i want to erase image in view (like erase drawing with Eraser).i did if view frame is 0,0,320,480 ,but i worry if the view frame has different size:
here my code:
UIGraphicsBeginImageContext(self.view.frame.size);
[myImageView.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(),kCGImageAlphaNone);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 10);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1, 0, 0, 10);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), point.x, point.y);
//this line code for erasing select the part of the image
CGContextClearRect (UIGraphicsGetCurrentContext(), CGRectMake(point.x, point.y, 30, 30));
//End the code
CGContextStrokePath(UIGraphicsGetCurrentContext());
myImageView.image = UIGraphicsGetImageFromCurrentImageContext();
Try the below code ..
UIGraphicsBeginImageContext(self.frame.size);
[imageView.image drawInRect:CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 30.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 1.0, 1.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastTouch.x, lastTouch.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
imageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Related
I am trying to create a path, then immediately retrieve it and modify it. The problem is that the path gets created and displayed correctly but then I am unable to retrieve it and modify it further.
UPDATE: The problem is that when I call CGContextClosePath in the second function the compiler returns this error:
: CGContextClosePath: no current point.
It basically does not "recognise" the old path and therefore it cannot close it. Any advice would be highly appreciated! Thanks!
Here is my code:
//Defined at the very beginning outside the functions
CGMutablePathRef _path;
//First function
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self];
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), BrushSize);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 1.0, 1.0, 1.0);
_path = CGPathCreateMutable();
CGContextAddPath (context, _path);
CGContextMoveToPoint(context, lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y);
CGContextStrokePath(context);
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//Second function
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); //kCGLineCapSquare, kCGLineCapButt, kCGLineCapRound
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), BrushSize); //1.0); // Brush size
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextSetRGBFillColor(context, 1.0, 0.4, 1.0, 1.0);
CGPathRef pathFill = CGPathCreateCopy (_path);
CGContextAddPath (context, pathFill);
CGContextClosePath(context);
CGContextFillPath(context);
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Try adding the path to the context again before you stroke it.
CGContextAddPath (UIGraphicsGetCurrentContext(), _path);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
It that doesn't work, try creating a copy of the original path and add a new line to that instead of trying to use the original. Use:
CGPathCreateCopy
I want to draw line between to imageviews (like linking the images..) in UIView. I have used
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextSetLineWidth(context, 2.0);
CGContextMoveToPoint(context, 0,0); //start at this point
CGContextAddLineToPoint(context, 20, 20); //draw to this point
CGContextStrokePath(context);
But here, my context is null. I dono whether i have to import any framework or import any headers. Any suggestion or sample will be appreciated.
Thanks in advance.
The very easy way is use label with height 1.:)
UILabel *seperator=[[UILabel alloc]initWithFrame:CGRectMake(0, 53, 233, 1)];
seperator.backgroundColor=[UIColor redColor];
[loginView addSubview:seperator];
UIGraphicsBeginImageContext(image_signature.image.size);
[yourImageView.image drawInRect:CGRectMake(0, 0, yourImageView.image.size.width, yourImageView.image.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 0, 0);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), 20, 20);
CGContextStrokePath(UIGraphicsGetCurrentContext());
[yourImageView setImage:UIGraphicsGetImageFromCurrentImageContext()];
UIGraphicsEndImageContext();
...and "yourImageView" is an imageview where you will draw the line. I suggest you to draw the line on each upper imageview, at the very bottom, it's an option.
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 90, 90.0);
CGContextAddLineToPoint(context, 120.0, 150.0);
CGContextStrokePath(context);
Hi want to choose colors in a coloring project that I am trying out.
I am new at this so this might be a silly question. I am using buttons to select different colors. But when the button is pressed the only thing that happens is that the last pixel of the line that was drawn changes to the selected color. In the code below the first tag erases the drawing and the second should change to color for the next line that will be drawn...
-(IBAction)buttonClicked:(UIButton *)sender {
switch (sender.tag)
{
case 1: {
drawImage.image = nil;
return;
}
//lastPoint.y -= 0;
break;
case 2: {
UIGraphicsBeginImageContext(self.view.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 3.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 1.0, 2.0, 1.0);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextFlush(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
break;
default:
break;
}
}
The code:
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
does not reallydraw a line since the start of the line CGContextMoveToPoint and the end of the line CGContextAddLineToPoint are the same point.
A couple of points, less code is better:
Eliminate the switch statement by having a target for each button.
Call UIGraphicsGetCurrentContext() once and save it in a var, just for clarity.
Example:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, 3.0);
CGContextSetRGBStrokeColor(context, 0.0, 1.0, 2.0, 1.0);
CGContextMoveToPoint(context, firstPoint.x, firstPoint.y);
CGContextAddLineToPoint(context, lastPoint.x, lastPoint.y);
CGContextStrokePath(context);
I used below code for free hand drawing on the whole view:
UIGraphicsBeginImageContext(self.view.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Now my requirement is something like this .. I should be able to draw on particular area of a view. So I modified the code like this ..
UIGraphicsBeginImageContext(CGSizeMake(300, 100));
[drawImage.image drawInRect:CGRectMake(0, 0, 400, 100)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
but the drawing is not proper. Please suggest me how to do this.
Create custome view like :
UIView *drawingView = [[UIView alloc] initWithFrame:CGRectMake(x, y,
300, 300)];
[self.view addSubView:drawingView];
And Then modify your code something like below :
UIGraphicsBeginImageContext(drawingView.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, drawingView.frame.size.width, drawingView.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
IS it possible to draw line with special shape for example like dotted(China Point) ? i draw line with below code
UIGraphicsBeginImageContext(self.view.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, 320, 480)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.867, 0.867, 0.867, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), startPoint.x, startPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), endPoint.x, endPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextFlush(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Maybe CGContextSetLineDash is what you want.
It sets the pattern for dashed lines in a graphics context.
void CGContextSetLineDash (
CGContextRef c,
CGFloat phase,
const CGFloat lengths[],
size_t count
);
This example draws a line with circles (diameter: 20 points, distance: 40 points):
CGContextSetLineWidth(context, 20.0);
CGFloat dash[] = {0.0, 40.0};
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineDash(context, 0.0, dash, 2);
CGContextMoveToPoint(context, 10.0, 30.0);
CGContextAddLineToPoint(context, 310.0, 30.0);
CGContextStrokePath(context);