I want to draw a triangle and elide text in the shape. I can restrict the triangle to an equilateral triangle and a fixed orientation ('upside down' or 'upside up'). Then I want to insert arbitrary text in the triangle such that the eliding is on word boundaries and not clipped.
Any simple algorithms? What methods are available in Objective-C?
I am thinking of calculating lines of rectangles of 'font height' and width bounded by the top-side as it intersects the triangle's sides. Then draw-text of the remaining text into each rectangle until done.
Wait for the 3.2 SDK...
Related
I am desperately trying to dynamically find the optimal size to draw a UILabel within a pie chart (see my outline below).
The label center should be in the middle of each piece of the pie, which is determined by the CGPoint at 1/2 radius and 1/2 pie piece (= startAngle+(endAngle-startAngle)/2).
Now the problem is, that neither the width nor the height of the UILabel are known. The width mostly depends on the label's center position (e.g. if the pie piece is the upper half circle, the width is widest). The label lines are "unlimited" (label.numberOfLines = 0) and label.text is user defined ("description" of the pie value). Only the fontSize range between minimum (6.0f) and maximum (14.0f) is defined.
I already thought of using a UITextView with the pie piece's UIBezierPath as exclusionPath, but then centering and resizing the UIFontSize won't work - at least I didn't find a way to do it.
Any hint on how to resolve this issue is much appreciated :)
I'm tying to draw two different shadows on some text to create an embossed effect. Here's the portion of my drawInRect where I draw the text with the first shadow (all the variables used are already defined):
CGContextSetShadowWithColor(context, textInnerShadowOffset, textInnerShadowBlurRadius, textInnerShadowColor.CGColor);
[textColor setFill];
[self.text drawInRect:rect withFont:self.font lineBreakMode:self.lineBreakMode alignment:self.textAlignment];
But now I'm faced with the problem of drawing the second shadow. I assume I'll need to change the shadow and draw the text again, but I need to do so without adding another copy of the text.
How can I draw text without really drawing the text itself? Changing the fill color to clearColor doesn't work. I've seen people use clipping masks for this, but AFAICT that will only work for simple shapes, not text.
Alternatively, is there an easier way to draw two shadows on the same text?
Two options, depending on the exact effect you want:
If you want the first, "upper" shadow to also contribute to the second, "lower" shadow underneath it, use a transparency layer.
Set your CGContext's shadow for the "lower" shadow
Create a transparency layer using CGContextBeginTransparencyLayer
Set the context's shadow for the "upper" shadow
Draw your text
End the transparency layer using CGContextEndTransparencyLayer
(Note that transparency layers can be quite expensive. It's best to call CGContextBeginTransparencyLayerWithRect and pass in as small a rect as you can.)
If you want the shadows to be independent -- the only thing that contributes to each shadow is the text -- you'll need to use a trick.
Set up the shadow with an additional large offset, big enough so that you can draw the text outside of the bounds of your context and have the shadow land in the correct place. That way you'll see only the shadow, but not the text.
Figure out what offset is "big enough". It will probably depend on the size of the context you're drawing into (based on your view), and maybe the bounds of the text.
Or, just fudge it: pick an absurdly large value like 5000 pt.
Set up your shadow. Add the big offset to its normal y offset.
Draw the text, offset vertically by the big offset.
Repeat 1-3 for each "lower" shadow, from back to front. Afterwards, draw the text and the "uppermost" shadow last, without the offset.
I have a view with custom drawRect method which has two text lines drawn in fixed width.
This view is being redrawn constantly at rate of about 16 timer per second with position of text and content of text changing all the time.
I also need my text to be drawn in such a way that it is clearly visible at any background, and for that purpose I do the following:
CGContextSetTextDrawingMode(ctx, kCGTextStroke); // Border mode
[string drawAtPoint:point withFont:font];
CGContextSetTextDrawingMode(ctx, kCGTextFill); // Text mode
[string drawAtPoint:point withFont:font];
This code draws the text in border mode with fixed line width, and then draws the text again at same position but in fill mode. In this way I get a blue text with white border around each letter.
The result is absolutely satisfactory for me except the performance.
Using Time Profiler I've noticed that about 70% of time spent for drawing the whole view is spent on execution of drawing the text in border (stroke) mode. But drawing in fill mode takes only 3% of the whole view drawing time. I think that this is not efficient considering the frequency of redrawing of the view.
So does anybody know how to draw the text with border around each letter in more efficient way?
Two options:
Use a shadow instead of drawing the outline: CGContextSetShadowWithColor
Cache the image of the string and it's outline using a CGLayer: CGLayerCreateWithContext
Explanation for 2:
Drawing text is highly optimized for the standard case where the letters are just filled with one color. Individual glyphs (letters) are not rendered from the outline each time. Instead the glyphs are drawn only once into buffered images which are cached and reused.
Since drawing outlines is seldom there's probably no caching of glyphs or other optimizations for this mode. So the idea is to do the caching yourself: Draw the whole string into one image, keep that image around and draw it instead of the text from within your drawRect: method.
There are several options how to do that:
Use a CGBitmapContext
Use UIGraphicsBeginImageContext
Use a CGLayer
I'm looking to implement something like the famous "letterpress" effect in my application. Here's what I'm talking about: (just a quick example made in PShop)
As you can see, it looks like it's pressed into the background. I wonder if it's possible to do something like this on the Mac dynamically. Is there a way? Thanks!
You can do the gradient fill portion of the text using the code I provide in this answer. Check the coordinate space first, because I described that for the iPhone, which has an inverted Y axis when compared to the Mac's normal Quartz coordinates.
The text is first used to create a clipping path, and the gradient is drawn within that path.
As far as the internal shadow, you might be able to draw this after the gradient is drawn by using CGContextSetShadowWithColor() with an appropriate downward offset and black color, then drawing the text again using just the stroke of the text. deanWombourne has some sample code for a similar task in his answer here.
Draw the text with a normal font to create a black and white bitmap of the text.
Draw another image that is is the same size and completely filled with the gray-to-white gradient you have above.
Create a completely white image with the same size as your other images.
Draw your back and white text image (1) onto the white image (3) with NSCompositeDestinationOut.
This gives you a white image with your text cut out.
Draw the white image with the text cut out on top of the gradient image and apply a shadow while drawing.
What's the difference between Stroke and Fill drawing in graphics context (iPhone SDK)
Stroke is line drawing, Fill is "colouring in" (for want of a better term).
So in the case of a shape (like a circle), the stroke is the border (circumference) and the fill is the body (interior).
Stroke only draws stuff on the border of the path.
Fill only draws stuff in the interior of the path.