ColorOverlayDimmer.java revision cf94c5fa8ae8edb7e26a623133207415ceeed187 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.graphics;
15
16import android.content.Context;
17import android.graphics.Canvas;
18import android.graphics.Color;
19import android.graphics.Paint;
20import android.support.v17.leanback.R;
21import android.view.View;
22
23/**
24 * Helper class for assigning dim color to Paint.
25 * The class holds alpha value according to current active level.
26 */
27public final class ColorOverlayDimmer {
28
29    private final float mActiveLevel;
30    private final float mDimmedLevel;
31
32    private final Paint mPaint;
33
34    private int mAlpha;
35    private float mAlphaFloat;
36
37    /**
38     * Constructor for this ColorOverlayDimmer class.
39     *
40     * @param dimColor    The color for fully dimmed.  Only r/g/b are used, alpha channel is
41     *                    ignored.
42     * @param activeLevel The Level of dimming for when the view is in its Active state. Must be a
43     *                    float value between 0.0 and 1.0.
44     * @param dimmedLevel The Level of dimming for when the view is in its Dimmed state. Must be a
45     *                    float value between 0.0 and 1.0.
46     */
47    public static ColorOverlayDimmer createOverlayColorDimmer(int dimColor, float activeLevel,
48            float dimmedLevel) {
49        return new ColorOverlayDimmer(dimColor, activeLevel, dimmedLevel);
50    }
51
52    /**
53     * Constructor to create a default ColorOverlayDimmer.
54     */
55    public static ColorOverlayDimmer createDefault(Context context) {
56        return new ColorOverlayDimmer(
57                context.getResources().getColor(R.color.lb_view_dim_mask_color), 0,
58                context.getResources().getFraction(R.dimen.lb_view_dimmed_level, 1, 1));
59    }
60
61    private ColorOverlayDimmer(int dimColor, float activeLevel, float dimmedLevel) {
62        if (activeLevel < 0 || activeLevel > 1) {
63            throw new IllegalArgumentException("activeLevel must be between 0 and 1");
64        }
65        if (dimmedLevel < 0 || dimmedLevel > 1) {
66            throw new IllegalArgumentException("dimmedLevel must be between 0 and 1");
67        }
68        mPaint = new Paint();
69        dimColor = Color.rgb(Color.red(dimColor), Color.green(dimColor), Color.blue(dimColor));
70        mPaint.setColor(dimColor);
71        mActiveLevel = activeLevel;
72        mDimmedLevel = dimmedLevel;
73    }
74
75    /**
76     * Set level of active and change alpha value and paint object.
77     * @param level Between 0 for dim and 1 for fully active.
78     */
79    public void setActiveLevel(float level) {
80        mAlphaFloat = (mDimmedLevel + level * (mActiveLevel - mDimmedLevel));
81        mAlpha = (int) (255 * mAlphaFloat);
82        mPaint.setAlpha(mAlpha);
83    }
84
85    /**
86     * Returns true if dimmer needs to draw.
87     */
88    public boolean needsDraw() {
89        return mAlpha != 0;
90    }
91
92    /**
93     * Returns the alpha value for dimmer.
94     */
95    public int getAlpha() {
96        return mAlpha;
97    }
98
99    /**
100     * Returns the float value between 0~1,  corresponding to alpha between 0~255.
101     */
102    public float getAlphaFloat() {
103        return mAlphaFloat;
104    }
105
106    /**
107     * Returns the paint object set to current alpha value.
108     */
109    public Paint getPaint() {
110        return mPaint;
111    }
112
113    /**
114     * Change r,g,b of color according to current dim level.  Keeps alpha of color.
115     */
116    public int applyToColor(int color) {
117        float f = 1 - mAlphaFloat;
118        return Color.argb(Color.alpha(color),
119                (int)(Color.red(color) * f),
120                (int)(Color.green(color) * f),
121                (int)(Color.blue(color) * f));
122    }
123
124    /**
125     * Draw a dim color overlay on top of a child view inside canvas of parent view.
126     * @param c   Canvas of parent view.
127     * @param v   Child of parent view.
128     * @param includePadding  Set to true to draw overlay on padding area of the view.
129     */
130    public void drawColorOverlay(Canvas c, View v, boolean includePadding) {
131        c.save();
132        float dx = v.getLeft() + v.getTranslationX();
133        float dy = v.getTop() + v.getTranslationY();
134        c.translate(dx, dy);
135        c.concat(v.getMatrix());
136        c.translate(-dx, -dy);
137        if (includePadding) {
138            c.drawRect(v.getLeft(), v.getTop(), v.getRight(), v.getBottom(), mPaint);
139        } else {
140            c.drawRect(v.getLeft() + v.getPaddingLeft(),
141                    v.getTop() + v.getPaddingTop(),
142                    v.getRight() - v.getPaddingRight(),
143                    v.getBottom() - v.getPaddingBottom(), mPaint);
144        }
145        c.restore();
146    }
147}
148