packages/SystemUI/src/com/android/systemui/recents/misc/Utilities.java

/*
 * Copyright (C) 2014 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.systemui.recents.misc;

import android.animation.Animator;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewParent;

import java.util.ArrayList;

/* Common code */
public class Utilities {

    /**
     * @return the first parent walking up the view hierarchy that has the given class type.
     *
     * @param parentClass must be a class derived from {@link View}
     */
    public static <T extends View> T findParent(View v, Class<T> parentClass) {
        ViewParent parent = v.getParent();
        while (parent != null) {
            if (parent.getClass().equals(parentClass)) {
                return (T) parent;
            }
            parent = parent.getParent();
        }
        return null;
    }

    /** Scales a rect about its centroid */
    public static void scaleRectAboutCenter(Rect r, float scale) {
        if (scale != 1.0f) {
            int cx = r.centerX();
            int cy = r.centerY();
            r.offset(-cx, -cy);
            r.left = (int) (r.left * scale + 0.5f);
            r.top = (int) (r.top * scale + 0.5f);
            r.right = (int) (r.right * scale + 0.5f);
            r.bottom = (int) (r.bottom * scale + 0.5f);
            r.offset(cx, cy);
        }
    }

    /** Maps a coorindate in a descendant view into the parent. */
    public static float mapCoordInDescendentToSelf(View descendant, View root,
            float[] coord, boolean includeRootScroll) {
        ArrayList<View> ancestorChain = new ArrayList<View>();

        float[] pt = {coord[0], coord[1]};

        View v = descendant;
        while(v != root && v != null) {
            ancestorChain.add(v);
            v = (View) v.getParent();
        }
        ancestorChain.add(root);

        float scale = 1.0f;
        int count = ancestorChain.size();
        for (int i = 0; i < count; i++) {
            View v0 = ancestorChain.get(i);
            // For TextViews, scroll has a meaning which relates to the text position
            // which is very strange... ignore the scroll.
            if (v0 != descendant || includeRootScroll) {
                pt[0] -= v0.getScrollX();
                pt[1] -= v0.getScrollY();
            }

            v0.getMatrix().mapPoints(pt);
            pt[0] += v0.getLeft();
            pt[1] += v0.getTop();
            scale *= v0.getScaleX();
        }

        coord[0] = pt[0];
        coord[1] = pt[1];
        return scale;
    }

    /** Maps a coordinate in the root to a descendent. */
    public static float mapCoordInSelfToDescendent(View descendant, View root,
            float[] coord, Matrix tmpInverseMatrix) {
        ArrayList<View> ancestorChain = new ArrayList<View>();

        float[] pt = {coord[0], coord[1]};

        View v = descendant;
        while(v != root) {
            ancestorChain.add(v);
            v = (View) v.getParent();
        }
        ancestorChain.add(root);

        float scale = 1.0f;
        int count = ancestorChain.size();
        tmpInverseMatrix.set(Matrix.IDENTITY_MATRIX);
        for (int i = count - 1; i >= 0; i--) {
            View ancestor = ancestorChain.get(i);
            View next = i > 0 ? ancestorChain.get(i-1) : null;

            pt[0] += ancestor.getScrollX();
            pt[1] += ancestor.getScrollY();

            if (next != null) {
                pt[0] -= next.getLeft();
                pt[1] -= next.getTop();
                next.getMatrix().invert(tmpInverseMatrix);
                tmpInverseMatrix.mapPoints(pt);
                scale *= next.getScaleX();
            }
        }

        coord[0] = pt[0];
        coord[1] = pt[1];
        return scale;
    }

    /** Calculates the constrast between two colors, using the algorithm provided by the WCAG v2. */
    public static float computeContrastBetweenColors(int bg, int fg) {
        float bgR = Color.red(bg) / 255f;
        float bgG = Color.green(bg) / 255f;
        float bgB = Color.blue(bg) / 255f;
        bgR = (bgR < 0.03928f) ? bgR / 12.92f : (float) Math.pow((bgR + 0.055f) / 1.055f, 2.4f);
        bgG = (bgG < 0.03928f) ? bgG / 12.92f : (float) Math.pow((bgG + 0.055f) / 1.055f, 2.4f);
        bgB = (bgB < 0.03928f) ? bgB / 12.92f : (float) Math.pow((bgB + 0.055f) / 1.055f, 2.4f);
        float bgL = 0.2126f * bgR + 0.7152f * bgG + 0.0722f * bgB;
        
        float fgR = Color.red(fg) / 255f;
        float fgG = Color.green(fg) / 255f;
        float fgB = Color.blue(fg) / 255f;
        fgR = (fgR < 0.03928f) ? fgR / 12.92f : (float) Math.pow((fgR + 0.055f) / 1.055f, 2.4f);
        fgG = (fgG < 0.03928f) ? fgG / 12.92f : (float) Math.pow((fgG + 0.055f) / 1.055f, 2.4f);
        fgB = (fgB < 0.03928f) ? fgB / 12.92f : (float) Math.pow((fgB + 0.055f) / 1.055f, 2.4f);
        float fgL = 0.2126f * fgR + 0.7152f * fgG + 0.0722f * fgB;

        return Math.abs((fgL + 0.05f) / (bgL + 0.05f));
    }

    /** Returns the base color overlaid with another overlay color with a specified alpha. */
    public static int getColorWithOverlay(int baseColor, int overlayColor, float overlayAlpha) {
        return Color.rgb(
            (int) (overlayAlpha * Color.red(baseColor) +
                    (1f - overlayAlpha) * Color.red(overlayColor)),
            (int) (overlayAlpha * Color.green(baseColor) +
                    (1f - overlayAlpha) * Color.green(overlayColor)),
            (int) (overlayAlpha * Color.blue(baseColor) +
                    (1f - overlayAlpha) * Color.blue(overlayColor)));
    }

    /**
     * Cancels an animation ensuring that if it has listeners, onCancel and onEnd
     * are not called.
     */
    public static void cancelAnimationWithoutCallbacks(Animator animator) {
        if (animator != null) {
            animator.removeAllListeners();
            animator.cancel();
        }
    }
}