AvoidXfermode.java revision 7df951595fa99bb4ead7891a2d70e3281314c51e 
1/*
2 * Copyright (C) 2008 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
19/**
20 * AvoidXfermode xfermode will draw the src everywhere except on top of the
21 * opColor or, depending on the Mode, draw only on top of the opColor.
22 */
23public class AvoidXfermode extends Xfermode {
24
25    // these need to match the enum in SkAvoidXfermode.h on the native side
26    public enum Mode {
27        AVOID   (0),    //!< draw everywhere except on the opColor
28        TARGET  (1);    //!< draw only on top of the opColor
29
30        Mode(int nativeInt) {
31            this.nativeInt = nativeInt;
32        }
33        final int nativeInt;
34    }
35
36    /** This xfermode draws, or doesn't draw, based on the destination's
37     * distance from an op-color.
38     *
39     * There are two modes, and each mode interprets a tolerance value.
40     *
41     * Avoid: In this mode, drawing is allowed only on destination pixels that
42     * are different from the op-color.
43     * Tolerance near 0: avoid any colors even remotely similar to the op-color
44     * Tolerance near 255: avoid only colors nearly identical to the op-color
45
46     * Target: In this mode, drawing only occurs on destination pixels that
47     * are similar to the op-color
48     * Tolerance near 0: draw only on colors that are nearly identical to the op-color
49     * Tolerance near 255: draw on any colors even remotely similar to the op-color
50     */
51    public AvoidXfermode(int opColor, int tolerance, Mode mode) {
52        if (tolerance < 0 || tolerance > 255) {
53            throw new IllegalArgumentException("tolerance must be 0..255");
54        }
55        native_instance = nativeCreate(opColor, tolerance, mode.nativeInt);
56    }
57
58    private static native int nativeCreate(int opColor, int tolerance,
59                                           int nativeMode);
60}
61