I would like to rewrite the Apple source code, GLPaint application, but not using OpenGL like the example, I would like to use Core Graphics library. But I stuck in displaying the texture like GLPaint.
This is my code in Core Graphics:
- (void) drawLineFromPoint: (CGPoint) fromPoint toPoint: (CGPoint) toPoint {
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImage.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
UIImage * image = [UIImage imageNamed:#"Particle.png"];
UIColor * color = [UIColor colorWithPatternImage:image];
CGContextSetStrokeColorWithColor(context, color.CGColor);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, 5.0);
CGContextBeginPath(context);
CGContextMoveToPoint(context, fromPoint.x, fromPoint.y);
CGContextAddLineToPoint(context, toPoint.x, toPoint.y);
CGContextStrokePath(context);
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
--- But I receive this result:
--- I would like to have this result:
Does my code wrong? Any one can help me on this? Thank you very much.
If you don't want the pattern, don't set a colour with a pattern image as your stroke colour.
Instead of
UIImage * image = [UIImage imageNamed:#"Particle.png"];
UIColor * color = [UIColor colorWithPatternImage:image];
Just do
UIColor *color = [UIColor blackColor];
Kindly make sure you have the Particle.png added to the project. Also check the constants kBrushScale and kPalette* in GLPaint code.
Related
My line of code:
UIColor *brushPattern=[[UIColor alloc]initWithPatternImage:[UIImage imageNamed:#"Frame-1#2x.png"]];
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(),brushPattern.CGColor);
Image pattern
url
Which does not draw like brush pattern whereas it fill pattern in UIView
I have used the following code for the same
At ViewDidLoad or Where ever your going to start the assign this
patternColor = [UIColor colorWithPatternImage:image]
This will resolve your memory issues and below code willhelp you
UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, [[UIScreen mainScreen] scale]);
CGContextRef context = UIGraphicsGetCurrentContext();
[view.image drawInRect:CGRectMake(0, 0, view.frame.size.width, view.frame.size.height)];
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, 10);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), patternColor.CGColor);
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextBeginPath(context);
CGContextMoveToPoint(context, lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y);
CGContextStrokePath(context);
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
How to draw a line on the UIImageView? I am using the UIImageView Sub Class, Its not support drawRect: method. I want to draw a line on the image view. How can I do this? Please help me. I am using below code for draw line.
- (void)drawRect:(CGRect)rect {
CGContextRef c = UIGraphicsGetCurrentContext();
CGFloat red[4] = {1.0f, 0.0f, 0.0f, 1.0f};
CGContextSetStrokeColor(c, red);
CGContextBeginPath(c);
CGContextMoveToPoint(c, 5.0f, 5.0f);
CGContextAddLineToPoint(c, 50.0f, 50.0f);
CGContextStrokePath(c);
}
The following code works by creating a new image the same size as the original, drawing a copy of the original image onto the new image, then drawing a 1 pixel line along to the top of the new image.
// UIImage *originalImage = <the image you want to add a line to>
// UIColor *lineColor = <the color of the line>
UIGraphicsBeginImageContext(originalImage.size);
// Pass 1: Draw the original image as the background
[originalImage drawAtPoint:CGPointMake(0,0)];
// Pass 2: Draw the line on top of original image
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 1.0);
CGContextMoveToPoint(context, 0, 0);
CGContextAddLineToPoint(context, originalImage.size.width, 0);
CGContextSetStrokeColorWithColor(context, [lineColor CGColor]);
CGContextStrokePath(context);
// Create new image
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// Tidy up
UIGraphicsEndImageContext();
First, I wouldn't use a UIImageView. In fact the docs say...
If your subclass needs custom drawing code, it is recommended you use
UIView as the base class.
Use a UIView.
In the UIView add a UIImageView subView and put the image in there. Now you can do you custom drawing in the drawRect method of the UIView and it will appear on top of the image.
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextSetLineWidth(context, 5.0);
CGContextStrokeRect(context, self.bounds);
}
If this isn't working then the drawRect method probably isn't being called. Set a breakpoint to test it.
The best way to go about it in my opinion would be to take a invisible UIView of the same size as UIImageView for drawing and implement the touch methods on the UIView for drawing.
you can use something like:
CGPoint temp=[touch locationInView:self];
Use this in methods like:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
Store all the points in an array and then draw those points on the UIImageView as it is.
Refer to Muhammad Saad Ansari
With Swift
func drawLines ( originalImage:UIImage, lineColor:CGColor ) -> UIImage{
UIGraphicsBeginImageContextWithOptions(originalImage.size,false,0.0)
originalImage.drawInRect(CGRectMake( 0, 0, originalImage.size.width, originalImage.size.height ))
let context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 0, 0);
CGContextAddLineToPoint(context, originalImage.size.width, 0);
CGContextSetStrokeColorWithColor(context,lineColor);
CGContextStrokePath(context);
// Create new image
var newImage = UIGraphicsGetImageFromCurrentImageContext();
// Tidy up
UIGraphicsEndImageContext();
return newImage
}
I am creating a simple drawing application in which I have a UIView in background & UIImageView in foreground. I am doing some drawing stuff in UIView and I have set an image in UIImageView. I want to add the transparency effect in UIImageView to show the lines behind the image. I know I can do this by reducing alpha, but I don’t want to change the alpha of image.
I want to do it with CGContextSetBlendMode, but I don’t know how to do this. Kindly help me to resolve this issue.
Thanks!
IMAGE http://www.freeimagehosting.net/q3237
UIImage *img = [UIImage imageNamed:#"Image.png"];
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
[img drawInRect:CGRectMake(0, 0, 768, 1004) blendMode:kCGBlendModeDarken alpha:1]; [imageView.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width,self.view.frame.size.height)];
CGContextSetBlendMode(ctx, kCGBlendModeDarken);
imageView.image = UIGraphicsGetImageFromCurrentImageContext();
No need to keep imageview do it like this..
Since you are drawing on two different context you wont be able to use blend modes across them. For that you need to draw other stuff on your drawing view and then draw your image..
- (void)drawRect:(CGRect)rect {
// do ur drawing stuff first
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, self.bounds, self.image.CGImage);
CGContextSetBlendMode(context, kCGBlendModeSaturation);
CGContextSetRGBFillColor(context, 0.0, 0.0, 0.0, 1.0);
CGContextFillRect(context, rect);
}
I have a custom view with that code :
- (void)drawRect:(CGRect)rect
{
UIImage* theImage = [UIImage imageNamed:#"blue_arrow"];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 1.0);
CGContextSetTextDrawingMode(context, kCGTextFill);
CGPoint posOnScreen = self.center;
CGContextDrawImage(context, CGRectMake(posOnScreen.x - theImage.size.width/2,
posOnScreen.y - theImage.size.height/2,
theImage.size.width,
theImage.size.height),
theImage .CGImage);
}
The image is an arrow, pointiing to the top.
But when drawn, it is draw upside down, pointing to bottom.
What causes that problem ?
How may I correct that, naturally without side effect ?
This is because Core Graphics is using a flipped coordinate system.
You could try flipping the object you're drawing to using the isFlipped property.
Or you could try using this code in your drawing method (Source):
CGContextTranslateCTM(context, 0, image.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
is it possible to create such a UILabel with inner and outer shadow?
alt text http://dl.getdropbox.com/u/80699/Bildschirmfoto%202010-07-12%20um%2021.28.57.png
i only know shadowColor and shadowOffset
zoomed:
alt text http://dl.getdropbox.com/u/80699/Bildschirmfoto%202010-07-12%20um%2021.39.56.png
thanks!
The answer by dmaclach is only suitable for shapes that can easily be inverted. My solution is a custom view that works with any shape and also text. It requires iOS 4 and is resolution independent.
First, a graphical explanation of what the code does. The shape here is a circle.
The code draws text with a white dropshadow. If it's not required, the code could be refactored further, because the dropshadow needs to be masked differently. If you need it on an older version of iOS, you would have to replace the block and use an (annoying) CGBitmapContext.
- (UIImage*)blackSquareOfSize:(CGSize)size {
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
[[UIColor blackColor] setFill];
CGContextFillRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, size.width, size.height));
UIImage *blackSquare = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return blackSquare;
}
- (CGImageRef)createMaskWithSize:(CGSize)size shape:(void (^)(void))block {
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
block();
CGImageRef shape = [UIGraphicsGetImageFromCurrentImageContext() CGImage];
UIGraphicsEndImageContext();
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(shape),
CGImageGetHeight(shape),
CGImageGetBitsPerComponent(shape),
CGImageGetBitsPerPixel(shape),
CGImageGetBytesPerRow(shape),
CGImageGetDataProvider(shape), NULL, false);
return mask;
}
- (void)drawRect:(CGRect)rect {
UIFont *font = [UIFont fontWithName:#"HelveticaNeue-Bold" size:40.0f];
CGSize fontSize = [text_ sizeWithFont:font];
CGImageRef mask = [self createMaskWithSize:rect.size shape:^{
[[UIColor blackColor] setFill];
CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
[[UIColor whiteColor] setFill];
// custom shape goes here
[text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), 0) withFont:font];
[text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];
}];
CGImageRef cutoutRef = CGImageCreateWithMask([self blackSquareOfSize:rect.size].CGImage, mask);
CGImageRelease(mask);
UIImage *cutout = [UIImage imageWithCGImage:cutoutRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
CGImageRelease(cutoutRef);
CGImageRef shadedMask = [self createMaskWithSize:rect.size shape:^{
[[UIColor whiteColor] setFill];
CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, 1), 1.0f, [[UIColor colorWithWhite:0.0 alpha:0.5] CGColor]);
[cutout drawAtPoint:CGPointZero];
}];
// create negative image
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
[[UIColor blackColor] setFill];
// custom shape goes here
[text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];
UIImage *negative = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef innerShadowRef = CGImageCreateWithMask(negative.CGImage, shadedMask);
CGImageRelease(shadedMask);
UIImage *innerShadow = [UIImage imageWithCGImage:innerShadowRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
CGImageRelease(innerShadowRef);
// draw actual image
[[UIColor whiteColor] setFill];
[text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -0.5) withFont:font];
[[UIColor colorWithWhite:0.76 alpha:1.0] setFill];
[text_ drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), -1) withFont:font];
// finally apply shadow
[innerShadow drawAtPoint:CGPointZero];
}
Although Steve's answer does work, it didn't scale to my particular case and so I ended up creating an inner shadow by applying a shadow to a CGPath after clipping my context:
CGContextRef context = UIGraphicsGetCurrentContext();
// clip context so shadow only shows on the inside
CGPathRef roundedRect = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:4].CGPath;
CGContextAddPath(context, roundedRect);
CGContextClip(context);
CGContextAddPath(context, roundedRect);
CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, 0), 3, [UIColor colorWithWhite:0 alpha:1].CGColor);
CGContextSetStrokeColorWithColor(context, [UIColor colorWithWhite:0 alpha:1].CGColor);
CGContextStrokePath(context);
Which results in:
You can change the shadow offset and blur to change the shadow style. If you need it to be darker, you can also successively add and then stroke the same CGPath, which will make the shadows pile up.
I use FXLabel for inner shadow, look here https://github.com/nicklockwood/FXLabel.
Yes, I have a blog post about it here. The short answer is to borrow the JTAInnerShadowLayer from here, subclass UILabel, and change its layerclass by overriding + (Class)layerClass so that it returns JTAInnerShadowLayer class like this:
+ (Class)layerClass
{
return [JTAInnerShadowLayer class];
}
Then in the init method for the layer set up the JTAInnerShadowLayer something like this:
[self setBackgroundColor:[UIColor clearColor]];
JTAInnerShadowLayer *innerShadow = (JTAInnerShadowLayer *)[self layer];
[innerShadow setClipForAnyAlpha:YES];
[innerShadow setOutsideShadowSize:CGSizeMake(0.0, 1.0) radius:1.0];
[innerShadow setInsideShadowSize:CGSizeMake (0.0, 4.0) radius:6.0];
/* Uncomment this to make the label also draw the text (won't work well
with black text!*/
//[innerShadow drawOriginalImage];
(or just borrow the JTAIndentLabel class).
You will have to do your own custom drawing to get an inner shadow. There's no way currently to do it with a standard UILabel.
Here's a reasonable explanation on doing inner shadow with Quartz.
Inner shadow in Core Graphics
Try PaintCode trial version! For beginners, you'll learn how to create custom drawings. It's very nice! :3 You can use it for practice or for learning, but don't use it all the time, you should also learn how to create drawings on your own.
Disclaimer: I'm not an endorser, I was just amazed by my discovery. ;)