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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_HWUI_UV_MAPPER_H
#define ANDROID_HWUI_UV_MAPPER_H
#include "Rect.h"
namespace android {
namespace uirenderer {
/**
* This class can be used to map UV coordinates from the [0..1]
* range to other arbitrary ranges. All the methods below assume
* that the input values lie in the [0..1] range already.
*/
class UvMapper {
public:
/**
* Using this constructor is equivalent to not using any mapping at all.
* UV coordinates in the [0..1] range remain in the [0..1] range.
*/
UvMapper() : mIdentity(true), mMinU(0.0f), mMaxU(1.0f), mMinV(0.0f), mMaxV(1.0f) {}
/**
* Creates a new mapper with the specified ranges for U and V coordinates.
* The parameter minU must be < maxU and minV must be < maxV.
*/
UvMapper(float minU, float maxU, float minV, float maxV)
: mMinU(minU), mMaxU(maxU), mMinV(minV), mMaxV(maxV) {
checkIdentity();
}
/**
* Returns true if calling the map*() methods has no effect (that is,
* texture coordinates remain in the 0..1 range.)
*/
bool isIdentity() const { return mIdentity; }
/**
* Changes the U and V mapping ranges.
* The parameter minU must be < maxU and minV must be < maxV.
*/
void setMapping(float minU, float maxU, float minV, float maxV) {
mMinU = minU;
mMaxU = maxU;
mMinV = minV;
mMaxV = maxV;
checkIdentity();
}
/**
* Maps a single value in the U range.
*/
void mapU(float& u) const {
if (!mIdentity) u = lerp(mMinU, mMaxU, u);
}
/**
* Maps a single value in the V range.
*/
void mapV(float& v) const {
if (!mIdentity) v = lerp(mMinV, mMaxV, v);
}
/**
* Maps the specified rectangle in place. This method assumes:
* - left = min. U
* - top = min. V
* - right = max. U
* - bottom = max. V
*/
void map(Rect& texCoords) const {
if (!mIdentity) {
texCoords.left = lerp(mMinU, mMaxU, texCoords.left);
texCoords.right = lerp(mMinU, mMaxU, texCoords.right);
texCoords.top = lerp(mMinV, mMaxV, texCoords.top);
texCoords.bottom = lerp(mMinV, mMaxV, texCoords.bottom);
}
}
/**
* Maps the specified UV coordinates in place.
*/
void map(float& u1, float& v1, float& u2, float& v2) const {
if (!mIdentity) {
u1 = lerp(mMinU, mMaxU, u1);
u2 = lerp(mMinU, mMaxU, u2);
v1 = lerp(mMinV, mMaxV, v1);
v2 = lerp(mMinV, mMaxV, v2);
}
}
void dump() const {
ALOGD("mapper[minU=%.2f maxU=%.2f minV=%.2f maxV=%.2f]", mMinU, mMaxU, mMinV, mMaxV);
}
private:
static float lerp(float start, float stop, float amount) {
return start + (stop - start) * amount;
}
void checkIdentity() {
mIdentity = mMinU == 0.0f && mMaxU == 1.0f && mMinV == 0.0f && mMaxV == 1.0f;
}
bool mIdentity;
float mMinU;
float mMaxU;
float mMinV;
float mMaxV;
};
} // namespace uirenderer
} // namespace android
#endif // ANDROID_HWUI_UV_MAPPER_H
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