I am using following code for Drawing Arc in DrawRect...I want to draw Arc only with gradient effect ...any help please?
CGContextSetAlpha(ctx, 0.5);
CGContextSetRGBFillColor(ctx, color.red, color.green, color.blue, color.alpha );
CGContextMoveToPoint(ctx, cX, cY);
CGContextAddArc(ctx, cX, cY, radious+10, (startDeg-90)*M_PI/180.0, (endDeg-90)*M_PI/180.0, 0);
CGContextClosePath(ctx);
CGContextFillPath(ctx);
First create an arc then use the following code to apply gradient effect to the path,
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 0.965, 0.965, 0.965, 1.0, // Start color
0.603, 0.603, 0.603, 1.0 }; // 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), CGRectGetMaxY(currentBounds));
CGContextDrawLinearGradient(UIGraphicsGetCurrentContext(), glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
Related
I'm pretty new with core graphics. I need to draw a full circle. How do I go about it? I currently have a masked circle.
I referred to this example.
//Use the draw rect to draw the Background, the Circle and the Handle
-(void)drawRect:(CGRect)rect{
[super drawRect:rect];
CGContextRef ctx = UIGraphicsGetCurrentContext();
/** Draw the Background **/
//Create the path
CGContextAddArc(ctx, self.frame.size.width/2, self.frame.size.height/2, radius, 0, M_PI *2, 0);
// CGContextFillEllipseInRect(ctx, CGRectMake(self.frame.size.height/2, self.frame.size.width/2, 100, 100));
// CGContextSetRGBFillColor(ctx, 0.5, 0.5, 0.5, 1.0);
//Set the stroke color to black
[[UIColor greenColor]setStroke];
//Define line width and cap
CGContextSetLineWidth(ctx, TB_BACKGROUND_WIDTH);
CGContextSetLineCap(ctx, kCGLineCapButt);
CGContextDrawPath(ctx, kCGPathStroke);
UIGraphicsBeginImageContext(CGSizeMake(TB_SLIDER_SIZE,TB_SLIDER_SIZE));
CGContextRef imageCtx = UIGraphicsGetCurrentContext();
CGContextAddArc(imageCtx, self.frame.size.width/2 , self.frame.size.height/2, radius, 0, ToRad(self.self.startAngle), 0);
[[UIColor redColor]set];
CGContextSetLineWidth(imageCtx, TB_LINE_WIDTH);
CGContextDrawPath(imageCtx, kCGPathStroke);
//save the context content into the image mask
CGImageRef mask = CGBitmapContextCreateImage(UIGraphicsGetCurrentContext());
UIGraphicsEndImageContext();
CGContextSaveGState(ctx);
CGContextClipToMask(ctx, self.bounds, mask);
CGImageRelease(mask);
//list of components
CGFloat components[8] = {
0.0, 0.0, 1.0, 1.0, // Start color - Blue
1.0, 1.0, 1.0, 1.0 }; // End color - Violet
CGColorSpaceRef baseSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(baseSpace, components, NULL, 2);
CGColorSpaceRelease(baseSpace), baseSpace = NULL;
//Gradient direction
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
//Draw the gradient
CGContextDrawLinearGradient(ctx, gradient, startPoint, endPoint, 0);
CGGradientRelease(gradient), gradient = NULL;
CGContextRestoreGState(ctx);
/** Draw the handle **/
[self drawTheHandle:ctx];
}
CGContextDrawPath(imageCtx, kCGPathFill);
make the backgroup width and line width to 140 and it works!!
#define TB_BACKGROUND_WIDTH 140 //The width of the dark background
#define TB_LINE_WIDTH 140 //The width of the active area (the gradient) and the width of the handle
I want to draw a gradient inside a polygon using core graphics. I am able to draw a hexagon using the code below but i don't know how to fill this hexagon with a gradient color. Any help will be really appreciated.
- (void)drawRect:(CGRect)rect
{
// Drawing code.
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);
CGContextSetLineWidth(context, 2.0);
CGPoint center;
center = CGPointMake(210.0, 90.0);
CGContextMoveToPoint(context, center.x, center.y + 60.0);
for(int i = 1; i < 6; ++i)
{
CGFloat x = 60.0 * sinf(i * 2.0 * M_PI / 6.0);
CGFloat y = 60.0 * cosf(i * 2.0 * M_PI / 6.0);
CGContextAddLineToPoint(context, center.x + x, center.y + y);
}
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathFillStroke);
}
Use following code for Gradient fill
CGContextRef context = UIGraphicsGetCurrentContext();
CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
CGFloat colors[] =
{
0.62890625, 0.859375, 10.9921875, 1.00,
0.65625, 0.8046875, 0.9453125, 1.00,
};
CGGradientRef gradient = CGGradientCreateWithColorComponents(rgb, colors, NULL, sizeof(colors)/(sizeof(colors[0])*4));
CGColorSpaceRelease(rgb);
// now we can actually create the shape and fill it
CGPoint start, end;
CGContextSetRGBFillColor(context, 0, 0, 0.6, 0.1);
CGContextFillEllipseInRect(context, CGRectMake(0.0, 0.0, 100.0, 100.0));
CGContextStrokeEllipseInRect(context, CGRectMake(0.0, 0.0, 100.0, 100.0));
// Gradient
CGRect myrect = CGRectMake(0.0, 0.0, rect.size.width, rect.size.height);
CGContextSaveGState(context);
CGContextClipToRect(context, myrect);
start = CGPointMake(myrect.origin.x, myrect.origin.y + myrect.size.height * 0.25);
end = CGPointMake(myrect.origin.x, myrect.origin.y + myrect.size.height * 1.0);
CGContextDrawLinearGradient(context, gradient, start, end, kCGGradientDrawsBeforeStartLocation);
CGContextRestoreGState(context);
I have the following UIView custom class:
#implementation BackgroundView
- (void)drawRect:(CGRect)rect
{
CGContextRef currentContext = UIGraphicsGetCurrentContext();
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
float r = (255.0)/(255.0);
float g = (165.0)/(255.0);
float b = (0.0)/(255.0);
float rr = (238.0)/(255.0);
float gg = (118.0)/(255.0);
float bb = (0.0)/(255.0);
CGFloat components[8] = { r, g, b, 1.0, // Start color
rr, gg, bb, 1.0 }; // 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);
}
#end
Basically, it's supposed to make an orange gradient. The values "r", "g", and "b" are for a light orange, and the values "rr", "gg", "bb" are for a dark orange. But it doesn't work. Only the top of the frame is orange, and the bottom of the frame is black. I can't seem to get rid of the black.
What values would I use for an orange nice gradient. Can someone please look for mistakes? I can't find any. Thanks so much!
That's because you specify that the end point for your gradient is in middle of the currentBounds - see this line:
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
To get rid of the black make sure the y coordinate is at the bottom of your view.
Alternatively, you could use this code to extend your gradient after the end point
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, kCGGradientDrawsAfterEndLocation);
I was wondering if anyone knows how to take an Image using CoreGraphics and add a gloss effect like you see on iOS. Specifically I want to take an image that gets downloaded from the web and style it like this. I've searched high and low and all I found was examples of how to do it in PhotoShop and not in code. Any code snippets or pointers to resources that can help I would appreciate.
I figured it out on my own after wasting a few hours trying to figure this out... Here's my code:
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth, float ovalHeight) {
float fw, fh;
if (ovalWidth == 0 || ovalHeight == 0) {
CGContextAddRect(context, rect);
return;
}
CGContextSaveGState(context);
CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM (context, ovalWidth, ovalHeight);
fw = CGRectGetWidth (rect) / ovalWidth;
fh = CGRectGetHeight (rect) / ovalHeight;
CGContextMoveToPoint(context, fw, fh/2);
CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);
CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);
CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);
CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1);
CGContextClosePath(context);
CGContextRestoreGState(context);
}
static void addGlossPath(CGContextRef context, CGRect rect) {
CGFloat quarterHeight = CGRectGetMidY(rect) / 2;
CGContextSaveGState(context);
CGContextBeginPath(context);
CGContextMoveToPoint(context, -20, 0);
CGContextAddLineToPoint(context, -20, quarterHeight);
CGContextAddQuadCurveToPoint(context, CGRectGetMidX(rect), quarterHeight * 3, CGRectGetMaxX(rect) + 20, quarterHeight);
CGContextAddLineToPoint(context, CGRectGetMaxX(rect) + 20, 0);
CGContextClosePath(context);
CGContextRestoreGState(context);
}
UIImage *applyIconHighlightToImage(UIImage *icon) {
UIImage *newImage;
CGContextRef context;
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
CGRect currentBounds = CGRectMake(0, 0, icon.size.width, icon.size.height);
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGFloat locations[2] = {0.0, 1.0};
CGFloat components[8] = {1.0, 1.0, 1.0, 0.75, 1.0, 1.0, 1.0, 0.2};
UIGraphicsBeginImageContext(icon.size);
context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);
addRoundedRectToPath(context, currentBounds, 10, 10);
CGContextClosePath(context);
CGContextClip(context);
[icon drawInRect:currentBounds];
addGlossPath(context, currentBounds);
CGContextClip(context);
rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, 2);
CGContextDrawLinearGradient(context, glossGradient, topCenter, midCenter, 0);
UIGraphicsPopContext();
newImage = UIGraphicsGetImageFromCurrentImageContext();
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
UIGraphicsEndImageContext();
return newImage;
}
Edit:
Wanted to make sure I gave credit where credit is due. Thanks to Brad Larson for the code on adding a glossy gradient.
I provide code to draw a glossy gradient using Core Graphics in my answer here.
If all that you wish to do is overlay a gloss effect on your image, it may be more performant to generate this using a CAGradientLayer, as decribed by Mirko in his answer there.
I have not really done much programming with Core Graphics. And I tend to stick with QuartzCore now that it does a lot of what I need through the layer property :)
However, I have a UIView, which is currently gradient. I'd like to add rounded corners to this UIView and the layer property does not do this when I draw the 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, 0.95, // Start color
1.0, 1.0, 1.0, 0.60 }; // 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), CGRectGetMaxY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}
I am not really sure where I should be rounding in the drawRect method. Thanks.
Have you checked previous question postings? I read one a while back about masking UIViews. I think the same applies pretty much on all objects which use drawRect
How to mask a square image into an image with round corners in the iPhone SDK?
Here's what I did, and it works fine as far as I can tell.
First, I borrowed Mr NilObject's code snippet from the above mentioned post.
I modified it to fit in an object (as he wrote it as a C function instead of a method)
I subclass UIView to create my own custom view. I overload initWithRect: to make my background transparent.
So basically:
set transparent background (in init), or clipping will be uggly
in drawRect, first clip, then draw inside the clipped area
The following is a working example:
//
// TeleView.m
//
#import "TeleView.h"
#implementation TeleView
/**** in init methods, set background to transparent,
otherwise, clipping shows a black background ****/
- (id) initWithFrame:(CGRect)frame {
if((self = [super initWithFrame:frame])) {
[self setBackgroundColor:[UIColor colorWithWhite:0.0f alpha:0.0f]];
}
return self;
}
- (void) clipCornersToOvalWidth:(float)ovalWidth height:(float)ovalHeight
{
float fw, fh;
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect rect = CGRectMake(0.0f, 0.0f, self.frame.size.width, self.frame.size.height);
if (ovalWidth == 0 || ovalHeight == 0) {
CGContextAddRect(context, rect);
return;
}
CGContextSaveGState(context);
CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM (context, ovalWidth, ovalHeight);
fw = CGRectGetWidth (rect) / ovalWidth;
fh = CGRectGetHeight (rect) / ovalHeight;
CGContextMoveToPoint(context, fw, fh/2);
CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);
CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);
CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);
CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1);
CGContextClosePath(context);
CGContextRestoreGState(context);
}
-(void)drawRect:(CGRect)rect {
CGContextRef currentContext = UIGraphicsGetCurrentContext();
/**** here is what I modified. ****/
[self clipCornersToOvalWidth:20.0f height:20.0f];
CGContextClip(currentContext);
/**** below this is your own code ****/
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 1.0, 0.0, 0.0, 0.60, // Start color
0.0, 1.0, 0.0, 0.40 }; // 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), CGRectGetMaxY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}
#end
NSArray *colors = [NSArray arrayWithObjects:fromColor.CGColor,toColor.CGColor, nil];
NSNumber *stopOne = [NSNumber numberWithFloat:0.0];
NSNumber *stopTwo = [NSNumber numberWithFloat:1.0];
NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, nil];
CAGradientLayer *headerLayer = [CAGradientLayer layer];
headerLayer.colors = colors;
headerLayer.locations = locations;
headerLayer.borderColor = borderColor.CGColor; // border line color**strong text**
headerLayer.borderWidth = width;// For Thickness of border line
headerLayer.cornerRadius = radius;//For Rounded Corner if You want to make rounded Corner
headerLayer.frame = frame;
[view.layer insertSublayer:headerLayer atIndex:0];
Also make sure to import "QuartzCore" framework