We have an issue with transparency. While writing an image to Context with gradient, transparency (which is unwanted) is getting applied. We are not sure why this has been getting applied. We need the context to be "ONLY" with Gradient but not with "TRANSPARENCY".
Attaching the snippet of the code for your reference.
- (UIImage *)ReflectImage:(CGFloat)refFract {
int reflectionHeight = self.size.height * refFract;
CGImageRef gradientMaskImage = NULL;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGContextRef gradientBitmapContext = CGBitmapContextCreate(nil, 1, reflectionHeight,
8, 0, colorSpace, kCGImageAlphaNone);
CGFloat colors[] = {0.0, 1.0, 1.0, 1.0};
CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2);
CGColorSpaceRelease(colorSpace);
CGPoint gradientStartPoint = CGPointMake(0, reflectionHeight);
CGPoint gradientEndPoint = CGPointZero;
CGContextDrawLinearGradient(gradientBitmapContext, grayScaleGradient, gradientStartPoint,
gradientEndPoint, kCGGradientDrawsAfterEndLocation);
CGGradientRelease(grayScaleGradient);
CGContextSetGrayFillColor(gradientBitmapContext, 0.0, 0.5);
CGContextFillRect(gradientBitmapContext, CGRectMake(0, 0, 1, reflectionHeight));
gradientMaskImage = CGBitmapContextCreateImage(gradientBitmapContext);
CGContextRelease(gradientBitmapContext);
CGImageRef reflectionImage = CGImageCreateWithMask(self.CGImage, gradientMaskImage);
CGImageRelease(gradientMaskImage);
CGSize size = CGSizeMake(self.size.width, self.size.height + reflectionHeight);
UIGraphicsBeginImageContext(size);
[self drawAtPoint:CGPointZero];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, CGRectMake(0, self.size.height, self.size.width, reflectionHeight), reflectionImage);
UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRelease(reflectionImage);
return result;
}
So, can someone please let me know why this is so? It would be of great help if this issue gets resolved.
Thanks!!
I didn't try running any of this, but you do seem to be passing an alpha value to CGContextSetGrayFillColor.
Also, the use of "device gray" has been generally discouraged. You might want to double check to make sure that the color space you're getting back has the same number of components as you expect it to.
Related
I have an PNG image and I want to fill that image with gradient. Is this possible?
Means on the time of touch on iPad that part should be fill with gradient.
Just like in flood fill image fill with simple color(R+G+B).
I want that image fill gradient.
Thanx in advance for help.
And this is my line of code where i am find irregular shape and then fill the color by touch i need to modified it.
- (unsigned char*)rawDataFromImage:(UIImage*)image
{
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
NSLog(#"w=%d,h=%d",width,height);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = malloc(height * width * 4);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);
return rawData;
}
If any one having different solution for that so please give me.
I don't want to draw color on image i want to touch and fill on image but with gradient.
-(void)drawRect:(CGRect)rect
{
CGContextRef currentContext = UIGraphicsGetCurrentContext();
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 1.0, 1.0, 1.0, 0.35, // Start color
1.0, 1.0, 1.0, 0.06 }; // End color
rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}
i want to draw 12 images in a circle representing the watch numbers, i have read all topics on stackoverflow regarding images with transparent border but it's not working in my case
-(UIImage *)addImageNumber_:(UIImage *)img {
int w = img.size.width;
int h = img.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
CGContextSetShouldAntialias(context,YES);
CGContextSetAllowsAntialiasing( context ,YES );
CGAffineTransform transform;
for (int x=0; x<=11; x++) {
UIImage *timg1 = [UIImage imageNamed:#"2.png"];
CGRect imageRect = CGRectMake(0, 0, timg1.size.width+2, timg1.size.height+2);
UIGraphicsBeginImageContext(imageRect.size);
[timg1 drawInRect:CGRectMake(1,1,timg1.size.width,timg1.size.height)];
timg1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
transform = CGAffineTransformIdentity;
CGContextDrawImage(context, CGRectMake((w-26)/2, 0, 26, 30), timg1.CGImage);
transform = CGAffineTransformConcat(transform, CGAffineTransformMakeTranslation(-w/2, -w/2));
transform = CGAffineTransformConcat(transform, CGAffineTransformMakeRotation(radians(30)));
transform = CGAffineTransformConcat(transform, CGAffineTransformMakeTranslation(w/2, w/2));
CGContextConcatCTM(context, transform);
}
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:imageMasked];
}
UIViewEdgeAntialiasing = YES;
UIImage *img = [UIImage imageNamed:#"test.png"];
UIImage *img2 = [self addImageNumber_:img ];
R1.image = img2;
[self.view addSubview:R1];
test img is the background of the watch , 2.png is a transparent png with transparent borders
numbers at 12'o clock and 6'o clock looks ok because they are not rotated the rest are jaggy
Never say UIGraphicsBeginImageContext(imageRect.size). Say UIGraphicsBeginImageContextWithOptions(imageRect.size, NO, 0). That way, on a double-resolution screen, you'll get a double-resolution graphics context.
You could even try a resolution value of 4 to increase the resolution even further.
Of course, the fact that you're starting with a pre-drawn image of a "2" might limit your resolution; you can't make a silk purse out of a sow's ear. You could be a lot better off drawing the "2" from scratch as a string.
try
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
Swift 3:
context!.interpolationQuality = .high
I'm trying to add a text to an UIImage and I'm getting a pixelated drawing.
I have tried some other answers with no success:
Drawing on the retina display using CoreGraphics - Image pixelated
Retina display core graphics font quality
Drawing with Core Graphics looks chunky on Retina display
My code:
-(UIImage *)addText:(UIImage *)imgV text:(NSString *)text1
{
int w = self.frame.size.width * 2;
int h = self.frame.size.height * 2;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate
(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), imgV.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
char* text = (char *)[text1 cStringUsingEncoding:NSASCIIStringEncoding];
CGContextSelectFont(context, "Arial", 24, kCGEncodingMacRoman);
// Adjust text;
CGContextSetTextDrawingMode(context, kCGTextInvisible);
CGContextShowTextAtPoint(context, 0, 0, text, strlen(text));
CGPoint pt = CGContextGetTextPosition(context);
float posx = (w/2 - pt.x)/2.0;
float posy = 54.0;
CGContextSetTextDrawingMode(context, kCGTextFill);
CGContextSetRGBFillColor(context, 255, 255, 255, 1.0);
CGContextShowTextAtPoint(context, posx, posy, text, strlen(text));
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:imageMasked];
}
Like Peter said, use UIGraphicsBeginImageContextWithOptions. You might want to pass image.scale to the scale attribute (where image.scale is the scale of one of the images you're drawing), or simply use [UIScreen mainScreen].scale.
This code can be made simpler overall. Try something like:
// Create the image context
UIGraphicsBeginImageContextWithOptions(_baseImage.size, NO, _baseImage.scale);
// Draw the image
CGRect rect = CGRectMake(0, 0, _baseImage.size.width, _baseImage.size.height);
[_baseImage drawInRect:rect];
// Get a vertically centered rect for the text drawing
rect.origin.y = (rect.size.height - FONT_SIZE) / 2 - 2;
rect = CGRectIntegral(rect);
rect.size.height = FONT_SIZE;
// Draw the text
UIFont *font = [UIFont boldSystemFontOfSize:FONT_SIZE];
[[UIColor whiteColor] set];
[text drawInRect:rect withFont:font lineBreakMode:NSLineBreakByClipping alignment:NSTextAlignmentCenter];
// Get and return the new image
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
Where text is an NSString object.
I was facing the exact same problem and posted a question last night to which no-one replied. I have combined fnf's suggested changes with Clif Viegas's answer in the following question:
CGContextDrawImage draws image upside down when passed UIImage.CGImage
to come up with the solution. My addText method is slightly different from yours:
+(UIImage *)addTextToImage:(UIImage *)img text:(NSString *)text1{
int w = img.size.width;
int h = img.size.height;
CGSize size = CGSizeMake(w, h);
if (UIGraphicsBeginImageContextWithOptions != NULL) {
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
} else {
UIGraphicsBeginImageContext(size);
}
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, 0,h);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
char* text = (char *)[text1 cStringUsingEncoding:NSASCIIStringEncoding];// \"05/05/09\";
CGContextSelectFont(context, "Times New Roman", 14, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);
CGContextSetRGBFillColor(context, 0, 0, 0, 1);
//rotate text
CGContextSetTextMatrix(context, CGAffineTransformMakeRotation( -M_PI/8 ));
CGContextShowTextAtPoint(context, 70, 88, text, strlen(text));
CGColorSpaceRelease(colorSpace);
UIGraphicsEndImageContext();
return newImg;
}
In summary, what I have done is add
if (UIGraphicsBeginImageContextWithOptions != NULL) {
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
} else {
UIGraphicsBeginImageContext(size);
}
Remove
// CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
and put
CGContextRef context = UIGraphicsGetCurrentContext();
instead. But this causes the image to be upside down. Hence I put
CGContextTranslateCTM(context, 0,h);
CGContextScaleCTM(context, 1.0, -1.0);
just before
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
This way you can use CG functions instead of using drawInRect etc.
Don't forget
UIGraphicsEndImageContext
at the end. Hope this helps.
From http://replyz.com/c/1244746-does-anyone-know-the-exact-cgcolorref-used-to-create-the-selection-highlight-when-using-uitableviewcellselectionstyleblue#
I saw someone did it with Code and he said the highlighted color is from a UIImage.
Where can I find the image?
(I want to highlight a UIButton with the UITableViewCellSelectionStyleBlue color)
I found the link http://replyz.com/c/1244746-does-anyone-know-the-exact-cgcolorref-used-to-create-the-selection-highlight-when-using-uitableviewcellselectionstyleblue# including some code which can be used to create the highlight. And I create a new UIImage with the Code.
Here is the code:
+ (UIImage *) imageForSelectedBlue {
CGRect rect = CGRectMake(0, 0, 10, 10);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 0.021, 0.548, 0.962, 1.000, 0.008, 0.364, 0.900, 1.000 };
CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB();
CGGradientRef selectionGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(context, selectionGradient, startPoint, endPoint, 0);
CGGradientRelease(selectionGradient);
CGColorSpaceRelease(rgbColorspace);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Actually, you can set the background image of the button. It is more efficient.
[button setBackgroundImage:buttonBackgroundPressed forState:UIControlStateHighlighted];
I'm creating an image by combining two other images, using CGContext. Even if I have the #2x images, I can't succeed to create an retina image.
Here's my code. Could you please help ?
-(UIImage*)makePinImageWithImage:(UIImage*)icon {
UIImage * pin = [UIImage imageNamed:#"defaultPin.png"]; // I have the #2x one.
int w = pin.size.width;
int h = pin.size.height;
CGRect iconRect = CGRectMake(16, 47, 24, 26); // the frame where mix icon in pin
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 8 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
// Drawing pin in context
CGContextDrawImage(context, CGRectMake(0, 0, w, h), pin.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
// Drawing icon in context
CGContextDrawImage(context, iconRect, icon.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
// Getting back the final image
CGImageRef imageCG = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
UIImage * createdImage = [UIImage imageWithCGImage:imageCG];
CGImageRelease(imageCG);
return createdImage;
}
Thanks
This code is done in a text window, should more or less do what you want.
(UIImage*)makePinImageWithImage:(UIImage*)icon // this code assumes this image is #2x if the device is
{
UIImage *pin = [UIImage imageNamed:#"defaultPin.png"]; // I have the #2x one.
CGFloat w = rintf(pin.size.width);
CGFloat h = rintf(pin.size.height);
UIGraphicsBeginImageContextWithOptions(CGSizeMake(w, h), YES, 0); // 0 means let iOS deal with scale for you
CGContextRef context = UIGraphicsGetCurrentContext();
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, h);
CGContextConcatCTM(context, flipVertical);
CGRect iconRect = CGRectMake(16, 47, 24, 26); // the frame where mix icon in pin
// Drawing pin in context
CGContextDrawImage(context, CGRectMake(0, 0, w, h), [pin CGImage]); // CGImage is a method, not a property
//CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // this does not do anything does it? You never do a FillRect...
// Drawing icon in context
CGContextDrawImage(context, iconRect, [icon CGImage]);
//CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // this does not do anything does it? You never do a FillRect...
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image; // will be either normally sized or retina sized depending on environment
}