The following method should create a FILLED triangle image but it only creates an outline.
Why does it not FILL? Going bonkers with this one. I hope it gets answered so that the next poor soul struggling with this can clear the hurdle and save an hour of their life.
Here is the method I wrote:
+ (UIImage *)triangleWithSize:(CGSize)imageSize
{
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetShouldAntialias(context, YES);
// set parameters
CGContextSetLineWidth(context, 1);
CGContextSetStrokeColorWithColor(context, [UIColor yellowColor].CGColor);
CGContextSetFillColorWithColor(context, [UIColor yellowColor].CGColor);
// draw triangle
CGContextBeginPath(context);
CGContextMoveToPoint(context, imageSize.width, 0);
CGContextAddLineToPoint(context, imageSize.width, imageSize.height);
CGContextMoveToPoint(context, imageSize.width, imageSize.height);
CGContextAddLineToPoint(context, 0, imageSize.height / 2);
CGContextMoveToPoint(context, 0, imageSize.height / 2);
CGContextAddLineToPoint(context, imageSize.width, 0);
// CGContextFillPath(context);
// CGContextClosePath(context);
// stroke and fill?
CGContextDrawPath(context, kCGPathFillStroke);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIGraphicsPopContext();
return image;
}
Any help is appreciated.
I found the answer from the following post:
CGContext line drawing: CGContextFillPath not working?
One of the last answers provides an example using CGMutablePathRef. For a triangle, I used the following code:
CGMutablePathRef pathRef = CGPathCreateMutable();
CGPathMoveToPoint(pathRef, NULL, imageSize.width, 0);
CGPathAddLineToPoint(pathRef, NULL, imageSize.width, imageSize.height);
CGPathAddLineToPoint(pathRef, NULL, 0, imageSize.height / 2);
CGPathAddLineToPoint(pathRef, NULL, imageSize.width, 0);
CGPathCloseSubpath(pathRef);
CGContextAddPath(context, pathRef);
CGContextFillPath(context);
CGContextAddPath(context, pathRef);
CGContextStrokePath(context);
CGPathRelease(pathRef);
I don't know why the original method I used above does not work however. I will figure that out next.
Related
I need to change the background color of the currently tabbed page in my UITabBarController. I've searched through every stackoverflow post I could find but nothing worked for me. I thought there would be something like UITabBar.Appearance.SelectedImageTintColor, just for the background color but it doesn't seem so.
For example, I want to change the color of that part when I am on the right tab:
Does someone know how to do that?
You could invoked the following code in your UITabBarController
public xxxTabBarController()
{
//...set ViewControllers
this.TabBar.BarTintColor = UIColor.Red;
}
Update
//3.0 here is if you have three child page in tab , set it as the current value in your project
//
var size = new CGSize(TabBar.Frame.Width / 3.0, IsFullScreen());
this.TabBar.SelectionIndicatorImage = ImageWithColor(size,UIColor.Green);
double IsFullScreen()
{
double height = 64;
if (UIDevice.CurrentDevice.CheckSystemVersion(11, 0))
{
if (UIApplication.SharedApplication.Delegate.GetWindow().SafeAreaInsets.Bottom > 0.0)
{
height = 84;
}
}
return height;
}
UIImage ImageWithColor(CGSize size, UIColor color)
{
var rect = new CGRect(0, 0, size.Width, size.Height);
UIGraphics.BeginImageContextWithOptions(size, false, 0);
CGContext context = UIGraphics.GetCurrentContext();
context.SetFillColor(color.CGColor);
context.FillRect(rect);
UIImage image = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return image;
}
The trick is to use the SelectionIndicatorImage Property of the UITabBar and generate a completely filled image with your desired color using the following method:
private UIImage ImageWithColor(CGSize size)
{
CGRect rect = new CGRect(0, 0, size.Width, size.Height);
UIGraphics.BeginImageContext(size);
using (CGContext context = UIGraphics.GetCurrentContext())
{
context.SetFillColor(UIColor.Green); //change color if necessary
context.FillRect(rect);
}
UIImage image = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return image;
}
To initialize everything we override ViewWillLayoutSubviews() like this:
public override void ViewWillLayoutSubviews()
{
base.ViewWillLayoutSubviews();
// The tabbar height will always be 49 unless we force it to reevaluate it's size on runtime ...
myTabBar.InvalidateIntrinsicContentSize();
double height = myTabBar.Frame.Height;
CGSize size = new CGSize(new nfloat(myTabBar.Frame.Width / myTabBar.Items.Length, height));
// Now get our all-green image...
UIImage image = ImageWithColor(size);
// And set it as the selection indicator
myTabBar.SelectionIndicatorImage = image;
}
As mentioned in this article (google translating it step by step when necessary lol) calling InvalidateIntrinsicContentSize() will force the UITabBar to reevaluate it's size and will get you the actual runtime height of the tab bar (instead of the constant 49 height value from XCode).
I'm trying to make a distortion shader for water in my game. I have the screen's rendertarget, and the water mask rendertarget, and I'm try to simply capture the pixels underneath the mask, but I can't get it to work. When I pass the textures, it's as if they're both completely transparent. What could I be doing wrong?
Shader:
texture Screen;
texture Mask;
float2 Offset;
sampler ScreenSampler = sampler_state
{
Texture = <Screen>;
};
sampler MaskSampler = sampler_state
{
Texture = <Mask>;
};
float4 PixelShaderFunction(float2 texCoord: TEXCOORD0) : COLOR
{
float4 mask = tex2D(MaskSampler, texCoord);
float4 color = tex2D(ScreenSampler, texCoord + Offset);
if (mask.a > 0)
{
return color;
}
return mask;
}
technique Technique0
{
pass Pass0
{
PixelShader = compile ps_4_0 PixelShaderFunction();
}
}
Render target:
Doldrums.Game.Graphics.GraphicsDevice.SetRenderTarget(renderTargetDistortion);
Doldrums.Game.Graphics.GraphicsDevice.Clear(Color.Transparent);
waterEffect.Parameters["Screen"].SetValue(Doldrums.RenderTarget);
waterEffect.Parameters["Mask"].SetValue(renderTargetWater);
waterEffect.Parameters["Offset"].SetValue(Doldrums.Camera.ToScreen(renderTargetPosition));
sprites.Begin(SpriteSortMode.Deferred, null, null, null, null, waterEffect);
sprites.Draw(renderTargetWater, Vector2.Zero, Color.White);
sprites.End();
Finally, rendering the rendertarget:
sprites.Draw(renderTargetDistortion, renderTargetPosition, Color.White);
I had the exact same "issue"using monogame during my development. The problem here is easily fixed, change this:
sprites.Begin(**SpriteSortMode.Deferred**, null, null, null, null, waterEffect);
sprites.Draw(renderTargetWater, Vector2.Zero, Color.White);
sprites.End();
To another mode like this:
sprites.Begin(**SpriteSortMode.Immediate**, null, null, null, null, waterEffect);
sprites.Draw(renderTargetWater, Vector2.Zero, Color.White);
sprites.End();
Have fun :)
I'm creating many colour variations of an image using Core Graphics. I need to create about 320 in total but gradually, the memory usage of the app keeps increasing until it crashes. From Instruments, I see that more CGImage objects are being created and stay alive. I want to release them because I store the images to the cache directory in PNG format.
I have searched through all other solutions I could find without success. Any help is appreciated. Thanks.
Here's the main part:
+(UIImage *)tintedImageFromImage:(UIImage *)sourceImage colour:(UIColor *)color intensity:(float)intensity {
if (UIGraphicsBeginImageContextWithOptions != NULL) {
UIGraphicsBeginImageContextWithOptions(sourceImage.size, NO, 0.0);
} else {
UIGraphicsBeginImageContext(sourceImage.size);
}
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect rect = CGRectMake(0, 0, sourceImage.size.width, sourceImage.size.height);
// draw alpha-mask
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextDrawImage(context, rect, sourceImage.CGImage);
// draw tint color, preserving alpha values of original image
CGContextSetBlendMode(context, kCGBlendModeSourceIn);
[color setFill];
CGContextFillRect(context, rect);
//Set the original greyscale template as the overlay of the new image
sourceImage = [self verticallyFlipImage:sourceImage];
[sourceImage drawInRect:CGRectMake(0,0, sourceImage.size.width,sourceImage.size.height) blendMode:kCGBlendModeMultiply alpha:intensity];
UIImage *colouredImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
colouredImage = [self verticallyFlipImage:colouredImage];
return colouredImage;
}
this is used to flip the image:
+(UIImage *)verticallyFlipImage:(UIImage *)originalImage {
UIImageView *tempImageView = [[UIImageView alloc] initWithImage:originalImage];
UIGraphicsBeginImageContext(tempImageView.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, tempImageView.frame.size.height);
CGContextConcatCTM(context, flipVertical);
[tempImageView.layer renderInContext:context];
UIImage *flippedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return flippedImage;
}
Add to verticallyFlipImage the line tempImageView.image = nil; in order to make the image view release the image. This solves the problem.
I am trying to built an animated circle which would be drawn clockwise until it becomes complete circle as illustrated in iPhone Core Animation - Drawing a Circle
Problem is that CALayer object is not added or build. I tested and saw that it is not accessing my drawInContext:CGContextRef and animatingArc methods.
What so far I have done is:
In AnimateArc.h
#interface AnimateArc : CALayer {
CAShapeLayer *circle;
}
-(void) animatingArc;
#end
In AnimateArc.m
-(void) drawInContext:(CGContextRef)ctx
{
CGFloat radius = 50.0;
circle = [CAShapeLayer layer];
//make a circular shape
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0.0, 0.0, 2 * radius, 2 * radius) cornerRadius:radius].CGPath;
CGPoint centerPoint = CGPointMake(CGRectGetWidth(self.bounds)/2, CGRectGetHeight(self.bounds)/2);
//center the shape in self.view
circle.position = centerPoint;
//configure appearence of circle
circle.fillColor = [UIColor clearColor].CGColor;
circle.strokeColor = [UIColor blackColor].CGColor;
circle.lineWidth = 5;
/*CGPointMake((self.contentsCenter.size.width), (self.contentsCenter.size.height));*/
//path the circle
CGContextAddArc(ctx, centerPoint.x, centerPoint.y, radius, 0.0, 2 * M_PI, 0);
CGContextClosePath(ctx);
//fill it
CGContextSetFillColorWithColor(ctx, [UIColor redColor].CGColor);
CGContextFillPath(ctx); }
///////////////////////////////////////////////////////////////////////
-(void) animatingArc
{
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"arcEnd"];
anim.duration = 20.0; //animate over 20 seconds
anim.repeatCount = 1.0; //animate only once
anim.removedOnCompletion = NO; //Reamin there after completion
//animate from start to end
anim.fromValue = [NSNumber numberWithFloat:50.0f];
anim.toValue = [NSNumber numberWithFloat:150.0f];
//experiment with timing to get appearence to look the way you want
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
//add animation to circle
[circle addAnimation:anim forKey:#"animatingArc"];
}
/////////////////////
//needed since key not part of animatable properties
+(BOOL) needsDisplayForKey:(NSString *)key
{
if([key isEqualToString:#"arcEnd"])
return YES;
else
return [super needsDisplayForKey:key];
}
//ensure custom properties copied to presentation layer
-(id) initWithLayer:(id)layer
{
if((self = [super initWithLayer:layer]))
{
if ([layer isKindOfClass:[AnimateArc class]])
{
AnimateArc *other = (AnimateArc *) layer;
[other setNeedsDisplay];
}
}
return self; }
And finally in my viewController,
- (void)viewDidLoad
{
[super viewDidLoad];
[self.view.layer addSublayer:AnimateArcObject];
[AnimateArcObject animatingArc];
}
Apology for bad formatting.... Please can someone tell me what am I doing wrong? I have also doubt that my code can crash at any place after accessing those two functions since I am novice about Core Animation and haven't got any idea that I am in right direction or not.
Any help will be appreciated. Thanks.
From my painful experience with CoreAnimation, you must always set the bounds property of any CALayer you instantiate.
So, you're layer is not showing because you are missing something like:
layer.bounds = CGRectMake(0, 0, width, height);
you should place this as soon as you instantiate the layer, and make it a habit to do so, so you don't fall into it again.
As for your code crashing, sorry. It's too distributed and I am not sure how it's linked together, so I can't help you there.
After little searching, I thought that I am going in wrong direction. So I deleted this AnimateArc file and added new one which is inheriting from UIViewController.
Then in viewDidLoad Method, I wrote the code from this link to create circle and animations using path.
In parent view controller, I added AnimatedArc ViewController's subview. Now its working perfectly :)
My OnPaint() function calls several other drawing functions.
void CGraph::OnPaint ()
{
CPaintDC dc(this);
// CMemDC DC(&dc);
dc.SetViewportOrg (0, 400);
dc.SetMapMode(MM_ISOTROPIC);
dc.SetWindowExt(1000, 800);
dc.SetViewportExt(1000, -800);
ProcessData ();
DrawCoordinateSystem (&dc);
DrawGrid (&dc);
DrawGraph (&dc);
}
Example of DrawCoordianteSystem:
void CGraph::DrawCoordinateSystem (CDC* pDC)
{
CPen PenBlack (PS_SOLID, 1, RGB(0, 0, 0));
pDC->SelectObject (PenBlack);
// Rectangle round the system
pDC->Rectangle (0, -400, 1000, 400);
// Horizontal axis
pDC->MoveTo (0, 0);
pDC->LineTo (1000, 0);
pDC->SetTextColor (RGB(0,0,0));
pDC->SetBkColor (RGB(240, 240, 240));
pDC->TextOut (1001, 0, L"0");
// Vertical axis
pDC->MoveTo (0, -400);
pDC->LineTo (0, 400);
}
I now want to avoid flickering with CMemDC. However, i can't get it to work right. Can somebody show me how to implement CMemDC right?
Thanks
You need to load the memory DC with a bitmap to then BitBlt to the screen DC.
Try something like:
CDC dcMem;
CBitmap bitmap;
dcMem.CreateCompatibleDC( pDC );
bitmap.CreateCompatibleBitmap(pDC, rect.Width(), rect.Height())
CBitmap* pOldBitmap = dcMem.SelectObject(&bitmap);
... DO ALL YOUR DRAWING TO dcMem ...
pDC->BitBlt(rect.left, rect.top, rect.Width(), rect.Height(), &dcMem, 0, 0, SRCCOPY);
dcMem.SelectObject(pOldBitmap)
To avoid flickers you should draw everything on CMemDC and BitBlt it to the real DC.
Secondly add windows message handler for WM_ERASEBKGND message and change the code to
BOOL CGraph::OnEraseBkgnd(CDC* pDC)
{
return TRUE;
}