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      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 
     22 namespace android {
     23 namespace 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  */
     30 class UvMapper {
     31 public:
     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 
    111 private:
    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