Question

Is there any way to highlight tab icon image programmatically without using separate drawable resource?

I tried using PorterDuffColorFilter but it doesn’t look good:

// apply a color mask to the icon to mark it as selected
int selectedIconMaskColor = view.getResources().getColor(R.color.tab_icon_selected);
PorterDuffColorFilter selectedIconFilter = new PorterDuffColorFilter(selectedIconMaskColor,
  PorterDuff.Mode.SRC_ATOP);
copyIconDrawable.setColorFilter(selectedIconFilter);

Are there any other alternatives?

Answer 1

I ended up using simple image manipulation class:

import android.graphics.Bitmap;
import android.graphics.Color;

/**
 * Image with support for filtering.
 */
public class FilteredImage {

  private Bitmap image;

  private int width;

  private int height;

  private int[] colorArray;

  /**
   * Constructor.
   * 
   * @param img the original image
   */
  public FilteredImage(Bitmap img) {
    this.image = img;
    width = img.getWidth();
    height = img.getHeight();

    colorArray = new int[width * height];
    image.getPixels(colorArray, 0, width, 0, 0, width, height);

    applyHighlightFilter();
  }

  /**
   * Get the color for a specified pixel.
   * 
   * @param x x
   * @param y y
   * @return color
   */
  public int getPixelColor(int x, int y) {
    return colorArray[y * width + x];
  }

  /**
   * Gets the image.
   * 
   * @return Returns the image.
   */
  public Bitmap getImage() {
    return image;
  }

  /**
   * Applies green highlight filter to the image.
   */
  private void applyHighlightFilter() {
    int a;
    int r;
    int g;
    int b;
    for (int x = 0; x < width; x++) {
      for (int y = 0; y < height; y++) {

        int c = getPixelColor(x, y);

        a = Color.alpha(c);
        r = Color.red(c);
        g = Color.green(c);
        b = Color.blue(c);

        r = (int) (r * 0.8);
        g = (int) (g * 1.6);
        b = (int) (b * 0.8);

        if (r > 255) {
          r = 255;
        }
        if (r < 0) {
          r = 0;
        }
        if (g > 255) {
          g = 255;
        }
        if (g < 0) {
          g = 0;
        }
        if (b > 255) {
          b = 255;
        }
        if (b < 0) {
          b = 0;
        }

        int resultColor = Color.argb(a, r, g, b);
        image.setPixel(x, y, resultColor);
      }
    }
  }

}