/*
* Copyright (C) 2007 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.
*/
package android.graphics;
import android.util.FloatMath;
import java.util.Arrays;
/**
* 4x5 matrix for transforming the color and alpha components of a Bitmap.
* The matrix can be passed as single array, and is treated as follows:
*
* <pre>
* [ a, b, c, d, e,
* f, g, h, i, j,
* k, l, m, n, o,
* p, q, r, s, t ]</pre>
*
* <p>
* When applied to a color <code>[R, G, B, A]</code>, the resulting color
* is computed as:
* </p>
*
* <pre>
* R’ = a*R + b*G + c*B + d*A + e;
* G’ = f*R + g*G + h*B + i*A + j;
* B’ = k*R + l*G + m*B + n*A + o;
* A’ = p*R + q*G + r*B + s*A + t;</pre>
*
* <p>
* That resulting color <code>[R’, G’, B’, A’]</code>
* then has each channel clamped to the <code>0</code> to <code>255</code>
* range.
* </p>
*
* <p>
* The sample ColorMatrix below inverts incoming colors by scaling each
* channel by <code>-1</code>, and then shifting the result up by
* <code>255</code> to remain in the standard color space.
* </p>
*
* <pre>
* [ -1, 0, 0, 0, 255,
* 0, -1, 0, 0, 255,
* 0, 0, -1, 0, 255,
* 0, 0, 0, 1, 0 ]</pre>
*/
@SuppressWarnings({ "MismatchedReadAndWriteOfArray", "PointlessArithmeticExpression" })
public class ColorMatrix {
private final float[] mArray = new float[20];
/**
* Create a new colormatrix initialized to identity (as if reset() had
* been called).
*/
public ColorMatrix() {
reset();
}
/**
* Create a new colormatrix initialized with the specified array of values.
*/
public ColorMatrix(float[] src) {
System.arraycopy(src, 0, mArray, 0, 20);
}
/**
* Create a new colormatrix initialized with the specified colormatrix.
*/
public ColorMatrix(ColorMatrix src) {
System.arraycopy(src.mArray, 0, mArray, 0, 20);
}
/**
* Return the array of floats representing this colormatrix.
*/
public final float[] getArray() { return mArray; }
/**
* Set this colormatrix to identity:
* <pre>
* [ 1 0 0 0 0 - red vector
* 0 1 0 0 0 - green vector
* 0 0 1 0 0 - blue vector
* 0 0 0 1 0 ] - alpha vector
* </pre>
*/
public void reset() {
final float[] a = mArray;
Arrays.fill(a, 0);
a[0] = a[6] = a[12] = a[18] = 1;
}
/**
* Assign the src colormatrix into this matrix, copying all of its values.
*/
public void set(ColorMatrix src) {
System.arraycopy(src.mArray, 0, mArray, 0, 20);
}
/**
* Assign the array of floats into this matrix, copying all of its values.
*/
public void set(float[] src) {
System.arraycopy(src, 0, mArray, 0, 20);
}
/**
* Set this colormatrix to scale by the specified values.
*/
public void setScale(float rScale, float gScale, float bScale,
float aScale) {
final float[] a = mArray;
for (int i = 19; i > 0; --i) {
a[i] = 0;
}
a[0] = rScale;
a[6] = gScale;
a[12] = bScale;
a[18] = aScale;
}
/**
* Set the rotation on a color axis by the specified values.
* <p>
* <code>axis=0</code> correspond to a rotation around the RED color
* <code>axis=1</code> correspond to a rotation around the GREEN color
* <code>axis=2</code> correspond to a rotation around the BLUE color
* </p>
*/
public void setRotate(int axis, float degrees) {
reset();
float radians = degrees * (float)Math.PI / 180;
float cosine = FloatMath.cos(radians);
float sine = FloatMath.sin(radians);
switch (axis) {
// Rotation around the red color
case 0:
mArray[6] = mArray[12] = cosine;
mArray[7] = sine;
mArray[11] = -sine;
break;
// Rotation around the green color
case 1:
mArray[0] = mArray[12] = cosine;
mArray[2] = -sine;
mArray[10] = sine;
break;
// Rotation around the blue color
case 2:
mArray[0] = mArray[6] = cosine;
mArray[1] = sine;
mArray[5] = -sine;
break;
default:
throw new RuntimeException();
}
}
/**
* Set this colormatrix to the concatenation of the two specified
* colormatrices, such that the resulting colormatrix has the same effect
* as applying matB and then applying matA.
* <p>
* It is legal for either matA or matB to be the same colormatrix as this.
* </p>
*/
public void setConcat(ColorMatrix matA, ColorMatrix matB) {
float[] tmp;
if (matA == this || matB == this) {
tmp = new float[20];
} else {
tmp = mArray;
}
final float[] a = matA.mArray;
final float[] b = matB.mArray;
int index = 0;
for (int j = 0; j < 20; j += 5) {
for (int i = 0; i < 4; i++) {
tmp[index++] = a[j + 0] * b[i + 0] + a[j + 1] * b[i + 5] +
a[j + 2] * b[i + 10] + a[j + 3] * b[i + 15];
}
tmp[index++] = a[j + 0] * b[4] + a[j + 1] * b[9] +
a[j + 2] * b[14] + a[j + 3] * b[19] +
a[j + 4];
}
if (tmp != mArray) {
System.arraycopy(tmp, 0, mArray, 0, 20);
}
}
/**
* Concat this colormatrix with the specified prematrix.
* <p>
* This is logically the same as calling setConcat(this, prematrix);
* </p>
*/
public void preConcat(ColorMatrix prematrix) {
setConcat(this, prematrix);
}
/**
* Concat this colormatrix with the specified postmatrix.
* <p>
* This is logically the same as calling setConcat(postmatrix, this);
* </p>
*/
public void postConcat(ColorMatrix postmatrix) {
setConcat(postmatrix, this);
}
///////////////////////////////////////////////////////////////////////////
/**
* Set the matrix to affect the saturation of colors.
*
* @param sat A value of 0 maps the color to gray-scale. 1 is identity.
*/
public void setSaturation(float sat) {
reset();
float[] m = mArray;
final float invSat = 1 - sat;
final float R = 0.213f * invSat;
final float G = 0.715f * invSat;
final float B = 0.072f * invSat;
m[0] = R + sat; m[1] = G; m[2] = B;
m[5] = R; m[6] = G + sat; m[7] = B;
m[10] = R; m[11] = G; m[12] = B + sat;
}
/**
* Set the matrix to convert RGB to YUV
*/
public void setRGB2YUV() {
reset();
float[] m = mArray;
// these coefficients match those in libjpeg
m[0] = 0.299f; m[1] = 0.587f; m[2] = 0.114f;
m[5] = -0.16874f; m[6] = -0.33126f; m[7] = 0.5f;
m[10] = 0.5f; m[11] = -0.41869f; m[12] = -0.08131f;
}
/**
* Set the matrix to convert from YUV to RGB
*/
public void setYUV2RGB() {
reset();
float[] m = mArray;
// these coefficients match those in libjpeg
m[2] = 1.402f;
m[5] = 1; m[6] = -0.34414f; m[7] = -0.71414f;
m[10] = 1; m[11] = 1.772f; m[12] = 0;
}
}
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