When two or more color matrix image filters are connected together, and the non-leaf matrices do not require clamping, we can concatenate their matrices and apply them together.

Review URL: https://codereview.appspot.com/6489054

git-svn-id: http://skia.googlecode.com/svn/trunk@5931 2bbb7eff-a529-9590-31e7-b0007b416f81

3 files changed, 103 insertions, 28 deletions

diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index c688310111..45ad024d45 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -14,19 +14,19 @@
 
 SK_DEFINE_INST_COUNT(SkImageFilter)
 
-SkImageFilter::SkImageFilter(int numInputs, SkImageFilter** inputs)
-  : fNumInputs(numInputs), fInputs(new SkImageFilter*[numInputs]) {
-    for (int i = 0; i < numInputs; ++i) {
+SkImageFilter::SkImageFilter(int inputCount, SkImageFilter** inputs)
+  : fInputCount(inputCount), fInputs(new SkImageFilter*[inputCount]) {
+    for (int i = 0; i < inputCount; ++i) {
         fInputs[i] = inputs[i];
         SkSafeRef(fInputs[i]);
     }
 }
 
-SkImageFilter::SkImageFilter(int numInputs, ...)
-  : fNumInputs(numInputs), fInputs(new SkImageFilter*[numInputs]) {
+SkImageFilter::SkImageFilter(int inputCount, ...)
+  : fInputCount(inputCount), fInputs(new SkImageFilter*[inputCount]) {
     va_list ap;
-    va_start(ap, numInputs);
-    for (int i = 0; i < numInputs; ++i) {
+    va_start(ap, inputCount);
+    for (int i = 0; i < inputCount; ++i) {
         fInputs[i] = va_arg(ap, SkImageFilter*);
         SkSafeRef(fInputs[i]);
     }
@@ -34,15 +34,15 @@ SkImageFilter::SkImageFilter(int numInputs, ...)
 }
 
 SkImageFilter::~SkImageFilter() {
-    for (int i = 0; i < fNumInputs; i++) {
+    for (int i = 0; i < fInputCount; i++) {
         SkSafeUnref(fInputs[i]);
     }
     delete[] fInputs;
 }
 
 SkImageFilter::SkImageFilter(SkFlattenableReadBuffer& buffer)
-    : fNumInputs(buffer.readInt()), fInputs(new SkImageFilter*[fNumInputs]) {
-    for (int i = 0; i < fNumInputs; i++) {
+    : fInputCount(buffer.readInt()), fInputs(new SkImageFilter*[fInputCount]) {
+    for (int i = 0; i < fInputCount; i++) {
         if (buffer.readBool()) {
             fInputs[i] = static_cast<SkImageFilter*>(buffer.readFlattenable());
         } else {
@@ -52,8 +52,8 @@ SkImageFilter::SkImageFilter(SkFlattenableReadBuffer& buffer)
 }
 
 void SkImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
-    buffer.writeInt(fNumInputs);
-    for (int i = 0; i < fNumInputs; i++) {
+    buffer.writeInt(fInputCount);
+    for (int i = 0; i < fInputCount; i++) {
         SkImageFilter* input = getInput(i);
         buffer.writeBool(input != NULL);
         if (input != NULL) {
@@ -65,7 +65,7 @@ void SkImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
 SkBitmap SkImageFilter::getInputResult(int index, Proxy* proxy,
                                        const SkBitmap& src, const SkMatrix& ctm,
                                        SkIPoint* loc) {
-    SkASSERT(index < fNumInputs);
+    SkASSERT(index < fInputCount);
     SkImageFilter* input = getInput(index);
     SkBitmap result;
     if (input && input->filterImage(proxy, src, ctm, &result, loc)) {
@@ -118,3 +118,7 @@ bool SkImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
 bool SkImageFilter::asNewCustomStage(GrCustomStage**, GrTexture*) const {
     return false;
 }
+
+SkColorFilter* SkImageFilter::asColorFilter() const {
+    return NULL;
+}
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index f9c8cef5c1..f8df51fbd0 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -8,11 +8,56 @@
 #include "SkColorFilterImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
+#include "SkColorMatrixFilter.h"
 #include "SkDevice.h"
 #include "SkColorFilter.h"
 #include "SkFlattenableBuffers.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]);
+        }
+    }
+}
+
+// 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.
+// Same goes for all components.
+bool component_needs_clamping(SkScalar row[5]) {
+    SkScalar maxValue = row[4] / 255;
+    SkScalar minValue = row[4] / 255;
+    for (int i = 0; i < 4; ++i) {
+        if (row[i] > 0)
+            maxValue += row[i];
+        else
+            minValue += row[i];
+    }
+    return (maxValue > 1) || (minValue < 0);
+}
+
+bool matrix_needs_clamping(SkScalar matrix[20]) {
+    return component_needs_clamping(matrix)
+        || component_needs_clamping(matrix+5)
+        || component_needs_clamping(matrix+10)
+        || component_needs_clamping(matrix+15);
+}
+
+};
+
 SkColorFilterImageFilter::SkColorFilterImageFilter(SkColorFilter* cf, SkImageFilter* input) : INHERITED(input), fColorFilter(cf) {
+    SkASSERT(cf);
     SkSafeRef(cf);
 }
 
@@ -34,11 +79,29 @@ bool SkColorFilterImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& sourc
                                              const SkMatrix& matrix,
                                              SkBitmap* result,
                                              SkIPoint* loc) {
-    SkBitmap src = this->getInputResult(proxy, source, matrix, loc);
-    SkColorFilter* cf = fColorFilter;
-    if (NULL == cf) {
-        *result = src;
-        return true;
+    SkImageFilter* parent = getInput(0);
+    SkScalar colorMatrix[20];
+    SkBitmap src;
+    SkColorFilter* cf;
+    if (parent && fColorFilter->asColorMatrix(colorMatrix)) {
+        SkColorFilter* parentColorFilter;
+        SkScalar parentMatrix[20];
+        while (parent && (parentColorFilter = parent->asColorFilter())
+                      && parentColorFilter->asColorMatrix(parentMatrix) 
+                      && !matrix_needs_clamping(parentMatrix)) {
+            SkScalar combinedMatrix[20];
+            mult_color_matrix(parentMatrix, colorMatrix, combinedMatrix);
+            memcpy(colorMatrix, combinedMatrix, 20 * sizeof(SkScalar));
+            parent = parent->getInput(0);
+        }
+        if (!parent || !parent->filterImage(proxy, source, matrix, &src, loc)) {
+            src = source;
+        }
+        cf = SkNEW_ARGS(SkColorMatrixFilter, (colorMatrix));
+    } else {
+        src = this->getInputResult(proxy, source, matrix, loc);
+        cf = fColorFilter;
+        cf->ref();
     }
 
     SkAutoTUnref<SkDevice> device(proxy->createDevice(src.width(), src.height()));
@@ -46,9 +109,13 @@ bool SkColorFilterImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& sourc
     SkPaint paint;
 
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-    paint.setColorFilter(fColorFilter);
+    paint.setColorFilter(cf)->unref();
     canvas.drawSprite(src, 0, 0, &paint);
 
     *result = device.get()->accessBitmap(false);
     return true;
 }
+
+SkColorFilter* SkColorFilterImageFilter::asColorFilter() const {
+    return fColorFilter;
+}
diff --git a/src/effects/SkTestImageFilters.cpp b/src/effects/SkTestImageFilters.cpp
index a51149d6a8..a672c337f7 100755
--- a/src/effects/SkTestImageFilters.cpp
+++ b/src/effects/SkTestImageFilters.cpp
@@ -101,8 +101,9 @@ SkComposeImageFilter::SkComposeImageFilter(SkFlattenableReadBuffer& buffer) : IN
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkMergeImageFilter::initAllocModes() {
-    if (numInputs()) {
-        size_t size = sizeof(uint8_t) * numInputs();
+    int inputCount = countInputs();
+    if (inputCount) {
+        size_t size = sizeof(uint8_t) * inputCount;
         if (size <= sizeof(fStorage)) {
             fModes = SkTCast<uint8_t*>(fStorage);
         } else {
@@ -116,7 +117,8 @@ void SkMergeImageFilter::initAllocModes() {
 void SkMergeImageFilter::initModes(const SkXfermode::Mode modes[]) {
     if (modes) {
         this->initAllocModes();
-        for (int i = 0; i < numInputs(); ++i) {
+        int inputCount = countInputs();
+        for (int i = 0; i < inputCount; ++i) {
             fModes[i] = SkToU8(modes[i]);
         }
     } else {
@@ -148,13 +150,14 @@ SkMergeImageFilter::~SkMergeImageFilter() {
 
 bool SkMergeImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                         SkIRect* dst) {
-    if (numInputs() < 1) {
+    if (countInputs() < 1) {
         return false;
     }
 
     SkIRect totalBounds;
 
-    for (int i = 0; i < numInputs(); ++i) {
+    int inputCount = countInputs();
+    for (int i = 0; i < inputCount; ++i) {
         SkImageFilter* filter = getInput(i);
         SkIRect r;
         if (filter) {
@@ -180,7 +183,7 @@ bool SkMergeImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
 bool SkMergeImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
                                        const SkMatrix& ctm,
                                        SkBitmap* result, SkIPoint* loc) {
-    if (numInputs() < 1) {
+    if (countInputs() < 1) {
         return false;
     }
 
@@ -201,7 +204,8 @@ bool SkMergeImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
     OwnDeviceCanvas canvas(dst);
     SkPaint paint;
 
-    for (int i = 0; i < numInputs(); ++i) {
+    int inputCount = countInputs();
+    for (int i = 0; i < inputCount; ++i) {
         SkBitmap tmp;
         const SkBitmap* srcPtr;
         SkIPoint pos = *loc;
@@ -233,7 +237,7 @@ void SkMergeImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
 
     buffer.writeBool(fModes != NULL);
     if (fModes) {
-        buffer.writeByteArray(fModes, numInputs() * sizeof(fModes[0]));
+        buffer.writeByteArray(fModes, countInputs() * sizeof(fModes[0]));
     }
 }
 
@@ -241,7 +245,7 @@ SkMergeImageFilter::SkMergeImageFilter(SkFlattenableReadBuffer& buffer) : INHERI
     bool hasModes = buffer.readBool();
     if (hasModes) {
         this->initAllocModes();
-        SkASSERT(buffer.getArrayCount() == numInputs() * sizeof(fModes[0]));
+        SkASSERT(buffer.getArrayCount() == countInputs() * sizeof(fModes[0]));
         buffer.readByteArray(fModes);
     } else {
         fModes = 0;