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

Question

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

I am using the Paint.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.

@CrandellWS help me to understand, what exactly do you want from this question? Isn't it just count width of the screen by `getWindowManager().getDefaultDisplay().getMetrics(metrics)` and dividing measured text-width by it? (regarding your own question you mentioned, just set fontSize based on the `dp`'s width of the screen, etc.) — Konstantin Loginov, Feb 01 '16 at 18:28
I was trying to draw attention to My own question honestly -> http://stackoverflow.com/questions/35117278/canvas-drawtext-with-pixel-perfect-t‌ext-on-a-canvas which I solved and you can use that solution to create the answer for this question. The reputation is not super important to me so feel free to collect easy 50... — CrandellWS, Feb 01 '16 at 18:38
@GideonKain you can use layout percentage support library and can give percentage to widgets. you can check out sample here. http://www.androidauthority.com/using-the-android-percent-support-library-630715/ — Wasim K. Memon, Feb 04 '16 at 08:37

score 1 · Answer 1 · answered Feb 04 '16 at 06:07

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);
}

Andrii Khrystovyi · Answer 2 · 2016-02-05T15:22:37.283

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.

good answer, that will be useful and better on resources than my suggestion. — CrandellWS, Feb 05 '16 at 17:44

score 0 · Answer 3 · edited Feb 05 '16 at 15:25

0

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;
}

edited Feb 05 '16 at 15:25

thiagolr

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answered Feb 04 '16 at 05:32

Rakesh

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You will need to use bounds to get the pixel height and width – CrandellWS Feb 04 '16 at 05:42
try reworking your answer perhaps this will help http://stackoverflow.com/a/35193695/1815624 – CrandellWS Feb 04 '16 at 06:08

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

3 Answers3

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