1/*
2 * Copyright (C) 2013 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
17#ifndef ANDROID_HWUI_UV_MAPPER_H
18#define ANDROID_HWUI_UV_MAPPER_H
19
20#include "Rect.h"
21
22namespace android {
23namespace uirenderer {
24
25/**
26 * This class can be used to map UV coordinates from the [0..1]
27 * range to other arbitrary ranges. All the methods below assume
28 * that the input values lie in the [0..1] range already.
29 */
30class UvMapper {
31public:
32    /**
33     * Using this constructor is equivalent to not using any mapping at all.
34     * UV coordinates in the [0..1] range remain in the [0..1] range.
35     */
36    UvMapper(): mIdentity(true), mMinU(0.0f), mMaxU(1.0f), mMinV(0.0f), mMaxV(1.0f) {
37    }
38
39    /**
40     * Creates a new mapper with the specified ranges for U and V coordinates.
41     * The parameter minU must be < maxU and minV must be < maxV.
42     */
43    UvMapper(float minU, float maxU, float minV, float maxV):
44        mMinU(minU), mMaxU(maxU), mMinV(minV), mMaxV(maxV) {
45        checkIdentity();
46    }
47
48    /**
49     * Returns true if calling the map*() methods has no effect (that is,
50     * texture coordinates remain in the 0..1 range.)
51     */
52    bool isIdentity() const {
53        return mIdentity;
54    }
55
56    /**
57     * Changes the U and V mapping ranges.
58     * The parameter minU must be < maxU and minV must be < maxV.
59     */
60    void setMapping(float minU, float maxU, float minV, float maxV) {
61        mMinU = minU;
62        mMaxU = maxU;
63        mMinV = minV;
64        mMaxV = maxV;
65        checkIdentity();
66    }
67
68    /**
69     * Maps a single value in the U range.
70     */
71    void mapU(float& u) const {
72        if (!mIdentity) u = lerp(mMinU, mMaxU, u);
73    }
74
75    /**
76     * Maps a single value in the V range.
77     */
78    void mapV(float& v) const {
79        if (!mIdentity) v = lerp(mMinV, mMaxV, v);
80    }
81
82    /**
83     * Maps the specified rectangle in place. This method assumes:
84     * - left = min. U
85     * - top = min. V
86     * - right = max. U
87     * - bottom = max. V
88     */
89    void map(Rect& texCoords) const {
90        if (!mIdentity) {
91            texCoords.left = lerp(mMinU, mMaxU, texCoords.left);
92            texCoords.right = lerp(mMinU, mMaxU, texCoords.right);
93            texCoords.top = lerp(mMinV, mMaxV, texCoords.top);
94            texCoords.bottom = lerp(mMinV, mMaxV, texCoords.bottom);
95        }
96    }
97
98    /**
99     * Maps the specified UV coordinates in place.
100     */
101    void map(float& u1, float& v1, float& u2, float& v2) const {
102        if (!mIdentity) {
103            u1 = lerp(mMinU, mMaxU, u1);
104            u2 = lerp(mMinU, mMaxU, u2);
105            v1 = lerp(mMinV, mMaxV, v1);
106            v2 = lerp(mMinV, mMaxV, v2);
107        }
108    }
109
110    void dump() const {
111        ALOGD("mapper[minU=%.2f maxU=%.2f minV=%.2f maxV=%.2f]", mMinU, mMaxU, mMinV, mMaxV);
112    }
113
114private:
115    static float lerp(float start, float stop, float amount) {
116        return start + (stop - start) * amount;
117    }
118
119    void checkIdentity() {
120        mIdentity = mMinU == 0.0f && mMaxU == 1.0f && mMinV == 0.0f && mMaxV == 1.0f;
121    }
122
123    bool mIdentity;
124    float mMinU;
125    float mMaxU;
126    float mMinV;
127    float mMaxV;
128};
129
130}; // namespace uirenderer
131}; // namespace android
132
133#endif // ANDROID_HWUI_UV_MAPPER_H
134