Why Drawing Arc using canvas on different devices is showing of different Radius Arc

Question

I am drawing an Arc using canvas. On my device(1080 * 1920) it looks like good, but on my friend device(720 * 1280) the radius of Arc increased.

I am setting Height and Width based on device Screen Height and width. So the Height and width for device I am getting different for different device. But Size of Arc drawn is of different size.

Please help me on this. Thanks in advance.

    @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            // Get Screen Width in Pixel
            int width = Helper.getScreenWidth(context);
            // Get Screen Height in Pixel
            int height = Helper.getScreenHeight(context);
            // Get Device Density
            int density = Helper.getDeviceDensity(context);
            setMeasuredDimension(width, height / density);
        }

/**
     * Get Screen Height
     * @param context context
     * @return int
     */
public static int getScreenHeight(Context context) {
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        DisplayMetrics metrics = new DisplayMetrics();
        display.getMetrics(metrics);
        int height = metrics.heightPixels;
        return height;
    }

    /**
     * Get Screen Width
     * @param context context
     * @return int
     */
    public static int getScreenWidth(Context context) {
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        DisplayMetrics metrics = new DisplayMetrics();
        display.getMetrics(metrics);
        int width = metrics.widthPixels;
        return width;
    }

    /**
     * Get Device Screen Density
     * @param context context
     * @return int
     */
    public static int getDeviceDensity(Context context) {
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        DisplayMetrics metrics = new DisplayMetrics();
        display.getMetrics(metrics);
        int density = (int) metrics.density;
        return density;
    }

use dp(device pixels) that way you don't have to handle the logic for different screen sizes — Bhargav, Dec 01 '15 at 11:10
Actually I am drawing Arc programatically, so how I can use dp..???? — Sanni Raj, Dec 01 '15 at 11:22
inside `onDraw`, why dont you use `getWidth` / `getHeight` directly? — pskink, Dec 01 '15 at 11:24
Ya i am using in that way only, x = getWidth(); y = getHeight(); — Sanni Raj, Dec 01 '15 at 11:26
I am calculating x as canvas width and y as canvas height. Then after that I am making the centre of Arc using those values. Arc centre(x/2, y) — Sanni Raj, Dec 01 '15 at 11:36
ya exactly...the circle is drawing fine, but the arc size is different for different device — Sanni Raj, Dec 01 '15 at 11:43
arc size means, the radius of arc size is different for different devices — Sanni Raj, Dec 02 '15 at 06:26

score 0 · Answer 1 · edited May 23 '17 at 11:52

Use dp(device pixels) that way you don't have to handle the logic for different screen sizesConvert from dp to pixel:

public int dpToPx(int dp) {
    DisplayMetrics displayMetrics = getContext().getResources().getDisplayMetrics();
    int px = Math.round(dp * (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));       
    return px;
}

So wherever you are passing raw ints for width and height instead pass dpToPx(yourRawInt);

For more information on converting from dp to px and px to dp check this answer

Why Drawing Arc using canvas on different devices is showing of different Radius Arc

1 Answers1