Merge "Improve ColorMatrix docs" into lmp-mr1-dev

graphics/java/android/graphics/ColorMatrix.java

@@ -21,23 +21,43 @@ import android.util.FloatMath;
 import java.util.Arrays;
 
 /**
- *  4x5 matrix for transforming the color+alpha components of a Bitmap.
+ * 4x5 matrix for transforming the color and alpha components of a Bitmap.
- *  The matrix is stored in a single array, and its treated as follows:
+ * 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 ]
+ *    p, q, r, s, t ]</pre>
- * </pre>
+ *
+ * <p>
+ * When applied to a color <code>[R, G, B, A]</code>, the resulting color
+ * is computed as:
+ * </p>
  *
- * When applied to a color <code>[r, g, b, a]</code>, the resulting color
- * is computed as (after clamping):
  * <pre>
- *   R' = a*R + b*G + c*B + d*A + e;
+ *   R&rsquo; = a*R + b*G + c*B + d*A + e;
- *   G' = f*R + g*G + h*B + i*A + j;
+ *   G&rsquo; = f*R + g*G + h*B + i*A + j;
- *   B' = k*R + l*G + m*B + n*A + o;
+ *   B&rsquo; = k*R + l*G + m*B + n*A + o;
- *   A' = p*R + q*G + r*B + s*A + t;
+ *   A&rsquo; = p*R + q*G + r*B + s*A + t;</pre>
- * </pre>
+ *
+ * <p>
+ * That resulting color <code>[R&rsquo;, G&rsquo;, B&rsquo;, A&rsquo;]</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 {
@@ -117,9 +137,11 @@ public class ColorMatrix {
 
     /**
      * 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();
@@ -153,8 +175,10 @@ public class ColorMatrix {
     /**
      * 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. It is legal for either matA or
+     * as applying matB and then applying matA.
-     * matB to be the same colormatrix as this.
+     * <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;
@@ -183,16 +207,20 @@ public class ColorMatrix {
     }
 
     /**
-     * Concat this colormatrix with the specified prematrix. This is logically
+     * Concat this colormatrix with the specified prematrix.
-     * the same as calling setConcat(this, 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. This is logically
+     * Concat this colormatrix with the specified postmatrix.
-     * the same as calling setConcat(postmatrix, this);
+     * <p>
+     * This is logically the same as calling setConcat(postmatrix, this);
+     * </p>
      */
     public void postConcat(ColorMatrix postmatrix) {
         setConcat(postmatrix, this);
@@ -201,8 +229,9 @@ public class ColorMatrix {
     ///////////////////////////////////////////////////////////////////////////
 
     /**
-     * Set the matrix to affect the saturation of colors. A value of 0 maps the
+     * Set the matrix to affect the saturation of colors.
-     * color to gray-scale. 1 is identity.
+     *
+     * @param sat A value of 0 maps the color to gray-scale. 1 is identity.
      */
     public void setSaturation(float sat) {
         reset();
@@ -242,4 +271,3 @@ public class ColorMatrix {
         m[10] = 1;  m[11] = 1.772f;     m[12] = 0;
     }
 }
-