Collapse consecutive SkTableColorFilters

src/effects/SkColorFilterImageFilter.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorFilterImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkColorMatrixFilter.h"
 #include "SkDevice.h"
 #include "SkColorFilter.h"
 #include "SkReadBuffer.h"
+#include "SkTableColorFilter.h"
 #include "SkWriteBuffer.h"
 
 namespace {
 
 void mult_color_matrix(SkScalar a[20], SkScalar b[20], SkScalar out[20]) {
     for (int j = 0; j < 4; ++j) {
         for (int i = 0; i < 5; ++i) {
             out[i+j*5] = 4 == i ? a[4+j*5] : 0;
             for (int k = 0; k < 4; ++k)
-                out[i+j*5] += SkScalarMul(a[k+j*5], b[i+k*5]);
+                out[i+j*5] += a[k+j*5] * b[i+k*5];
         }
     }
 }
+
+// Combines the two lookup tables so that making a lookup using OUT has
+// the same effect as making a lookup through B then A.
+void combine_color_tables(const uint8_t a[4 * 256],
+                          const uint8_t b[4 * 256],
+                          uint8_t out[4 * 256]) {
+    for (int i = 0; i < 4; i++) {
+        for (int j = 0; j < 256; j++) {
+            out[i * 256 + j] = a[i * 256 + b[i * 256 + j]];
+        }
+    }
+}
 
 // To detect if we need to apply clamping after applying a matrix, we check if
 // any output component might go outside of [0, 255] for any combination of
 // input components in [0..255].
 // Each output component is an affine transformation of the input component, so
 // the minimum and maximum values are for any combination of minimum or maximum
 // values of input components (i.e. 0 or 255).
 // E.g. if R' = x*R + y*G + z*B + w*A + t
 // Then the maximum value will be for R=255 if x>0 or R=0 if x<0, and the
 // minimum value will be for R=0 if x>0 or R=255 if x<0.
@@ skipping 14 matching lines @@
     return component_needs_clamping(matrix)
         || component_needs_clamping(matrix+5)
         || component_needs_clamping(matrix+10)
         || component_needs_clamping(matrix+15);
 }
 
 };
 
 SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID) {
-    SkASSERT(cf);
     if (NULL == cf) {
         return NULL;
     }
-    SkScalar colorMatrix[20], inputMatrix[20];
+
     SkColorFilter* inputColorFilter;
-    if (input && cf->asColorMatrix(colorMatrix)
-              && input->asColorFilter(&inputColorFilter)
-              && (inputColorFilter)) {
+    if (input && input->asColorFilter(&inputColorFilter) && inputColorFilter) {
         SkAutoUnref autoUnref(inputColorFilter);
-        if (inputColorFilter->asColorMatrix(inputMatrix) && !matrix_needs_clamping(inputMatrix)) {
+
+        // Try to collapse two consecutive matrix filters
+        SkScalar colorMatrix[20], inputMatrix[20];
+        if (cf->asColorMatrix(colorMatrix) && inputColorFilter->asColorMatrix(inputMatrix)
+                                           && !matrix_needs_clamping(inputMatrix)) {
             SkScalar combinedMatrix[20];
             mult_color_matrix(colorMatrix, inputMatrix, combinedMatrix);
             SkAutoTUnref<SkColorFilter> newCF(SkColorMatrixFilter::Create(combinedMatrix));
             return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
         }
+
+        // Try to collapse two consecutive table filters
+        SkBitmap colorTable, inputTable;
+        if (cf->asComponentTable(&colorTable) && inputColorFilter->asComponentTable(&inputTable)) {
+            uint8_t combinedTable[4 * 256];
+            SkAutoLockPixels colorLock(colorTable);
+            SkAutoLockPixels inputLock(inputTable);
+
+            combine_color_tables(colorTable.getAddr8(0, 0), inputTable.getAddr8(0, 0),
+                                 combinedTable);
+            SkAutoTUnref<SkColorFilter> newCF(SkTableColorFilter::CreateARGB(
+                        &combinedTable[256 * 0],
+                        &combinedTable[256 * 1],
+                        &combinedTable[256 * 2],
+                        &combinedTable[256 * 3])
+            );
+
+            return SkNEW_ARGS(SkColorFilterImageFilter, (newCF, input->getInput(0), cropRect, 0));
+        }
     }
+
     return SkNEW_ARGS(SkColorFilterImageFilter, (cf, input, cropRect, uniqueID));
 }
 
 SkColorFilterImageFilter::SkColorFilterImageFilter(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID)
     : INHERITED(1, &input, cropRect, uniqueID), fColorFilter(SkRef(cf)) {
 }
 
 SkFlattenable* SkColorFilterImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
@@ skipping 62 matching lines @@
     if (this->getInput(0)) {
         this->getInput(0)->toString(str);
     }
 
     str->appendf(") color filter: ");
     fColorFilter->toString(str);
 
     str->append(")");
 }
 #endif