services/core/java/com/android/server/display/color/DisplayWhiteBalanceTintController.java

/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.server.display.color;

import static com.android.server.display.color.DisplayTransformManager.LEVEL_COLOR_MATRIX_DISPLAY_WHITE_BALANCE;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.ColorSpace;
import android.hardware.display.ColorDisplayManager;
import android.opengl.Matrix;
import android.os.IBinder;
import android.util.Slog;
import android.view.SurfaceControl;
import android.view.SurfaceControl.DisplayPrimaries;

import com.android.internal.R;
import com.android.internal.annotations.VisibleForTesting;

import java.io.PrintWriter;
import java.lang.System;

final class DisplayWhiteBalanceTintController extends TintController {

    // Three chromaticity coordinates per color: X, Y, and Z
    private static final int NUM_VALUES_PER_PRIMARY = 3;
    // Four colors: red, green, blue, and white
    private static final int NUM_DISPLAY_PRIMARIES_VALS = 4 * NUM_VALUES_PER_PRIMARY;
    private static final int COLORSPACE_MATRIX_LENGTH = 9;

    private final Object mLock = new Object();
    @VisibleForTesting
    int mTemperatureMin;
    @VisibleForTesting
    int mTemperatureMax;
    private int mTemperatureDefault;
    @VisibleForTesting
    float[] mDisplayNominalWhiteXYZ = new float[NUM_VALUES_PER_PRIMARY];
    @VisibleForTesting
    ColorSpace.Rgb mDisplayColorSpaceRGB;
    private float[] mChromaticAdaptationMatrix;
    @VisibleForTesting
    int mCurrentColorTemperature;
    private float[] mCurrentColorTemperatureXYZ;
    @VisibleForTesting
    boolean mSetUp = false;
    private float[] mMatrixDisplayWhiteBalance = new float[16];
    private Boolean mIsAvailable;

    @Override
    public void setUp(Context context, boolean needsLinear) {
        mSetUp = false;
        final Resources res = context.getResources();

        ColorSpace.Rgb displayColorSpaceRGB = getDisplayColorSpaceFromSurfaceControl();
        if (displayColorSpaceRGB == null) {
            Slog.w(ColorDisplayService.TAG,
                    "Failed to get display color space from SurfaceControl, trying res");
            displayColorSpaceRGB = getDisplayColorSpaceFromResources(res);
            if (displayColorSpaceRGB == null) {
                Slog.e(ColorDisplayService.TAG, "Failed to get display color space from resources");
                return;
            }
        }

        // Make sure display color space is valid
        if (!isColorMatrixValid(displayColorSpaceRGB.getTransform())) {
            Slog.e(ColorDisplayService.TAG, "Invalid display color space RGB-to-XYZ transform");
            return;
        }
        if (!isColorMatrixValid(displayColorSpaceRGB.getInverseTransform())) {
            Slog.e(ColorDisplayService.TAG, "Invalid display color space XYZ-to-RGB transform");
            return;
        }

        final String[] nominalWhiteValues = res.getStringArray(
                R.array.config_displayWhiteBalanceDisplayNominalWhite);
        float[] displayNominalWhiteXYZ = new float[NUM_VALUES_PER_PRIMARY];
        for (int i = 0; i < nominalWhiteValues.length; i++) {
            displayNominalWhiteXYZ[i] = Float.parseFloat(nominalWhiteValues[i]);
        }

        final int colorTemperatureMin = res.getInteger(
                R.integer.config_displayWhiteBalanceColorTemperatureMin);
        if (colorTemperatureMin <= 0) {
            Slog.e(ColorDisplayService.TAG,
                    "Display white balance minimum temperature must be greater than 0");
            return;
        }

        final int colorTemperatureMax = res.getInteger(
                R.integer.config_displayWhiteBalanceColorTemperatureMax);
        if (colorTemperatureMax < colorTemperatureMin) {
            Slog.e(ColorDisplayService.TAG,
                    "Display white balance max temp must be greater or equal to min");
            return;
        }

        final int colorTemperature = res.getInteger(
                R.integer.config_displayWhiteBalanceColorTemperatureDefault);

        synchronized (mLock) {
            mDisplayColorSpaceRGB = displayColorSpaceRGB;
            mDisplayNominalWhiteXYZ = displayNominalWhiteXYZ;
            mTemperatureMin = colorTemperatureMin;
            mTemperatureMax = colorTemperatureMax;
            mTemperatureDefault = colorTemperature;
            mSetUp = true;
        }

        setMatrix(mTemperatureDefault);
    }

    @Override
    public float[] getMatrix() {
        return mSetUp && isActivated() ? mMatrixDisplayWhiteBalance
                : ColorDisplayService.MATRIX_IDENTITY;
    }

    @Override
    public void setMatrix(int cct) {
        if (!mSetUp) {
            Slog.w(ColorDisplayService.TAG,
                    "Can't set display white balance temperature: uninitialized");
            return;
        }

        if (cct < mTemperatureMin) {
            Slog.w(ColorDisplayService.TAG,
                    "Requested display color temperature is below allowed minimum");
            cct = mTemperatureMin;
        } else if (cct > mTemperatureMax) {
            Slog.w(ColorDisplayService.TAG,
                    "Requested display color temperature is above allowed maximum");
            cct = mTemperatureMax;
        }

        Slog.d(ColorDisplayService.TAG, "setDisplayWhiteBalanceTemperatureMatrix: cct = " + cct);

        synchronized (mLock) {
            mCurrentColorTemperature = cct;

            // Adapt the display's nominal white point to match the requested CCT value
            mCurrentColorTemperatureXYZ = ColorSpace.cctToXyz(cct);

            mChromaticAdaptationMatrix =
                    ColorSpace.chromaticAdaptation(ColorSpace.Adaptation.BRADFORD,
                            mDisplayNominalWhiteXYZ, mCurrentColorTemperatureXYZ);

            // Convert the adaptation matrix to RGB space
            float[] result = ColorSpace.mul3x3(mChromaticAdaptationMatrix,
                    mDisplayColorSpaceRGB.getTransform());
            result = ColorSpace.mul3x3(mDisplayColorSpaceRGB.getInverseTransform(), result);

            // Normalize the transform matrix to peak white value in RGB space
            final float adaptedMaxR = result[0] + result[3] + result[6];
            final float adaptedMaxG = result[1] + result[4] + result[7];
            final float adaptedMaxB = result[2] + result[5] + result[8];
            final float denum = Math.max(Math.max(adaptedMaxR, adaptedMaxG), adaptedMaxB);

            Matrix.setIdentityM(mMatrixDisplayWhiteBalance, 0);
            for (int i = 0; i < result.length; i++) {
                result[i] /= denum;
                if (!isColorMatrixCoeffValid(result[i])) {
                    Slog.e(ColorDisplayService.TAG, "Invalid DWB color matrix");
                    return;
                }
            }

            java.lang.System.arraycopy(result, 0, mMatrixDisplayWhiteBalance, 0, 3);
            java.lang.System.arraycopy(result, 3, mMatrixDisplayWhiteBalance, 4, 3);
            java.lang.System.arraycopy(result, 6, mMatrixDisplayWhiteBalance, 8, 3);
        }
    }

    @Override
    public int getLevel() {
        return LEVEL_COLOR_MATRIX_DISPLAY_WHITE_BALANCE;
    }

    @Override
    public boolean isAvailable(Context context) {
        if (mIsAvailable == null) {
            mIsAvailable = ColorDisplayManager.isDisplayWhiteBalanceAvailable(context);
        }
        return mIsAvailable;
    }

    @Override
    public void dump(PrintWriter pw) {
        synchronized (mLock) {
            pw.println("    mSetUp = " + mSetUp);
            if (!mSetUp) {
                return;
            }

            pw.println("    mTemperatureMin = " + mTemperatureMin);
            pw.println("    mTemperatureMax = " + mTemperatureMax);
            pw.println("    mTemperatureDefault = " + mTemperatureDefault);
            pw.println("    mCurrentColorTemperature = " + mCurrentColorTemperature);
            pw.println("    mCurrentColorTemperatureXYZ = "
                    + matrixToString(mCurrentColorTemperatureXYZ, 3));
            pw.println("    mDisplayColorSpaceRGB RGB-to-XYZ = "
                    + matrixToString(mDisplayColorSpaceRGB.getTransform(), 3));
            pw.println("    mChromaticAdaptationMatrix = "
                    + matrixToString(mChromaticAdaptationMatrix, 3));
            pw.println("    mDisplayColorSpaceRGB XYZ-to-RGB = "
                    + matrixToString(mDisplayColorSpaceRGB.getInverseTransform(), 3));
            pw.println("    mMatrixDisplayWhiteBalance = "
                    + matrixToString(mMatrixDisplayWhiteBalance, 4));
        }
    }

    /**
     * Format a given matrix into a string.
     *
     * @param matrix the matrix to format
     * @param columns number of columns in the matrix
     */
    private String matrixToString(float[] matrix, int columns) {
        if (matrix == null || columns <= 0) {
            Slog.e(ColorDisplayService.TAG, "Invalid arguments when formatting matrix to string");
            return "";
        }

        final StringBuilder sb = new StringBuilder("");
        for (int i = 0; i < matrix.length; i++) {
            if (i % columns == 0) {
                sb.append("\n      ");
            }
            sb.append(String.format("%9.6f", matrix[i]));
        }
        return sb.toString();
    }

    private ColorSpace.Rgb makeRgbColorSpaceFromXYZ(float[] redGreenBlueXYZ, float[] whiteXYZ) {
        return new ColorSpace.Rgb(
                "Display Color Space",
                redGreenBlueXYZ,
                whiteXYZ,
                2.2f // gamma, unused for display white balance
        );
    }

    private ColorSpace.Rgb getDisplayColorSpaceFromSurfaceControl() {
        final IBinder displayToken = SurfaceControl.getInternalDisplayToken();
        if (displayToken == null) {
            return null;
        }

        DisplayPrimaries primaries = SurfaceControl.getDisplayNativePrimaries(displayToken);
        if (primaries == null || primaries.red == null || primaries.green == null
                || primaries.blue == null || primaries.white == null) {
            return null;
        }

        return makeRgbColorSpaceFromXYZ(
                new float[]{
                        primaries.red.X, primaries.red.Y, primaries.red.Z,
                        primaries.green.X, primaries.green.Y, primaries.green.Z,
                        primaries.blue.X, primaries.blue.Y, primaries.blue.Z,
                },
                new float[]{primaries.white.X, primaries.white.Y, primaries.white.Z}
        );
    }

    private ColorSpace.Rgb getDisplayColorSpaceFromResources(Resources res) {
        final String[] displayPrimariesValues = res.getStringArray(
                R.array.config_displayWhiteBalanceDisplayPrimaries);
        float[] displayRedGreenBlueXYZ =
                new float[NUM_DISPLAY_PRIMARIES_VALS - NUM_VALUES_PER_PRIMARY];
        float[] displayWhiteXYZ = new float[NUM_VALUES_PER_PRIMARY];

        for (int i = 0; i < displayRedGreenBlueXYZ.length; i++) {
            displayRedGreenBlueXYZ[i] = Float.parseFloat(displayPrimariesValues[i]);
        }

        for (int i = 0; i < displayWhiteXYZ.length; i++) {
            displayWhiteXYZ[i] = Float.parseFloat(
                    displayPrimariesValues[displayRedGreenBlueXYZ.length + i]);
        }

        return makeRgbColorSpaceFromXYZ(displayRedGreenBlueXYZ, displayWhiteXYZ);
    }

    private boolean isColorMatrixCoeffValid(float coeff) {
        if (Float.isNaN(coeff) || Float.isInfinite(coeff)) {
            return false;
        }

        return true;
    }

    private boolean isColorMatrixValid(float[] matrix) {
        if (matrix == null || matrix.length != COLORSPACE_MATRIX_LENGTH) {
            return false;
        }

        for (int i = 0; i < matrix.length; i++) {
            if (!isColorMatrixCoeffValid(matrix[i])) {
                return false;
            }
        }

        return true;
    }

}