I have a font where unfortunately the numbers and letters are different heights. I need to display a reference code which is a mix of letters and numbers and the uneven heights of the characters looks jarring. Is it possible with core text (or another technology on iOS) to render certain characters with a slightly stretched height so that it looks even numbers and letters are displayed together.
E.g i have the string '23Rt59RQ' I need the 2,3,5,9 to be rendered with a larger height.
AFAICT, there's nothing in the CGContext API (which is what you'd want to use for laying out sets of glyphs) which would directly, easily facilitate this.
If it's really very important to use the font you are using, you could make separate calls to CGContextShowGlyphsAtPositions for alphabetic and numeral characters, calling CGContextSetFontSize each time so that the end result ends up matching, but this is a lot of overhead for just drawing text, and will probably result in undesirable performance.
My real advice would be to pick a better font so that this isn't even an issue :)
In the end of used regex to identify the character groups and then created an attributed string varying the font size in the font given in the NSFontAttributeName attribute according to which characters were to be displayed.
Kinda hacky but it had the desired effect.
Related
I have a plist file which I decode to load data onto my application.
This plist file contains String type values that gets mapped to UILabel's text property.
I noticed that the truncating behavior of the text in the label is not always the same.
To be more specific, the three dots that are added when the text is truncated are, as opposed to my expectation, two kinds: one being ... and the other being ⋯ which appears to be this unicode character in this link.
I checked UILabel's attribute settings but I was unable to find any settings related to this behavior.
Has anyone else experienced this problem and standardized the truncating character to be ...?
Here is the image describing the problem mentioned above. Both labels have 2 lines and have new line escape character inserted between the first line and the second line of text. I am posting a link to this image because apparently I don't have enough reputation to post an image.
varying truncating characters of UILabel
IMO this is a bug in UILabel, and it may be worth opening a Feedback about it.
TL;DR: I recommend using TTTAttributedLabel.
Long-winded answer, because this was such an interesting question:
UILabel uses a different ellipsis based on the language script being truncated. As you've noticed, for most scripts, they use HORIZONTAL ELLIPSIS (…), or something very similar. But for Chinese, Japanese, and Korean (CJK), they use MIDLINE HORIZONTAL ELLIPSIS (⋯), or again, something very similar. The only other exception I've found is Burmese, which uses three circles that I don't recognize.
In my tests, all the following used …: Latin, Cyrillic, Bengali, Arabic, Hebrew, Hindi, Thai, Kannada, Nepali, and Mongolian (I kid. iOS can't layout Mongolian. Nobody can layout Mongolian, but it still uses …). UILabel even uses … for Lao, even though I thought ຯ was specifically for that, but I guess eventually everything becomes Latin.
The problem with UILabel being so clever for CJK and Burmese is that it decides what character to use exclusively by looking at the first character being removed. And it thinks SPACE is Latin (or at least not "special").
So what to do? My recommendation is probably to use TTTAttributedLabel, since it lets you configure the truncation character, and more importantly, is open source so you can fix it if it's not working the way you want.
The second option would be to truncate the text by hand using techniques like the one described in How to change truncate characters in UILabel?. There are probably better ways to do it using CTFrameGetVisibleStringRange instead of constantly shrinking the string until it fits, but I don't know if it's worth the effort. (If that path sounds useful, I could probably write up something that does it. It's just probably not worth the trouble.)
And the final option I know is to replace the SPACE character with an "equivalent" CJK character. The closest I've found that works is HANGUL FILLER (U+3164), but I don't like it. It's too wide, and I expect that it will make Korean uncomfortable to read (but I rarely try to read Korean, so I may be wrong here):
With SPACE: 안녕 하세요
With FILLER: 안녕ㅤ하세요
There's also HALFWIDTH HANGUL FILLER (U+FFA0), which is better, but UILabel seems to make it zero width (this may be a font issue, so maybe worth trying):
With SPACE: 안녕 하세요
With HALF: 안녕ﾠ하세요
let string = "안녕 하세요"
let filler = "\u{3164}"
label.text = string.replacingOccurrences(of: " ", with: filler)
OTOH, you may run into the same problem if you use any other non-CJK characters, like Latin punctuation or Arabic numerals. So this solution may not scale. And you should make sure that Voice Over properly ignores it.
I am trying to draw an NSAttributedString (actually, a constructed NSMutableAttributedString) where the "original" text has been struck and replacement text inserted above it (I'm trying to replicate the look/feel of an Ancient Greek manuscript).
My technique is a combination of NSBaselineOffsetAttributeName with NSKernAttributeName, but it appears that using a negative value for NSKernAttributeName "wipes away" the strikethrough of the text, even if the characters don't overlap.
If I put an extra space after the "A" character (in the original text), the "A" gets the strikethrough, but the "EI" is also offset to the right. So, it appears that the offset/kerning of the "EI" text affects how much of the strikethrough actually occurs.
Here's what I'd like to reproduce (I don't care about the angle; it's not about a picture-perfect reproduction; just the gist):
Here's what is currently happening:
This is when I add an extra space after the strikethrough:
So, the only other thing I can think of would be to render a separate NSAttributedString in the correct place, separate from the current one, but I have no idea how to calculate the location of a specific character in an NSAttributedString when it's drawn. I'm drawing to a PDF, not to any on-screen control like a UILabel. Alternatively, I could draw the "strikethrough" myself as a line, but that seems to still require knowing the coordinates for the text in question, which is calculated on-the-fly, and I hope to use this method to reproduce a large sample of ancient texts, which means doing it by hand just isn't a good answer here.
Anything I'm missing, or any out-of-the-box ideas to try?
I have seen here people needing to calculate the size of the NSString given a size but I need to do the opposite.
Given a specified rect (or fixed UITextView, or multiline UILabel, no scrolling) I need to know:
if it managed to show all the chars of my NSString
if not, what is the last char shown
So that I can display the remaining text in another UITextView (of course if I could use a single UITextView I would not have this problem).
At first it seems a simple thing to do, but actually I am not finding a way, intuitively I think I could use either UITextView's:
textView.contentSize.height;
or NSString's:
sizeWithFont:constrainedToSize:lineBreakMode:
or a combination of the two, but I need to be precise and those methods do not help me in telling what is the last character that managed to fit the visible area of the UITextView.
Not sure if this is actually possible, but is a requirement of my client who thinks programming iOS is like printing a newspaper and expects to be able to format text around an image....
You could maybe get the maximum height of one line of text from a one character long string.
If you use that with sizeWithFont:constrainedToSize:lineBreakMode: then you should be able to know if your text runs onto more than one line (if the cgsize height is greater than the height of one line of text).
In order to find out the last character (or word) you would have to loop around the length of the string adding characters (or words) as you go and checking for when the cgsize height increases to add a new line, this will give you the character point when to split into multiple strings ( for multiple fields/labels/textviews ) or when to insert line breaks into the text ( if using a single multi-line textview or label ).
I hope you find an easier way...
I need to compute the width of a column with many rows (column AutoSize feature). Using Canvas.TextWidth is far too slow.
Current solution: My current solution uses a text measurer class that builds a lookup table for a fixed alphabet once and then computes the width of a given string very fast by adding up character widths retrieved from the lookup table. For characters not contained in the lookup table, the average character width is used (also computed once).
Problem: This works well for European languages but not for Asian languages.
Question: What's the best way to tackle this problem? How can such an AutoSize feature be realized without the relatively slow Canvas functions and without depending on a specific alphabet?
Thanks for any help.
You said you want to get the maximum text width for a column. Can't you, say, take only the 4 or 5 longest strings and get their widths? That way you won't have to find the width for all items and can save quite some time.
Or you use your cache to find the rough length of the strings and then refine that by getting the actual width for the top 4 or 5 items you found.
I don't think it matters a lot whether you use Canvas.TextWidth or GetTextExtentPoint32. Just use one of these to get the exact widths, after you used one of the methods above to guesstimate the longest/widest strings.
To those who think this doesn't work
If the poster of the original question thinks it could work, I have no reason to think it won't. He knows best what kind of strings can be in the columns he has.
But that is not my main argument. He already wrote that he does a preliminary textwidth by adding the predetermined individual widths of the characters. That does not take into account any kerning. Well, kerning can only make a string narrower, so it still makes sense to check only the top 4 or 5 items for the exact width. The biggest problem that can occur is that the column could be a few pixels too wide, no more. But it will be a lot faster than using TextWidth or GetTextExtentPoint32 or similar functions on each entry (assuming more than 5 entries), and that is what the original poster wanted. I suggest that those who don't believe me simply try it out.
As for using the pure string length: even that is probably good enough. Yes, 'WWW' is probably wider than '!!!!!', but the original poster will probably know best wat kind of string material he has, and if it is feasible. '!!!!!' or 'WWW' are not the usual entries one expects. Especially if you consider that not only one single string is checked, but the longest 4 or 5 strings (or whatever number turns out to be optimal). It is very unlikely that the widest string is not among them. But the original poster can tell if that is possible or feasible. He seems to think it is.
So stop the downvoting and try it out for yourself.
I'm afraid you have to use Canvas.TextWidth, or your implementation will be imprecise. The width of text depends on the font kerning, where different character sequences may have different widths (not just the total of individual character widths).
Me, I cut out the middle-man and use the Windows API directly. Specifically, I use GetTextExtentPoint32 with the .Handle of the Canvas. There's nothing you can do to be faster, other than caching results in some way, and frankly you'll just add overhead.
How can I fully justify a block of text (like MS Word does, not only on the right and not only on the left but on both sides)?
I want to justify some texts (mainly arabic text) adjusted to certain screen size (some handheld device screen actually, and its text viewer doesn't have this function) and save this text as justified. So I can reload and reuse it again elsewhere.
(The problem with MS word is, that if you copy the justified text from MS Word and paste it to another editor it'll copy it un-justified).
Update : for now I'm thinking of doing it like this:
get-a-word
get-word-width
add-word-to-total-Word and add-Word-width-to-total-word-width
check if total-Word-width = myscreen-width then continue
else if total-Word-width is between myscree-wdith and (myscreen-width -3) then
add-spaces-To-total-word until it = myscreen-width
This is what I'm thinking now, but I put this question up and hope to see if there is a better solution, or somebody else already implemented it.
PS: I hope I have made my question clear and I'm sorry for bad expression if there is.
edit1 : changed the title to make it more clear.
If you want to justify plain text, you can only add extra spaces to the lines to get them align on the left and right. Unfortunately the character widths differ in fonts; so doing it this way will only work for a certain font, unless you limit yourself to monospaced fonts where all characters have the same size.
If you want a result like in Word, adding spaces won't cut it. Word will not add spaces, but stretch and shrink the existing spaces. This information is lost when you copy and paste it into another app.
Either way, justifying is an optimization problem. If you are interested in a good solution and its implementation: have a look a TeX. For an implementation that works on plain text with monospaced fonts have a look at par
There are some API calls that may help:
ExtTextOut and GetCharacterPlacement
Look at the GCP_JUSTIFY flag for GetCharacterPlacement
ExtTextOut is used by Canvas.TextRect
The problem you are going to face is always going to be differences in the rendering of the font. Word handles full justification by adjusting kerning as well as adjusting the number of pixels between words by a few (either way). The end result is lined up both margins. This pixel adjustment is done BOTH ways, and as evenly as possible.
To properly handle this in your portable device you will have to also perform the same algorithm for the display of the text there.
If this is not possible, then the ONLY way you can even get somewhat close would be to add whitespace between words.
As has been pointed out in other answers Word does full justification by stretching the existing spaces often by very small amounts. This is only possible if you have full control over how your text is drawn on the screen (which word - or any other windows program has).
You only real option in this regard would be to implement your own text viewer on the platform you are targeting. Eg you would need to draw the text on the screen yourself (any platform that allows games should allow you to draw on the screen). However this seems like an awful lot of trouble to get justified text.
Sorry couldn't be of more help.