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.
Related
I am writing some text to a quartz context.
I have a box of 500 x 200 pixels and I am writing some text inside. The box can have any aspect ratio but the text will always write with the font proportions as it is. What I want is to scale the font vertically and keep the horizontal scale.
See the picture. The first box represents what I am getting, the second one, what I want.
this is how I am writing it...
CGRect rect = CGRectMake(0,0,500,200);
[myText drawInRect:rect
withFont:aFont
lineBreakMode:UILineBreakModeTailTruncation
alignment:UITextAlignmentCenter];
is there a way to scale the font vertically?
NOTE: as this is being written in a PDF context, I don't want to
render the text to a image context and scale it vertically, because I
don't want to lose resolution.
thanks
- (void) scaleTextVerticallyWithContext:(CGContextRef)myContext withRect:(CGRect)contextRect
{
CGFloat w, h;
w = contextRect.size.width;
h = contextRect.size.height;
CGAffineTransform myTextTransform;
CGContextSelectFont (myContext, "Helvetica-Bold", h/10, kCGEncodingMacRoman);
CGContextSetCharacterSpacing (myContext, 10);
CGContextSetTextDrawingMode (myContext, kCGTextFillStroke);
CGContextSetRGBFillColor (myContext, 0, 1, 0, .5);
CGContextSetRGBStrokeColor (myContext, 0, 0, 1, 1);
/*
* CGAffineTransformMakeScale ( CGFloat sx, CGFloat sy );
* sx: The factor by which to scale the x-axis of the coordinate system.
* sy: The factor by which to scale the y-axis of the coordinate system.
*/
myTextTransform = CGAffineTransformMakeScale(1,8);
CGContextSetTextMatrix (myContext, myTextTransform);
CGContextShowTextAtPoint (myContext, 40, 0, "Hello There", 9);
}
- (void)drawRect:(CGRect)rect{
// Drawing code
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect viewBounds = self.bounds;
CGContextTranslateCTM(context, 0, viewBounds.size.height);
CGContextScaleCTM(context, 1, -1);
[self scaleTextVerticallyWithContext:context withRect:viewBounds];
}
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);
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));
I am writing a simple practice. However, my text is flip upside down when I trying to use CGContext to put some string on the UIView, I am wondering why and how to change it into correct format.
Here is my code in the drawRect
char *string = "TEST";
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextBeginPath(context);
CGContextSelectFont (context,"Helvetica-Bold",12, kCGEncodingMacRoman);
CGContextShowTextAtPoint(context, 5, 5, string, strlen(string));
CGContextClosePath(context);
Thanx for your help.
CoreGraphics uses cartesian coordinates, so you need to translate your context before doing any drawing
CGContextRef context = UIGraphicsGetCurrentContext();
// transforming context
CGContextTranslateCTM(context, 0.0, rect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// your drawing code
Quartz2D has an inverted y axis - handy eh? If you are inside a drawRect method, you can use the following to flip the text over.
CGContextTranslateCTM(context, 0.0, rect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
Another way is;
transform = CGAffineTransformMake(1.0,0.0,0.0,-1.0,0.0,0.0);
CGContextSetTextMatrix(context, transform);
Or on one line;
CGContextSetTextMatrix(context, CGAffineTransformMake(1.0,0.0, 0.0, -1.0, 0.0, 0.0));
Use the UIKit additions in NSString:
NSString *string = #"TEST";
[string drawAtPoint:CGPointMake(5, 5)
withFont:[UIFont boldSystemFontOfSize:12]];
I try to draw a string in this texture:
http://picasaweb.google.it/lh/photo/LkYWBv_S_9v2d6BAfbrhag?feat=directlink
but the green numbers seem vertical flipped.
I've created my context in this way:
colorSpace = CGColorSpaceCreateDeviceRGB();
data = malloc(height * width * 4);
context = CGBitmapContextCreate(data, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
and i've draw the strings:
UIGraphicsPushContext(context);
for(int i=0;i<packs.size();++i)
{
CGPoint points[4] =
{
gltextures[i].texCoords[0] * size.width, //0
gltextures[i].texCoords[1] * size.height, //1
gltextures[i].texCoords[2] * size.width, //2
gltextures[i].texCoords[3] * size.height, //3
gltextures[i].texCoords[4] * size.width, //4
gltextures[i].texCoords[5] * size.height, //5
gltextures[i].texCoords[6] * size.width, //6
gltextures[i].texCoords[7] * size.height //7
};
CGRect debugRect = CGRectMake
(
gltextures[i].texCoords[0] * size.width,
gltextures[i].texCoords[1] * size.height,
gltextures[i].width,
gltextures[i].height
);
CGContextSetStrokeColorWithColor(context, [[UIColor redColor] CGColor]);
CGContextAddLines(context, points, 4);
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathStroke);
NSString* s = [NSString stringWithFormat:#"%d",gltextures[i].texID];
UIFont* font = [UIFont fontWithName:#"Arial" size:12];
CGContextSetRGBFillColor(context, 0, 1, 0, 1);
[s drawAtPoint:points[0] withFont:font];
}
UIGraphicsPopContext();
The transformation matrix seems the Identity matrix... no CGAffineTransform is applied to THIS context.
If the string is flipped, maybe, all my images are flipped!
Any suggestion?
PS: sorry for my english ;)
As describe here, the coordinate system for a context within a UIView or its layer is inverted when compared to the normal Quartz drawing space. However, when using Quartz to draw to an image, this is no longer the case. The UIStringDrawing Cocoa Touch category on NSString that gives you the -drawAtPoint:withFont: method assumes an inverted layout, and that's why you're seeing the flipped text in your image.
One way to work around this would be to save the graphics state, apply an invert transform to the image, draw the text, and restore the old graphics state. This would look something like the following:
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0f, self.bounds.size.height);
CGContextScaleCTM(context, 1.0f, -1.0f);
[text drawAtPoint:CGPointMake(0.0f, 0.0f) withFont:font];
CGContextRestoreGState(context);
This is a fairly crude example, in that I believe it just draws the text at the bottom of the image, but you should be able to adjust the translation or the coordinate of the text to place it where it's needed.
Better save the text 's matrix before draw, otherwise it will affect other text draw by CoreGraphic:
CGContextSaveGState(ctx);
CGAffineTransform save = CGContextGetTextMatrix(ctx);
CGContextTranslateCTM(ctx, 0.0f, self.bounds.size.height);
CGContextScaleCTM(ctx, 1.0f, -1.0f);
[str drawAtPoint:point withFont:font];
CGContextSetTextMatrix(ctx, save);
CGContextRestoreGState(ctx);