I'm trying to simulate the user location animation in MapKit (where-by the user's position is represented by a pulsating blue dot). I've created a custom subclass of MKAnnotationView and in the drawRect method I'm attempting to cycle through a set of colors. Here's a simpler implementation of what I'm doing:
- (void)drawRect:(CGRect)rect {
float magSquared = event.magnitude * event.magnitude;
CGContextRef context = UIGraphicsGetCurrentContext();
if (idx == -1) {
r[0] = 1.0; r[1] = 0.5; r[2] = 0;
b[0] = 0; b[1] = 1.0; b[2] = 0.5;
g[0] = 0.5; g[1] = 0; g[2] = 1.0;
idx = 0;
}
// CGContextSetRGBFillColor(context, 1.0, 1.0 - magSquared * 0.015, 0.211, .6);
CGContextSetRGBFillColor(context, r[idx], g[idx], b[idx], 0.75);
CGContextFillEllipseInRect(context, rect);
idx++;
if (idx > 3) idx = 0;
}
Unfortunately this just causes the annotations to be one of the 3 different colors and doesn't cycle through them. Is there a way to force the MKAnnotations to continually redraw so that it appears to be animated?
You are free to call setNeedsDisplay on your annotation view whenever you want it to redraw. The easiest way to do this would be for the annotation view itself to set up a timer that fired every 1/60th of a second or so.
A more sophisticated approach would be to put your drawing code into a custom CALayer and apply a repeating Core Animation animation to it. See my answer to "Animating a custom property of CALayer subclass" for an approach.
Related
I have a problem when i try to join lines. Here is a picture:
and I like that it looks like this:
and my code is:
- (void) drawRect:(CGRect)rect {
[super drawRect:rect];
CGContextRef context = UIGraphicsGetCurrentContext();
const CGFloat *components = CGColorGetComponents(self.lineColor.CGColor);
CGFloat red;
CGFloat green;
CGFloat blue;
CGFloat alpha;
if(CGColorGetNumberOfComponents(self.lineColor.CGColor) == 2)
{
red = 1;
green = 1;
blue = 1;
alpha = 1;
}
else
{
red = components[0];
green = components[1];
blue = components[2];
alpha = components[3];
if (alpha <= 0) alpha = 1;
}
// set the stroke color and width
CGContextSetRGBStrokeColor(context, red, green, blue, alpha);
CGContextSetLineWidth(context, 2.0);
if (self.points.count >0) {
BezierPoint *firstPoint = [self.points objectAtIndex:0];
CGContextMoveToPoint(context, firstPoint.center.x, firstPoint.center.y);
int index = 0;
for (BezierPoint *point in self.points ) {
if(index == 0){
index++;
continue;
}
CGContextAddLineToPoint(context, point.center.x, point.center.y);
}
CGContextAddLineToPoint(context, firstPoint.center.x, firstPoint.center.y);
}
CGContextSetRGBFillColor(context, 0.0, 0.0, 0.0, 0.0);
CGContextDrawPath(context, kCGPathFillStroke);
}
the problem I have is that for every point you add, the lines overlap and I would like that as I stay I add points for geometric figure that globulins do not overlap
If anyone can help me I will thank!!
I would move the logic that determines the order the lines are drawn to your view controller, and access the data needed to draw the view with from a delegate using a protocol. Views should not own their data. For example, in your .h try something like;
#import <UIKit/UIKit.h>
#protocol CowDrawViewDataSource
-(NSArray *) pointsToDraw;
#end
#interface CowDrawView : UIView
#property (nonatomic , weak) id <CowDrawViewDataSource> dataSource;
#end
Then, (and I hope this does answer you question) in the view controller, you set as your views delegate, construct the
-(NSArray *) pointsToDraw;
method, in such a way, to send your array of points in an order in from which they can be drawn. Say by finding the point the top/left point, then the top/right, then bottom/right, bottom/left. (although such an approach might not work so well with irregular polygons, and shapes that are contiguous, but not polygons.)
After you figure out how to get the array in the order you want, you can get it in your drawRect by sending a message to it's delegate such as
NSArray *points = [self.dataSource pointToDraw];
with little re-work in the drawRect it's self.
The easy way to correct your problem is first draw only single line segments between two points and see the results. Then you can form loops. I guess you are not assigning perfect coordinates points or your loop must consist of :
CGContextAddLineToPoint(context, point.center.x, point.center.y);
And then,
CGContextMoveToPoint(context, point.center.x, point.center.y);
This shows that first draw line and move to next point.
Hope this helps.
I am drawing cells from a grid with a NSTimer every 0.1 Seconds.
The size is about 96x64 => 6144 cells / images.
If i am drawing images instead of (e.g.) green rectangles it is 4 times slower !
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);
CGContextSetRGBFillColor(context, 0, 0, 0, 1);
CGContextFillRect(context, CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height));
int cellSize = self.bounds.size.width / WIDTH;
double xOffset = 0;
for (int i = 0; i < WIDTH;i++)
{
for (int j = 0; j < HEIGHT;j++)
{
NSNumber *currentCell = [self.state.board objectAtIndex:(i*HEIGHT)+j];
if (currentCell.intValue == 1)
{
[image1 drawAtPoint:CGPointMake(xOffset + (cellSize * i),cellSize * j )];
}
else if (currentCell.intValue == 0){
[image2 drawAtPoint:CGPointMake(xOffset + (cellSize * i),cellSize * j )];
}
}
}
UIGraphicsPopContext();
}
Any idea how to makes this faster if i want to draw png or jpg in each rectangle?
The images are already scaled to an appropriate size.
a) Don't redraw the images/rects that are outside the view's bounds.
b) Don't redraw the images/rects that are outside the dirtyRect
c) Don't redraw the images/rects that haven't changes since the
previous update.
d) Use a layer to prerender the images, so you don't need to render
them at drawing time.
This scenario is exactly what Instruments is there for. Use it. Anyone here making a suggestion is guessing about what the bottleneck is.
That said, I'm going to guess at what the bottleneck is. You are drawing 6114 images using the CPU (confirm this by using the time profiler. Find your drawRect method, and check where the most time is spent. If it's drawInRect, then that's your problem)
If that's the case, how do we reduce its usage? An easy win would be to only redraw the images we need to draw. CALayers make this easy. Remove your drawRect method, add a sublayer to your view's layer for each image, and set the images as your layers' content properties. Instead of invalidating the view when an image needs to change, just switch the relevant layer's content property to the new image.
Another nice thing about CALayers is that they cache layer content on the GPU, meaning that the redraws that do happen will require less CPU time and won't block the rest of you app as much when they do happen.
If the overhead of that many layers is unacceptable (again, Instruments is your friend), check out CAReplicatorLayer. It's less flexible than having many CALayers, but allows a single image to be replicated many times with minimal overhead.
I tried to improve your code from performance perspective. However, check my comment about bottlenecks, too.
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
//UIGraphicsPushContext(context); //not needed UIView does it anyway
//use [UIView backgroundColor] instead of this
//CGContextSetRGBFillColor(context, 0, 0, 0, 1);
//CGContextFillRect(context, CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height));
int cellSize = self.bounds.size.width / WIDTH;
double xOffset = 0;
CGRect cellFrame = CGRectMake(0, 0, cellSize, cellSize);
NSUinteger cellIndex = 0;
for (int i = 0; i < WIDTH; i++) {
cellFrame.origin.x = xOffset;
for (int j = 0; j < HEIGHT; j++, cellIndex++) {
cellFrame.origin.y = 0;
if (CGRectIntersectsRect(rect, cellFrame) {
NSNumber *currentCell = [self.state.board objectAtIndex:cellIndex];
if (currentCell.intValue == 1) {
[image1 drawInRect:cellFrame];
}
else if (currentCell.intValue == 0) {
[image2 drawInRect:cellFrame];
}
}
cellFrame.origin.y += cellSize;
}
cellFrame.origin.x += cellSize;
}
//UIGraphicsPopContext(context); //not needed UIView does it anyway
}
Use CGRectIntersects to check if the rect of your image is inside the dirtyRect to check if you need to draw it.
Can you let me know what is the best way to draw a line or rectangle on a scene layer using Cocos2d ios4 iphone.
So far have tried Texture2d, but it is more like a paint brush and is not so good. Tried drawing a line using draw method, but previous line disappears on drawing another line.
Basically want to draw multiple horizontal ,vertical, oblique beams. Please suggest. Any code would help a lot .
The code to draw using texture is below:
CGPoint start = edge.start;
CGPoint end = edge.end;
// begin drawing to the render texture
[target begin];
// for extra points, we'll draw this smoothly from the last position and vary the sprite's
// scale/rotation/offset
float distance = ccpDistance(start, end);
if (distance > 1)
{
int d = (int)distance;
for (int i = 0; i < d; i++)
{
float difx = end.x - start.x;
float dify = end.y - start.y;
float delta = (float)i / distance;
[brush setPosition:ccp(start.x + (difx * delta), start.y + (dify * delta))];
[brush setScale:0.3];
// Call visit to draw the brush, don't call draw..
[brush visit];
}
}
// finish drawing and return context back to the screen
[target end];
The rendering is not good esp. with oblique lines as the scaling affects the quality.
Cheers
You could create a separate layer and call the draw method like this:
-(void) draw
{
CGSize s = [[Director sharedDirector] winSize];
drawCircle( ccp(s.width/2, s.height/2), circleSize, 0, 50, NO);
It's for a circle but the principle is the same. This is from a project I made a while back and it worked then. Don't know if anything has changed since.
You need to add draw method to your layer:
-(void) draw {
// ...
}
Inside it you can use some openGL like functions and cocos2d wrapper methods for openGL.
Hint: other methods can be called inside draw method.
But keep in mind that using other name for method
containing openGL instructions, that's not called inside draw mentioned above simply won't work.
Even when called from update method or other method used by scheduleUpdate selector.
So you will end up with something like this:
-(void) draw {
glEnable(GL_LINE_SMOOTH);
glColor4ub(255, 0, 100, 255);
glLineWidth(4);
CGPoint verts[] = { ccp(0,200), ccp(300,200) };
ccDrawLine(verts[0], verts[1]);
[self drawSomething];
[self drawSomeOtherStuffFrom:ccp(a,b) to:ccp(c,d)];
[someObject doSomeDrawingAsWell];
}
For more information check out cocos2d-iphone programming guide :
http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide:draw_update?s[]=schedule#draw
I am struggling to get my custom drawing code to render at the proper scale for all iOS devices, i.e., older iPhones, those with retina displays and the iPad.
I have a subclass of UIView that has a custom class that displays a vector graphic. It has a scale property that I can set. I do the scaling in initWithCoder when the UIView loads and I first instantiate the vector graphic. This UIView is shown when the user taps a button on the home screen.
At first I tried this:
screenScaleFactor = 1.0;
if ([UIScreen instancesRespondToSelector:#selector(scale)]) {
screenScaleFactor = [[UIScreen mainScreen] scale];
}
// and then I multiply stuff by screenScale
... which worked for going between normal iPhones and retina iPhones, but chokes on the iPad. As I said, you can get to the UIView at issue by tapping a button on the home screen. When run on the iPad, if you display the UIView when at 1X, it works, but at 2X I get a vector graphic that twice as big as it should be.
So I tried this instead:
UPDATE: This block is the one that's right. (with the corrected spelling, of course!)
screenScaleFactor = 1.0;
if ([self respondsToSelector:#selector(contentScaleFactor)]) { //EDIT: corrected misspellng.
screenScaleFactor = (float)self.contentScaleFactor;
}
// again multiplying stuff by screenScale
Which works at both 1X and 2X on the iPad and on the older iPhones, but on a retina display, the vector graphic is half the size it should be.
In the first case, I query the UIScreen for its scale property and in the second case, I'm asking the parent view of the vector graphic for its contentsScaleFactor. Neither of these seem to get me where I want for all cases.
Any suggestions?
UPDATE:
Here's the method in my subclassed UIView (it's called a GaugeView):
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGAffineTransform t0 = CGContextGetCTM(context);
t0 = CGAffineTransformInvert(t0);
CGContextConcatCTM(context, t0);
[needle updateBox];
[needle draw: context];
}
needle is of class VectorSprite which is a subclass of Sprite which is subclassed from NSObject. These are from a programming book I'm working through. needle has the scale property that I set.
updateBox comes from Sprite and looks like this:
- (void) updateBox {
CGFloat w = width*scale;
CGFloat h = height*scale;
CGFloat w2 = w*0.5;
CGFloat h2 = h*0.5;
CGPoint origin = box.origin;
CGSize bsize = box.size;
CGFloat left = -kScreenHeight*0.5;
CGFloat right = -left;
CGFloat top = kScreenWidth*0.5;
CGFloat bottom = -top;
offScreen = NO;
if (wrap) {
if ((x+w2) < left) x = right + w2;
else if ((x-w2) > right) x = left - w2;
else if ((y+h2) < bottom) y = top + h2;
else if ((y-h2) > top) y = bottom - h2;
}
else {
offScreen =
((x+w2) < left) ||
((x-w2) > right) ||
((y+h2) < bottom) ||
((y-h2) > top);
}
origin.x = x-w2*scale;
origin.y = y-h2*scale;
bsize.width = w;
bsize.height = h;
box.origin = origin;
box.size = bsize;
}
Sprite also has the draw and drawBody methods which are:
- (void) draw: (CGContextRef) context {
CGContextSaveGState(context);
// Position the sprite
CGAffineTransform t = CGAffineTransformIdentity;
t = CGAffineTransformTranslate(t,x,y);
t = CGAffineTransformRotate(t,rotation);
t = CGAffineTransformScale(t,scale,scale);
CGContextConcatCTM(context, t);
// draw sprite body
[self drawBody: context];
CGContextRestoreGState(context);
}
- (void) drawBody: (CGContextRef) context {
// Draw your sprite here, centered
// on (x,y)
// As an example, we draw a filled white circle
if (alpha < 0.05) return;
CGContextBeginPath(context);
CGContextSetRGBFillColor(context, r,g,b,alpha);
CGContextAddEllipseInRect(context, CGRectMake(-width/2,-height/2,width,height));
CGContextClosePath(context);
CGContextDrawPath(context,kCGPathFill);
}
How, exactly, are you rendering the graphic?
This should be handled automatically in drawRect: (the context you get should be already 2x). This should also be handled automatically with UIGraphicsBeginImageContextWithOptions(size,NO,0); if available (if you need to fall back to UIGraphicsBeginImageContext(), assume a scale of 1). You shouldn't need to worry about it unless you're drawing the bitmap yourself somehow.
You could try something like self.contentScaleFactor = [[UIScreen mainScreen] scale], with appropriate checks first (this might mean if you display it in an iPad at 2x, you'll get high-res graphics).
Fundamentally, there's not much difference between an iPad in 2x mode and a "retina display", except that the iPad can switch between 1x and 2x.
Finally, there's a typo: #selector(contentsScaleFactor) has an extra s.
I want to draw an image that would effectively be a circular progress indicator on a UIButton. Because the image is supposed to represent progress of a task, I do not think I should handle the drawing code in the view's drawrect method.
I have a thread that is performing some tasks. After each task, it calls a method on the main thread. The called method is supposed to update the image on the button.
In the button update method, I create a CGContextRef by using CGBitmapContextCreate.
Then I use the button's frame to create a CGRect.
Then I attempt to draw into using the context I created.
Lastly I set NeedsDisplay and clean up.
But none of this is inside the view's drawrect method.
I would like to know if anyone has used CGContext to draw on / in a view on-demand in a view while the view is being displayed.
I would like to get some ideas regarding an approach to doing this.
Here is an encapsulated version of what I am doing now:
CGContextRef xContext = nil;
CGColorSpaceRef xColorSpace;
CGRect xRect;
void* xBitmapData;
int iBMPByteCount;
int iBMPBytesPerRow;
float fBMPWidth = 20.0f;
float fBMPHeight = 20.0f;
float fPI = 3.14159;
float fRadius = 25.0f;
iBMPBytesPerRow = (fBMPWidth * 4);
iBMPByteCount = (iBMPBytesPerRow * fBMPHeight);
xColorSpace = CGColorSpaceCreateDeviceRGB();
xBitmapData = malloc(iBMPByteCount);
xContext = CGBitmapContextCreate(xBitmapData, fBMPWidth, fBMPHeight, 8, iBMPBytesPerRow, xColorSpace, kCGImageAlphaPremultipliedFirst);
CGColorSpaceRelease(xColorSpace);
UIGraphicsPushContext(xContext);
xRect = CGRectMake(30.0f, 400.0f, 50.0f, 50.0f);
float fWidth = xRect.size.width;
float fHeight = xRect.size.height;
CGContextClearRect(xContext, xRect);
CGContextSetRGBStrokeColor(xContext, 0.5f, 0.6f, 0.7f, 1.0f);
CGContextSetLineWidth(xContext, 1.0f);
float fArcBegin = 45.0f * fPI / 180.0f;
float fArcEnd = 90.0f * fPI / 180.0f;
CGContextSetFillColor(xContext, CGColorGetComponents( [[UIColor greenColor] CGColor]));
CGContextMoveToPoint(xContext, fWidth, fHeight);
CGContextAddArc(xContext, fWidth, fHeight, fRadius, fArcBegin, fArcEnd, 0);
CGContextClosePath(xContext);
CGContextFillPath(xContext);
UIGraphicsPopContext;
CGContextRelease(xContext);
[self.view setNeedsDisplay];
// [self.view setNeedsDisplayInRect: xRect];
The above is a little bit wonky because I've tried different tweaks. However, I think it communicates what I am trying to do.
Alternative approach:
You could create a series of images that represent the progress updates and then replace the UIButton currentImage property with the setImage:forState: method at each step of the process. This doesn't require drawing in the existing view and this approach has worked well for me to show simple "animation" of images (buttons or other).
Would this approach work for you? If not, why not?
Bart
This was really bugging me so after dealing with a series of silly, but necessary issues regarding the project I want this functionality for, I played around with it.
The end result is that I can now arbitrarily draw an arc representing the progress of a particular background task to a button.
The goal was to draw something like the little indicator in the lower right hand corner of the XCode windows while a project is being cleaned or compiled.
I created a function that will draw and fill an arc and return it as a UIImage.
The worker thread calls method (PerformSelectorOnMainThread) with the current values and a button identifier. In the called method, I call the arc image function with the percentage filled and such.
example call:
oImg = [self ArcImageCreate:100.0f fWidth:100.0f
fPercentFilled: 0.45f fAngleStart: 0.0f xFillColor:[UIColor blueColor]];
Then set the background image of the button:
[oBtn setBackgroundImage: oImg forState: UIControlStateNormal];
Here is the function:
It is not finished, but it works well enough to illustrate how I am doing this.
/**
ArcImageCreate
#ingroup UngroupedFunctions
#brief Create a filled or unfilled solid arc and return it as a UIImage.
Allows for dynamic / arbitrary update of an object that allows a UIImage to be drawn on it. \
This can be used for some sort of pie chart or progress indicator by Image Flipping.
#param fHeight The height of the created UIImage.
#param fWidth The width of the created UIImage.
#param fPercentFilled A percentage of the circle to be filled by the arc. 0.0 to 1.0.
#param AngleStart The angle where the arc should start. 0 to 360. Clock Reference.
#param xFillColor The color of the filled area.
#return Pointer to a UIImage.
#todo [] Validate object creation at each step.
#todo [] Convert PercentFilled (0.0 to 1.0) to appropriate radian(?) (-3.15 to +3.15)
#todo [] Background Image Support. Allow for the arc to be drawn on top of an image \
and the whole thing returned.
#todo [] Background Image Reduction. Background images will have to be resized to fit the specfied size. \
Do not want to return a 65KB object because the background is 60K or whatever.
#todo [] UIColor RGBA Components. Determine a decent method of extracting RGVA values \
from a UIColor*. Check out arstechnica.com/apple/guides/2009/02/iphone-development-accessing-uicolor-components.ars \
for an idea.
*/
- (UIImage*) ArcImageCreate: (float)fHeight fWidth:(float)fWidth fPercentFilled:(float)fPercentFilled fAngleStart:(float)fAngleStart xFillColor:(UIColor*)xFillColor
{
UIImage* fnRez = nil;
float fArcBegin = 0.0f;
float fArcEnd = 0.0f;
float fArcPercent = 0.0f;
UIColor* xArcColor = nil;
float fArcImageWidth = 0.0f;
float fArcImageHeight = 0.0f;
CGRect xArcImageRect;
CGContextRef xContext = nil;
CGColorSpaceRef xColorSpace;
void* xBitmapData;
int iBMPByteCount;
int iBMPBytesPerRow;
float fPI = 3.14159;
float fRadius = 25.0f;
// #todo Force default of 100x100 px if out of bounds. \
// Check max image dimensions for iPhone. \
// If negative, flip values *if* values are 'reasonable'. \
// Determine minimum useable pixel dimensions. 10x10 px is too small. Or is it?
fArcImageWidth = fHeight;
fArcImageHeight = fWidth;
// Get the passed target percentage and clip it between 0.0 and 1.0
fArcPercent = (fPercentFilled 1.0f) ? 1.0f : fPercentFilled;
fArcPercent = (fArcPercent > 1.0f) ? 1.0f : fArcPercent;
// Get the passed start angle and clip it between 0.0 to 360.0
fArcBegin = (fAngleStart 359.0f) ? 0.0f : fAngleStart;
fArcBegin = (fArcBegin > 359.0f) ? 0.0f : fArcBegin;
fArcBegin = (fArcBegin * fPI) / 180.0f;
fArcEnd = ((360.0f * fArcPercent) * fPI) / 180.0f;
//
if (xFillColor == nil) {
// random color
} else {
xArcColor = xFillColor;
}
// Calculate memory required for image.
iBMPBytesPerRow = (fArcImageWidth * 4);
iBMPByteCount = (iBMPBytesPerRow * fArcImageHeight);
xBitmapData = malloc(iBMPByteCount);
// Create a color space. Behavior changes at OSXv10.4. Do not rely on it for consistency across devices.
xColorSpace = CGColorSpaceCreateDeviceRGB();
// Set the system to draw. Behavior changes at OSXv10.3.
// Both of these work. Not sure which is better.
// xContext = CGBitmapContextCreate(xBitmapData, fArcImageWidth, fArcImageHeight, 8, iBMPBytesPerRow, xColorSpace, kCGImageAlphaPremultipliedFirst);
xContext = CGBitmapContextCreate(NULL, fArcImageWidth, fArcImageHeight, 8, iBMPBytesPerRow, xColorSpace, kCGImageAlphaPremultipliedFirst);
// Let the system know the colorspace reference is no longer required.
CGColorSpaceRelease(xColorSpace);
// Set the created context as the current context.
// UIGraphicsPushContext(xContext);
// Define the image's box.
xArcImageRect = CGRectMake(0.0f, 0.0f, fArcImageWidth, fArcImageHeight);
// Clear the image's box.
// CGContextClearRect(xContext, xRect);
// Draw the ArcImage's background image.
// CGContextDrawImage(xContext, xArcImageRect, [oBackgroundImage CGImage]);
// Set Us Up The Transparent Drawing Area.
CGContextBeginTransparencyLayer(xContext, nil);
// Set the fill and stroke colors
// #todo [] Determine why SetFilColor does not. Use alternative method.
// CGContextSetFillColor(xContext, CGColorGetComponents([xArcColor CGColor]));
// CGContextSetFillColorWithColor(xContext, CGColorGetComponents([xArcColor CGColor]));
// Test Colors
CGContextSetRGBFillColor(xContext, 0.3f, 0.4f, 0.5f, 1.0f);
CGContextSetRGBStrokeColor(xContext, 0.5f, 0.6f, 0.7f, 1.0f);
CGContextSetLineWidth(xContext, 1.0f);
// Something like this to reverse drawing?
// CGContextTranslateCTM(xContext, TranslateXValue, TranslateYValue);
// CGContextScaleCTM(xContext, -1.0f, 1.0f); or CGContextScaleCTM(xContext, 1.0f, -1.0f);
// Test Vals
// fArcBegin = 45.0f * fPI / 180.0f; // 0.785397
// fArcEnd = 90.0f * fPI / 180.0f; // 1.570795
// Move to the start point and draw the arc.
CGContextMoveToPoint(xContext, fArcImageWidth/2.0f, fArcImageHeight/2.0f);
CGContextAddArc(xContext, fArcImageWidth/2.0f, fArcImageHeight/2.0f, fRadius, fArcBegin, fArcEnd, 0);
// Ask the OS to close the arc (current point to starting point).
CGContextClosePath(xContext);
// Fill 'er up. Implicit path closure.
CGContextFillPath(xContext);
// CGContextEOFillPath(context);
// Close Transparency drawing area.
CGContextEndTransparencyLayer(xContext);
// Create an ImageReference and create a UIImage from it.
CGImageRef xCGImageTemp = CGBitmapContextCreateImage(xContext);
CGContextRelease(xContext);
fnRez = [UIImage imageWithCGImage: xCGImageTemp];
CGImageRelease(xCGImageTemp);
// UIGraphicsPopContext;
return fnRez;
}