How to convert text width in pixels to percent of screen width/height?

I am measuring a string text to see if I should add a \n for wrapping.

I am using the P开发者_StackOverflow中文版aint.measureText function, and it works most of the time but it occurs to me that this isn't accurate since a px doesn't equal a dp - I've seen online how to convert pixels to dp, but instead what I would rather do is convert px to a percentage of the screen size for example

If a is 8 pixels wide, how would I say:

float LetterWidthPercent = _______ //get width of character in percent of screen width
float LetterHeightPercent = _______ //get height of character in percent of screen height

This way I could just see:

 if (LineOfTextWidth >= ScreenWidth * 0.9f) //90%

This would be an extremely useful function to have handy.

You will need to get the screen width through DisplayMetrics or how ever...

For getting the character size use paint with bounds to calculate.

characterWidth/screenWidth = characterScreenPercentage

I made it a double but you can easily change it to a float.

For Characters:

public Double characterToScreenWidthPercentage(Character c) {
    Paint paint = new Paint();
    Rect boundA = new Rect();
    DisplayMetrics metrics = new DisplayMetrics();
    ((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE))
            .getDefaultDisplay().getMetrics(metrics);
    paint.getTextBounds(Character.toString(c), 0, 1, boundA);
    Log.v("fn", Integer.toString(boundA.width()));
    Log.v("fn", Integer.toString(metrics.widthPixels));
    Log.v("fn", Double.toString((float) boundA.width() / (float) metrics.widthPixels));
    return ((double) boundA.width() / (double) metrics.widthPixels);
}

For strings:

public Double stringToScreenWidthPercentage(String str) {
    Paint paint = new Paint();
    Rect boundA = new Rect();
    DisplayMetrics metrics = new DisplayMetrics();
    ((WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE))
            .getDefaultDisplay().getMetrics(metrics);
    paint.getTextBounds(str, 0, 1, boundA);
    Log.v("fn", Integer.toString(boundA.width()));
    Log.v("fn", Integer.toString(metrics.widthPixels));
    Log.v("fn", Double.toString((float) boundA.width() / (float) metrics.widthPixels));
    return ((double) boundA.width() / (double) metrics.widthPixels);
}

public static double measureWeightPercent(Context context, String textToMeasure) {
    DisplayMetrics metrics = new DisplayMetrics();
    ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE))
            .getDefaultDisplay().getMetrics(metrics);

    TextView view = new TextView(context);
    view.setText(textToMeasure);
    view.measure(metrics.widthPixels, metrics.heightPixels);

    double textWidth = view.getMeasuredWidth();

    return textWidth / (metrics.widthPixels / 100);
}

You can measure a TextView with text inside before(or instead) drawing it on a screen. At this way you can set any font or textSize for TextView and always know how many percents the text will have on the screen.

You can use following methods to convert do to pixel and pixel to dp.

Convert dp to pixel:

public int dpToPixel(int dp) {
    DisplayMetrics dm= getContext().getResources().getDisplayMetrics();
    int pixel = Math.round(dp * (dm.xdpi / DisplayMetrics.DENSITY_DEFAULT));       
    return pixel
}

Convert pixel to dp:

public int pixelToDp(int pixel) {
    DisplayMetrics dm = getContext().getResources().getDisplayMetrics();
    int dp = Math.round(pixel / (dm.xdpi / DisplayMetrics.DENSITY_DEFAULT));
    return dp;
}