Custom Cell Selected - iphone

I am drawing a custom cell, to achieve a certain look I want. However, I want to perform a different drawing based on if the cell is select. I really do not just want the default colors.
I changed content's views background color the view in this method:
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
However, it just did not appear correctly, mainly it did not take into account the accessary and just colored it until the accessory indicator. Is there a better way to accomplish this?
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
// Background
CGContextSetFillColorWithColor(context, CELL_BACKGROUND_COLOR);
CGContextMoveToPoint(context, 0.0f, 0.0f);
CGContextAddLineToPoint(context, rect.size.width, 0.0f);
CGContextAddLineToPoint(context, rect.size.width, rect.size.height);
CGContextAddLineToPoint(context, 0.0f, rect.size.height);
CGContextClosePath(context);
CGContextFillPath(context);
// Top line
CGContextSetStrokeColorWithColor(context, CELL_TOP_LINE_COLOR);
CGContextSetLineWidth(context, CELL_LINE_WIDTH);
CGContextSetLineCap(context, kCGLineCapSquare);
CGContextMoveToPoint(context, 0.0f, 0.0f);
CGContextAddLineToPoint(context, rect.size.width, 0.0f);
CGContextStrokePath(context);
//Bottom line
CGContextSetStrokeColorWithColor(context, CELL_BOTTOM_LINE_COLOR);
CGContextSetLineWidth(context, CELL_LINE_WIDTH);
CGContextSetLineCap(context, kCGLineCapSquare);
CGContextMoveToPoint(context, 0.0f, rect.size.height);
CGContextAddLineToPoint(context, rect.size.width, rect.size.height);
CGContextStrokePath(context);
}

I think you should modify your drawRect method and change how your color are set depending of the isSelected property. Changing the content's view background when the setSelected method will probably don't change anything since it will be overriding by the drawRect method.

I'm using this :
if(self.highlighted || self.selected) {
//set text color
textColor = [UIColor colorWithRed:204.0/255.0 green:255.0/255.0 blue:0 alpha:1.0];
//set background color
[[UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.7] set];
CGContextFillRect(context, r);
}
Also check selectionStyleproperty of your cell.

I found a solution that works great, it also draws underneath the default accessory views, like the accessory indicator. I created custom view's called BackgroundView and SelectedBackgroundView, I just use the drawRect method to create a custom drawing. It works great, and performance seems to be okay. If anyone wants to see the full code let me know.
[cell setBackgroundView:[[BackgroundView alloc] init]];
[cell setSelectedBackgroundView:[[SelectedBackgroundView alloc] init]];

Related

Make UiView sub class but background color show black color

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.

Multicolor line drawing

I am creating a drawing app. One of the features is multicolour line drawing. It should work like user touch up the screen and leads on it drawing a line. Colour of the line changes smoothly. Like that http://www.examples.pavelgatilov.com/Screen%20Shot%202013-09-22%20at%208.37.42%20PM.png
I tried several approaches, but haven't been lucky.
My line drawing method is below:
- (void) drawLineFrom:(CGPoint)from to:(CGPoint)to width:(CGFloat)width
{
self.drawColor = toolColor;
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextScaleCTM(ctx, 1.0f, -1.0f);
CGContextTranslateCTM(ctx, 0.0f, -self.frame.size.height);
if (drawImage != nil) {
CGRect rect = CGRectMake(0.0f, 0.0f, self.frame.size.width, self.frame.size.height);
CGContextDrawImage(ctx, rect, drawImage.CGImage);
}
CGContextSetLineCap(ctx, kCGLineCapRound);
CGContextSetLineWidth(ctx, width);
CGContextSetStrokeColorWithColor(ctx, self.drawColor.CGColor);
CGContextMoveToPoint(ctx, from.x, from.y);
CGContextAddLineToPoint(ctx, to.x, to.y);
CGContextStrokePath(ctx);
CGContextFlush(ctx);
drawImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
drawLayer.contents = (id)drawImage.CGImage;
}
Thanks for your help
Depending on exactly what colours, how they change and what effect you want / what happens with turns in the line, you may want to look at some combination of:
CGContextDrawLinearGradient with masking to the users drawn path.
colorWithPatternImage:
CGContextDrawLinearGradient drawn behind another layer and drawing transparency into the top layer with kCGBlendModeClear

Pushing/Popping Graphics Context

I've been going through the Standford University IOS lessons and I am stuck on understanding what UIGraphicsPushContext and UIGraphicsPopContext does (lesson 4). From the notes, it is explained that these methods can be used to avoid affecting the current graphics states from other utility methods. Here is the example provided in the notes:
- (void)drawGreenCircle:(CGContextRef)ctxt {
UIGraphicsPushContext(ctxt);
[[UIColor greenColor] setFill];
// draw my circle
UIGraphicsPopContext();
}
- (void)drawRect:(CGRect)aRect {
CGContextRef context = UIGraphicsGetCurrentContext();
[[UIColor redColor] setFill];
// do some stuff
[self drawGreenCircle:context];
// do more stuff and expect fill color to be red
}
However, when I try to test this, I don't seem to get this result. Below is a simple test case I've made that gets the current context in drawRect, sets the color, calls a utility method that sets the color to green, returns to drawRect and draws a line. I would expect based on the notes on the Standford site that the line would be red since I pushed/popped the context in my drawGreenCircle. (I realize I am not actually drawing any circle in drawGreenCircle) But I get a green line in drawRect. It seems that my drawGreenCircle method did change the color and did not revert it back to red. I would like to know what I am missing about this concept.
- (void)drawGreenCircle:(CGContextRef)ctxt {
//Doesn't actually draw circle --Just testing if the color reverts
//to red in drawRect after this returns
UIGraphicsPushContext(ctxt);
[[UIColor greenColor] setStroke];
UIGraphicsPopContext();
}
- (void)drawRect:(CGRect)aRect {
CGContextRef context = UIGraphicsGetCurrentContext();
[[UIColor redColor] setStroke];
// do some stuff
[self drawGreenCircle:context];
CGContextBeginPath(context);
CGContextMoveToPoint(context, 100, 100);
CGContextAddLineToPoint(context, 500, 100);
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathFillStroke);
}
You need CGContextSaveGState and CGContextRestoreGState instead. The following code works:
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
[[UIColor greenColor] setFill];
[[UIColor blackColor] setStroke];
[self drawBlueCircle:context];
CGContextMoveToPoint(context, 55, 5);
CGContextAddLineToPoint(context, 105, 100);
CGContextAddLineToPoint(context, 5, 100);
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathFillStroke);
}
- (void)drawBlueCircle:(CGContextRef)context {
CGContextSaveGState(context);
[[UIColor blueColor] setFill];
CGContextAddEllipseInRect(context, CGRectMake(0, 0, 100, 100));
CGContextDrawPath(context, kCGPathFillStroke);
CGContextRestoreGState(context);
}
Source

Using UIGraphicsPushContext(context) and UIGraphicsPopContext()

Very frustrating experience understanding UIGraphicsPushContext(context) and UIGraphicsPopContext()
My understanding is that I can set attributes of the context like the stroke color and then push the context on a stack so I can set a new color for the current context. When I'm done doing that I can return to the context by popping it.
Below is my code. When I run the code below two lines are drawn in blue. What I expect to happen is: that I first set the color green. Go to the blueLine function and push the green context. Draw in blue. Then pop the green context. Allowing the drawLine function to drawn in green.
Here is a screenshot of what is drawn (two blue lines): http://dl.dropbox.com/u/1207310/iOS%20Simulator%20Screen%20shot%20Feb%205%2C%202012%209.00.35%20PM.png
Any help is GREATLY appreciated! Thank you.
- (void)drawBlueLine:(CGContextRef)context
{
UIGraphicsPushContext(context);
[[UIColor blueColor] setStroke];
CGContextBeginPath(context);
CGContextMoveToPoint(context, self.bounds.origin.x, 100);
CGContextAddLineToPoint(context, self.bounds.origin.x+self.bounds.size.width, 200);
CGContextStrokePath(context);
UIGraphicsPopContext();
}
- (void)drawLine:(CGContextRef)context
{
UIGraphicsPushContext(context);
CGContextBeginPath(context);
CGContextMoveToPoint(context, self.bounds.origin.x, 200);
CGContextAddLineToPoint(context, self.bounds.origin.x+self.bounds.size.width, 300);
CGContextStrokePath(context);
UIGraphicsPopContext();
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
[[UIColor redColor] setStroke];
CGContextSetLineWidth(context, 5.0);
[self drawBlueLine:context];
[self drawLine:context];
}
Or shouldn't this work?
- (void)drawLine:(CGContextRef)oldContext
{
UIGraphicsPushContext(oldContext); //makes oldContext the current context but there is a copy on the stack
[[UIColor blueColor] setStroke];
CGContextBeginPath(oldContext);
CGContextMoveToPoint(oldContext, self.bounds.origin.x, 200);
CGContextAddLineToPoint(oldContext, self.bounds.origin.x+self.bounds.size.width, 300);
CGContextStrokePath(oldContext);
UIGraphicsPopContext(); //previous oldContext is moved back into place containing red?
}
- (void)drawRect:(CGRect)rect
{
CGContextRef oldContext = UIGraphicsGetCurrentContext();
[[UIColor redColor] setStroke];
[self drawLine:oldContext];
//anything I draw here should be red. Shouldn't it?`
What UIGraphicsPushContext and UIGraphicsPopContext does as change which context is being used for drawing, not necessarily save and restore any given context's state. What your code is doing is simply repetitively replacing the context that was current prior to the call to drawRect: with the context you grab with UIGraphicsGetCurrentContext (they are likely to be the same anyway).
If you want to save an restore a given context's state, use CGContextSaveGState and CGContextRestoreGState instead.
The problem is the way you are setting the color, you need to use
CGContextSetStrokeColorWithColor(context, color)
like this:
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor)
and
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor)
so that the color is connected to the context.
[[UIColor redColor] setStroke];
is changing the color for all strokes...I'm curious if it would overide the above function if it was set for the context, I think it would not...

Why I can't draw something on my UIView?

This is my Main View, I just want it draw some thing to test, but I find that my UI don't have any thing, here is the code:
- (void)viewDidLoad {
[super viewDidLoad];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 100.0f, 100.0f);
CGContextAddLineToPoint(context, 200.0f, 200.0f);
CGContextStrokePath(context);
}
This is the sample code I copied online. I assume the code is correct, it does not have any error, but nothing appear. Or... ... this code should not paste on viewDidLoad?
viewDidLoad doesn't have a context. You will need to create an image context, do your drawing, produce an image, then add it to the view like so:
UIGraphicsBeginImageContext();
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 100.0f, 100.0f);
CGContextAddLineToPoint(context, 200.0f, 200.0f);
CGContextStrokePath(context);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *imgView = [[UIImageView alloc] initWithImage:img];
[self.view addSubview:imgView];
[imgView release];
Edit:
viewDidLoad is a UIViewController method, not a UIView method. I assume this code is in your controller, am I correct? Also, viewDidLoad is only called after loading a view from a nib. Did you use a nib (xib built with Interface Builder) or did you create your view programmatically?
To draw on the view using your code, you need to override -drawRect: instead of -viewDidLoad.
- (void)drawRect:(CGRect)rect {
[super drawRect:rect]; // not necessary
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextMoveToPoint(context, 100.0f, 100.0f);
CGContextAddLineToPoint(context, 200.0f, 200.0f);
CGContextStrokePath(context);
}