What is wrong with this drawRect method in my iPhone app custom UIView class? It's supposed to draw a colored circle, however it draws a black square of proper width and height.
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
UIColor *c = [UIColor redColor];
const CGFloat *components = CGColorGetComponents([c CGColor]);
CGFloat red = components[0];
CGFloat green = components[1];
CGFloat blue = components[2];
CGFloat al = components[3];
CGContextSetRGBFillColor(context, red, green, blue, al);
CGContextFillEllipseInRect(context, CGRectMake(x, y, width, width));
}
Try this:
- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextAddEllipseInRect(ctx, CGRectMake(x, y, width, width));
CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor redColor] CGColor]));
CGContextFillPath(ctx);
}
Hope this works fine.
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetFillColorWithColor(context , [UIColor redColor].CGColor;
CGContextFillEllipseInRect(context, CGRectMake(x, y, width, width));
}
Related
I am trying to draw an image like below with libraries in iOS; but i couldn't.
I think it is very easy to draw but i couldn't achieve.
After i accomplish to draw i will place a label over it.
Use this as your drawRect method:
- (void)drawRect:(CGRect)rect
//// General Declarations
CGContextRef context = UIGraphicsGetCurrentContext();
//// Shadow Declarations
UIColor* shadow = [UIColor blackColor];
CGSize shadowOffset = CGSizeMake(1, 1);
CGFloat shadowBlurRadius = 2;
//// Frames
CGRect frame = rect;
//// Abstracted Graphic Attributes
CGRect shadowBoxRect = CGRectMake(CGRectGetMinX(frame) + 0, CGRectGetMinY(frame) + 0, 40, 40);
CGFloat shadowBoxCornerRadius = 4;
//// ShadowBox Drawing
UIBezierPath* shadowBoxPath = [UIBezierPath bezierPathWithRoundedRect: shadowBoxRect cornerRadius: shadowBoxCornerRadius];
[[UIColor lightGrayColor] setFill];
[shadowBoxPath fill];
////// ShadowBox Inner Shadow
CGRect shadowBoxBorderRect = CGRectInset([shadowBoxPath bounds], -shadowBlurRadius, -shadowBlurRadius);
shadowBoxBorderRect = CGRectOffset(shadowBoxBorderRect, -shadowOffset.width, -shadowOffset.height);
shadowBoxBorderRect = CGRectInset(CGRectUnion(shadowBoxBorderRect, [shadowBoxPath bounds]), -1, -1);
UIBezierPath* shadowBoxNegativePath = [UIBezierPath bezierPathWithRect: shadowBoxBorderRect];
[shadowBoxNegativePath appendPath: shadowBoxPath];
shadowBoxNegativePath.usesEvenOddFillRule = YES;
CGContextSaveGState(context);
{
CGFloat xOffset = shadowOffset.width + round(shadowBoxBorderRect.size.width);
CGFloat yOffset = shadowOffset.height;
CGContextSetShadowWithColor(context,
CGSizeMake(xOffset + copysign(0.1, xOffset), yOffset + copysign(0.1, yOffset)),
shadowBlurRadius,
shadow.CGColor);
[shadowBoxPath addClip];
CGAffineTransform transform = CGAffineTransformMakeTranslation(-round(shadowBoxBorderRect.size.width), 0);
[shadowBoxNegativePath applyTransform: transform];
[[UIColor grayColor] setFill];
[shadowBoxNegativePath fill];
}
CGContextRestoreGState(context);
}
Inner shadows are hard to do with CoreGraphics -- basically, you need to negate your path and draw a drop shadow below it, clipped to your original path.
You can take a look at PaintCode and it will show you the code. It has a 15-min demo mode if you don't want to purchase it, that should be enough for your needs.
You could try this:
#import <QuartzCore/QuartzCore.h>
and in your code , after making the your view set these:
self.layer.cornerRadius = x;
self.layer.masksToBounds = TRUE;
This allows you to have rounded corners on your view. And if you calculate the radius to match your view , you should get the desired look.
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.backgroundColor = [UIColor grayColor];
}
return self;
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context =UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
// And draw with a blue fill color
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);
// Draw them with a 2.0 stroke width so they are a bit more visible.
CGContextSetLineWidth(context, 2.0);
CGContextAddRect(context, self.bounds);
CGContextStrokePath(context);
// Close the path
CGContextClosePath(context);
// Fill & stroke the path
CGContextDrawPath(context, kCGPathFillStroke);
self.layer.cornerRadius = self.bounds.size.width/12;
self.layer.masksToBounds = TRUE;
}
I think it will be helpful to you.
Try the below code where myView is the UIView to which you want to set the shadow.
myView.layer.cornerRadius = 5.0f;
myView.layer.masksToBounds = YES;
[myView.layer setShadowColor:[[UIColor blackColor] colorWithAlphaComponent: 0.5]];
[myView.layer setShadowOffset:CGSizeMake(0, -1)];
Hope this helps.-
I got a requirements to display a UILabel with background split between two colors, like in this image:
(colors here are black at the bottom and 50% gray at the top - but this is not important). I tried setting the label's background colour to 50% grey in the interface builder and then do this in the code:
CALayer *sl1 = [[[CALayer alloc] init] autorelease];
sl1.frame = CGRectMake(0, lbl.frame.size.height / 2, lbl.frame.size.width, score1.frame.size.height/2);
sl1.backgroundColor = [[UIColor blackColor] CGColor];
[lbl.layer insertSublayer:sl1 atIndex:0];
Unfortunately, this resulted in the black part being drawn over the text, so the label looks like this:
which is, needless to say, is not something I need. So how can I get this background without turning to custom images? The issue is I need to have UILabel's like this in several places, different sizes - so I would need to create multiple versions of the background image.
Any ideas? Thanks.
this works:
UILabel* myLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 100, 100, 50)];
myLabel.text = #"Ciao";
myLabel.textColor = [UIColor greenColor];
UIGraphicsBeginImageContext(CGSizeMake(100, 50));
CGContextRef context = UIGraphicsGetCurrentContext();
// drawing with a gray fill color
CGContextSetRGBFillColor(context, 0.4, 0.4, 0.4, 1.0);
// Add Filled Rectangle,
CGContextFillRect(context, CGRectMake(0.0, 0.0, 100, 50));
// drawing with a black fill color
CGContextSetRGBFillColor(context, 0., 0., 0., .9);
// Add Filled Rectangle,
CGContextFillRect(context, CGRectMake(0.0, 25, 100, 25));
UIImage* resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
myLabel.backgroundColor = [UIColor colorWithPatternImage:resultingImage];
[self.view addSubview:myLabel];
Use UIColor's +colorWithPatternImage:. Pass in a 1px by the UILabel's height image and it will be "tiled" across the the width of the view.
myLabel.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"label-background.png"]];
first you have to subclass the UILabel and override it's drawRect: method like this for gradient background
- (void)drawRect:(CGRect)rect
{
//////////////GET REFERENCE TO CURRENT GRAPHICS CONTEXT
CGContextRef context = UIGraphicsGetCurrentContext();
//////////////CREATE BASE SHAPE WITH ROUNDED CORNERS FROM BOUNDS
CGRect activeBounds = self.bounds;
CGFloat cornerRadius = 10.0f;
CGFloat inset = 6.5f;
CGFloat originX = activeBounds.origin.x + inset;
CGFloat originY = activeBounds.origin.y + inset;
CGFloat width = activeBounds.size.width - (inset*2.0f);
CGFloat height = activeBounds.size.height - (inset*2.0f);
CGRect bPathFrame = CGRectMake(originX, originY, width, height);
CGPathRef path = [UIBezierPath bezierPathWithRoundedRect:bPathFrame cornerRadius:cornerRadius].CGPath;
//////////////CREATE BASE SHAPE WITH FILL AND SHADOW
CGContextAddPath(context, path);
CGContextSetFillColorWithColor(context, [UIColor colorWithRed:210.0f/255.0f green:210.0f/255.0f blue:210.0f/255.0f alpha:1.0f].CGColor);
CGContextSetShadowWithColor(context, CGSizeMake(0.0f, 1.0f), 6.0f, [UIColor colorWithRed:0.0f/255.0f green:0.0f/255.0f blue:0.0f/255.0f alpha:1.0f].CGColor);
CGContextDrawPath(context, kCGPathFill);
//////////////CLIP STATE
CGContextSaveGState(context); //Save Context State Before Clipping To "path"
CGContextAddPath(context, path);
CGContextClip(context);
//////////////DRAW GRADIENT
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
size_t count = 3;
CGFloat locations[3] = {0.0f, 0.57f, 1.0f};
CGFloat components[12] =
{ 0.0f/255.0f, 0.0f/255.0f, 0.0f/255.0f, 1.0f, //1
5.0f/255.0f, 5.0f/255.0f, 5.0f/255.0f, 1.0f, //2
10.0f/255.0f, 10.0f/255.0f, 10.0f/255.0f, 1.0f}; //3
CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, count);
CGPoint startPoint = CGPointMake(activeBounds.size.width * 0.5f, 0.0f);
CGPoint endPoint = CGPointMake(activeBounds.size.width * 0.5f, activeBounds.size.height);
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGColorSpaceRelease(colorSpace);
CGGradientRelease(gradient);
}
This will draw black to white gradient background
May this will help you
Happy Codding :)
the above code is from this site http://mobile.tutsplus.com/tutorials/iphone/ios-sdk-uialertview-custom-graphics/
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 am trying to do a custom tab bar with a transparent triangle that points into the tab bar's view.
Right now I am drawing a linear gradient and a gloss in the drawRect method for the background of this tab bar. I just need to add the transparent triangle on there. I know how to draw a triangle. I just need to know how to make it transparent to show the background beneath the tab bar view.
Anyone know how to do this?
Update
Here is the current code:
void drawGlossAndGradient(CGContextRef context, CGRect rect, CGColorRef startColor, CGColorRef endColor)
{
drawLinearGradient(context, rect, startColor, endColor);
CGColorRef glossColor1 = [UIColor colorWithRed:1.0 green:1.0
blue:1.0 alpha:0.35].CGColor;
CGColorRef glossColor2 = [UIColor colorWithRed:1.0 green:1.0
blue:1.0 alpha:0.1].CGColor;
CGRect topHalf = CGRectMake(rect.origin.x, rect.origin.y,
rect.size.width, rect.size.height/2);
drawLinearGradient(context, topHalf, glossColor1, glossColor2);
}
void drawLinearGradient(CGContextRef context, CGRect rect, CGColorRef startColor, CGColorRef endColor)
{
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat locations[] = { 0.0, 1.0 };
NSArray *colors = [NSArray arrayWithObjects:(__bridge id)startColor, (__bridge id)endColor, nil];
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) colors, locations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextSaveGState(context);
CGContextAddRect(context, rect);
CGContextClip(context);
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGContextRestoreGState(context);
CGGradientRelease(gradient);
CGColorSpaceRelease(colorSpace);
}
- (void)drawTriangle
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGPoint pt1 = CGPointMake(0.0f, 0.0f);
CGPoint pt2 = CGPointMake(10.0f, 10.0f);
CGPoint pt3 = CGPointMake(20.0f, 0.0f);
CGPoint vertices[] = {pt1, pt2, pt3, pt1};
CGContextBeginPath(context);
CGContextAddLines(context, vertices, 3);
CGContextClosePath(context);
CGContextClip(context);
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGColorRef lightColor = [UIColor colorWithRed:65.0f/255.0f green:64.0f/255.0f
blue:66.0f/255.0f alpha:1.0].CGColor;
CGColorRef darkColor = [UIColor colorWithRed:37.0/255.0 green:31.0/255.0
blue:32.0/255.0 alpha:1.0].CGColor;
[self drawTriangle];
CGRect viewRect = self.bounds;
drawGlossAndGradient(context, viewRect, lightColor, darkColor);
}
I added the clip suggested below but that just made my background with the gradient and the gloss dissappear and the triangle become gray. Does anyone know what I am doing wrong here?
If you draw this gradient in drawRect: method just add clipping path before it.
Example:
-(void)drawRect:(CGRect)rect {
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGPoint vertices[] = {coordinates of vertices};
CGContextBeginPath(ctx);
CGContextAddLines(ctx, vertices, sizeof(vertices)/sizeof(CGPoint));
CGContextClosePath(ctx);
CGContextClip(ctx);
// draw the gradient
}
Vertices - is an array with 7 points. 1 point per each corner of self.bounds and 3 points which are define the triangle.
For example:
(0) (1) (3) (4)
_____ ________________
| \ / |
| V |
| (2) |
(6) |_______________________|(5)
CGPoint vertices[7] = {CGPointZero, // origin
p1, p2, p3, // vertices of the triangle
{self.bounds.size.width, 0},
{self.bounds.size.width, self.bounds.size.height},
{0, self.bounds.size.height}
}
If anybody needs, this is a code to draw a colored triangle in a UITableView without using UIImageView. This method is good because, the size of triangle can vary and it is drawn programmatically. Also, you can probably change colors and make triangle transparent.
#implementation RRTriangleView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, 0.0, 0.0);
CGPathAddLineToPoint(path, NULL, - self.bounds.size.height / 2.0, self.bounds.size.height / 2.0);
CGPathAddLineToPoint(path, NULL, 0.0, self.bounds.size.height);
CGPathAddLineToPoint(path, NULL, 0.0f, 0.0f);
CAShapeLayer *shapeLayer = [CAShapeLayer layer];
[shapeLayer setPath:path];
[shapeLayer setFillColor:[COLOR_CUSTOM_LIGHT_BLUE CGColor]];
[shapeLayer setStrokeColor:[COLOR_CUSTOM_LIGHT_BLUE CGColor]];
[shapeLayer setPosition:CGPointMake(self.bounds.size.width, 0.0f)];
[[self layer] addSublayer:shapeLayer];
CGPathRelease(path);
}
return self;
}
Init this TriangleView and add it to your cell, when it is selected :
- (RRTriangleView *)triangleView
{
if (! _triangleView) {
_triangleView = [[RRTriangleView alloc] initWithFrame:self.bounds];
_triangleView.layer.backgroundColor = [[UIColor clearColor] CGColor];
_triangleView.clipsToBounds = NO;
}
return _triangleView;
}
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
//[super setSelected:selected animated:animated];
if (selected) {
[self addSubview:self.triangleView];
}
else {
[self.triangleView removeFromSuperview];
}
}
The size of triangleView is like your cell's view, it is transparent and it is drawn above.
I beleive that
[view setBackgroundColor:[UIColor clearColor]];
[view setOpaque:NO];
will make your view transparent.
I want to preserve previous drawing in drawRect (the system clears it down each time) and it seems that the way to go is to use a bitmap context and sure enough, this works except that now my colour is gone leaving only black and white instead.
Here is my "static" context
-(id)initWithCoder:(NSCoder *)aDecoder {
...
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
contextRef = CGBitmapContextCreate(NULL,
320,
640,
8,
320*4,
colorSpace,
kCGImageAlphaPremultipliedLast);
...
}
and here is my replacement context:
-(void)drawRect:(CGRect)rect {
myDrawRoutine();
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, rect, CGBitmapContextCreateImage(contextRef));
}
And this is the draw routine's guts:
...
// CGContextRef context = UIGraphicsGetCurrentContext();
CGContextRef context = contextRef;
if( !(context) )
return;
CGContextSetFillColor(context, CGColorGetComponents([co CGColor]));
CGContextSetStrokeColor(context, CGColorGetComponents([co CGColor]));
CGContextFillEllipseInRect(context, CGRectMake((*i)->x,
(*i)->y,
(*i)->diam,
(*i)->diam));
...
}
Thanks tonclon
That has made a hell of an increase in speed :)
But it still draws in black and white :(
Here is the above code + modifications...
Here is my "static context":
-(id)initWithCoder:(NSCoder *)aDecoder {
...
}
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
contextRef = CGBitmapContextCreate(NULL,
320,
640,
8,
320*4,
colorSpace,
kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colorSpace);
cglayer = CGLayerCreateWithContext(contextRef, CGSizeMake(320.0f, 640.0f), NULL);
contextRef = CGLayerGetContext(cglayer);
...
}
and here is my "replacement context" i.e. the cglayer is used instead (the context is no longer replaced).
-(void)drawRect:(CGRect)rect {
for(std::vector<Body*>::iterator i = bodyVec.begin(); i < bodyVec.end(); ++i)
move(i);
CGContextRef context = UIGraphicsGetCurrentContext();
// CGContextDrawImage(context, rect, CGBitmapContextCreateImage(contextRef));
CGContextDrawLayerInRect(context, rect, cglayer);
}
(The "draw routine's guts" remain the same.)
At last! Thanks to this thread
Extracting rgb from UIColor
I got the answer - use CGContextSetRGBFillColor instead and then feed it with the RGB from CGColorGetComponents indirectly.
CGColorRef color = [co CGColor];
int numComponents = CGColorGetNumberOfComponents(color);
CGFloat red;
CGFloat green;
CGFloat blue;
CGFloat alpha;
if (numComponents == 4)
{
const CGFloat *components = CGColorGetComponents(color);
red = components[0];
green = components[1];
blue = components[2];
alpha = components[3];
}
// CGContextSetFillColor(context, CGColorGetComponents([co CGColor]));
// CGContextSetStrokeColor(context, CGColorGetComponents([co CGColor]));
CGContextSetRGBFillColor(context, red, green, blue, alpha);
CGContextSetRGBStrokeColor(context, red, green, blue, alpha);
CGContextFillEllipseInRect(context, CGRectMake((*i)->x,
(*i)->y,
(*i)->diam,
(*i)->diam));
}