I am generating a pdf with certain format in which I placed a rectangular box with the help of the below code...
CGContextRef context = UIGraphicsGetCurrentContext();
CGPathRef path = CGPathCreateWithRect(CGRectMake(40, rectPosition, 540, 150), NULL);
[[UIColor whiteColor] setFill];
//[[UIColor blackColor] setStroke];
CGContextAddPath(context, path);
CGContextDrawPath(context, kCGPathFillStroke);
CGPathRelease(path);
I achieve it but now I want to set the text inside the rectangle and I tried drawRect method and many other... Do help if anyone knows.
- (void)drawText:(CGFloat)xPosition yPosition:(CGFloat)yPosition canvasWidth:(CGFloat)canvasWidth canvasHeight:(CGFloat)canvasHeight
{
//Here you Can Write whatever you want to add in the rectangle
}
Related
I am trying to draw a Bezier path, an arc of a given angle, in response to a pan gesture. Here's what I have inside the function called by the pan gesture:
UIGraphicsBeginImageContext(self.frame.size);
UIBezierPath *path = [self createArcPath];
[[UIColor blackColor] setStroke];
[[UIColor redColor] setFill];
CGContextRef *ref = UIGraphicsGetCurrentContext();
path.lineWidth = 5;
[path fill];
[path stroke];
UIGraphicsEndImageContext();
And here is createArcPath:
- (UIBezierPath *)createArcPath
{
UIBezierPath *aPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150)
radius:75
startAngle:0
endAngle:DEGREES_TO_RADIANS(135)
clockwise:YES];
return aPath;
}
I don't get an error, but I just don't get anything on my screen relating to the arc. What am I missing? This is in a method of a UIView subclass.
I also tried the following method in - (id)initWithFrame:
UIColor *color =[UIColor redColor];
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, width);
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextSetStrokeColorWithColor(context, color.CGColor);
CGRect myOval = {100, 100, self.radius, self.radius};
CGContextAddEllipseInRect(context, myOval);
UIGraphicsEndImageContext();
I also don't see anything. What am I missing? Can these methods not be called from a UIView?
The UIGraphicsBeginImageContext/UIGraphicsEndImageContext calls create an off-screen context that you can draw into, then extract an image from. Since it's an off-screen context nothing shows on the screen.
What you probably want to do is create a custom subclass of UIView that overrides drawRect. In your code that responds to user gestures, change the data structure(s) that represent your drawing, then call setNeedsDisplay to trigger the system to ask your view to redraw itself by calling your drawRect method.
As an alternative you can set up your custom view to install a CAShapeLayer in the view, then change the path on the layer, then call setNeedsDisplay on the layer.
I am looking for the way how to draw a hollow circle using Core Graphics (CGContext) in iOS. I tried to do it using the code:
- (void)drawRect:(CGRect)rect {
[super drawRect:rect];
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 8.0);
CGContextSetStrokeColor(ctx, CGColorGetComponents([[UIColor redColor] CGColor]));
CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor blueColor] CGColor]));
CGContextFillEllipseInRect(ctx, rect);
CGContextFillPath(ctx);
}
but it draws the filled circle.
Since this question is over discussed here but other examples like this give me only filled circles.
If you want to draw a circle within the rect, using Stroke methods and the rect in parameter you will draw a part of the cercle outside the rect.
You then have two choices, assuming you know the width of the circle you want to draw.
First, you can stroke the line, but you have to draw it in a smaller rect :
-(void)drawRect:(CGRect)rect {
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGFloat innerWidth = 8;
[[UIColor redColor] setStroke];
CGContextSetLineWidth(ctx, innerWidth);
// We add an ellipsis shifted by half the inner Width
CGContextAddEllipseInRect(ctx, CGRectInset(rect, innerWidth, innerWidth));
// Stroke the path
CGContextStrokePath(ctx);
}
You can also fill the circles using the even-odd rule (Apple docs)
-(void)drawRect:(CGRect)rect {
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGFloat innerWidth = 8;
[[UIColor redColor] setStroke];
// Add the outer circle
CGContextAddEllipseInRect(ctx, rect);
// Add the inner circle
CGContextAddEllipseInRect(ctx, CGRectInset(rect, innerWidth, innerWidth));
// Fill the path using the EO rule
CGContextEOFillPath(ctx);
}
If you only want the circle outline, don't fill it.
- (void)drawRect:(CGRect)rect {
[super drawRect:rect];
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 8.0);
[[UIColor redColor] set];
CGContextStrokeEllipseInRect(ctx, rect);
}
Use CGContextStrokeEllipseInRect instead of CGContextFillEllipseInRect. And since you haven't built a path in the current context, get rid of CGContextFillPath.
One way you could do it is draw a filled circle and then draw a slightly smaller circle with CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeClear)
After your code add something like
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 5.0);
CGContextSetBlendMode(ctx,kCGBlendModeClear)
CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor blueColor] CGColor]));
CGContextFillEllipseInRect(ctx, rect);
CGContextFillPath(ctx);
UIGraphicsEndImageContext();
I use CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeClear) in my drawing application, which is probably a better use. Stroking the path will probably work for you.
I am overriding drawRect method in order to draw ellipse
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor mainColorYellow].CGColor);
CGRect rectangle = CGRectMake(0.0, 2.0, rect.size.width , rect.size.height - 4.0);
CGContextAddEllipseInRect(context, rectangle);
CGContextStrokePath(context);
}
How can I change fill color on ellipse? I tried using CGContextSetFillColorWithColor(CGContextRef c, CGColorRef color) but without result.
There is two different operations, fill and stroke. Stroke es the border, fill is the inside. You are only doing the border. You can control the fill and border color independently. You have, however, to render both explicitly. For example:
[[UIColor yellowColor] setFill];
[[UIColor blackColor] setStroke];
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0.0, 2.0, rect.size.width , rect.size.height - 4.0)];
path.lineWidth = 2.0;
[path fill];
[path stroke];
Notice I wrote the code in a more modern quartz. The context is implicit. Hope it helps.
Just add below:
CGContextFillEllipseInRect(context, rectangle);
I want to fill the remaining part of a CGCntext after drawing a rect? How can I do that? Thank you!
But the thing is, I set the blend mode of the cgcontext kCGBlendModeClear. I want to make the little rect in the context to transparent. If a draw the background first, can I still see the image in the rect?
If you want to fill the context (whose frame is bigRect), except for a rectangle inside it (whose frame is smallRect):
CGContextBeginPath(context);
CGContextAddRect(context, bigRect);
CGContextAddRect(context, smallRect);
CGContextSetFillColorWithColor(context, color);
CGContextEOFillPath(context, bigRect);
Do the background first...
CGRect bounds = [self bounds];
[[UIColor blackColor] set];
UIBezierPath* backgroundPath = [UIBezierPath bezierPathWithRect:bounds];
[backgroundPath fill];
CGRect innerRect = CGRectMake(self.bounds-10,
self.bounds-10,
self.bounds.width-20
self.bounds.height-20);
[[UIColor redColor] set];
UIBezierPath* foregroundPath = [UIBezierPath bezierPathWithRect:innerRect];
[foregroundPath fill];
Draw your background and then use CGContextClearRect to clear the area you want to be transparent.
arbitrary shape:
// do your foreground drawing
CGPathRef arbitraryShape; // asign your arbitrary shape
CGContextBeginPath(ctx);
CGContextAddRect(ctx, bounds); // rect in full size of the context
CGContextAddPath(ctx, arbitraryShape); // set the area you dont want to be drawn on
CGContextClip(ctx);
// do your background drawing
Currently I am working on a paint app for iOS. I am stuck with applying shadow effect to a particular drawn path. I have use UIBezierpath to draw paths. Is there any way to apply shadow effect on UIBezierpath?
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextSetShadowWithColor(context, CGSizeMake(0, 5), 5.0, [[UIColor blackColor]CGColor]);
CGContextDrawPath(context, kCGPathFill);
Something like this may help u..
CGContextSetShadowWithColor(context, CGSizeZero, 20, [path.color CGColor])
I think this may help you to show shadow effect