In my app I am displaying a table where the individual cells are editable text fields (i.e. EditText objects). I am currently struggling calculating appropriate widths for these.
If I set the width to be as many "Ems" as the displayed text has characters, my fields are much to wide by about a factor of 2 and the table looks ugly and wastes lots of precious screen space. Setting the width in "Ems" is essentially like assuming the worst case, i.e. the width of a string under the assumption that it contains only the broadest characters in a font, usually 'M' (hence the name of the method), 'm', 'W', or '_'). But on average strings contain narrower characters and so most of these fields are half empty and much too wide for their actual content. I am thus desperately seeking a way to calculate a better fitting width, not that worst case width.
The "normal" way to do this in Java (in AWT or Swing at least) is to asks a widget's current Font (actually a Font's FontMetrics), to calculate and return the width that will be necessary to display a given string in pixels. But how does one obtain a TextView's Font? I haven't found any method to obtain a (Text)View's font and/or calculate a more appropriate width given the actual content of a cell's text string. How does one do that in Android?
Michael
I just found the "missing link": <TextView>.getPaint() is the answer!
The "Paint" then has methods like <Paint>.measureText(...) to calculate a string's width and <Paint>.ascent() and <Paint>.descent() to calculate a string's height.
Michael
Related
I am writing an app about eye test. It is necessary to set the standard text size. I used the following code but it showed what I did not expect.
Typeface type=Typeface.createFromAsset(getAssets(),"Optotypes.ttf");
textView2.setTypeface(type);
textView2.setTextSize(TypedValue.COMPLEX_UNIT_MM,25);
textView2.setText(randomLetter);
I expected the textview show a 2.5cm letter but it is not the exact length/height still.
This situation appear also on different device.
The next problem is that the size is different between the original font and ttf I added. (the original font didn't show the text with 2.5cm also.
Is my code wrong or anything else i missed ? Thanks guys . it is important to me.
I think you're missing how Android handles text sizes.
In Android, you should specify text size in SP units, so Android can scale it accordingly to the user's font size preferences. Never specify hardcoded pixels or centimeters.
Check this references for documentation on the subject:
http://developer.android.com/guide/topics/resources/more-resources.html#Dimension
http://developer.android.com/reference/android/widget/TextView.html#attr_android:textSize
What is the difference between "px", "dp", "dip" and "sp" on Android?
If you want to set the text size in SP programatically, you can do this
// same as android:textSize="15sp" in XML
textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, 15);
-- EDIT
Keep in mind that by just setting a certain text size it doesn't mean that every letter will be of that size. Remember that there are multiple letters with multiple sizes. For instance, with a size of 20mm, this is what you get
Because Android needs to accommodate every possible character in a textview with the size you provided. That being said, textSize is not 100% accurate to what you provide to it.
If this is not enough for you, please provide more details of the problem you have at hands.
I have a question about one android text rendering detail:
Whether current character rendered width depends from previos character in android text renderer (for example in textview)?
For example if char 'x' have width equals x_w and 'y' - y_w, will string "xy" always have with equals
x_w + y_w
?
Some more details:
The point is that I should measure strings as quiсk as possible. I want to measure once each letter (character) from text using Paint.getTextWidths(...) and then jsut use work with characters width.
Depends on the font. It's not something I would assume, if you want the width of a string, measure the full string.
If you absolutely need that, use a monospace font.
For example textview with size 33.0 dp in xml. It means double number or it has other features?
I assume you're referring to either layout_width or layout_height; in this case these numbers are always floating point. The ".0" on the end has no particular significance.
See http://developer.android.com/reference/android/R.attr.html#layout_width for more information.
I am trying to make a sign (the ones that drivers use at the airport to find someone "Mr Smith") and I wanted the sign to have the largest Font size possible, (its for a tablet), I could write a function to change the size depending on the length of the Text but is there a way of doing natively/better?
Thanks
The most flexible way is to create a custom view that draws the text in onDraw(). When drawing the text (with one of Canvas.drawText()) you will have to provide a Paint, and that would let you know the precise length of text, not just length of string (see Paint.measureText()).
This way you would have plenty of ways to calculate and redistribute the space (and it would totally rely on you how).
One way I can think of is calculating the length for a huge font size and then using the h/w ratio to see if I want to fill the screen in width or height.
I have TextView with height and width as fill parent. Is it possible to find out how many characters can this layout hold?
Do you mean how many characters can be entered into the textview and still be fully visible without scrolling? For proportional fonts, that will depend on the specific characters typed, including where the line break opportunities are. I don't think there's a simple way to compute that.