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androidcanvasscreen-density

Drawing on Canvas issue in high end devices

I want to draw a SeekBar on canvas programmatically. I wrote code to set the LayoutParams of the SeekBar based on device density. I am using switch case with device density like

final DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics();
if(metrics.densityDpi <= DisplayMetrics.DENSITY_LOW){
        zoomBarParams = new LinearLayout.LayoutParams(18,
                LayoutParams.FILL_PARENT);
        } else if (metrics.densityDpi <= DisplayMetrics.DENSITY_MEDIUM){
            zoomBarParams = new LinearLayout.LayoutParams(24,
                    LayoutParams.FILL_PARENT);

        }else if (metrics.densityDpi <= DisplayMetrics.DENSITY_HIGH){
            zoomBarParams = new LinearLayout.LayoutParams(24,
                    LayoutParams.FILL_PARENT);

        }else if (metrics.densityDpi <= DisplayMetrics.DENSITY_XHIGH){
            zoomBarParams = new LinearLayout.LayoutParams(31,
                    LayoutParams.FILL_PARENT);


        }else if (metrics.densityDpi <= DisplayMetrics.DENSITY_XXHIGH){
            zoomBarParams = new LinearLayout.LayoutParams(60,
                    LayoutParams.FILL_PARENT);

        }else if (metrics.densityDpi <= DisplayMetrics.DENSITY_XXXHIGH){
            zoomBarParams = new LinearLayout.LayoutParams(60,
                    LayoutParams.FILL_PARENT);

        } else {
            zoomBarParams = new LinearLayout.LayoutParams(60,
                    LayoutParams.FILL_PARENT);

        }

But this isn't working in high end devices like Samsung Note 5, Galaxy S6 Edge etc..I believe that these devices comes in the density range XXXHIGH, then why is this not working?? Is there any relation between device density and screen size while drawing on canvas? Any help will be greatly appreciated.

Solution

  • Why don't you try to get rid of all the if else cases and make something generic? Since you need to put different pixel values depending on the screen size, you can use dp instead.

    You can get px from dp depending on the screen density of the device and use that in LayoutParams.

    public static float convertDpToPixel(float dp, Context context){
    Resources resources = context.getResources();
    DisplayMetrics metrics = resources.getDisplayMetrics();
    float px = dp * ((float)metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT); // You can cache "((float)metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT)" to avoid re-calculation.
    return px;
}

    So you will create the param like this:

    zoomBarParams = new LinearLayout.LayoutParams(convertDpToPixel(DP_VALUE, context),
                LayoutParams.FILL_PARENT);

    where DP_VALUE will remain constant across all devices.

    I hope this might solve your problem.