I'm trying to draw some text on the iPhone, but in landscape mode, where the home button is on the left. So I need to somehow twist the numbers (I'm guessing I use a transform) ?
Here's what I have now:
CGContextSetRGBFillColor(context, 1.0, 0, 0, 1.0);
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextSelectFont(context, "Helvetica", 20, kCGEncodingMacRoman);
CGContextSetTextMatrix(context, CGAffineTransformMakeRotation(M_PI/2));
CGContextSetTextDrawingMode(context, kCGTextFill);
NSString *t = [NSString stringWithFormat:#"%i",seconds];
const char *str=[t UTF8String];
CGContextShowTextAtPoint(context,6.0,15.0,str,strlen(str));
What do I need to add to rotate the text so that it can be read when the phone is landscape with the home button on the left.
You have to apply two transformation matrices. The first one will flip the text and the second one will rotate it. Try the following code:
CGContextSetRGBFillColor(context, 1.0, 0, 0, 1.0);
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextSelectFont(context, "Helvetica", 20, kCGEncodingMacRoman);
CGAffineTransform xform = CGAffineTransformMake(
1.0, 0.0,
0.0, -1.0,
0.0, 0.0);
CGContextSetTextMatrix(context, xform);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(M_PI_2));
CGContextSetTextDrawingMode(context, kCGTextFill);
NSString *t = [NSString stringWithFormat:#"%i",seconds];
const char *str=[t UTF8String];
CGContextShowTextAtPoint(context,6.0,15.0,str,strlen(str));
Related
I want to draw a filled rectangle in my viewContoller's view.
I wrote the code below in viewDidLoad. But there is no change.
What is wrong?
CGRect rectangle = CGRectMake(0, 100, 320, 100);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextFillRect(context, rectangle);
You can't do it in a viewController.
You need to extend your View and add the code under "drawRect:"
this will change the drawing logic of your view.
-(void) drawRect:(CGRect)rect{
[super drawRect:rect];
CGRect rectangle = CGRectMake(0, 100, 320, 100);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextFillRect(context, rectangle);
}
modern 2018 solution..
override func draw(_ rect: CGRect) {
let r = CGRect(x: 5, y: 5, width: 10, height: 10)
UIColor.yellow.set()
UIRectFill(r)
}
that's it.
Just for clarity:
If You need to draw a rectangle which has the same fill and border color, then You can replace:
CGContextSetRGBFillColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
with:
[[UIColor redColor] set];
You can't render directly in viewDidLoad; it's the views themselves that would have to run this in their drawRect method.
The easiest way to "draw" a rectangle is to place a UIView with a background color & border in your view. (You can set the border via the view's CALayer's methods. i.e. myView.layer.borderColor = [[UIColor redColor] CGColor];)
I am trying to draw a line with a shadow but I do not want to keep the line but only the shadow.
I have attempted to set the stroke color of the line to clear but when I do that the shadow also disappears.
The following code creates 2 lines, i only want to keep the shadow because it looks nicer and its not pixelated like the line.
Is this possible?
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0);
CGContextSetShouldAntialias(UIGraphicsGetCurrentContext(), YES);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat components[4] = {0.0, 0.0, 0.0, 1.0};
CGColorRef shadowColor = CGColorCreate(colorSpace, components);
CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(10,10), 4.0, shadowColor);
Thanks.
So you can't do this directly because the shadow reflects the path, so if you make the path transparent, the shadow will also be transparent. There are a few workarounds I can think of (depends on exactly what you're doing) but one sneaky way would just be to draw the shadow far enough below the path that you can just draw over it, basically erasing it. For example, if the background is white, this will accomplish what you want:
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0);
CGContextSetLineWidth(context, 10.0);
CGContextMoveToPoint(context, 10.0, 30.0);
CGContextAddLineToPoint(context, 310.0, 30.0);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat components[4] = {0.0, 0.0, 0.0, 1.0};
CGColorRef shadowColor = CGColorCreate(colorSpace, components);
CGContextSetShadowWithColor(context, CGSizeMake(0.0f,20.0f), 4.0, shadowColor);
CGContextStrokePath(context);
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 10.0);
CGContextMoveToPoint(context, 10.0, 30.0);
CGContextAddLineToPoint(context, 310.0, 30.0);
CGContextStrokePath(context);
}
hope this helps.
why dont you just draw your line as a shadow. Dont have the shadow drawn but instead draw a black line with .25 or less alpha and offset it to where you would expect the shadow to be.
As you can see in the code below I do some transformations on my UIView before writing some text. It seems though that the position of the text is affected by the aforementioned transformations.
Is there any way to 'pop' these displacements so I can then write my text in relation to the original 0,0 coordinate?
//turn PDF upsidedown
CGAffineTransform transform = CGAffineTransformIdentity;
transform = CGAffineTransformMakeTranslation(100, aUIView.bounds.size.height+300);
transform = CGAffineTransformScale(transform, 0.5, -0.5);
CGContextConcatCTM(pdfContext, transform);
// Draw view into PDF
// Is renderInContext deprecated? Something to look into.
[aUIView.layer renderInContext:pdfContext];
CGContextSelectFont (pdfContext, "Helvetica", 14, kCGEncodingMacRoman);
CGContextSetTextDrawingMode (pdfContext, kCGTextFill);
CGContextSetRGBFillColor (pdfContext, 0, 0, 0, 1);
CGContextSetTextMatrix(pdfContext, CGAffineTransformMake(1.0,0.0, 0.0, -1.0, 0.0, 0.0));
const char *text = "THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG TEST 1";
CGContextShowTextAtPoint (pdfContext, 10.0, 10.0, text, strlen(text));
I think CGContextSaveGState(cntx) and CGContextRestoreGState(cntx) are what you are looking for.
When I draw some text using CGContext, it is drawn mirrored.
I tried to apply some transformations, then it is draw well, but then the rest of the drawing and all coordinates seems to be draw bad.
I tried to save and restore the context, before and ater drawing the text (and aplying transformation), but that does not help.
How some text must be drawn onto a View using CGContext without affecting the rest of the drawing, nor the onscreen CGPoint coords for that text ?
Can you clarify what you mean as 'mirrored'? Here is some code for drawing some black text. It should not be 'mirrored'.
CGRect viewBounds = self.bounds;
CGContextTranslateCTM(ctx, 0, viewBounds.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextSetRGBFillColor(ctx, 0.0, 1.0, 0.0, 1.0);
CGContextSetLineWidth(ctx, 2.0);
CGContextSelectFont(ctx, "Helvetica", 10.0, kCGEncodingMacRoman);
CGContextSetCharacterSpacing(ctx, 1.7);
CGContextSetTextDrawingMode(ctx, kCGTextFill);
CGContextShowTextAtPoint(ctx, 100.0, 100.0, "SOME TEXT", 9);
I think you have to reverse the text matrix :
CGAffineTransform transform = CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, 0.0);
CGContextSetTextMatrix(context, transform);
My code is
-(UIImage *)addText:(UIImage *)img text:(NSString *)text1
{
int w = img.size.width;
int h = img.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1);
char* text = (char *)[text1 cStringUsingEncoding:NSASCIIStringEncoding];
CGContextSelectFont(context, "Arial", 18, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);
CGContextSetRGBFillColor(context, 255, 255, 255, 2);
CGContextShowTextAtPoint(context, 10, 170, text, strlen(text));
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:imageMasked];
}
How can we change the color of the text programmatically?
Answers will be greatly appreciated!
My guess is just change the last instance of CGContextSetRGBFillColor to the RGB value you'd like. Right now it's white. Change the 255, 255, 255 part to the corresponding RGB value you'd like (0.0 - 1.0 range per color channel). ie. Red would be 1.0, 0.0, 0.0; Blue 0.0, 0.0, 1.0, Yellow 1.0, 1.0, 0; Black 0.0, 0.0, 0.0; etc.... Good luck
Edit: range is 0.0-1.0 not 0-255
CGContextSetRGBFillColor(context, 255, 255, 255, 2);
How can we change the color of the text programmatically?
That's one way, although you're doing it wrong. See the documentation; all four of those values are out of range, with three of them being way out of range.