I have a UIScrollView that contains a subview that I want to fill with a texture.
- (void)drawRect:(CGRect)rect {
CGImageRef image_to_tile_ret_ref = CGImageRetain(wood.CGImage);
CGRect tile_rect;
tile_rect.size = wood.size;
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextBeginPath(context);
CGContextMoveToPoint(context, 0, 0);
CGContextDrawTiledImage(context, tile_rect, image_to_tile_ret_ref);
// Something here to make it fill a big area
CGContextFillPath(context);
CGImageRelease(image_to_tile_ret_ref);
}
This just seems to fill the visible area of the scroll view and when I scroll, the rest is white. How do I draw a rectangle beyond the bounds of the rect? Is that bad?
If you want to draw a background color in this is too much. UIScrollView can have a background color. That color can be created from a patter that is an image.
You can create a pattern color
UIColor * bgColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"imgname.png"]];
scrollView.backgroundColor = bgColor;
Related
I have taken a UiView subclass but it's background color is not changing
This class I am using these method
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:CGRectMake(50, 80, 200, 200)];
if (self)
{
// Initialization code
}
return self;
}
- (void)drawRect:(CGRect)rect{
CGContextRef context = UIGraphicsGetCurrentContext();
[[UIColor darkGrayColor]setFill];
CGContextClearRect(context, rect);
CGContextSetLineWidth(context, 2.0);
CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context, [UIColor orangeColor].CGColor);
CGContextMoveToPoint(context, 1, 1);
CGContextAddLineToPoint(context, 100, 100);
CGContextStrokePath(context); // and draw
}
I am calling this class to main view controller
Newclass *obj =[[Newsclass alloc]init];
obj.backgroundColor =[UIColor redColor];
[self.view addsubview :obj];
but background color by default show black color. It is not changing
if i implemented background-color code init with frame method or
draw rect method than not changing.
if i code it
- (id)initWithCoder:(NSCoder*)aDecoder
than it's method not called
please suggest me UIview subclass black background color how to change
First of all, you should do the color part in UIView file.
if (self = [super initWithFrame:CGRectMake(220,60, 100, 300)])
{
self.backgroundColor =[UIColor greenColor];
}
how ever you don't need to do in this case... ;)
it will definitely change your background color. But what happens next is that Draw rect method is called ,your color is no more visible as the draw rect method draws a view above it (whatever you draw in that method).
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGRect rectangle = CGRectMake(0,0,200,300);
CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
CGContextFillRect(context, rectangle);
}
You just cannot directly set the background color of cgcontext, you have to fill that context with color.
please make sure that you replace rectangle by rectangular frame of your view. It works like a charm for me.
Im trying to implement a crop feature for my app like the one Instagram has.
Example: http://i.imgur.com/Dq12OAx.png
I need to create an UIView in the form of a rectangle with a square "hole" in the middle.
I have no idea where to start so all help is appreciated.
Its pretty easy. Just subclass UIView, and override drawrect.
- (void)drawRect:(CGRect)rect {
//draw the non-transparent view here, or fill the whole view like
[[UIColor blackColor] setFill];
UIRectFill( rect);
//define the position and size of the "hole"
CGRect yourHole = CGRectMake(left, top, width, height);
//fill that section with clear color
[[UIColor clearColor] setFill];
UIRectFill( yourHole );
}
I have two rectangles (two closed sub cgpaths).
Rectangle B is small and is present inside Rectangle A. All edges within it.
Is there a direct way to fill color area external to the rectangle B.
CAShapeLayer fillExternalColor something like that? If not a direct way, how to do this programmatically?
A - Purple color
B - Yellow color
So I tried drawing A and then drawing B. I wanted B to be of clear color (for now I put Yellow) but then I see purple color of A..
I found CGRectIntersection method that gives AnB and CGRectUnion method that gives AuB.
Is there a method that gives the rest of the area which is AuB - AnB?
You are using a CAShapeLayer. If your fillColor and your strokeColor are both opaque (alpha 1.0), you can simply set the layer's backgroundColor to fill those pixels that are within the layer's bounds but outside of its stroked and filled path.
My test code:
#implementation ViewController {
CAShapeLayer *layer;
}
- (void)viewDidLoad {
[super viewDidLoad];
layer = [CAShapeLayer layer];
layer.path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 50, 250, 250)].CGPath;
layer.fillColor = [UIColor yellowColor].CGColor;
layer.strokeColor = [UIColor whiteColor].CGColor;
layer.lineWidth = 4;
layer.backgroundColor = [UIColor purpleColor].CGColor;
[self.view.layer addSublayer:layer];
}
- (void)viewDidLayoutSubviews {
layer.frame = self.view.bounds;
}
#end
Result:
I wanted to add red border inner rectangle on UIImage with masked outer part.
I came through this page. The following code is using CGContextEOFillPath can be helpful to others like me. (Some of the code is gathered from other pages.)
-(UIImage ) imageByDrawingBorderRectOnImage:(UIImage )image theRect:(CGRect)theRect
{
// begin a graphics context of sufficient size
UIGraphicsBeginImageContext(image.size);
// draw original image into the context
[image drawAtPoint:CGPointZero];
// get the context for CoreGraphics
CGContextRef ctx = UIGraphicsGetCurrentContext();
// set stroking color and to draw rect
[[UIColor redColor] setStroke];
// drawing with a red stroke color
CGContextSetRGBStrokeColor(ctx, 1.0, 0.0, 0.0, 1.0);
// the line width to 3
CGContextSetLineWidth(ctx, 3.0);
// Add Stroke Rectangle,
CGContextStrokeRect(ctx, theRect);
// Now draw fill outside part with partial alpha gray color
// drawing with a gray stroke color
CGMutablePathRef aPath = CGPathCreateMutable();
// outer rectangle
CGRect rectangle = CGRectMake( 0, 0, image.size.width, image.size.height);
CGPathAddRect(aPath, nil, rectangle);
// innter rectangle
CGPathAddRect(aPath, nil, theRect);
// set gray transparent color
CGContextSetFillColorWithColor(ctx, [UIColor colorWithRed:0.75 green:0.75 blue:0.75 alpha:0.5].CGColor);
// add the path to Context
CGContextAddPath(ctx, aPath);
// This method uses Even-Odd Method to draw in outer rectangle
CGContextEOFillPath(ctx);
// make image out of bitmap context
UIImage *retImage = UIGraphicsGetImageFromCurrentImageContext();
// free the context
UIGraphicsEndImageContext();
return retImage;
}
Regards.
Assuming A is the bigger shape, B is the smaller, inner shape, and bounds refers to the containing rect of A (probably the bounds of the view)
Clip shape B to the context (-addClip should do it)
CGContextClearRect the bounds
Fill shape A
Edit, found the source of this code
Given HoleView : UIView you must set:
self.opaque = NO;
self.backgroudColor = [UIColor clearColor];
and in drawRect:
[[UIColor purpleColor] setFill];
UIRectFill(A);
CGRect gapRectIntersection = CGRectIntersection(B, A);
[[UIColor clearColor] setFill];
UIRectFill(gapRectIntersection);
kCAFillRuleEvenOdd
Specifies the even-odd winding rule. Count the total number of path crossings. If the number of crossings is even, the point is outside the path. If the number of crossings is odd, the point is inside the path and the region containing it should be filled.
Available in OS X v10.6 and later.
Declared in CAShapeLayer.h.
Refer to :CAShapeLayer Class reference
I need to darken a UIImageView when it gets touched, almost exactly like icons on the springboard (home screen).
Should I be added UIView with a 0.5 alpha and black background. This seems clumsy. Should I be using Layers or something (CALayers).
I would let a UIImageView handle the actual drawing of the image, but toggle the image to one that's been darkened in advance. Here's some code I've used to generate darkened images with alpha maintained:
+ (UIImage *)darkenImage:(UIImage *)image toLevel:(CGFloat)level
{
// Create a temporary view to act as a darkening layer
CGRect frame = CGRectMake(0.0, 0.0, image.size.width, image.size.height);
UIView *tempView = [[UIView alloc] initWithFrame:frame];
tempView.backgroundColor = [UIColor blackColor];
tempView.alpha = level;
// Draw the image into a new graphics context
UIGraphicsBeginImageContext(frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[image drawInRect:frame];
// Flip the context vertically so we can draw the dark layer via a mask that
// aligns with the image's alpha pixels (Quartz uses flipped coordinates)
CGContextTranslateCTM(context, 0, frame.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextClipToMask(context, frame, image.CGImage);
[tempView.layer renderInContext:context];
// Produce a new image from this context
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage *toReturn = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
UIGraphicsEndImageContext();
[tempView release];
return toReturn;
}
How about subclassing UIView and adding a UIImage ivar (called image)? Then you could override -drawRect: something like this, provided you had a boolean ivar called pressed that was set while touched.
- (void)drawRect:(CGRect)rect
{
[image drawAtPoint:(CGPointMake(0.0, 0.0))];
// if pressed, fill rect with dark translucent color
if (pressed)
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSaveGState(ctx);
CGContextSetRGBFillColor(ctx, 0.5, 0.5, 0.5, 0.5);
CGContextFillRect(ctx, rect);
CGContextRestoreGState(ctx);
}
}
You would want to experiment with RGBA values above. And, of course, non-rectangular shapes would require a bit more work - like a CGMutablePathRef.
UIImageView can have multiple images; you could have two versions of the image and switch to the darker one when needed.
I want something as follows
UIImage *solid = [UIImage imageWithColor:[UIColor darkGrayColor]];
to create an image with respect to some color.
how to do it in iPhone sdk.
You can draw the color into a CGContext and then capture an image from it:
- (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size {
//Create a context of the appropriate size
UIGraphicsBeginImageContext(size);
CGContextRef currentContext = UIGraphicsGetCurrentContext();
//Build a rect of appropriate size at origin 0,0
CGRect fillRect = CGRectMake(0,0,size.width,size.height);
//Set the fill color
CGContextSetFillColorWithColor(currentContext, color.CGColor);
//Fill the color
CGContextFillRect(currentContext, fillRect);
//Snap the picture and close the context
UIImage *retval = UIGraphicsGetImageFromCurrentImageContext(void);
UIGraphicsEndImageContext();
return retval;
}
If you're just trying to create a solid rectangle of colour why not just do something like
UIView *solid = [[UIView alloc] initWithFrame:someFrame];
solid.backgroundColor = [UIColor greyColor];
And then add the view to whatever subview you want to show the solid colour.
(That is, of course only if that's what you're trying to achieve. Maybe you aren't)