Does anyone know an easy way to draw arbitrary text in a Cocoa NSOpenGLView? I have a couple of constraints.
The text on screen may change from frame to frame (for example, a framerate display in the corner)
I would like to be able to select any font installed on the system at any size
Have you taken a look at the Cocoa OpenGL sample code? It includes "a texture class for strings, showing how to use an NSImage to write a string into and then texture from for high quality font rendering."
Related
I have an app, its a small game using opengles with GLKit.
No im wondering how it works when i want to draw text on
my screen (if it is possible).
How can i do it?
i draw all of my game objects using images (wrapped in some kind
of sprite). its possible to scale, to move, and to rotate.
everything works fine.
but finding out how it works to print text on that glkview
gets me deep inside of problems ^^
I dont want to use uiimages cause i also dont know how
to present uiimages on a glkview.
There are a number of ways to do what you want:
1) Have an image with all the text glyphs you need in it. For example, if your application is in English, you'd have the 26 uppercase and 26 lowercase letters in the image. Upload that texture to the GPU and use the proper texture coordinates or glSubTexImage2d() to pull out the glyphs you need. (It's not clear to me if this is what you meant by not wanting a UIImage. It doesn't have to be a UIImage, though that's probably easiest.)
2) Every time you need to display text, draw it on the CPU on the fly, and upload the entire word, phrase, or sentence as a texture. You could create a CGBitmapContext and use Core Graphics to draw text to it. Then upload it using glTexImage2D().
3) Get the individual glyphs out of the fonts and draw directly using the bezier curves that make up the glyphs. This allows for 3D extrusion, too. However, this option is the most time consuming to code and probably least performant. It also involves dealing with the many small problems that fonts have (like degenerate segments, and incorrect winding orders). IF you want to go down this path, I think maybe Core Text can help.
There are at least two clean ways to do this, depending on your requirements.
While documentation advises against compositing over a CAEAGLLayer (GLKView), it works quite well, at least in recent iOS versions, when transparent content is layered on top of the CAEAGLLayer. For example, try dropping a UITextView, with opaque set to false and a clear background color, on top of a GLKView in your Storyboard in Interface Builder in the Apple GLKit template or your app. In my test on an iPhone 5, frame rendering time remained around 1ms, even while scrolling in the text view. If your text needs are static, or you don't want the user to interact with the text, use CATextLayer as a child layer of your EAGLLayer instead of a view.
The second approach is to render the text into a texture. You can then composite the text onto your view by disabling the depth buffer and rendering the texture on a full screen rectangle. Look at UIGraphicsBeginImageContextWithOptions to see how to render to an offscreen image with Quartz. UIGraphicsGetImageFromCurrentImageContext allows you to retrieve the UIImage to use as a texture.
Is it possible to draw some noise on top of a rect I filled using NSRectFill? I need to make my app that draws a custom title bar look wonderful on 10.7 before release, and to make it look a little more like iTunes. I would love if this is possible using no images, but if I have to include a PNG or something as a mask, I'd be fine with that.
Thanks!
You can either use drawing logic (drawing a lot of small rects, lines or other polygons), or use NSImage's drawing methods, like for instance: drawInRect:fromRect:operation:fraction:
I can draw rich-text with Core Text, the problem is placing images flowing with the text.
(iOS SDK 4.1)
I'm try to drawing some kind of rich-text. Problem is designer placed many icons among text. So the text what I have to draw is something like this:
Here is a word <an icon image>, and another words.
The image(<another icon>) should be placed like a glyph.
It's part of text, not an example.
<icon> are images. (This is not a code. Just an illustration.)
I can draw this by laying out all of them manually, but it's too hard keeping complex text layout behaviors. So I'm finding a way to draw this with Core Text.
I got solution.
The key of laying out non-text content is CTRunDelegate.
Core Text does not support non-text content, so you have to make blank spaces for them, and draw or place them yourself later.
A part of NSAttributedString attributed with kCTRunDelegateAttributeName will call registered callback to determine width of each glyph. This will let you make blank space for each non-text object.
However, after drawing the text with Core Text, the layout information stored with frame/line/run will invalidated. So you have to draw/place non-text contents after layout with framesetter/typesetter, but before drawing.
This link describes basic usage of CTRunDelegate:
How to use CTRunDelegate in iPad?
There is a problem with Core Text. Originally, CTRunDelegate designed to support variable width and vertical alignment via CTRunDelegateCallbacks.getAscent and CTRunDelegateCallbacks.getDescent. But vertical alignment feature doesn't work currently. This might be a bug.
I described this problem here:
Aligning multiple sized text vertical center instead of baseline with Core Text in iOS
If you have informations about this problem, please see my question at the link.
You simply set a delegate for a given CTRun and the delegate object is responsible to let know Core Text what is the CTRun ascent space, descent space and width.
When Core Text "reaches" a CTRun which has a CTRunDelegate it asks the delegate - how much width should I leave for this chunk of data, how high should it be? This way you build a hole in the text - then you draw your image in that very spot.
Here is a blog about Core Text.It has the answer for you .
How To Create a Simple Magazine App with Core Text
I'd like to create statusbar with text effect like in Safari or iTunes, i.e. recessed text.
However, if I simply add shadow in Interface Builder using Core Animation panel, OS X's worst text rendering kicks in:
What's the trick to get recessed text on a label and keep proper subpixel rendering?
There is a built-in way to do this:
[[yourTextField cell] setBackgroundStyle:NSBackgroundStyleRaised];
It's a cheap old trick: You draw the text in white at an offset and then draw the black text on top of it.
There is a hook for shadows in the text-drawing system, NSAttributedString's NSShadowAttributeName. But testing this out, it appears to kill the subpixel antialiasing as well.
Is it possible to convert a vector image into Quartz 2D code (mac) so that
image can be drawn programmatically?
Not easily, you would have to write all the code yourself to do this. You might like to have a look at the Opacity image editor, which allows you to generate images and export them as Quartz or Cocoa drawing code.
What kind of vector image?
NSImage loads PDFs the same way it loads bitmaps.
NSImage is Quartz 2D drawing, but if you meant that you need a CGImage, NSImage in 10.6 has a method for getting one. However, CGImage is explicitly bitmap based, unlike NSImage. The parameters you pass to -[NSImage CGImageForRect:context:hints:] will determine how the art is rasterized. It will be rasterized the same way it would be if drawing to the passed rect in the passed context.
You can use Vector code http://www.vectorcodeapp.com to generate core graphics code, which you may use programmatically, or even use to generate postscripts.