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Commit 82e484b4 authored by wilsonshih's avatar wilsonshih Committed by Wei Sheng Shih
Browse files

Add luminance condition to validate color contrast. 

Reference WCAG to calculate color contrast via luminance, add this as
one condition for similar color validate.

Bug: 184830058
Test: atest SplashscreenTests
Change-Id: I93bad2a8ff813036e71757e50f82b6d0ea7f81d5
parent 692496d9

libs/WindowManager/Shell/src/com/android/wm/shell/startingsurface/SplashscreenContentDrawer.java

+21 −5
Original line number Diff line number Diff line
@@ -435,6 +435,18 @@ public class SplashscreenContentDrawer { 
        if (a == b) {

            return true;

        }

        final float lumA = Color.luminance(a);

        final float lumB = Color.luminance(b);

        final float contrastRatio = lumA > lumB

                ? (lumA + 0.05f) / (lumB + 0.05f) : (lumB + 0.05f) / (lumA + 0.05f);

        if (DEBUG) {

            Slog.d(TAG, "isRgbSimilarInHsv a: " + Integer.toHexString(a)

                    + " b " + Integer.toHexString(b) + " contrast ratio: " + contrastRatio);

        }

        if (contrastRatio < 2) {

            return true;

        }



        final float[] aHsv = new float[3];

        final float[] bHsv = new float[3];

        Color.colorToHSV(a, aHsv);
@@ -445,14 +457,18 @@ public class SplashscreenContentDrawer { 


        // Calculate the difference between two colors based on the HSV dimensions.

        final float normalizeH = minAngle / 180f;

        final double square = Math.pow(normalizeH, 2)

                + Math.pow(aHsv[1] - bHsv[1], 2)

                + Math.pow(aHsv[2] - bHsv[2], 2);

        final double squareH = Math.pow(normalizeH, 2);

        final double squareS = Math.pow(aHsv[1] - bHsv[1], 2);

        final double squareV = Math.pow(aHsv[2] - bHsv[2], 2);

        final double square = squareH + squareS + squareV;

        final double mean = square / 3;

        final double root = Math.sqrt(mean);

        if (DEBUG) {

            Slog.d(TAG, "hsvDiff " + minAngle + " a: " + Integer.toHexString(a)

                    + " b " + Integer.toHexString(b) + " ah " + aHsv[0] + " bh " + bHsv[0]

            Slog.d(TAG, "hsvDiff " + minAngle

                    + " ah " + aHsv[0] + " bh " + bHsv[0]

                    + " as " + aHsv[1] + " bs " + bHsv[1]

                    + " av " + aHsv[2] + " bv " + bHsv[2]

                    + " sqH " + squareH + " sqS " + squareS + " sqV " + squareV

                    + " root " + root);

        }

        return root < 0.1;