Expand modulate, add, subtract, extract component glsl helpers.

src/gpu/gl/GrGLSL.h

Index: src/gpu/gl/GrGLSL.h
===================================================================
--- src/gpu/gl/GrGLSL.h	(revision 8735)
+++ src/gpu/gl/GrGLSL.h	(working copy)
@@ -9,6 +9,7 @@
 #define GrGLSL_DEFINED
 
 #include "gl/GrGLInterface.h"
+#include "GrColor.h"
 #include "GrTypesPriv.h"
 
 class GrGLShaderVar;
@@ -103,10 +104,38 @@
 bool GrGLSLSetupFSColorOuput(GrGLSLGeneration gen,
                              const char* nameIfDeclared,
                              GrGLShaderVar* var);
+/**
+ * Converts a GrSLType to a string containing the name of the equivalent GLSL type.
+ */
+static const char* GrGLSLTypeString(GrSLType t) {
+    switch (t) {
+        case kVoid_GrSLType:
+            return "void";
+        case kFloat_GrSLType:
+            return "float";
+        case kVec2f_GrSLType:
+            return "vec2";
+        case kVec3f_GrSLType:
+            return "vec3";
+        case kVec4f_GrSLType:
+            return "vec4";
+        case kMat33f_GrSLType:
+            return "mat3";
+        case kMat44f_GrSLType:
+            return "mat4";
+        case kSampler2D_GrSLType:
+            return "sampler2D";
+        default:
+            GrCrash("Unknown shader var type.");
+            return ""; // suppress warning
+    }
+}
 
-/** Convert a count of 1..n floats into the corresponding type enum,
-    e.g. 1 -> kFloat_GrSLType, 2 -> kVec2_GrSLType, ... */
-GrSLType GrSLFloatVectorType(int count);
+/** Return the type enum for a vector of floats of length n (1..4),
+    e.g. 1 -> "float", 2 -> "vec2", ... */
+static inline const char* GrGLSLFloatVectorTypeString(int n) {
+    return GrGLSLTypeString(GrSLFloatVectorType(n));
+}
 
 /** Return the GLSL swizzle operator for a homogenous component of a vector
     with the given number of coordinates, e.g. 2 -> ".y", 3 -> ".z" */
@@ -119,21 +148,60 @@
 const char* GrGLSLVectorNonhomogCoords(GrSLType type);
 
 /**
-  * Produces a string that is the result of modulating two inputs. The inputs must be vec4 or
-  * float. The result is always a vec4. The inputs may be expressions, not just identifier names.
-  * Either can be NULL or "" in which case the default params control whether vec4(1,1,1,1) or
-  * vec4(0,0,0,0) is assumed. It is an error to pass kNone for default<i> if in<i> is NULL or "".
-  * Note that when if function determines that the result is a zeros or ones vec then any expression
-  * represented by in0 or in1 will not be emitted. The return value indicates whether a zeros, ones
-  * or neither was appended.
+  * Produces a string that is the result of modulating two inputs. The inputs must be vecN or
+  * float. The result is always a vecN. The inputs may be expressions, not just identifier names.
+  * Either can be NULL or "" in which case the default params control whether a vector of ones or
+  * zeros. It is an error to pass kNone for default<i> if in<i> is NULL or "". Note that when if
+  * function determines that the result is a zeros or ones vec then any expression represented by
+  * or in1 will not be emitted (side effects won't occur). The return value indicates whether a
+  * known zeros or ones vector resulted. The output can be supressed when known vector is produced
+  * by passing true for omitIfConstVec.
   */
-GrSLConstantVec GrGLSLModulate4f(SkString* outAppend,
-                                 const char* in0,
-                                 const char* in1,
-                                 GrSLConstantVec default0 = kOnes_GrSLConstantVec,
-                                 GrSLConstantVec default1 = kOnes_GrSLConstantVec);
+template <int N>
+GrSLConstantVec GrGLSLModulatef(SkString* outAppend,
+                                const char* in0,
+                                const char* in1,
+                                GrSLConstantVec default0 = kOnes_GrSLConstantVec,
+                                GrSLConstantVec default1 = kOnes_GrSLConstantVec,
+                                bool omitIfConstVec = false);
 
 /**
+ * Produces a string that is the result of adding two inputs. The inputs must be vecN or
+ * float. The result is always a vecN. The inputs may be expressions, not just identifier names.
+ * Either can be NULL or "" in which case the default params control whether a vector of ones or
+ * zeros. It is an error to pass kNone for default<i> if in<i> is NULL or "". Note that when if
+ * function determines that the result is a zeros or ones vec then any expression represented by
+ * or in1 will not be emitted (side effects won't occur). The return value indicates whether a
+ * known zeros or ones vector resulted. The output can be supressed when known vector is produced
+ * by passing true for omitIfConstVec.
+ */
+template <int N>
+GrSLConstantVec GrGLSLAddf(SkString* outAppend,
+                           const char* in0,
+                           const char* in1,
+                           GrSLConstantVec default0 = kZeros_GrSLConstantVec,
+                           GrSLConstantVec default1 = kZeros_GrSLConstantVec,
+                           bool omitIfConstVec = false);
+
+/**
+ * Produces a string that is the result of adding two inputs. The inputs must be vecN or
+ * float. The result is always a vecN. The inputs may be expressions, not just identifier names.
+ * Either can be NULL or "" in which case the default params control whether a vector of ones or
+ * zeros. It is an error to pass kNone for default<i> if in<i> is NULL or "". Note that when if
+ * function determines that the result is a zeros or ones vec then any expression represented by
+ * or in1 will not be emitted (side effects won't occur). The return value indicates whether a
+ * known zeros or ones vector resulted. The output can be supressed when known vector is produced
+ * by passing true for omitIfConstVec.
+ */
+template <int N>
+GrSLConstantVec GrGLSLSubtractf(SkString* outAppend,
+                                const char* in0,
+                                const char* in1,
+                                GrSLConstantVec default0 = kZeros_GrSLConstantVec,
+                                GrSLConstantVec default1 = kZeros_GrSLConstantVec,
+                                bool omitIfConstVec = false);
+
+/**
  * Does an inplace mul, *=, of vec4VarName by mulFactor. If mulFactorDefault is not kNone then
  * mulFactor may be either "" or NULL. In this case either nothing will be appended (kOnes) or an
  * assignment of vec(0,0,0,0) will be appended (kZeros). The assignment is prepended by tabCnt tabs.
@@ -148,18 +216,14 @@
                                  GrSLConstantVec mulFactorDefault = kOnes_GrSLConstantVec);
 
 /**
-  * Produces a string that is the result of adding two inputs. The inputs must be vec4 or float.
-  * The result is always a vec4. The inputs may be expressions, not just identifier names. Either
-  * can be NULL or "" in which case if the default is kZeros then vec4(0,0,0,0) is assumed. It is an
-  * error to pass kOnes for either default or to pass kNone for default<i> if in<i> is NULL or "".
-  * Note that if the function determines that the result is a zeros vec any expression represented
-  * by in0 or in1 will not be emitted. The return value indicates whether a zeros vec was appended
-  * or not.
-  */
-GrSLConstantVec GrGLSLAdd4f(SkString* outAppend,
-                            const char* in0,
-                            const char* in1,
-                            GrSLConstantVec default0 = kZeros_GrSLConstantVec,
-                            GrSLConstantVec default1 = kZeros_GrSLConstantVec);
+ * Given an expression that evaluates to a GLSL vec4, extract a component. If
+ */
+GrSLConstantVec GrGLSLGetComponent4f(SkString* outAppend,
+                                     const char* expr,
+                                     GrColorComponentFlags component,
+                                     GrSLConstantVec defaultExpr = kNone_GrSLConstantVec,
+                                     bool omitIfConst = false);
 
+#include "GrGLSL_impl.h"
+
 #endif