How to Distinguish UI Controls by Color Using UiAutomator in Android

Detecting a UI element’s dominant blue color with UiAutomator

The following routine captures a screenshot of the device, extracts the bitmap of a target UiObject, scans every pixel inside the object’s visible bounds, computes the average value of the blue channel, and returns true when the average exceeds a configurable threshold (default 200). This technique enables color‑based assertions in Android UI tests where a control’s appearance changes under different conditions.

public boolean isBlue(UiObject uiObject) throws UiObjectNotFoundException {
    // Capture the current screen to a temporary file
    screenShot("test");
    String path = "/mnt/sdcard/123/test.png";
    Bitmap bitmap = BitmapFactory.decodeFile(path);

    // Get the rectangle that encloses the UI element
    Rect rect = uiObject.getVisibleBounds();
    int left   = rect.left;
    int right  = rect.right;
    int top    = rect.top;
    int bottom = rect.bottom;

    // Accumulate the blue component of each pixel
    long blueSum = 0;
    int pixelCount = 0;
    for (int x = left; x < right; x++) {
        for (int y = top; y < bottom; y++) {
            int color = bitmap.getPixel(x, y);
            blueSum += Color.blue(color);
            pixelCount++;
        }
    }
    // Compute the average blue intensity (0‑255)
    int avgBlue = (int) (blueSum / pixelCount);
    // Threshold can be tuned per application
    return avgBlue > 200;
}

Utility methods for retrieving individual color channels

For finer‑grained checks you may need the exact red, green, or blue value at a specific coordinate. The helpers below reuse the same screenshot‑capture logic and return the requested channel or the full RGB triplet.

public int getRedPixel(int x, int y) {
    screenShot("test");
    String path = "/mnt/sdcard/123/test.png";
    Bitmap bitmap = BitmapFactory.decodeFile(path);
    int color = bitmap.getPixel(x, y);
    return Color.red(color);
}

public int getGreenPixel(int x, int y) {
    screenShot("test");
    String path = "/mnt/sdcard/123/test.png";
    Bitmap bitmap = BitmapFactory.decodeFile(path);
    int color = bitmap.getPixel(x, y);
    return Color.green(color);
}

public int getBluePixel(int x, int y) {
    screenShot("test");
    String path = "/mnt/sdcard/123/test.png";
    Bitmap bitmap = BitmapFactory.decodeFile(path);
    int color = bitmap.getPixel(x, y);
    return Color.blue(color);
}

public int[] getRGBcolorPixel(int x, int y) {
    screenShot("testDemo");
    String path = "/mnt/sdcard/123/testDemo.png";
    Bitmap bitmap = BitmapFactory.decodeFile(path);
    int color = bitmap.getPixel(x, y);
    int red   = Color.red(color);
    int green = Color.green(color);
    int blue  = Color.blue(color);
    return new int[] { red, green, blue };
}

Practical considerations

Performance: Scanning every pixel inside a UI element can be costly on large controls. Limit the region or sample a subset of pixels if execution time becomes an issue.

Threshold tuning: The default value of 200 works for bright blue backgrounds on typical devices. Adjust the threshold based on device screen density, UI theme, or ambient lighting conditions.

File handling: The screenshot is saved to /mnt/sdcard/123/. Ensure the directory exists and the test runner has write permissions.

Re‑usability: The utility methods capture a fresh screenshot each call. If multiple color checks are needed for the same UI state, capture once and reuse the Bitmap to avoid redundant I/O.