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Calculate max number of characters (having predefined size eg 20dp) that will fit in a text view android

I need to calculate how many characters (having pre-defined size eg 20dp) will fit on the text view to divide the long text into different Views? Like any reader app
I'm using the following code that works fine for a single line. My question is how to determine the max number of lines that will fit in text view in various screen sizes?
string abc = "This string is a loooong string";
final float densityMultiplier = getResources().getDisplayMetrics().density;
final float scaledPx = 20 * densityMultiplier;
int numChars;
Paint paint = txtArea.getPaint();
paint.setTextSize(scaledPx);
for (numChars = 1; numChars <= abc.length(); ++numChars)
{
if (paint.measureText(abc, 0, numChars) >= screenWidthDp)
{
break;
}
}

Simply use TextView.getLineHeight() to get height of a line

Get absolute position for a given offset on TextView (Android)

I have a TextView in which I want to place a solid color block over given words of the TextView, for example:
"This is a text string, I want to put a rectangle over this WORD" - so, "WORD" would have a rectangle with a solid color over it.
To do this, I am thinking about overriding the onDraw(Canvas canvas) method, in order to draw a block over the text. My only problem is to find an efficient way to get the absolute position of a given word or character.
Basically, I am looking for something that does the exact opposite of the getOffsetForPosition(float x, float y) method

Based on this post: How get coordinate of a ClickableSpan inside a TextView?, I managed to use this code in order to put a rectangle on top of the text:
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
// Initialize global value
TextView parentTextView = this;
Rect parentTextViewRect = new Rect();
// Find where the WORD is
String targetWord = "WORD";
int startOffsetOfClickedText = this.getText().toString().indexOf(targetWord);
int endOffsetOfClickedText = startOffsetOfClickedText + targetWord.length();
// Initialize values for the computing of clickedText position
Layout textViewLayout = parentTextView.getLayout();
double startXCoordinatesOfClickedText = textViewLayout.getPrimaryHorizontal((int)startOffsetOfClickedText);
double endXCoordinatesOfClickedText = textViewLayout.getPrimaryHorizontal((int)endOffsetOfClickedText);
// Get the rectangle of the clicked text
int currentLineStartOffset = textViewLayout.getLineForOffset((int)startOffsetOfClickedText);
int currentLineEndOffset = textViewLayout.getLineForOffset((int)endOffsetOfClickedText);
boolean keywordIsInMultiLine = currentLineStartOffset != currentLineEndOffset;
textViewLayout.getLineBounds(currentLineStartOffset, parentTextViewRect);
// Update the rectangle position to his real position on screen
int[] parentTextViewLocation = {0,0};
parentTextView.getLocationOnScreen(parentTextViewLocation);
double parentTextViewTopAndBottomOffset = (
//parentTextViewLocation[1] -
parentTextView.getScrollY() +
parentTextView.getCompoundPaddingTop()
);
parentTextViewRect.top += parentTextViewTopAndBottomOffset;
parentTextViewRect.bottom += parentTextViewTopAndBottomOffset;
// In the case of multi line text, we have to choose what rectangle take
if (keywordIsInMultiLine){
WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
int screenHeight = display.getHeight();
int dyTop = parentTextViewRect.top;
int dyBottom = screenHeight - parentTextViewRect.bottom;
boolean onTop = dyTop > dyBottom;
if (onTop){
endXCoordinatesOfClickedText = textViewLayout.getLineRight(currentLineStartOffset);
}
else{
parentTextViewRect = new Rect();
textViewLayout.getLineBounds(currentLineEndOffset, parentTextViewRect);
parentTextViewRect.top += parentTextViewTopAndBottomOffset;
parentTextViewRect.bottom += parentTextViewTopAndBottomOffset;
startXCoordinatesOfClickedText = textViewLayout.getLineLeft(currentLineEndOffset);
}
}
parentTextViewRect.left += (
parentTextViewLocation[0] +
startXCoordinatesOfClickedText +
parentTextView.getCompoundPaddingLeft() -
parentTextView.getScrollX()
);
parentTextViewRect.right = (int) (
parentTextViewRect.left +
endXCoordinatesOfClickedText -
startXCoordinatesOfClickedText
);
canvas.drawRect(parentTextViewRect, paint);
}

You can use spans for that.
First you create a spannable for your text, like this:
Spannable span = new SpannableString(text);
Then you put a span around the word that you want to highlight, somewhat like this:
span.setSpan(new UnderlineSpan(), start, end,
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
Unfortunately I don't know of an existing span that puts a border around a word. I found UnderlineSpan, and also BackgroundColorSpan, perhaps these are also useful for you, or you can have a look at the code and see if you can create a BorderSpan based on one of those.

Instead of drawing a rectangle over the WORD, you could simply replace its characters with an appropriate unicode symbol like U+25AE (▮ Black vertical rectangle).
So you'd get
"This is a text string, I want to put a rectangle over this ▮▮▮▮"
If that is sufficient. See for example Wikipedia for a wast list of unicode symbols.
If you actually need to paint that black box you can do the following as long as your text is in a single line:
Calculate the width of the text part before 'WORD' as explained here to find the left edge of the box and calcuate the width of 'WORD' using the same method to find the width of the box.
For a multiline text the explained method might also work but I think you'll have to do quite a lot of work here.

use getLayout().getLineBottom and textpaint.measureText to manually do the reverse calculation of getOffsetForPosition.
below is an example of using the calculated x,y for some textOffset to position the handle drawable when the textview gets clicked.
class TextViewCustom extends TextView{
float lastX,lastY;
#Override
public boolean onTouchEvent(MotionEvent event) {
boolean ret = super.onTouchEvent(event);
lastX=event.getX();
lastY=event.getY();
return ret;
}
BreakIterator boundary;
Drawable handleLeft;
private void init() {// call it in constructors
boundary = BreakIterator.getWordInstance();
handleLeft=getResources().getDrawable(R.drawable.abc_text_select_handle_left_mtrl_dark);
setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
int line = getLayout().getLineForVertical((int) lastY);
int offset = getLayout().getOffsetForHorizontal(line, lastX);
int wordEnd = boundary.following(offset);
int wordStart = boundary.previous();
CMN.Log(getText().subSequence(wordStart, wordEnd));
int y = getLayout().getLineBottom(line);
int trimA = getLayout().getLineStart(line);
float x = getPaddingLeft()+getPaint().measureText(getText(), trimA, wordStart);
x-=handleLeft.getIntrinsicWidth()*1.f*9/12;
handleLeft.setBounds((int)x,y,(int)(x+handleLeft.getIntrinsicWidth()),y+handleLeft.getIntrinsicHeight());
invalidate();
}
});
}
#Override
public void setText(CharSequence text, BufferType type) {
super.setText(text, type);
if(boundary!=null)
boundary.setText(text.toString());
}
}

Android.how to calculate the wide of string?

MY code is
Paint paint= new Paint();
paint.setTextSize(size);
int iRet = 0;
if (str != null && str.length() > 0) {
int len = str.length();
float[] widths = new float[len];
paint.getTextWidths(str, widths);
for (int j = 0; j < len; j++) {
iRet += (int) Math.ceil(widths[j]);
}
}
return iRet;
I want to get the width of string ,but the return result has errors with TextView.
Don't know the right way.
thanks.
I show it in the virtual machine.

To calculate text width you should use:
public float measureText (String text)
method in class Paint, it will return measured width of text in paint.

you can try to use canvas,Once a time I found the Textview can't show my text in right size ,so I use Canvas draw the text out ,the I get the width I want,that's maybe some wrong cause by dp,sp or px.

you can use:
int width = paint.measureText("this text");
measureText(String text) will return width of text.

you can measure it by calling the measureText() of paint class here is the code for that-
Paint p=new paint();
int value = p.measureText("give input string to measure");

Measuring text height to be drawn on Canvas ( Android )

Any straight forward way to measure the height of text?
The way I am doing it now is by using Paint's measureText() to get the width, then by trial and error finding a value to get an approximate height. I've also been messing around with FontMetrics, but all these seem like approximate methods that suck.
I am trying to scale things for different resolutions. I can do it, but I end up with incredibly verbose code with lots of calculations to determine relative sizes. I hate it! There has to be a better way.

There are different ways to measure the height depending on what you need.
#1 getTextBounds
If you are doing something like precisely centering a small amount of fixed text, you probably want getTextBounds. You can get the bounding rectangle like this
Rect bounds = new Rect();
mTextPaint.getTextBounds(mText, 0, mText.length(), bounds);
int height = bounds.height();
As you can see for the following images, different strings will give different heights (shown in red).
These differing heights could be a disadvantage in some situations when you just need a constant height no matter what the text is. See the next section.
#2 Paint.FontMetrics
You can calculate the hight of the font from the font metrics. The height is always the same because it is obtained from the font, not any particular text string.
Paint.FontMetrics fm = mTextPaint.getFontMetrics();
float height = fm.descent - fm.ascent;
The baseline is the line that the text sits on. The descent is generally the furthest a character will go below the line and the ascent is generally the furthest a character will go above the line. To get the height you have to subtract ascent because it is a negative value. (The baseline is y=0 and y descreases up the screen.)
Look at the following image. The heights for both of the strings are 234.375.
If you want the line height rather than just the text height, you could do the following:
float height = fm.bottom - fm.top + fm.leading; // 265.4297
These are the bottom and top of the line. The leading (interline spacing) is usually zero, but you should add it anyway.
The images above come from this project. You can play around with it to see how Font Metrics work.
#3 StaticLayout
For measuring the height of multi-line text you should use a StaticLayout. I talked about it in some detail in this answer, but the basic way to get this height is like this:
String text = "This is some text. This is some text. This is some text. This is some text. This is some text. This is some text.";
TextPaint myTextPaint = new TextPaint();
myTextPaint.setAntiAlias(true);
myTextPaint.setTextSize(16 * getResources().getDisplayMetrics().density);
myTextPaint.setColor(0xFF000000);
int width = 200;
Layout.Alignment alignment = Layout.Alignment.ALIGN_NORMAL;
float spacingMultiplier = 1;
float spacingAddition = 0;
boolean includePadding = false;
StaticLayout myStaticLayout = new StaticLayout(text, myTextPaint, width, alignment, spacingMultiplier, spacingAddition, includePadding);
float height = myStaticLayout.getHeight();

What about paint.getTextBounds() (object method)

#bramp's answer is correct - partially, in that it does not mention that the calculated boundaries will be the minimum rectangle that contains the text fully with implicit start coordinates of 0, 0.
This means, that the height of, for example "Py" will be different from the height of "py" or "hi" or "oi" or "aw" because pixel-wise they require different heights.
This by no means is an equivalent to FontMetrics in classic java.
While width of a text is not much of a pain, height is.
In particular, if you need to vertically center-align the drawn text, try getting the boundaries of the text "a" (without quotes), instead of using the text you intend to draw.
Works for me...
Here's what I mean:
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.LINEAR_TEXT_FLAG);
paint.setStyle(Paint.Style.FILL);
paint.setColor(color);
paint.setTextAlign(Paint.Align.CENTER);
paint.setTextSize(textSize);
Rect bounds = new Rect();
paint.getTextBounds("a", 0, 1, bounds);
buffer.drawText(this.myText, canvasWidth >> 1, (canvasHeight + bounds.height()) >> 1, paint);
// remember x >> 1 is equivalent to x / 2, but works much much faster
Vertically center aligning the text means vertically center align the bounding rectangle - which is different for different texts (caps, long letters etc). But what we actually want to do is to also align the baselines of rendered texts, such that they did not appear elevated or grooved. So, as long as we know the center of the smallest letter ("a" for example) we then can reuse its alignment for the rest of the texts. This will center align all the texts as well as baseline-align them.

The height is the text size you have set on the Paint variable.
Another way to find out the height is
mPaint.getTextSize();

You could use the android.text.StaticLayout class to specify the bounds required and then call getHeight(). You can draw the text (contained in the layout) by calling its draw(Canvas) method.

You can simply get the text size for a Paint object using getTextSize() method.
For example:
Paint mTextPaint = new Paint (Paint.ANTI_ALIAS_FLAG);
//use densityMultiplier to take into account different pixel densities
final float densityMultiplier = getContext().getResources()
.getDisplayMetrics().density;
mTextPaint.setTextSize(24.0f*densityMultiplier);
//...
float size = mTextPaint.getTextSize();

You must use Rect.width() and Rect.Height() which returned from getTextBounds() instead. That works for me.

If anyone still has problem, this is my code.
I have a custom view which is square (width = height) and I want to assign a character to it. onDraw() shows how to get height of character, although I'm not using it. Character will be displayed in the middle of view.
public class SideBarPointer extends View {
private static final String TAG = "SideBarPointer";
private Context context;
private String label = "";
private int width;
private int height;
public SideBarPointer(Context context) {
super(context);
this.context = context;
init();
}
public SideBarPointer(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
init();
}
public SideBarPointer(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.context = context;
init();
}
private void init() {
// setBackgroundColor(0x64FF0000);
}
#Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
height = this.getMeasuredHeight();
width = this.getMeasuredWidth();
setMeasuredDimension(width, width);
}
protected void onDraw(Canvas canvas) {
float mDensity = context.getResources().getDisplayMetrics().density;
float mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
Paint previewPaint = new Paint();
previewPaint.setColor(0x0C2727);
previewPaint.setAlpha(200);
previewPaint.setAntiAlias(true);
Paint previewTextPaint = new Paint();
previewTextPaint.setColor(Color.WHITE);
previewTextPaint.setAntiAlias(true);
previewTextPaint.setTextSize(90 * mScaledDensity);
previewTextPaint.setShadowLayer(5, 1, 2, Color.argb(255, 87, 87, 87));
float previewTextWidth = previewTextPaint.measureText(label);
// float previewTextHeight = previewTextPaint.descent() - previewTextPaint.ascent();
RectF previewRect = new RectF(0, 0, width, width);
canvas.drawRoundRect(previewRect, 5 * mDensity, 5 * mDensity, previewPaint);
canvas.drawText(label, (width - previewTextWidth)/2, previewRect.top - previewTextPaint.ascent(), previewTextPaint);
super.onDraw(canvas);
}
public void setLabel(String label) {
this.label = label;
Log.e(TAG, "Label: " + label);
this.invalidate();
}
}

How to get string width on Android?

I would like to get height too if possible.

You can use the getTextBounds(String text, int start, int end, Rect bounds) method of a Paint object. You can either use the paint object supplied by a TextView or build one yourself with your desired text appearance.
Using a Textview you Can do the following:
Rect bounds = new Rect();
Paint textPaint = textView.getPaint();
textPaint.getTextBounds(text, 0, text.length(), bounds);
int height = bounds.height();
int width = bounds.width();

If you just need the width you can use:
float width = paint.measureText(string);
http://developer.android.com/reference/android/graphics/Paint.html#measureText(java.lang.String)

There are two different width measures for a text. One is the number of pixels which has been drawn in the width, the other is the number of 'pixels' the cursor should be advanced after drawing the text.
paint.measureText and paint.getTextWidths returns the number of pixels (in float) which the cursor should be advanced after drawing the given string. For the number of pixels painted use paint.getTextBounds as mentioned in other answer. I believe this is called the 'Advance' of the font.
For some fonts these two measurements differ (alot), for instance the font Black Chancery have letters which extend past the other letters (overlapping) - see the capital 'L'. Use paint.getTextBounds as mentioned in other answer to get pixels painted.

I have measured width in this way:
String str ="Hiren Patel";
Paint paint = new Paint();
paint.setTextSize(20);
Typeface typeface = Typeface.createFromAsset(getAssets(), "Helvetica.ttf");
paint.setTypeface(typeface);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.FILL);
Rect result = new Rect();
paint.getTextBounds(str, 0, str.length(), result);
Log.i("Text dimensions", "Width: "+result.width());
This would help you.

Most likely you want to know the painted dimensions for a given string of text with a given font (i.e. a particular Typeface such as the “sans-serif” font family with a BOLD_ITALIC style, and particular size in sp or px).
Rather than inflating a full-blown TextView, you can go lower level and work with a Paint object directly for single-line text, for example:
// Maybe you want to construct a (possibly static) member for repeated computations
Paint paint = new Paint();
// You can load a font family from an asset, and then pick a specific style:
//Typeface plain = Typeface.createFromAsset(assetManager, pathToFont);
//Typeface bold = Typeface.create(plain, Typeface.DEFAULT_BOLD);
// Or just reference a system font:
paint.setTypeface(Typeface.create("sans-serif",Typeface.BOLD));
// Don't forget to specify your target font size. You can load from a resource:
//float scaledSizeInPixels = context.getResources().getDimensionPixelSize(R.dimen.mediumFontSize);
// Or just compute it fully in code:
int spSize = 18;
float scaledSizeInPixels = TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP,
spSize,
context.getResources().getDisplayMetrics());
paint.setTextSize(scaledSizeInPixels);
// Now compute!
Rect bounds = new Rect();
String myString = "Some string to measure";
paint.getTextBounds(myString, 0, myString.length(), bounds);
Log.d(TAG, "width: " + bounds.width() + " height: " + bounds.height());


For multi-line or spanned text (SpannedString), consider using a StaticLayout, in which you provide the width and derive the height. For 
a very elaborate answer on measuring and drawing text to a canvas in a custom view doing that, see: https://stackoverflow.com/a/41779935/954643
Also worth noting #arberg's reply below about the pixels painted vs the advance width ("number of pixels (in float) which the cursor should be advanced after drawing the given string"), in case you need to deal with that.

I'd like to share a better way (more versatile then the current accepted answer) of getting the exact width of a drawn text (String) with the use of static class StaticLayout:
StaticLayout.getDesiredWidth(text, textPaint))
this method is more accurate than textView.getTextBounds(), since you can calculate width of a single line in a multiline TextView, or you might not use TextView to begin with (for example in a custom View implementation).
This way is similar to textPaint.measureText(text), however it seems to be more accurate in rare cases.

simplay i tack max charcter in the line and defieded it with max space and create new line
v_y = v_y + 30;
String tx = "مبلغ وقدرة : "+ AmountChar+" لا غير";
myPaint.setTextAlign(Paint.Align.RIGHT);
int pxx = 400;
int pxy = v_y ;
int word_no = 1;
int word_lng = 0;
int max_word_lng = 45;
int new_line = 0;
int txt_lng = tx.length();
int words_lng =0;
String word_in_line = "" ;
for (String line : tx.split(" "))
{
word_lng = line.length() ;
words_lng += line.length() + 1;
if (word_no == 1 )
{word_in_line = line;
word_no += 1;
}
else
{ word_in_line += " " + line;
word_no += 1;
}
if (word_in_line.length() >= max_word_lng)
{
canvas.drawText(word_in_line, pxx, pxy, myPaint);
new_line += 1;
pxy = pxy + 30;
word_no = 1;
word_in_line = "";
}
if (txt_lng <= words_lng )
{ canvas.drawText(word_in_line, pxx, pxy, myPaint); }
}
v_y = pxy;