So I have a class A in which I have the following:
#implementation UIToolbar (A)
- (void)drawRect:(CGRect)rect {
UIColor *color = [UIColor colorWithWhite:0.0 alpha:1.0];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColor(context, CGColorGetComponents( [color CGColor]));
CGContextFillRect(context, rect);
self.tintColor = [UIColor colorWithWhite:0.0 alpha:1.0];
}
#end
and I have a class B, which I have the following:
#implementation UIToolbar (B)
- (void)drawRect:(CGRect)rect {
UIColor *color = [UIColor colorWithWhite:10.0 alpha:1.0];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColor(context, CGColorGetComponents( [color CGColor]));
CGContextFillRect(context, rect);
self.tintColor = [UIColor colorWithWhite:0.0 alpha:1.0];
}
#end
Question is why is it only the top level category called each time? I basically want to have a different UIToolbar color/configuration for each different UIViewController, how do I do so?
A and B are not classes, they're categories. Any given class can only have one implementation of a given method at a time. If you try to override a method in more than one category, which implementation you get is undefined. Indeed, it's not recommended to override methods in categories at all -- if you need to override, you should create a subclass.
When you use this implementation , this is all uitoolbar which are custom with the theme.
If your application is developed under ios5, you can use method setBackgroundImage:forToolbarPosition:barMetrics:.
If you develop under ios < 5 , you can implement an new class inherited from uitoolbar which have a custom drawRect.
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.
I have this code:
CGColorRef darkColor = [[UIColor colorWithRed:21.0/255.0 green:92.0/255.0 blue:136.0/255.0 alpha:1.0] CGColor];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, darkColor);
CGContextFillRect(context, CGRectMake(18, 62, 66, 66));
And I just put it in the viewdidload method of my view, but my view doesn't look any different than before. I've tried making it really big and bright red, but it's just not drawing. Is there some other initialization code that I need?
EDIT: After working with the answers given to me, I have this now in my veiwdidload:
[self.view addSubview:[[[imageBackground alloc] init] autorelease]];
and in imageBackground.m:
#implementation imageBackground
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.opaque = YES;
self.backgroundColor = [UIColor clearColor];
}
return self;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
CGColorRef darkColor = [[UIColor colorWithRed:21.0/255.0 green:92.0/255.0 blue:136.0/255.0 alpha:1.0] CGColor];
darkColor = [[UIColor colorWithRed:255.0 green:0.0 blue:0.0 alpha:1.0] CGColor];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, darkColor);
CGContextFillRect(context, CGRectMake(18, 62, 66, 66));
}
#end
Imagebackground.h subclasses UIView:
#import <UIKit/UIKit.h>
#interface imageBackground : UIView
#end
I still get no results out of it though.
EDIT2: Well, I solved it myself, but then realized progrmr had already told me how to solve it. I had to use [self.view addSubview:[[[imageBackground alloc] initWithFrame:CGRectMake(0, 0, 320, 480)] autorelease]]; instead of just plain alloc init.
Thanks glorifiedhacker for lots of help as well!
You need to subclass UIView (or one of its subclasses) and override the drawRect method:
- (void)drawRect:(CGRect)rect {
CGColorRef darkColor = [[UIColor colorWithRed:21.0/255.0 green:92.0/255.0 blue:136.0/255.0 alpha:1.0] CGColor];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, darkColor);
CGContextFillRect(context, CGRectMake(18, 62, 66, 66));
}
in order to get a valid graphics context into which you can draw. From Apple's documentation on UIView:
View drawing occurs on an as-needed basis. When a view is first shown,
or when all or part of it becomes visible due to layout changes, the
system asks the view to draw its contents. For views that contain
custom content using UIKit or Core Graphics, the system calls the
view’s drawRect: method. Your implementation of this method is
responsible for drawing the view’s content into the current graphics
context, which is set up by the system automatically prior to calling
this method. This creates a static visual representation of your
view’s content that can then be displayed on the screen.
The most simply way, without subclassing, is a procedure for whole code.
void DrawRectFrame(CGContext c, CGRect rc)
{
CGContextMoveToPoint(c, rc.origin.x, rc.origin.y);
CGContextAddLineToPoint(c, rc.origin.x+rc.size.width, rc.origin.y);
CGContextMoveToPoint(c, rc.origin.x+rc.size.width, rc.origin.y);
CGContextAddLineToPoint(c, rc.origin.x+rc.size.width, rc.origin.y+rc.size.height);
CGContextMoveToPoint(c, rc.origin.x+rc.size.width, rc.origin.y+rc.size.height);
CGContextAddLineToPoint(c, rc.origin.x, rc.origin.y+rc.size.height);
CGContextMoveToPoint(c, rc.origin.x, rc.origin.y+rc.size.height);
CGContextAddLineToPoint(c, rc.origin.x, rc.origin.y);
}
How can I remove the default gradient on a UINavigationBar? What property do I set to do this?
You can remove the gradient and set your own solid color by popping this code into the class that has the navigation bar. You can change the UIColor to whatever color you need. Note that this code needs to be outside of another implementation, so whatever .m file you put it in put it before the #implmentation of the class already implemented in that file.
#implementation UINavigationBar (UINavigationBarCategory)
- (void)drawRect:(CGRect)rect {
UIColor *color = [UIColor blueColor];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColor(context, CGColorGetComponents( [color CGColor]));
CGContextFillRect(context, rect);
}
#end
I have a main view with a picture on it.
I am trying to add a subview with [self.view addSubview:view2]; but I want the view2 background to be transparent. Have tried opaque=no and background color to clearcolor and also tried to subclass a uiview and rewrite the drawrect with:
#import "TransparentView.h"
#implementation TransparentView
- (id)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame]) {
[self setBackgroundColor:[UIColor clearColor]];
self.opaque=NO;
self.clearsContextBeforeDrawing=YES;
}
return self;
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClearRect(context, rect);
CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
CGContextFillRect(context, rect);
}
#end
But still doesn't display the background of the subview transparent... any ideas?
Try:
view.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.0];
view.opaque = NO;
Is the view being loaded from a nib file? If so, the -initWithFrame: won't be called; -initWithCoder: will be called instead. A better place to do this initialization might be in -viewDidLoad. But setting the background color to [UIColor clearColor] should definitely do the trick.
Try coloring the subview's background with a 0.0 for Alpha. That should make it completely transparent.
Something like this:
UIColor *myUIColor = [UIColor colorWithRed: 1.0 green: 1.0 blue: 1.0 alpha:0.0];
In the function
- (void)drawRect:(CGRect)rect
try to update
CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
to
const CGFloat BACKGROUND_OPACITY = 0.85; //Note: update this value to what you need
CGContextSetRGBFillColor(context, 1, 1, 1, BACKGROUND_OPACITY); // You can change 1,1,1 to the needed values
This link might help you
http://www.cocoawithlove.com/2009/04/showing-message-over-iphone-keyboard.html
I've had some cases where ... addSubview:clearView] seemed to reset the background color of clearView (WTF!) to something not clear. I added a
[clearView setBackgroundColor:nil];
somewhere after that and it seemed to help.
I am still struggling with drawing a line with CGContext. I have actually go to line to draw, but now I need the background of the Rect to be transparent so the existing background shows thru. Here's my test code:
(void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
CGContextSetAlpha(context,0.0);
CGContextFillRect(context, rect);
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 100.0,0.0);
CGContextAddLineToPoint(context,100.0, 100.0);
CGContextStrokePath(context);
}
Any ideas?
After UIGraphicsGetCurrentContext() call CGContextClearRect(context,rect)
Edit:
Alright, got it.
Your custom view with the line should have the following:
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self setBackgroundColor:[UIColor clearColor]];
}
return self;
}
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClearRect(context, rect);
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 100.0,0.0);
CGContextAddLineToPoint(context,100.0, 100.0);
CGContextStrokePath(context);
}
My test used this as a very basic UIViewController:
- (void)viewDidLoad {
[super viewDidLoad];
UIImageView *v = [[UIImageView alloc] initWithFrame:self.view.bounds];
[v setBackgroundColor:[UIColor redColor]];
[self.view addSubview:v];
TopView *t = [[TopView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:t];
[v release];
[t release];
}
Easy way:
- (id)initWithFrame:(CGRect)frame
{
if ((self = [super initWithFrame:frame]))
{
self.opaque = NO;
}
return self;
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClearRect(context, rect);
//your code
}
Init a context with opaque == false, Swift 3
UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
opaque
A Boolean flag indicating whether the bitmap is opaque. If you know the bitmap is fully opaque, specify true to ignore the alpha channel and optimize the bitmap’s storage. Specifying false means that the bitmap must include an alpha channel to handle any partially transparent pixels.
This is what worked for me with a UIImage which had been manually added using InterfaceBuilder.
- (id)initWithCoder:(NSCoder *)aDecoder {
if(self = [super initWithCoder:aDecoder]) {
self.backgroundColor = [UIColor clearColor];
}
return self;
}
-(void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 100.0,0.0);
CGContextAddLineToPoint(context,100.0, 100.0);
CGContextStrokePath(context);
}
David Kanarek's answer only works when you're manually creating your own UIImageView. If you've created a UIView and manually added it via Interface Builder then you will need a different approach like this calling the initWithCoder method instead.
I have the same problem, then I find it is.
I overwrite the init Method is -(id)initWithFrame:(CGRect)rect.
In this method self.background = [UIColor clearColor];
but i use this view in xib file !!! That will call the init method is
-(id)initWithCoder:(NSCoder*)aDecoder;
So overwrite all the init Method and setup BackgroundColor will work OK.
CGContextClearRect(context,rect)
If the provided context is a window or bitmap context, Quartz effectively clears the rectangle. For other context types, Quartz fills the rectangle in a device-dependent manner. However, you should not use this function in contexts other than window or bitmap contexts.
you can create a image context with this code:
cacheContext = CGBitmapContextCreate (cacheBitmap, size.width, size.height, 8, bitmapBytesPerRow, CGColorSpaceCreateDeviceRGB(), kCGImageAlphaPremultipliedLast);
CGContextSetRGBFillColor(cacheContext, 0, 0, 0, 0);
CGContextFillRect(cacheContext, (CGRect){CGPointZero, size});
the key is kCGImageAlphaPremultipliedLast.
Having trouble understanding the question here, but if you're unable to have a "background" UIView show through a "top" view into which you're drawing, one solution is topView.backgroundColor = [UIColor clearColor]; I was having (I think) this same problem and this solved it for me.