Android滤镜--ColorMatrixColorFilte

之前用到ColorMatrixColorFilter，其中除了传入一个五阶矩阵外，还可以使用ColorMatrix，调用其成员函数

    /**
     * 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;
    }

该方法为设置颜色缩放,可以实现颜色增强效果

    @Override
    protected void onDraw(Canvas canvas) {
        //画原图
        Paint paint = new Paint();
        RectF rectF = new RectF(100, 100, 100 + bitmap.getWidth() / 2, 100 + bitmap.getHeight() / 2);
        canvas.drawBitmap(bitmap, null, rectF, paint);

        //画设置ColorFilter效果后的图
        rectF = new RectF(600, 100, 600 + bitmap.getWidth() / 2, 100 + bitmap.getHeight() / 2);
        ColorMatrix colorMatrix = new ColorMatrix();
        //和颜色增强效果相同
        colorMatrix.setScale(1.2f, 1.2f, 1.2f, 1);
        paint.setColorFilter(new ColorMatrixColorFilter(colorMatrix));
        canvas.drawBitmap(bitmap, null, rectF, paint);
    }

缩放运算---乘法 -- 颜色增强.jpg

---

    /**
     * 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;
    }

设置饱和度

setSaturation.gif

---

    /**
     * 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();
        double radians = degrees * Math.PI / 180d;
        float cosine = (float) Math.cos(radians);
        float sine = (float) Math.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();
        }
    }

参数aixs为 0 红色轴，1，绿色，2，蓝色； 参数degrees为旋转的角度

setRotate.gif

---

    /**
     * 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);
        }
    }

组合效果，将两个ColorMatrix 的效果组合