I have an PNG image and I want to fill that image with gradient. Is this possible?
Means on the time of touch on iPad that part should be fill with gradient.
Just like in flood fill image fill with simple color(R+G+B).
I want that image fill gradient.
Thanx in advance for help.
And this is my line of code where i am find irregular shape and then fill the color by touch i need to modified it.
- (unsigned char*)rawDataFromImage:(UIImage*)image
{
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
NSLog(#"w=%d,h=%d",width,height);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = malloc(height * width * 4);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);
return rawData;
}
If any one having different solution for that so please give me.
I don't want to draw color on image i want to touch and fill on image but with gradient.
-(void)drawRect:(CGRect)rect
{
CGContextRef currentContext = UIGraphicsGetCurrentContext();
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 1.0, 1.0, 1.0, 0.35, // Start color
1.0, 1.0, 1.0, 0.06 }; // End color
rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}
From http://replyz.com/c/1244746-does-anyone-know-the-exact-cgcolorref-used-to-create-the-selection-highlight-when-using-uitableviewcellselectionstyleblue#
I saw someone did it with Code and he said the highlighted color is from a UIImage.
Where can I find the image?
(I want to highlight a UIButton with the UITableViewCellSelectionStyleBlue color)
I found the link http://replyz.com/c/1244746-does-anyone-know-the-exact-cgcolorref-used-to-create-the-selection-highlight-when-using-uitableviewcellselectionstyleblue# including some code which can be used to create the highlight. And I create a new UIImage with the Code.
Here is the code:
+ (UIImage *) imageForSelectedBlue {
CGRect rect = CGRectMake(0, 0, 10, 10);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 0.021, 0.548, 0.962, 1.000, 0.008, 0.364, 0.900, 1.000 };
CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB();
CGGradientRef selectionGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(context, selectionGradient, startPoint, endPoint, 0);
CGGradientRelease(selectionGradient);
CGColorSpaceRelease(rgbColorspace);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Actually, you can set the background image of the button. It is more efficient.
[button setBackgroundImage:buttonBackgroundPressed forState:UIControlStateHighlighted];
I'm using the LGViewHUD custom control to display a HUD in my iOS application. How can I set a custom background for this HUD?
An example of this behavior can be found here:
Use this code in your UIView -drawRect: method
size_t locationsCount = 2;
CGFloat locations[2] = {0.0f, 1.0f};
CGFloat colors[8] = {0.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.0f,0.75f};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, colors, locations, locationsCount);
CGColorSpaceRelease(colorSpace);
CGPoint center = CGPointMake(self.bounds.size.width/2, self.bounds.size.height/2);
float radius = MIN(self.bounds.size.width , self.bounds.size.height) ;
CGContextDrawRadialGradient (context, gradient, center, 0, center, radius, kCGGradientDrawsAfterEndLocation);
CGGradientRelease(gradient);
this was taken from here (line 189)
I have the following UIView custom class:
#implementation BackgroundView
- (void)drawRect:(CGRect)rect
{
CGContextRef currentContext = UIGraphicsGetCurrentContext();
CGGradientRef glossGradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
float r = (255.0)/(255.0);
float g = (165.0)/(255.0);
float b = (0.0)/(255.0);
float rr = (238.0)/(255.0);
float gg = (118.0)/(255.0);
float bb = (0.0)/(255.0);
CGFloat components[8] = { r, g, b, 1.0, // Start color
rr, gg, bb, 1.0 }; // End color
rgbColorspace = CGColorSpaceCreateDeviceRGB();
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, 0);
CGGradientRelease(glossGradient);
CGColorSpaceRelease(rgbColorspace);
}
#end
Basically, it's supposed to make an orange gradient. The values "r", "g", and "b" are for a light orange, and the values "rr", "gg", "bb" are for a dark orange. But it doesn't work. Only the top of the frame is orange, and the bottom of the frame is black. I can't seem to get rid of the black.
What values would I use for an orange nice gradient. Can someone please look for mistakes? I can't find any. Thanks so much!
That's because you specify that the end point for your gradient is in middle of the currentBounds - see this line:
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
To get rid of the black make sure the y coordinate is at the bottom of your view.
Alternatively, you could use this code to extend your gradient after the end point
CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, midCenter, kCGGradientDrawsAfterEndLocation);
EDIT:
I finally found a real simple solution to this problem, using the CAGradientLayer class, and the CALayer drawing functionalities.
Ole Begemann released a great UIView wrapper for CAGradientLayer class named OBGradientView.
This class allows you to easily create a gradient UIView in your application.
You then use the CALayer drawing functionalities to add the rounded corners and drop shadow values :
// Create the gradient view
OBGradientView *gradient = [[OBGradientView alloc] initWithFrame:someRect];
NSArray *colors = [NSArray arrayWithObjects:[UIColor redColor], [UIColor yellowColor], nil];
gradient.colors = colors;
// Set rounded corners and drop shadow
gradient.layer.cornerRadius = 5.0;
gradient.layer.shadowColor = [UIColor grayColor].CGColor;
gradient.layer.shadowOpacity = 1.0;
gradient.layer.shadowOffset = CGSizeMake(2.0, 2.0);
gradient.layer.shadowRadius = 3.0;
[self.view addSubview:gradient];
[gradient release];
Dont forget to add the QuartzCore framework to your project.
ORIGINAL QUESTION:
I have been working on a custom control that is a rounded rectangle button, filled with a linear gradient, and having a drop shadow.
I have filled the two first steps using this answer : link text
My problem is now to add a drop shadow under the resulting shape.
Actually, the context has been clipped to the rounded rect path, so when I use the CGContextSetShadow function, it doesn't draw it.
I tried to solve this problem by drawing the rounded rect twice, first with a plain color, so it draws the shadow, and then redraw it with the gradient fill.
It kinda worked, but I still can see a few pixels at the corners of the shape resulting from the first draw with a plain color, as you can see on this zoomed version :
http://img269.imageshack.us/img269/6489/capturedcran20100701192.png
It is almost good, but not perfect yet...
Here is my -drawRect: implementation :
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth, float ovalHeight)
{
float fw, fh;
if (ovalWidth == 0 || ovalHeight == 0) {
CGContextAddRect(context, rect);
return;
}
CGContextSaveGState(context);
CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
CGContextScaleCTM (context, ovalWidth, ovalHeight);
fw = CGRectGetWidth (rect) / ovalWidth;
fh = CGRectGetHeight (rect) / ovalHeight;
CGContextMoveToPoint(context, fw, fh/2);
CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);
CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);
CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);
CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1);
CGContextClosePath(context);
CGContextRestoreGState(context);
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGSize shadowOffset = CGSizeMake(10.0, 10.0);
CGFloat blur = 5.0;
rect.size.width -= shadowOffset.width + blur;
rect.size.height -= shadowOffset.height + blur;
CGContextSaveGState(context);
addRoundedRectToPath(context, rect, _radius, _radius);
CGContextSetShadow (context, shadowOffset, blur);
CGContextDrawPath(context, kCGPathFill);
CGContextRestoreGState(context);
addRoundedRectToPath(context, rect, _radius, _radius);
CGContextClip(context);
CGFloat colors[] =
{
_gradientStartColor.red, _gradientStartColor.green, _gradientStartColor.blue, _gradientStartColor.alpha,
_gradientEndColor.red, _gradientEndColor.green, _gradientEndColor.blue, _gradientEndColor.alpha
};
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(rgb, colors, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint gStartPoint = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint gEndPoint = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMaxY(currentBounds));
CGContextDrawLinearGradient(context, gradient, gStartPoint, gEndPoint, 0);
CGColorSpaceRelease(rgb);
CGGradientRelease(gradient);
}
Any ideas on how to do this in another way ?
Thanks !
In order to create a rounded corner view with a gradient background and drop shadow, here's what did:
The first part is very similar to what was provided in the question, it creates a rounded rect path using CGPathAddArcToPoint as described very well in this article. Here's a picture to help me understand it:
The second part works as follows:
Enable shadowing on the graphics context, add the path that was just defined, then fill that path. You can't apply the shadow to just the path itself (paths are not part of the graphics state), so you need to fill the path in order for the shadow to appear (I suppose a stroked path might also work?). You can't simply apply the shadow to a gradient since it's not really a standard fill (see this post for more info).
Once you have a filled rounded rect that creates the shadow, you need to draw the gradient over top of that. So add the path a second time in order to set the clipping area, then draw the gradient using CGContextDrawLinearGradient. I don't think you can easily "fill" a path with a gradient like you could with the earlier standard-fill step, so instead you fill the drawing area with the gradient and then clip to the rounded rectangle area that you're interested in.
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
CGGradientRef gradient = [self normalGradient];
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGMutablePathRef outlinePath = CGPathCreateMutable();
float offset = 5.0;
float w = [self bounds].size.width;
float h = [self bounds].size.height;
CGPathMoveToPoint(outlinePath, nil, offset*2.0, offset);
CGPathAddArcToPoint(outlinePath, nil, offset, offset, offset, offset*2, offset);
CGPathAddLineToPoint(outlinePath, nil, offset, h - offset*2.0);
CGPathAddArcToPoint(outlinePath, nil, offset, h - offset, offset *2.0, h-offset, offset);
CGPathAddLineToPoint(outlinePath, nil, w - offset *2.0, h - offset);
CGPathAddArcToPoint(outlinePath, nil, w - offset, h - offset, w - offset, h - offset * 2.0, offset);
CGPathAddLineToPoint(outlinePath, nil, w - offset, offset*2.0);
CGPathAddArcToPoint(outlinePath, nil, w - offset , offset, w - offset*2.0, offset, offset);
CGPathCloseSubpath(outlinePath);
CGContextSetShadow(ctx, CGSizeMake(4,4), 3);
CGContextAddPath(ctx, outlinePath);
CGContextFillPath(ctx);
CGContextAddPath(ctx, outlinePath);
CGContextClip(ctx);
CGPoint start = CGPointMake(rect.origin.x, rect.origin.y);
CGPoint end = CGPointMake(rect.origin.x, rect.size.height);
CGContextDrawLinearGradient(ctx, gradient, start, end, 0);
CGPathRelease(outlinePath);
}
- (CGGradientRef)normalGradient
{
NSMutableArray *normalGradientLocations = [NSMutableArray arrayWithObjects:
[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:1.0f],
nil];
NSMutableArray *colors = [NSMutableArray arrayWithCapacity:2];
UIColor *color = [UIColor colorWithRed:0.2745 green:0.2745 blue:0.2745 alpha:1.0];
[colors addObject:(id)[color CGColor]];
color = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:1.0];
[colors addObject:(id)[color CGColor]];
NSMutableArray *normalGradientColors = colors;
int locCount = [normalGradientLocations count];
CGFloat locations[locCount];
for (int i = 0; i < [normalGradientLocations count]; i++)
{
NSNumber *location = [normalGradientLocations objectAtIndex:i];
locations[i] = [location floatValue];
}
CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
CGGradientRef normalGradient = CGGradientCreateWithColors(space, (CFArrayRef)normalGradientColors, locations);
CGColorSpaceRelease(space);
return normalGradient;
}
I have solution that does not need pre-fill of the path. Advantage(?) is that the shadow can use transparency effects of the gradient (i.e. if gradient is from opaque to trasparent, shadow will be partially transparent as well) and is simpler.
It goes more or less like:
CGContextSetShadowWithColor();
CGContextBeginTransparencyLayer();
CGContextSaveGState();
CGContextClip();
CGGradientCreateWithColorComponents();
CGContextRestoreGState();
CGContextEndTransparencyLayer();
CGContextSetShadowWithColor(..., NULL);
I suppose that is beacuse CGContextBeginTransparencyLayer/CGContextEndTransparencyLayer is outside the clip and the shadow is applied to that layer (which contains gradient filled path). At least it seems to work for me.
For shadows you can use CGContextSetShadow()
This code will draw something with a shadow:
- (void)drawTheRealThingInContext:(CGContextRef)ctx
{
// calculate x, y, w, h and inset here...
CGContextMoveToPoint(ctx, x+inset, y);
CGContextAddLineToPoint(ctx, x+w-inset, y);
CGContextAddArcToPoint(ctx, x+w, y, x+w, y+inset, inset);
CGContextAddLineToPoint(ctx, x+w, y+w-inset);
CGContextAddArcToPoint(ctx,x+w, y+w, x+w-inset, y+w, inset);
CGContextAddLineToPoint(ctx, x+inset, y+w);
CGContextAddArcToPoint(ctx,x, y+w, x, y+w-inset, inset);
CGContextAddLineToPoint(ctx, x, y+inset);
CGContextAddArcToPoint(ctx,x, y, x+inset, y, inset);
}
- (void)drawRect:(CGRect)rect {
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGFloat color[4];color[0] = 1.0;color[1] = 1.0;color[2] = 1.0;color[3] = 1.0;
CGFloat scolor[4];scolor[0] = 0.4;scolor[1] = 0.4;scolor[2] = 0.4;scolor[3] = 0.8;
CGContextSetFillColor(ctx, color);
CGContextSaveGState(ctx);
CGSize myShadowOffset = CGSizeMake (3, -3);
CGContextSetShadow (ctx, myShadowOffset, 1);
CGContextBeginPath(ctx);
[self drawTheRealThingInContext:ctx];
CGContextFillPath(ctx);
CGContextRestoreGState(ctx);
}
Your (original) problem was that you were again drawing a shadow when you drew the gradient. This shadow had a (0,0) offset and a little bit of blur, that only shines through on the corners. In the line before CGContextDrawLinearGradient(…), add the following:
CGContextSetShadowWithColor(context, CGSizeMake(0, 0), 0, NULL);
The NULL color value disables shadowing and will remove the corner effect.