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     * Creates a new mapper with the specified ranges for U and V coordinates.
40     * The parameter minU must be < maxU and minV must be < maxV.
41     */
42    UvMapper(float minU, float maxU, float minV, float maxV)
43            : mMinU(minU), mMaxU(maxU), mMinV(minV), mMaxV(maxV) {
44        checkIdentity();
45    }
46
47    /**
48     * Returns true if calling the map*() methods has no effect (that is,
49     * texture coordinates remain in the 0..1 range.)
50     */
51    bool isIdentity() const { return mIdentity; }
52
53    /**
54     * Changes the U and V mapping ranges.
55     * The parameter minU must be < maxU and minV must be < maxV.
56     */
57    void setMapping(float minU, float maxU, float minV, float maxV) {
58        mMinU = minU;
59        mMaxU = maxU;
60        mMinV = minV;
61        mMaxV = maxV;
62        checkIdentity();
63    }
64
65    /**
66     * Maps a single value in the U range.
67     */
68    void mapU(float& u) const {
69        if (!mIdentity) u = lerp(mMinU, mMaxU, u);
70    }
71
72    /**
73     * Maps a single value in the V range.
74     */
75    void mapV(float& v) const {
76        if (!mIdentity) v = lerp(mMinV, mMaxV, v);
77    }
78
79    /**
80     * Maps the specified rectangle in place. This method assumes:
81     * - left = min. U
82     * - top = min. V
83     * - right = max. U
84     * - bottom = max. V
85     */
86    void map(Rect& texCoords) const {
87        if (!mIdentity) {
88            texCoords.left = lerp(mMinU, mMaxU, texCoords.left);
89            texCoords.right = lerp(mMinU, mMaxU, texCoords.right);
90            texCoords.top = lerp(mMinV, mMaxV, texCoords.top);
91            texCoords.bottom = lerp(mMinV, mMaxV, texCoords.bottom);
92        }
93    }
94
95    /**
96     * Maps the specified UV coordinates in place.
97     */
98    void map(float& u1, float& v1, float& u2, float& v2) const {
99        if (!mIdentity) {
100            u1 = lerp(mMinU, mMaxU, u1);
101            u2 = lerp(mMinU, mMaxU, u2);
102            v1 = lerp(mMinV, mMaxV, v1);
103            v2 = lerp(mMinV, mMaxV, v2);
104        }
105    }
106
107    void dump() const {
108        ALOGD("mapper[minU=%.2f maxU=%.2f minV=%.2f maxV=%.2f]", mMinU, mMaxU, mMinV, mMaxV);
109    }
110
111private:
112    static float lerp(float start, float stop, float amount) {
113        return start + (stop - start) * amount;
114    }
115
116    void checkIdentity() {
117        mIdentity = mMinU == 0.0f && mMaxU == 1.0f && mMinV == 0.0f && mMaxV == 1.0f;
118    }
119
120    bool mIdentity;
121    float mMinU;
122    float mMaxU;
123    float mMinV;
124    float mMaxV;
125};
126
127};  // namespace uirenderer
128};  // namespace android
129
130#endif  // ANDROID_HWUI_UV_MAPPER_H
131