// aligns with the image's alpha pixels (Quartz uses flipped coordinates)
CGContextTranslateCTM(context, 0, frame.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextClipToMask(context, frame, image.CGImage);
[tempView.layer renderInContext:context];
// Produce a new image from this context
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage *toReturn = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
UIGraphicsEndImageContext();
[tempView release];
return toReturn;
}
How about subclassing UIView and adding a UIImage ivar (called image)? Then you could override -drawRect: something like this, provided you had a boolean ivar called pressed that was set while touched.
- (void)drawRect:(CGRect)rect
{
[image drawAtPoint:(CGPointMake(0.0, 0.0))];
// if pressed, fill rect with dark translucent color
if (pressed)
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSaveGState(ctx);
CGContextSetRGBFillColor(ctx, 0.5, 0.5, 0.5, 0.5);
CGContextFillRect(ctx, rect);
CGContextRestoreGState(ctx);
}
}
You would want to experiment with RGBA values above. And, of course, non-rectangular shapes would require a bit more work - like a CGMutablePathRef.
UIImageView can have multiple images; you could have two versions of the image and switch to the darker one when needed.
How can i take an UIImage and give it a black border programmatically?
If i can receive code, it will be great.
tnx
If you only need to display the border you can do that with Core Animation on the UIImageView's layer. If you need to do it on the image itself then you will need to create a new image, draw the old image into the new image and then draw a rect on top of it.
- (UIImage*)imageWithBorderFromImage:(UIImage*)source;
{
CGSize size = [source size];
UIGraphicsBeginImageContext(size);
CGRect rect = CGRectMake(0, 0, size.width, size.height);
[source drawInRect:rect blendMode:kCGBlendModeNormal alpha:1.0];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 0.5, 1.0, 1.0);
CGContextStrokeRect(context, rect);
UIImage *testImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return testImg;
}
This will put a pink border on an image and return the new image.
I'd have a look at this:
Can I Edit the Pixels of the UIImage's Property CGImage
As for the black border part, I assume you can figure that one out. Just iterate along each side and change the pixels to (0,0,0,255) for a certain amount.