Brightness of an image keeps increasing even when moving Seekbar's scrollbar left

Question

In my app, I want to be able to change the brightness of an image within an ImageView. I use seekbar for this purpose. It does change the brightness of the image when I move the scrollbar right but when I want to reduce the brightness and move left the brightness keeps increasing and the image become nearly white. Also it is so difficult to use the seekbar as a user. It doesn't move very smoothly. Can someone please help me to improve my code as I am a beginner in programming.

Here is part of the code:

On click of a button "filter" :

btn_filter.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {
      Log.e("EditPhoto", "counter value = " + counter);
      counter++;
      sbarBrightness = (SeekBar) findViewById(R.id.seekBarForBrightness);
        if (counter % 2 == 0) {
            sbarBrightness.setVisibility(View.INVISIBLE);
        } else {
            sbarBrightness.setVisibility(View.VISIBLE);
        }
    sbarBrightness.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
     int brightness;
     @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean
                                          fromUser) {

    brightness = progress;
    imageBitmap = doBrightness(imageBitmap, brightness);
    putGestureImageOnScreen(imageBitmap);
 }
   });
  }
 });

public static Bitmap doBrightness(Bitmap src, int value) {
    Log.e("Brightness", "Changing brightnhjh");

    int width = src.getWidth();
    int height = src.getHeight();
    Bitmap bmout = Bitmap.createBitmap(width, height, src.getConfig());
    int A, R, G, B;
    int pixel;
    for (int i = 0; i < width; ++i) {
        for (int j = 0; j < height; ++j) {
            pixel = src.getPixel(i, j);
            A = Color.alpha(pixel);
            R = Color.red(pixel);
            G = Color.green(pixel);
            B = Color.blue(pixel);
            R += value;
            if (R > 255) {
                R = 255;
            } else if (R < 0) {
                R = 0;
            }
            G += value;
            if (G > 255) {
                G = 255;
            } else if (G < 0) {
                G = 0;
            }
            B += value;
            if (B > 255) {
                B = 255;
            } else if (B < 0) {
                B = 0;
            }
            bmout.setPixel(i, j, Color.argb(A, R, G, B));
        }
    }
    return bmout;

}

Seekbar's declaration in the layout:

<SeekBar
    android:id="@+id/seekBarForBrightness"
    android:layout_width="500dp"
    android:layout_height="50dp"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    style="@style/tallerBarStyle"        
    android:layout_marginTop="64dp"
    android:visibility="invisible" />

and this its style is as below:

<style name="tallerBarStyle" parent="@android:style/Widget.SeekBar">
    <item name="android:indeterminateOnly">false</item>
    <item name="android:progressDrawable">@android:drawable/progress_horizontal</item>
    <item
     name="android:indeterminateDrawable">@android:drawable/progress_horizontal</item>
    <item name="android:minHeight">8dip</item>
    <item name="android:maxHeight">10dip</item>
</style>

Also I want to save the brightness level of the image such that when I pass the image to another activity, the brighness is not lost. Can someone please guide me, how can I achieve it.

Thanks.

Answer 1

The problem is caused by doing manipulation on the same Bitmap reference (imageBitmap = doBrightness(imageBitmap, brightness);). Hence, when you drag the slider to the left, you're still continuously increasing the brightness to the image.

Try

brightness = progress;
//imageBitmap = doBrightness(imageBitmap, brightness);
putGestureImageOnScreen(doBrightness(imageBitmap, brightness));

For your 2nd question, you can use Intent to transfer the brightness value to next Activity and do the brightness manipulation once to get the same result.