I am drawing triangle portion of the image using
UIImage *image = [UIImage imageNamed:#"sampleImage.png"];
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path,NULL,10.0f, 200.0f);
CGPathAddLineToPoint(path,NULL,200.0f,10.0f);
CGPathAddLineToPoint(path,NULL,200.0f,200.0f);
CGPathAddLineToPoint(path,NULL,200.0f,200.0f);
CGPathCloseSubpath(path);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(ctx, [UIColor blueColor].CGColor);
CGContextAddPath(ctx, path);
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, image.size.height);
CGContextConcatCTM(ctx, flipVertical);
CGContextClip(ctx);
CGContextDrawImage(ctx, CGRectMake(10, 10.0f, 200.0f, 200.0f), image.CGImage);
CGContextFillPath(ctx);
But i need entire image to be mapped into the triangle region. Is it possible to achieve this using core graphics?
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();
So I can't seem to be able to draw 2 CGMutablePathRef. Here's the code:
CGRect mainRect = CGRectMake(2, 2, rect.size.width-4, 210);
CGMutablePathRef mainPathRef = createRoundedRectForRect(mainRect, 4);
if (self.imageExists_){
[[UIColor colorWithRed:0 green:0 blue:0 alpha:1.0] set];
CGContextAddPath(context, mainPathRef);
CGContextClip(context);
UIGraphicsBeginImageContext(mainRect.size);
//need to flip the images to that it is drawn appropriately as CALayer uses a different coordinate system
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, 210);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, mainRect, self.highlightItem_.highlightStoryImage.CGImage);
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[scaledImage drawAtPoint:CGPointMake(0, 0)];
CGContextRestoreGState(context);
this draws the image just fine on the path I specified, clipped. But then I want to draw another rounded rect below it, so I did:
[[UIColor colorWithRed:0 green:0 blue:0 alpha:1.0] set];
CGFloat colors [] = {
0.20, 0.20, 0.20, 1.0,
0.17, 0.17, 0.17, 1.0
};
CGColorSpaceRef baseSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(baseSpace, colors, NULL, 2);
CGColorSpaceRelease(baseSpace), baseSpace = NULL;
CGContextSaveGState(context);
CGRect commentRect = CGRectMake(2, 215, rect.size.width-4, rect.size.height - 215);
CGMutablePathRef pathRef = createRoundedRectForRect(commentRect, 3);
CGContextAddPath(context, pathRef);
CGContextClip(context);
CGPoint startPoint = CGPointMake(CGRectGetMidX(commentRect), CGRectGetMinY(commentRect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(commentRect), CGRectGetMaxY(commentRect));
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGGradientRelease(gradient), gradient = NULL;
CGContextRestoreGState(context);
CGContextAddPath(context, pathRef);
CGContextDrawPath(context, kCGPathStroke);
Any idea why this doesn't work?
You've clipped the drawing to the first rect, but haven't reset the clipping path before drawing the second time. You need to save the graphics state before the first clipping path is invoked, I believe.
Your first snippet should look something like this:
CGContextSaveGState(...);
CGContextAddPath(...);
CGContextClip(...);
UIGraphicsBeginImageContext(...);
... rest of your drawing code...
CGContextRestoreGState(...);
and then the second code snippet.
I have a UIView with a dynamically generated graphic context. Its normal size is 100x100, but it can be scaled up to 200x200, so I want its size to be actually 200x200 in order to appear nicely and not blurred however it is displayed.
How can always draw it 200x200 in drawRect, being it displayed at a size of 100 or at a size of 200? If I'm showing it at 100x100, the rect passed to drawRect is smaller than the area I need to draw into.
My code:
- (void) drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
// prevent the drawings to be flipped
CGContextTranslateCTM(ctx, 0, rect.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
CGContextDrawImage(ctx, CGRectMake(0, 0, rect.size.width, rect.size.height), [UIImage imageNamed:#"actionBg.png"].CGImage);
// generate the overlay
if ([self isActive] == NO && self.fullDelay != 0) { // TODO: remove fullDelay check!
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef overlayCtx = UIGraphicsGetCurrentContext();
int segmentSize = (rect.size.height / [self fullDelay]);
for (int i=0; i<[self fullDelay]; i++) {
float alpha = 0.9 - (([self fullDelay] * 0.1) - (i * 0.1));
[[UIColor colorWithRed:120.0/255.0 green:14.0/255.0 blue:14.0/255.0 alpha:alpha] setFill];
if (currentDelay > i) {
CGRect r = CGRectMake(0, i * segmentSize, rect.size.width, segmentSize);
CGContextFillRect(overlayCtx, r);
}
[[UIColor colorWithRed:1 green:1 blue:1 alpha:0.3] setFill];
CGRect line = CGRectMake(0, (i * segmentSize) + segmentSize - 1 , rect.size.width, 1);
CGContextFillRect(overlayCtx, line);
}
UIImage *overlay = UIGraphicsGetImageFromCurrentImageContext();
UIImage *overlayMasked = [TDUtilities maskImage:overlay withMask:[UIImage imageNamed:#"actionMask.png"]];
// prevent the drawings to be flipped
CGContextTranslateCTM(ctx, 0, rect.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
// put the overlay
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextDrawImage(ctx, rect, overlayMasked.CGImage);
CGContextSetBlendMode(ctx, kCGBlendModeNormal);
UIGraphicsEndImageContext();
}
// prevent the drawings to be flipped
CGContextTranslateCTM(ctx, 0, rect.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
// draw the delay symbol
CGContextDrawImage(ctx, rect, [UIImage imageNamed:#"delaySymbol.png"].CGImage);
CGContextSetAlpha(ctx, 0.8);
// draw the symbol
NSString *imgName = [K_ACTION_IMAGES objectAtIndex:[self actionType]];
CGContextDrawImage(ctx, rect, [UIImage imageNamed:imgName].CGImage);
CGContextSetAlpha(ctx, 1);
// draw the delay number
imgName = [NSString stringWithFormat:#"%d.png", [self fullDelay]];
CGContextDrawImage(ctx, rect, [UIImage imageNamed:imgName].CGImage);
// draw the priority number
imgName = [NSString stringWithFormat:#"%d.png", [self actionType]];
CGContextDrawImage(ctx, CGRectMake(32, 0, rect.size.width, rect.size.height), [UIImage imageNamed:imgName].CGImage);
}
Have you called setNeedsDisplay method for you view after setting its frame
This is my coregraphics code:
void drawTopPaperBackground(CGContextRef context, CGRect rect) {
CGRect paper3 = CGRectMake(10, 14, 300, rect.size.height - 14);
CGRect paper2 = CGRectMake(13, 12, 294, rect.size.height - 12);
CGRect paper1 = CGRectMake(16, 10, 288, rect.size.height - 10);
//Shadow
CGContextSetShadowWithColor(context, CGSizeMake(0,0), 10, [[UIColor colorWithWhite:0 alpha:0.5]CGColor]);
CGPathRef path = createRoundedRectForRect(paper3, 0);
CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]);
CGContextAddPath(context, path);
CGContextFillPath(context);
//Layers of paper
CGContextSaveGState(context);
drawPaper(context, paper3);
drawPaper(context, paper2);
drawPaper(context, paper1);
CGContextRestoreGState(context);
}
void drawPaper(CGContextRef context, CGRect rect) {
//Shadow
CGContextSaveGState(context);
CGContextSetShadowWithColor(context, CGSizeMake(0,0), 1, [[UIColor colorWithWhite:0 alpha:0.5]CGColor]);
CGPathRef path = createRoundedRectForRect(rect, 0);
CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]);
CGContextAddPath(context, path);
CGContextFillPath(context);
CGContextRestoreGState(context);
//Gradient
CGContextSaveGState(context);
CGColorRef startColor = [UIColor colorWithWhite:0.92 alpha:1.0].CGColor;
CGColorRef endColor = [UIColor colorWithWhite:0.94 alpha:1.0].CGColor;
CGRect firstHalf = CGRectMake(rect.origin.x,
rect.origin.y, rect.size.width / 2, rect.size.height);
CGRect secondHalf = CGRectMake(rect.origin.x + (rect.size.width / 2),
rect.origin.y, rect.size.width / 2, rect.size.height);
drawVerticalGradient(context, firstHalf, startColor, endColor);
drawVerticalGradient(context, secondHalf, endColor, startColor);
CGContextRestoreGState(context);
CGContextSaveGState(context);
CGRect redRect = rectForRectWithInset(rect, -1);
CGMutablePathRef redPath = createRoundedRectForRect(redRect, 0);
CGContextSaveGState(context);
CGContextSetStrokeColorWithColor(context, [[UIColor blackColor] CGColor]);
CGContextAddPath(context, path);
CGContextClip(context);
CGContextAddPath(context, redPath);
CGContextSetShadowWithColor(context, CGSizeMake(0, 0), 15.0, [[UIColor colorWithWhite:0 alpha:0.1] CGColor]);
CGContextStrokePath(context);
CGContextRestoreGState(context);
}
The view is a UIScrollView, which contains a textview. Every time the user types something and goes onto a new line, I call [self setNeedsDisplay]; and it redraws the code. But when the view starts to get long - around 1000 height, it has very noticeable lag. How can i make this code more efficient? Can i take a line of pixels and make it just repeat that, or stretch it, all the way down?
You can draw your repeating background once, into an offscreen context, pull out the image from it, then create a UIColor with the pattern image and set that as your background colour. The image will then be tiled for you.
You start an image context with UIGraphicsBeginImageContextWithOptions(). The options include the size of your expected image - I assume this is the width of your scrollview and x pixels high, the opacity, and scale. Send 0 for the scale for automatic retina support.
You can then act as if you were within a drawRect method - so your functions above can be called as normal.
Then, extract the image:
UIImage *background = UIGraphicsGetImageFromCurrentImageContext();
End the image context:
UIGraphicsEndImageContext();
Then create the colour:
UIColor *backgroundColor = [UIColor colorWithPatternImage:background];
And set that as the background for your scrollview. Typed on a phone, so apologies for ... everything.
I haven't been able to find one single example on the internets that teaches me how to create a circle on the fly and then use this circle to clip an UIImage.
Here's my code, unfortunately it doesn't give me desired results.
//create a graphics context
UIGraphicsBeginImageContext(CGSizeMake(243, 243));
CGContextRef context = UIGraphicsGetCurrentContext();
//create my object in this context
CGContextAddEllipseInRect(context, CGRectMake(0, 0, 243, 243));
CGContextSetFillColor(context, CGColorGetComponents([[UIColor whiteColor] CGColor]));
CGContextFillPath(context);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
//create an uiimage from the ellipse
//Get the drawing image
CGImageRef maskImage = [image CGImage];
// Get the mask from the image
CGImageRef maskRef = CGImageMaskCreate(CGImageGetWidth(maskImage)
, CGImageGetHeight(maskImage)
, CGImageGetBitsPerComponent(maskImage)
, CGImageGetBitsPerPixel(maskImage)
, CGImageGetBytesPerRow(maskImage)
, CGImageGetDataProvider(maskImage)
, NULL
, false);
//finally clip the context to the mask.
CGContextClipToMask( context , CGRectMake(0, 0, 243, 243) , maskRef );
//draw the image
[firstPieceView.image drawInRect:CGRectMake(0, 0, 320, 480)];
// [firstPieceView drawRect:CGRectMake(0, 0, 320, 480)];
//extract a new image
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
NSLog(#"self.firstPieceView is %#", NSStringFromCGRect(self.firstPieceView.frame));
UIGraphicsEndImageContext();
self.firstPieceView.image = outputImage;
I would appreciate any directions.
I suspect you need to rephrase your question better.
There's plenty of example code for whatever you're trying to do out there.
Here's how you could implement a custom UIView subclass to clip am image to an ellipse:
- (void)drawInRect:(CGRect)rect {
UIImage image;// set/get from somewhere
CGImageRef imageRef = [image CGImageRef];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddEllipseInRect(context, self.bounds);
CGContextClip(context);
CGContextDrawImage(context, self.bounds, imageRef);
}
caveat emptor
Edit (a day later, free time produces):
- (void)drawRect:(CGRect)rect {
// we're ignoring rect and drawing the whole view
CGImageRef imageRef = [_image CGImage]; // ivar: UIImage *_image;
CGContextRef context = UIGraphicsGetCurrentContext();
// set the background to black
[[UIColor blackColor] setFill];
CGContextFillRect(context, self.bounds);
// modify the context coordinates,
// UIKit and CoreGraphics are oriented differently
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0, CGRectGetHeight(rect));
CGContextScaleCTM(context, 1, -1);
// add clipping path to the context, then execute the clip
// this is in effect for all drawing until GState restored
CGContextAddEllipseInRect(context, self.bounds);
CGContextClip(context);
// stretch the image to be the size of the view
CGContextDrawImage(context, self.bounds, imageRef);
CGContextRestoreGState(context);
}