In Photoshop, my designer used the "Range" setting to get the outer glow to "fill out" a little more. Here is a snapshot of the settings he used:
With the range in Photoshop set to 100%, here is the look:
That looks like my rendering on the iPhone using this code (assume the gradient fill and stroke around the circle are both working fine, we're only focusing on the glow):
CGContextAddPath(context, spectralImagePath);
CGContextSaveGState(context);
CGContextSetShadowWithColor(context, CGSizeMake(0.0, 0.0), 21.0, [[UIColor colorWithRed:65.0/255.0 green:79.0/255.0 blue:246.0/255.0 alpha:1.0] CGColor]);
CGContextSetBlendMode(context, kCGBlendModeScreen);
CGContextFillPath(context);
CGContextRestoreGState(context);
But, it needs to look like this (with range set to 50% in photoshop):
Notice how the shadow is a little more dense around the edges of the circle. Any ideas if Core Graphics contains a range-like property?
I don’t know of one. As an alternative, you might try just drawing the same shadowed path multiple times via repeated calls to CGContextFillPath.
Related
I have a sort of progress bar which is actually a visual representation of the read content of a book. This bar is a horizontal line which is filled up at areas the book was read at. As an example, if it's a 100 paged book, and the user has read only page 1 to 10 and 90 to 100, the progress bar will show the 10% area at the extreme left and 10% area at the extreme right filled with color.
I am currently using this code to draw rect for one reading session:
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect innerRect = CGRectInset(rect, 5, 5);
CGRect ProgressIndicator = CGRectMake(innerRect.origin.x, innerRect.origin.y, 20, innerRect.size.height);
CGContextSetStrokeColorWithColor(context, [[UIColor blueColor] CGColor]);
CGContextSetLineWidth(context, 5);
CGContextMoveToPoint(context, CGRectGetMinX(ProgressIndicator), CGRectGetMinY(ProgressIndicator));
CGContextAddLineToPoint(context, CGRectGetMaxX(ProgressIndicator), CGRectGetMinY(ProgressIndicator));
CGContextAddLineToPoint(context, CGRectGetMaxX(ProgressIndicator), CGRectGetMaxY(ProgressIndicator));
CGContextAddLineToPoint(context, CGRectGetMinX(ProgressIndicator), CGRectGetMaxY(ProgressIndicator));
CGContextClosePath(context);
CGContextStrokePath(context);
CGContextSetFillColorWithColor(context, [[UIColor blueColor]CGColor]);
CGContextFillRect(context, ProgressIndicator);
Now, this is just for one reading session and draws only one rect as the rectangular "read" portion on the bar. How do I manage the drawing if I have multiple rects (say in an array) to draw on the bar. I am afraid that I'll lose the current drawing once I draw another rect.
How do I use "for" loop to draw those multiple rects?
I know this might be a very dumb question but I tried finding a way around it but didn't succeed.
I'm going to suggest thinking about this a different way; keeping track of an arbitrary number of 'reading sessions' could be a very inefficient representation.
In situations like this rather than concatenating every time data from a 'reading session' I would suggest that a sparse representation might make your drawing easier - just keep track of which pages have been read, period, in an array or dictionary or a custom object.
Then, your drawing code could simply loop over the storage and draw a section in one color for 'read' and not draw, or draw another color, etc, for 'unread'.
Most of the apps today provides the tutorial that teaches the user to how to use the buttons in the app. This help page is normally in black color with a little alpha value (so only the background will semi-visible) with a bubble box that contains the text to define controls and the arrow which points to the corresponding component.
Here is the sample image.. (From the app MyThings)
This is the normal page
And if you swipe from bottom to top, the help view will appear like..
Here is my doubts:
Which one is best to create the images & text in this help view? Drawing the images & texts using Core Graphics or by simply putting an UIImageView with a png image? Which one is efficient?
There is no problem in implementing a UIImageView with a ready-made png image. From my knowledge, the problem here is the image file size and the loading time. If we consider the drawing method, my mind things about the following problems.
Drawing a rectangle is so easy. (Refer here). But what about drawing a rectangle with a curved corners?? Is there any function available that handle this case?
Then the arrow, that points the corresponding component.. How can we find the exact point that should be pointed? (till iPhone 4S, there is no problem I hope, iPhone 5 has different height)
How to draw this pointers from the particular position in the rectangle?
Any ideas?
Just confused!!
Drawing the bubbles & arrows with CG is better, IMHO. It will work even if you change completely the app (if you draw them correctly pointing to the center of the button, for instance). With images, you'll need to have several copies for the different displays resolutions and scales. Also, you'll need to update the arrows if you change anything.
I don't see any performance drawback. Both methods will draw the bubbles very fast. Also, think that you can cache the CG generated images for future use.
See these questions to know how to draw bubbles:
How to draw a “speech bubble” on an iPhone?
How to make a Thought Bubble using core graphic in iPhone
It seems logical to use the center of the button each bubble point to. Your drawing methods needs to know where to point the arrow and the current orientation (if the app rotates). It should take into account other bubbles, to avoid overlap. You can divide the space in rows and columns and assign free space to each bubble.
For better user experience, those bubbles should not consume taps. If you tap a button when the bubbles are visible, the intended action should be performed (instead of just hiding the bubbles and require a second tap).
in your case i would refer resizable and reusable images.I also have many overlay screens in my app and i ended up wit generating 5 6 generic items arrows, label background and rectangular background image for the uilabel.
i know drawing rectangular is easy but it might be just overload sometimes.
if you want to change the direction of those arrows you can apply layer transformation to a UIImageview as following
arrowIamgeView.transform = CGAffineTransformMakeRotation(-M_PI / 20);
and for rounded corners of rectangles i assume you could user textfields with a certain background color and set their layers' cornerradius property.
Finally I did it!!
From my one-day experience, I come to know that there is three ways to handle this situation.
Simply creating needed images as png files and just use UIImageView to show. (But remember, you should have a same image with different resolutions. This will increase your app size).
Second way of doing is, Showing the bubbles (or maybe a rectangle) by creating labels, text fields, etc.. with a arrow image. You may simply transform the image to change the pointing place of the arrow. (As, Ilker Baltaci said in the previous answer).
Third way is, by Core Graphics. You can draw whatever you want here. As of my knowledge, increasing the app's size or increasing the memory consume by initializing/allocating/retaining labels & text fields, we can try this by Core Graphics.
I've three views where I want to implement this help screen facility. For just three screen, I can use any of the three method, because, there is no much difference related to performance if we use it for little-needed situaions. But I tried with the third way, because, I really don't knew anything about Core Graphics. So its just for learning..
Problems that I faced:
The arrow should point the center of the button(or maybe top of the button). So finding this exact location is complex. I have used this feature only in 3 pages in my app. Each page contains maximum of 4 icons to describe. So I just hard coded the values (My another luck is, the app does not support landscape mode). But, if you want to use this feature for so many pages, you should define some arrays and a method that finds the center of icons by calculating its center with reference to, their origin, height & width, blah, blah..
The another problem is, you should ensure that the bubbles are not overlapping anywhere. Here also, we need a global method that finds the location for each bubble. The size of the bubble depends on, the text size that is going to be placed inside it. This is more complex problem and for just 3 screens, I'm not going to define a global method with hundreds of calculations. So I again just hard coded the origin point, height & width of each bubble with reference to the self.view
Last but not least.. The Arrow!! The height of arrow may vary with the bubble's place. The width of the bubble also may vary with height. Also, you should know the side & points of the bubble from which the arrow goes to the button. If you already fixed the places of the bubbles in your mind, these are not at all a problem for you.. :P
Now let's come the coding part,
- (void) createRect:(CGRect)rect xPoint:(float)x yPoint:(float)y ofHeight:(float)height ofWidth:(float)width toPointX:(float)toX toPointY:(float)toY withString:(NSString *)helpString inDirection:(NSString *)direction
{
float distance = 5.0;
float widthOfLine = 5.0;
float arrowLength = 15.0;
//Get current context
CGContextRef context = UIGraphicsGetCurrentContext();
//Set width of border & colors of bubble
CGContextSetLineWidth(context, widthOfLine);
CGContextSetStrokeColorWithColor(context, [[UIColor darkGrayColor] CGColor]);
CGContextSetFillColorWithColor(context, [[UIColor colorWithRed:0 green:0 blue:0 alpha:0.9] CGColor]);
CGContextBeginPath(context);
CGContextMoveToPoint(context, x, y);
CGContextAddLineToPoint(context, x+width, y);
CGContextAddQuadCurveToPoint(context, x+width, y, x+width+distance, y+distance);
CGContextAddLineToPoint(context, x+width+distance, y+distance+height);
CGContextAddQuadCurveToPoint(context, x+width+distance, y+distance+height, x+width, y+distance+height+distance);
CGContextAddLineToPoint(context, x, y+distance+height+distance);
CGContextAddQuadCurveToPoint(context, x, y+distance+height+distance, x-distance, y+distance+height);
CGContextAddLineToPoint(context, x-distance, y+distance);
CGContextAddQuadCurveToPoint(context, x-distance, y+distance, x, y);
CGContextDrawPath(context, kCGPathFillStroke);
//Draw curvely arrow from bubble to button (but without arrow mark)
CGContextBeginPath(context);
CGContextSetLineWidth(context, 5.0);
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGPoint startPoint = CGPointMake(x+(width/2.0), y+distance+distance+height);
CGPoint endPoint = CGPointMake(toX, toY);
CGContextMoveToPoint(context, startPoint.x, startPoint.y+5.0);
if ([direction isEqualToString:#"left"])
{
CGContextAddCurveToPoint(context, startPoint.x, startPoint.y+5.0, endPoint.x, endPoint.y, toX-10, toY);
}
else
{
CGContextAddCurveToPoint(context, startPoint.x, startPoint.y+5.0, endPoint.x, endPoint.y, toX+10, toY);
}
CGContextStrokePath(context);
//Draw the arrow mark
CGContextBeginPath(context);
CGContextSetLineWidth(context, 5.0);
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
if ([direction isEqualToString:#"left"])
{
CGContextMoveToPoint(context, toX-10.0, toY-arrowLength);
CGContextAddLineToPoint(context, toX-10.0, toY);
CGContextAddLineToPoint(context, toX-10.0+arrowLength, toY);
}
else
{
CGContextMoveToPoint(context, toX+10.0, toY-arrowLength);
CGContextAddLineToPoint(context, toX+10.0, toY);
CGContextAddLineToPoint(context, toX+10.0-arrowLength, toY);
}
CGContextStrokePath(context);
.......
.......
}
You can call this method from the drawRect: method like this..
[self createRect:rect xPoint:30.0 yPoint:250.0 ofHeight:100.0 ofWidth:100.0 toPointX:48.0 toPointY:430.0 withString:#"xxxxxxx" inDirection:#"left"];
[self createRect:rect xPoint:160.0 yPoint:100.0 ofHeight:100.0 ofWidth:100.0 toPointX:260.0 toPointY:420.0 withString:#"yyyyyyy" inDirection:#"right"];
And the final image will be like this..
I skipped triangle shape arrow, because this arrow type gives a handwriting effect.
Thanks to #djromero and Ilker Baltaci for your valuable answers.
My next confusion is about Drawing Texts!!!!! :P
Here's a sample view I have right now:
Ideally, I'd like to take a "chunk" out of the top, so any views underneath are now visible through that removed area (e.g. transparency).
I've tried creating a path, and then using CGContextClip to attempt a clip, but it doesn't seem to be clipping the shape like intended. Any ideas of how to do this, or even if it's possible at all?
Typically to do something like this, one would make a UIView with a transparent background color, and then draw the "background" manually through CoreGraphics. For instance, to make a view that is essentially a circle with a black background, you could do something like this in the drawRect method:
- (void)drawRect:(CGRect)dirtyRect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 0, 0, 0, 1);
CGContextFillElipseInRect(context, self.bounds);
}
For something more complicated than a simple circle, you should use CGContextBeginPath() in conjunction with the CGContextMoveToPoint() and CGContextAddLineToPoint() functions. This will allow you to make a transparent view with any opaque shape that you want for a background.
EDIT: To clip a background image to a certain path, you could do something like this:
CGContextSaveGState(context);
CGImageRef image = [[UIImage imageNamed:#"backgroundImage.png"] CGImage];
CGContextBeginPath(context);
// add your shape to the path
CGContextClipToPath(context);
CGContextDrawImage(context, self.bounds, image);
CGContextRestoreGState(context);
Obviously for repeating patterns you could use more than one call to CGContextDrawImage, but this is basically what needs to be done. Like I said above, you could use basic line drawing functions to add lines, rectangles, circles, and anything else to your path.
Use a [UIColor clearColor] in you V to make it transparent, you will probably have to set the view opaque to NO as well.
I have created a complex UIBezierPath that is composed of several path segments, solid, dashed, lines, colors, arcs, etc. So I have this and now I want to render it to a CGContext.
So, I convert it to a CGPathReference using
CGPathRef cgPath = CGPathCreateCopy(aBezierPath.CGPath);
The problem is this: in theory, if I want to draw a path on a CGContext, I have to define the stroke width, color, line style, blending mode, etc. for each segment that needs to be different, but the UIBezierPath I have already created contains all this information.
So, I wonder if there is a way to just to "stamp" the CGPath as it is on the CGContext, so it will be stamped with all the original information?
thanks.
DR, you're right: it is very confusing!
But I think Tom is correct, just use [aBezierPath stroke].
So, it would be something like this:
REF is a (CGContextRef) which you have built.
YOURBEZIERPATH is a (UIBezierPath*).
Inevitably you have to deal with the "drawing upside down" issue, so:
UIGraphicsPushContext(REF);
CGContextSaveGState(REF);
CGContextTranslateCTM(REF, 0, the height*);
CGContextScaleCTM(REF, 1.0, -1.0);
[YOURBEZIERPATH stroke];
CGContextRestoreGState(REF);
UIGraphicsPopContext();
So that's it.
Re your comment below: I have an array of UIBezierPaths. Each bezier has its own style and color.
Does this help? ... Replace the one "stroke" call, with a for loop:
UIGraphicsPushContext(REF);
CGContextSaveGState(REF);
CGContextTranslateCTM(REF, 0, the height*);
CGContextScaleCTM(REF, 1.0, -1.0);
for each of YOURBEZIERPATH in your array...
{
CGContextSaveGState(REF);
[YOURBEZIERPATH stroke];
CGContextRestoreGState(REF);
}
CGContextRestoreGState(REF);
UIGraphicsPopContext();
You actually do not need to bother using aBezierPath.CGPath, or, a copy thereof.
Again you are right, it is very confusing, the two worlds of UI and CG !!
*the height: often something like self.frame.size.height. I just include this for anyone looking for general example code in the future.
I have a UIView and within it I've drawn a line using Core Graphics by overriding drawRect. This view also contains one subview which also draws a line. However, whilst both views are using pretty much the same code (for testing purposes at least), the lines drawn on them do not appear the same:
As you can see - the dashed line at the top is noticeably thicker than the bottom one and I have no idea why. Below is the code used by the two UIViews in their drawRect methods. If you have any idea why this is happening then I'd appreciate your help and advice!
First View:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGFloat dashes[] = {1,1};
CGContextSetLineDash(context, 0.0, dashes, 2);
CGContextSetLineWidth(context, 0.6);
CGContextMoveToPoint(context, CGRectGetMinX(rect), CGRectGetMaxY(rect));
CGContextAddLineToPoint(context, CGRectGetMaxX(rect), CGRectGetMaxY(rect));
CGContextStrokePath(context);
SubUIView *view = [[SubUIView alloc] initWithFrame:rect];
[self addSubview:view];
[view release];
The view is definitely only being drawn once. I appreciate drawRect may not be the best place for adding a subview but the problem remains even with it added in the main initWithFrame method.
Second View:
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGFloat dashes[] = {1,1};
CGContextSetLineDash(context, 0.0, dashes, 2);
CGContextSetLineWidth(context, 0.6);
CGContextMoveToPoint(context, CGRectGetMinX(rect), CGRectGetMidY(rect));
CGContextAddLineToPoint(context, CGRectGetMaxX(rect), CGRectGetMidY(rect));
CGContextStrokePath(context);
It could be a result of anti-aliasing if your rect does not fall on integers. You can disable anti-aliasing with CGContextSetShouldAntialias( context, NO ). I think there's also a function for making a rect integral, but I can't remember what it is.
First, you should fix the problem of the drawing code being WET*. You say you're doing this “for testing purposes”, but this actually makes testing harder, since you have to change both pieces of code and/or keep straight which version you're working on. The worst case is when you change both pieces of code in different ways and have to merge them by hand.
I'd say move the dashed-line code to the subview, add properties for anything the two pieces of code need to do differently, and create two subviews (and not in drawRect:—seriously).
As for the actual problem: Well, I don't see a big image, I see a tiny image, and I can only guess that the greater boldness of the upper line than that of the lower line means that the upper line is thicker.
By the way, the rect is not necessarily the bounds of your image. Don't ever assume that it is, or you will get funky drawing when it isn't. Assume that it some section of the bounds—possibly, but possibly not, the whole thing. When you mean [self bounds], say [self bounds].
The problem is most likely the difference between CGRectGetMidY([self bounds]) and CGRectGetMaxY([self bounds]). One includes a fraction that splits a pixel, whereas the other is a multiple of one pixel or close to it. (Not necessarily a multiple of 1—on a Retina Display, 1 pt = 2 pixels, so 1 pixel = 0.5 pt.) Try flooring both numbers and optionally adding 0.5, and see which way you like better.
There's no way to make it work out perfectly with a 0.6-pt line width. There is simply no whole number of pixels that works out to. All you can do is work out what looks best and do that.
*Written Elsewhere Too, the opposite of DRY.