LinearGradient.java revision 8a6ad4a89d1b9ed61d3ec6f5bc12d479bc8d9f3b 
1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.graphics;
18
19import android.annotation.ColorInt;
20import android.annotation.NonNull;
21import android.annotation.Nullable;
22
23public class LinearGradient extends Shader {
24
25    private static final int TYPE_COLORS_AND_POSITIONS = 1;
26    private static final int TYPE_COLOR_START_AND_COLOR_END = 2;
27
28    /**
29     * Type of the LinearGradient: can be either TYPE_COLORS_AND_POSITIONS or
30     * TYPE_COLOR_START_AND_COLOR_END.
31     */
32    private int mType;
33
34    private float mX0;
35    private float mY0;
36    private float mX1;
37    private float mY1;
38    private int[] mColors;
39    private float[] mPositions;
40    private int mColor0;
41    private int mColor1;
42
43    private TileMode mTileMode;
44
45    /**
46     * Create a shader that draws a linear gradient along a line.
47     *
48     * @param x0           The x-coordinate for the start of the gradient line
49     * @param y0           The y-coordinate for the start of the gradient line
50     * @param x1           The x-coordinate for the end of the gradient line
51     * @param y1           The y-coordinate for the end of the gradient line
52     * @param colors       The colors to be distributed along the gradient line
53     * @param positions    May be null. The relative positions [0..1] of
54     *                     each corresponding color in the colors array. If this is null,
55     *                     the the colors are distributed evenly along the gradient line.
56     * @param tile         The Shader tiling mode
57    */
58    public LinearGradient(float x0, float y0, float x1, float y1, @NonNull @ColorInt int colors[],
59            @Nullable float positions[], @NonNull TileMode tile) {
60        if (colors.length < 2) {
61            throw new IllegalArgumentException("needs >= 2 number of colors");
62        }
63        if (positions != null && colors.length != positions.length) {
64            throw new IllegalArgumentException("color and position arrays must be of equal length");
65        }
66        mType = TYPE_COLORS_AND_POSITIONS;
67        mX0 = x0;
68        mY0 = y0;
69        mX1 = x1;
70        mY1 = y1;
71        mColors = colors.clone();
72        mPositions = positions != null ? positions.clone() : null;
73        mTileMode = tile;
74    }
75
76    /**
77     * Create a shader that draws a linear gradient along a line.
78     *
79     * @param x0       The x-coordinate for the start of the gradient line
80     * @param y0       The y-coordinate for the start of the gradient line
81     * @param x1       The x-coordinate for the end of the gradient line
82     * @param y1       The y-coordinate for the end of the gradient line
83     * @param color0   The color at the start of the gradient line.
84     * @param color1   The color at the end of the gradient line.
85     * @param tile     The Shader tiling mode
86    */
87    public LinearGradient(float x0, float y0, float x1, float y1,
88            @ColorInt int color0, @ColorInt int color1,
89            @NonNull TileMode tile) {
90        mType = TYPE_COLOR_START_AND_COLOR_END;
91        mX0 = x0;
92        mY0 = y0;
93        mX1 = x1;
94        mY1 = y1;
95        mColor0 = color0;
96        mColor1 = color1;
97        mColors = null;
98        mPositions = null;
99        mTileMode = tile;
100    }
101
102    @Override
103    long createNativeInstance(long nativeMatrix) {
104        if (mType == TYPE_COLORS_AND_POSITIONS) {
105            return nativeCreate1(nativeMatrix, mX0, mY0, mX1, mY1,
106                    mColors, mPositions, mTileMode.nativeInt);
107        } else { // TYPE_COLOR_START_AND_COLOR_END
108            return nativeCreate2(nativeMatrix, mX0, mY0, mX1, mY1,
109                    mColor0, mColor1, mTileMode.nativeInt);
110        }
111    }
112
113    /**
114     * @hide
115     */
116    @Override
117    protected Shader copy() {
118        final LinearGradient copy;
119        if (mType == TYPE_COLORS_AND_POSITIONS) {
120            copy = new LinearGradient(mX0, mY0, mX1, mY1, mColors.clone(),
121                    mPositions != null ? mPositions.clone() : null, mTileMode);
122        } else { // TYPE_COLOR_START_AND_COLOR_END
123            copy = new LinearGradient(mX0, mY0, mX1, mY1, mColor0, mColor1, mTileMode);
124        }
125        copyLocalMatrix(copy);
126        return copy;
127    }
128
129    private native long nativeCreate1(long matrix, float x0, float y0, float x1, float y1,
130            int colors[], float positions[], int tileMode);
131    private native long nativeCreate2(long matrix, float x0, float y0, float x1, float y1,
132            int color0, int color1, int tileMode);
133}
134