[PDF] Add support for Shaders.

- Shaders, or as they are referred to in PDF, patterns, are drawn in the coordinate system of the initial page, so when we canonicalize them, we have to consider the current transform and where they are constructed.

- Image shaders are tiled by default, this makes repeat and mirror modes easy, but means we have to draw a pattern as large as the current clip to support clamp mode.

- Gradient shaders are implemented with type 4 functions, which are basically small snippets of post script code.  I've tried to make the code generation modular and heavily commented to make it easy to understand or expand.

Review URL: http://codereview.appspot.com/4239061

git-svn-id: http://skia.googlecode.com/svn/trunk@905 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 862 insertions, 20 deletions

diff --git a/src/pdf/SkPDFCatalog.cpp b/src/pdf/SkPDFCatalog.cpp
index 493cbbeff5..afa9d9a1c9 100644
--- a/src/pdf/SkPDFCatalog.cpp
+++ b/src/pdf/SkPDFCatalog.cpp
@@ -68,6 +68,8 @@ int SkPDFCatalog::findObjectIndex(SkPDFObject* obj) const {
 
 int SkPDFCatalog::assignObjNum(SkPDFObject* obj) {
     int pos = findObjectIndex(obj);
+    // If this assert fails, it means you probably forgot to add an object
+    // to the resource list.
     SkASSERT(pos >= 0);
     uint32_t currentIndex = pos;
     if (fCatalog[currentIndex].fObjNumAssigned)
diff --git a/src/pdf/SkPDFDevice.cpp b/src/pdf/SkPDFDevice.cpp
index 6a38fac893..a0e1d281d2 100644
--- a/src/pdf/SkPDFDevice.cpp
+++ b/src/pdf/SkPDFDevice.cpp
@@ -25,6 +25,7 @@
 #include "SkPDFFont.h"
 #include "SkPDFFormXObject.h"
 #include "SkPDFTypes.h"
+#include "SkPDFShader.h"
 #include "SkPDFStream.h"
 #include "SkPDFUtils.h"
 #include "SkRect.h"
@@ -138,6 +139,7 @@ SkPDFDevice::SkPDFDevice(int width, int height, OriginTransform flipOrigin)
     fGraphicStack[0].fTextScaleX = SK_Scalar1;
     fGraphicStack[0].fTextFill = SkPaint::kFill_Style;
     fGraphicStack[0].fFont = NULL;
+    fGraphicStack[0].fShader = NULL;
     fGraphicStack[0].fGraphicState = NULL;
     fGraphicStack[0].fClip.setRect(0,0, width, height);
     fGraphicStack[0].fTransform.reset();
@@ -151,6 +153,7 @@ SkPDFDevice::~SkPDFDevice() {
     fGraphicStateResources.unrefAll();
     fXObjectResources.unrefAll();
     fFontResources.unrefAll();
+    fShaderResources.unrefAll();
 }
 
 void SkPDFDevice::setMatrixClip(const SkMatrix& matrix,
@@ -500,6 +503,18 @@ const SkRefPtr<SkPDFDict>& SkPDFDevice::getResourceDict() {
             fResourceDict->insert("Font", fonts.get());
         }
 
+        if (fShaderResources.count()) {
+            SkRefPtr<SkPDFDict> patterns = new SkPDFDict();
+            patterns->unref();  // SkRefPtr and new both took a reference.
+            for (int i = 0; i < fShaderResources.count(); i++) {
+                SkString nameString("P");
+                nameString.appendS32(i);
+                patterns->insert(nameString.c_str(),
+                                 new SkPDFObjRef(fShaderResources[i]))->unref();
+            }
+            fResourceDict->insert("Pattern", patterns.get());
+        }
+
         // For compatibility, add all proc sets (only used for output to PS
         // devices).
         const char procs[][7] = {"PDF", "Text", "ImageB", "ImageC", "ImageI"};
@@ -517,7 +532,8 @@ void SkPDFDevice::getResources(SkTDArray<SkPDFObject*>* resourceList) const {
     resourceList->setReserve(resourceList->count() +
                              fGraphicStateResources.count() +
                              fXObjectResources.count() +
-                             fFontResources.count());
+                             fFontResources.count() +
+                             fShaderResources.count());
     for (int i = 0; i < fGraphicStateResources.count(); i++) {
         resourceList->push(fGraphicStateResources[i]);
         fGraphicStateResources[i]->ref();
@@ -533,6 +549,11 @@ void SkPDFDevice::getResources(SkTDArray<SkPDFObject*>* resourceList) const {
         fFontResources[i]->ref();
         fFontResources[i]->getResources(resourceList);
     }
+    for (int i = 0; i < fShaderResources.count(); i++) {
+        resourceList->push(fShaderResources[i]);
+        fShaderResources[i]->ref();
+        fShaderResources[i]->getResources(resourceList);
+    }
 }
 
 SkRefPtr<SkPDFArray> SkPDFDevice::getMediaBox() const {
@@ -562,17 +583,78 @@ SkStream* SkPDFDevice::content() const {
     return result;
 }
 
-// Private
+void SkPDFDevice::updateGSFromPaint(const SkPaint& paint, bool forText) {
+    SkASSERT(paint.getPathEffect() == NULL);
 
-// TODO(vandebo) handle these cases.
-#define PAINTCHECK(x,y) NOT_IMPLEMENTED(newPaint.x() y, false)
+    NOT_IMPLEMENTED(paint.getMaskFilter() != NULL, false);
+    NOT_IMPLEMENTED(paint.getColorFilter() != NULL, false);
 
-void SkPDFDevice::updateGSFromPaint(const SkPaint& newPaint, bool forText) {
-    SkASSERT(newPaint.getPathEffect() == NULL);
+    SkPaint newPaint = paint;
 
-    PAINTCHECK(getMaskFilter, != NULL);
-    PAINTCHECK(getShader, != NULL);
-    PAINTCHECK(getColorFilter, != NULL);
+    // PDF treats a shader as a color, so we only set one or the other.
+    SkRefPtr<SkPDFShader> pdfShader;
+    const SkShader* shader = newPaint.getShader();
+    if (shader) {
+        // PDF positions patterns relative to the initial transform, so
+        // we need to apply the current transform to the shader parameters.
+        SkMatrix transform = fGraphicStack[fGraphicStackIndex].fTransform;
+        if (fFlipOrigin == kFlip_OriginTransform) {
+            transform.postScale(1, -1);
+            transform.postTranslate(0, fHeight);
+        }
+
+        // PDF doesn't support kClamp_TileMode, so we simulate it by making
+        // a pattern the size of the drawing service.
+        SkIRect bounds = fGraphicStack[fGraphicStackIndex].fClip.getBounds();
+        pdfShader = SkPDFShader::getPDFShader(*shader, transform, bounds);
+        SkSafeUnref(pdfShader.get());  // getShader and SkRefPtr both took a ref
+
+        // A color shader is treated as an invalid shader so we don't have
+        // to set a shader just for a color.
+        if (pdfShader.get() == NULL) {
+            newPaint.setColor(0);
+
+            // Check for a color shader.
+            SkShader::GradientInfo gradientInfo;
+            SkColor gradientColor;
+            gradientInfo.fColors = &gradientColor;
+            gradientInfo.fColorOffsets = NULL;
+            gradientInfo.fColorCount = 1;
+            if (shader->asAGradient(&gradientInfo) ==
+                    SkShader::kColor_GradientType) {
+                newPaint.setColor(gradientColor);
+            }
+        }
+    }
+
+    if (pdfShader) {
+        // pdfShader has been canonicalized so we can directly compare
+        // pointers.
+        if (fGraphicStack[fGraphicStackIndex].fShader != pdfShader.get()) {
+            int resourceIndex = fShaderResources.find(pdfShader.get());
+            if (resourceIndex < 0) {
+                resourceIndex = fShaderResources.count();
+                fShaderResources.push(pdfShader.get());
+                pdfShader->ref();
+            }
+            fContent.appendf("/Pattern CS /Pattern cs /P%d SCN /P%d scn\n",
+                             resourceIndex, resourceIndex);
+            fGraphicStack[fGraphicStackIndex].fShader = pdfShader.get();
+        }
+    } else {
+        SkColor newColor = newPaint.getColor();
+        newColor = SkColorSetA(newColor, 0xFF);
+        if (fGraphicStack[fGraphicStackIndex].fShader ||
+                fGraphicStack[fGraphicStackIndex].fColor != newColor) {
+            SkString colorString = toPDFColor(newColor);
+            fContent.append(colorString);
+            fContent.append("RG ");
+            fContent.append(colorString);
+            fContent.append("rg\n");
+            fGraphicStack[fGraphicStackIndex].fColor = newColor;
+            fGraphicStack[fGraphicStackIndex].fShader = NULL;
+        }
+    }
 
     SkRefPtr<SkPDFGraphicState> newGraphicState =
         SkPDFGraphicState::getGraphicStateForPaint(newPaint);
@@ -593,17 +675,6 @@ void SkPDFDevice::updateGSFromPaint(const SkPaint& newPaint, bool forText) {
         fGraphicStack[fGraphicStackIndex].fGraphicState = newGraphicState.get();
     }
 
-    SkColor newColor = newPaint.getColor();
-    newColor = SkColorSetA(newColor, 0xFF);
-    if (fGraphicStack[fGraphicStackIndex].fColor != newColor) {
-        SkString colorString = toPDFColor(newColor);
-        fContent.append(colorString);
-        fContent.append("RG ");
-        fContent.append(colorString);
-        fContent.append("rg\n");
-        fGraphicStack[fGraphicStackIndex].fColor = newColor;
-    }
-
     if (forText) {
         if (fGraphicStack[fGraphicStackIndex].fTextScaleX !=
                 newPaint.getTextScaleX()) {
diff --git a/src/pdf/SkPDFShader.cpp b/src/pdf/SkPDFShader.cpp
new file mode 100644
index 0000000000..4cbd4efb52
--- /dev/null
+++ b/src/pdf/SkPDFShader.cpp
@@ -0,0 +1,768 @@
+/*
+ * Copyright (C) 2011 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SkPDFShader.h"
+
+#include "SkCanvas.h"
+#include "SkPDFCatalog.h"
+#include "SkPDFDevice.h"
+#include "SkPDFTypes.h"
+#include "SkPDFUtils.h"
+#include "SkScalar.h"
+#include "SkStream.h"
+#include "SkThread.h"
+#include "SkTypes.h"
+
+static void transformBBox(const SkMatrix& matrix, SkRect* bbox) {
+    SkMatrix inverse;
+    inverse.reset();
+    matrix.invert(&inverse);
+    inverse.mapRect(bbox);
+}
+
+static void unitToPointsMatrix(const SkPoint pts[2], SkMatrix* matrix) {
+    SkVector    vec = pts[1] - pts[0];
+    SkScalar    mag = vec.length();
+    SkScalar    inv = mag ? SkScalarInvert(mag) : 0;
+
+    vec.scale(inv);
+    matrix->setSinCos(vec.fY, vec.fX);
+    matrix->preTranslate(pts[0].fX, pts[0].fY);
+    matrix->preScale(mag, mag);
+}
+
+/* Assumes t + startOffset is on the stack and does a linear interpolation on t
+   between startOffset and endOffset from prevColor to curColor (for each color
+   component), leaving the result in component order on the stack.
+   @param range                  endOffset - startOffset
+   @param curColor[components]   The current color components.
+   @param prevColor[components]  The previous color components.
+   @param result                 The result ps function.
+ */
+static void interpolateColorCode(SkScalar range, SkScalar* curColor,
+                                 SkScalar* prevColor, int components,
+                                 SkString* result) {
+    // Figure out how to scale each color component.
+    SkScalar multiplier[components];
+    for (int i = 0; i < components; i++) {
+        multiplier[i] = SkScalarDiv(curColor[i] - prevColor[i], range);
+    }
+
+    // Calculate when we no longer need to keep a copy of the input parameter t.
+    // If the last component to use t is i, then dupInput[0..i - 1] = true
+    // and dupInput[i .. components] = false.
+    bool dupInput[components];
+    dupInput[components - 1] = false;
+    for (int i = components - 2; i >= 0; i--) {
+        dupInput[i] = dupInput[i + 1] || multiplier[i + 1] != 0;
+    }
+
+    if (!dupInput[0] && multiplier[0] == 0) {
+        result->append("pop ");
+    }
+
+    for (int i = 0; i < components; i++) {
+        // If the next components needs t, make a copy.
+        if (dupInput[i]) {
+            result->append("dup ");
+        }
+
+        if (multiplier[i] == 0) {
+            result->appendScalar(prevColor[i]);
+            result->append(" ");
+        } else {
+            if (multiplier[i] != 1) {
+                result->appendScalar(multiplier[i]);
+                result->append(" mul ");
+            }
+            if (prevColor[i] != 0) {
+                result->appendScalar(prevColor[i]);
+                result->append(" add ");
+            }
+        }
+
+        if (dupInput[i]) {
+            result->append("exch\n");
+        }
+    }
+}
+
+/* Generate Type 4 function code to map t=[0,1) to the passed gradient,
+   clamping at the edges of the range.  The generated code will be of the form:
+       if (t < 0) {
+           return colorData[0][r,g,b];
+       } else {
+           if (t < info.fColorOffsets[1]) {
+               return linearinterpolation(colorData[0][r,g,b],
+                                          colorData[1][r,g,b]);
+           } else {
+               if (t < info.fColorOffsets[2]) {
+                   return linearinterpolation(colorData[1][r,g,b],
+                                              colorData[2][r,g,b]);
+               } else {
+
+                ...    } else {
+                           return colorData[info.fColorCount - 1][r,g,b];
+                       }
+                ...
+           }
+       }
+ */
+static void gradientFunctionCode(const SkShader::GradientInfo& info,
+                                 SkString* result) {
+    /* We want to linearly interpolate from the previous color to the next.
+       Scale the colors from 0..255 to 0..1 and determine the multipliers
+       for interpolation.
+       C{r,g,b}(t, section) = t - offset_(section-1) + t * Multiplier{r,g,b}.
+     */
+    static const int kColorComponents = 3;
+    SkScalar colorData[info.fColorCount][kColorComponents];
+
+    const SkScalar scale = SkScalarInvert(SkIntToScalar(255));
+    for (int i = 0; i < info.fColorCount; i++) {
+        colorData[i][0] = SkScalarMul(SkColorGetR(info.fColors[i]), scale);
+        colorData[i][1] = SkScalarMul(SkColorGetG(info.fColors[i]), scale);
+        colorData[i][2] = SkScalarMul(SkColorGetB(info.fColors[i]), scale);
+    }
+
+    // Clamp the initial color.
+    result->append("dup 0 le {pop ");
+    result->appendScalar(colorData[0][0]);
+    result->append(" ");
+    result->appendScalar(colorData[0][1]);
+    result->append(" ");
+    result->appendScalar(colorData[0][2]);
+    result->append(" }\n");
+
+    // The gradient colors.
+    for (int i = 1 ; i < info.fColorCount; i++) {
+        result->append("{dup ");
+        result->appendScalar(info.fColorOffsets[i]);
+        result->append(" le {");
+        if (info.fColorOffsets[i - 1] != 0) {
+            result->appendScalar(info.fColorOffsets[i - 1]);
+            result->append(" sub\n");
+        }
+
+        interpolateColorCode(info.fColorOffsets[i] - info.fColorOffsets[i - 1],
+                             colorData[i], colorData[i - 1], kColorComponents,
+                             result);
+        result->append("}\n");
+    }
+
+    // Clamp the final color.
+    result->append("{pop ");
+    result->appendScalar(colorData[info.fColorCount - 1][0]);
+    result->append(" ");
+    result->appendScalar(colorData[info.fColorCount - 1][1]);
+    result->append(" ");
+    result->appendScalar(colorData[info.fColorCount - 1][2]);
+
+    for (int i = 0 ; i < info.fColorCount; i++) {
+        result->append("} ifelse\n");
+    }
+}
+
+/* Map a value of t on the stack into [0, 1) for Repeat or Mirror tile mode. */
+static void tileModeCode(SkShader::TileMode mode, SkString* result) {
+    if (mode == SkShader::kRepeat_TileMode) {
+        result->append("dup truncate sub\n");  // Get the fractional part.
+        result->append("dup 0 le {1 add} if\n");  // Map (-1,0) => (0,1)
+        return;
+    }
+
+    if (mode == SkShader::kMirror_TileMode) {
+        // Map t mod 2 into [0, 1, 1, 0].
+        //               Code                     Stack
+        result->append("abs "                 // Map negative to positive.
+                       "dup "                 // t.s t.s
+                       "truncate "            // t.s t
+                       "dup "                 // t.s t t
+                       "cvi "                 // t.s t T
+                       "2 mod "               // t.s t (i mod 2)
+                       "1 eq "                // t.s t true|false
+                       "3 1 roll "            // true|false t.s t
+                       "sub "                 // true|false 0.s
+                       "exch "                // 0.s true|false
+                       "{1 exch sub} if\n");  // 1 - 0.s|0.s
+    }
+}
+
+static SkString linearCode(const SkShader::GradientInfo& info) {
+    SkString function("{pop\n"); // Just ditch the y value.
+    tileModeCode(info.fTileMode, &function);
+    gradientFunctionCode(info, &function);
+    function.append("}");
+    return function;
+}
+
+static SkString radialCode(const SkShader::GradientInfo& info) {
+    SkString function("{");
+    // Find the distance from the origin.
+    function.append("dup "      // x y y
+                    "mul "      // x y^2
+                    "exch "     // y^2 x
+                    "dup "      // y^2 x x
+                    "mul "      // y^2 x^2
+                    "add "      // y^2+x^2
+                    "sqrt\n");  // sqrt(y^2+x^2)
+
+    tileModeCode(info.fTileMode, &function);
+    gradientFunctionCode(info, &function);
+    function.append("}");
+    return function;
+}
+
+/* The math here is all based on the description in Two_Point_Radial_Gradient,
+   with one simplification, the coordinate space has been scaled so that
+   Dr = 1.  This means we don't need to scale the entire equation by 1/Dr^2.
+ */
+static SkString twoPointRadialCode(const SkShader::GradientInfo& info) {
+    SkScalar dx = info.fPoint[0].fX - info.fPoint[1].fX;
+    SkScalar dy = info.fPoint[0].fY - info.fPoint[1].fY;
+    SkScalar sr = info.fRadius[0];
+    SkScalar a = SkScalarMul(dx, dx) + SkScalarMul(dy, dy) - SK_Scalar1;
+    bool posRoot = info.fRadius[1] > info.fRadius[0];
+
+    // We start with a stack of (x y), copy it and then consume one copy in
+    // order to calculate b and the other to calculate c.
+    SkString function("{");
+    function.append("2 copy ");
+
+    // Calculate -b and b^2.
+    function.appendScalar(dy);
+    function.append(" mul exch ");
+    function.appendScalar(dx);
+    function.append(" mul add ");
+    function.appendScalar(sr);
+    function.append(" sub 2 mul neg dup dup mul\n");
+
+    // Calculate c
+    function.append("4 2 roll dup mul exch dup mul add ");
+    function.appendScalar(SkScalarMul(sr, sr));
+    function.append(" sub\n");
+
+    // Calculate the determinate
+    function.appendScalar(SkScalarMul(SkIntToScalar(4), a));
+    function.append(" mul sub abs sqrt\n");
+
+    // And then the final value of t.
+    if (posRoot) {
+        function.append("sub ");
+    } else {
+        function.append("add ");
+    }
+    function.appendScalar(SkScalarMul(SkIntToScalar(2), a));
+    function.append(" div\n");
+
+    tileModeCode(info.fTileMode, &function);
+    gradientFunctionCode(info, &function);
+    function.append("}");
+    return function;
+}
+
+static SkString sweepCode(const SkShader::GradientInfo& info) {
+    SkString function("{exch atan 360 div\n");
+    tileModeCode(info.fTileMode, &function);
+    gradientFunctionCode(info, &function);
+    function.append("}");
+    return function;
+}
+
+SkPDFShader::~SkPDFShader() {
+    SkAutoMutexAcquire lock(canonicalShadersMutex());
+    ShaderCanonicalEntry entry(this, fState.get());
+    int index = canonicalShaders().find(entry);
+    SkASSERT(index >= 0);
+    canonicalShaders().removeShuffle(index);
+    fResources.unrefAll();
+}
+
+void SkPDFShader::emitObject(SkWStream* stream, SkPDFCatalog* catalog,
+                             bool indirect) {
+    if (indirect)
+        return emitIndirectObject(stream, catalog);
+
+    fContent->emitObject(stream, catalog, indirect);
+}
+
+size_t SkPDFShader::getOutputSize(SkPDFCatalog* catalog, bool indirect) {
+    if (indirect)
+        return getIndirectOutputSize(catalog);
+
+    return fContent->getOutputSize(catalog, indirect);
+}
+
+void SkPDFShader::getResources(SkTDArray<SkPDFObject*>* resourceList) {
+    resourceList->setReserve(resourceList->count() + fResources.count());
+    for (int i = 0; i < fResources.count(); i++) {
+        resourceList->push(fResources[i]);
+        fResources[i]->ref();
+    }
+}
+
+// static
+SkPDFShader* SkPDFShader::getPDFShader(const SkShader& shader,
+                                       const SkMatrix& matrix,
+                                       const SkIRect& surfaceBBox) {
+    SkRefPtr<SkPDFShader> pdfShader;
+    SkAutoMutexAcquire lock(canonicalShadersMutex());
+    SkAutoTDelete<State> shaderState(new State(shader, matrix, surfaceBBox));
+
+    ShaderCanonicalEntry entry(NULL, shaderState.get());
+    int index = canonicalShaders().find(entry);
+    if (index >= 0) {
+        SkPDFShader* result = canonicalShaders()[index].fPDFShader;
+        result->ref();
+        return result;
+    }
+    // The PDFShader takes ownership of the shaderSate.
+    pdfShader = new SkPDFShader(shaderState.detach());
+    // Check for a valid shader.
+    if (pdfShader->fContent.get() == NULL) {
+        pdfShader->unref();
+        return NULL;
+    }
+    entry.fPDFShader = pdfShader.get();
+    canonicalShaders().push(entry);
+    return pdfShader.get();  // return the reference that came from new.
+}
+
+// static
+SkTDArray<SkPDFShader::ShaderCanonicalEntry>& SkPDFShader::canonicalShaders() {
+    // This initialization is only thread safe with gcc.
+    static SkTDArray<ShaderCanonicalEntry> gCanonicalShaders;
+    return gCanonicalShaders;
+}
+
+// static
+SkMutex& SkPDFShader::canonicalShadersMutex() {
+    // This initialization is only thread safe with gcc.
+    static SkMutex gCanonicalShadersMutex;
+    return gCanonicalShadersMutex;
+}
+
+// static
+SkPDFObject* SkPDFShader::rangeObject() {
+    // This initialization is only thread safe with gcc.
+    static SkPDFArray* range = NULL;
+    // This method is only used with canonicalShadersMutex, so it's safe to
+    // populate domain.
+    if (range == NULL) {
+        range = new SkPDFArray;
+        range->reserve(6);
+        range->append(new SkPDFInt(0))->unref();
+        range->append(new SkPDFInt(1))->unref();
+        range->append(new SkPDFInt(0))->unref();
+        range->append(new SkPDFInt(1))->unref();
+        range->append(new SkPDFInt(0))->unref();
+        range->append(new SkPDFInt(1))->unref();
+    }
+    return range;
+}
+
+SkPDFShader::SkPDFShader(State* state) : fState(state) {
+    if (fState.get()->fType == SkShader::kNone_GradientType) {
+        doImageShader();
+    } else {
+        doFunctionShader();
+    }
+}
+
+void SkPDFShader::doFunctionShader() {
+    SkString (*codeFunction)(const SkShader::GradientInfo& info) = NULL;
+    SkPoint transformPoints[2];
+
+    // Depending on the type of the gradient, we want to transform the
+    // coordinate space in different ways.
+    const SkShader::GradientInfo* info = &fState.get()->fInfo;
+    transformPoints[0] = info->fPoint[0];
+    transformPoints[1] = info->fPoint[1];
+    switch (fState.get()->fType) {
+        case SkShader::kLinear_GradientType:
+            codeFunction = &linearCode;
+            break;
+        case SkShader::kRadial_GradientType:
+            transformPoints[1] = transformPoints[0];
+            transformPoints[1].fX += info->fRadius[0];
+            codeFunction = &radialCode;
+            break;
+        case SkShader::kRadial2_GradientType: {
+            // Bail out if the radii are the same.  Not setting fContent will
+            // cause the higher level code to detect the resulting object
+            // as invalid.
+            if (info->fRadius[0] == info->fRadius[1]) {
+                return;
+            }
+            transformPoints[1] = transformPoints[0];
+            SkScalar dr = info->fRadius[1] - info->fRadius[0];
+            transformPoints[1].fX += dr;
+            codeFunction = &twoPointRadialCode;
+            break;
+        }
+        case SkShader::kSweep_GradientType:
+            transformPoints[1] = transformPoints[0];
+            transformPoints[1].fX += 1;
+            codeFunction = &sweepCode;
+            break;
+        case SkShader::kColor_GradientType:
+        case SkShader::kNone_GradientType:
+            SkASSERT(false);
+            return;
+    }
+
+    // Move any scaling (assuming a unit gradient) or translation
+    // (and rotation for linear gradient), of the final gradient from
+    // info->fPoints to the matrix (updating bbox appropriately).  Now
+    // the gradient can be drawn on on the unit segment.
+    SkMatrix mapperMatrix;
+    unitToPointsMatrix(transformPoints, &mapperMatrix);
+    SkMatrix finalMatrix = fState.get()->fCanvasTransform;
+    finalMatrix.preConcat(mapperMatrix);
+    finalMatrix.preConcat(fState.get()->fShaderTransform);
+    SkRect bbox;
+    bbox.set(fState.get()->fBBox);
+    transformBBox(finalMatrix, &bbox);
+
+    SkRefPtr<SkPDFArray> domain = new SkPDFArray;
+    domain->unref();  // SkRefPtr and new both took a reference.
+    domain->reserve(4);
+    domain->append(new SkPDFScalar(bbox.fLeft))->unref();
+    domain->append(new SkPDFScalar(bbox.fRight))->unref();
+    domain->append(new SkPDFScalar(bbox.fTop))->unref();
+    domain->append(new SkPDFScalar(bbox.fBottom))->unref();
+
+    SkString functionCode;
+    // The two point radial gradient further references fState.get()->fInfo
+    // in translating from x, y coordinates to the t parameter. So, we have
+    // to transform the points and radii according to the calculated matrix.
+    if (fState.get()->fType == SkShader::kRadial2_GradientType) {
+        SkShader::GradientInfo twoPointRadialInfo = *info;
+        SkMatrix inverseMapperMatrix;
+        mapperMatrix.invert(&inverseMapperMatrix);
+        inverseMapperMatrix.mapPoints(twoPointRadialInfo.fPoint, 2);
+        twoPointRadialInfo.fRadius[0] =
+            inverseMapperMatrix.mapRadius(info->fRadius[0]);
+        twoPointRadialInfo.fRadius[1] =
+            inverseMapperMatrix.mapRadius(info->fRadius[1]);
+        functionCode = codeFunction(twoPointRadialInfo);
+    } else {
+        functionCode = codeFunction(*info);
+    }
+
+    SkRefPtr<SkPDFStream> function = makePSFunction(functionCode, domain.get());
+    // Pass one reference to fResources, SkRefPtr and new both took a reference.
+    fResources.push(function.get());
+
+    SkRefPtr<SkPDFDict> pdfShader = new SkPDFDict;
+    pdfShader->unref();  // SkRefPtr and new both took a reference.
+    pdfShader->insert("ShadingType", new SkPDFInt(1))->unref();
+    pdfShader->insert("ColorSpace", new SkPDFName("DeviceRGB"))->unref();
+    pdfShader->insert("Domain", domain.get());
+    pdfShader->insert("Function", new SkPDFObjRef(function.get()))->unref();
+
+    fContent = new SkPDFDict("Pattern");
+    fContent->unref();  // SkRefPtr and new both took a reference.
+    fContent->insert("PatternType", new SkPDFInt(2))->unref();
+    fContent->insert("Matrix", SkPDFUtils::MatrixToArray(finalMatrix))->unref();
+    fContent->insert("Shading", pdfShader.get());
+}
+
+// SkShader* shader, SkMatrix matrix, const SkRect& surfaceBBox
+void SkPDFShader::doImageShader() {
+    fState.get()->fImage.lockPixels();
+
+    SkMatrix finalMatrix = fState.get()->fCanvasTransform;
+    finalMatrix.preConcat(fState.get()->fShaderTransform);
+    SkRect surfaceBBox;
+    surfaceBBox.set(fState.get()->fBBox);
+    transformBBox(finalMatrix, &surfaceBBox);
+
+    SkPDFDevice pattern(surfaceBBox.fRight, surfaceBBox.fBottom,
+                        SkPDFDevice::kNoFlip_OriginTransform);
+    SkCanvas canvas(&pattern);
+    canvas.clipRect(surfaceBBox, SkRegion::kReplace_Op);
+
+    const SkBitmap* image = &fState.get()->fImage;
+    int width = image->width();
+    int height = image->height();
+    SkShader::TileMode tileModes[2];
+    tileModes[0] = fState.get()->fImageTileModes[0];
+    tileModes[1] = fState.get()->fImageTileModes[1];
+
+    canvas.drawBitmap(*image, 0, 0);
+    SkRect patternBBox = SkRect::MakeWH(width, height);
+
+    // Tiling is implied.  First we handle mirroring.
+    if (tileModes[0] == SkShader::kMirror_TileMode) {
+        SkMatrix xMirror;
+        xMirror.setScale(-1, 1);
+        xMirror.postTranslate(2 * width, 0);
+        canvas.drawBitmapMatrix(*image, xMirror);
+        patternBBox.fRight += width;
+    }
+    if (tileModes[1] == SkShader::kMirror_TileMode) {
+        SkMatrix yMirror;
+        yMirror.setScale(1, -1);
+        yMirror.postTranslate(0, 2 * height);
+        canvas.drawBitmapMatrix(*image, yMirror);
+        patternBBox.fBottom += height;
+    }
+    if (tileModes[0] == SkShader::kMirror_TileMode &&
+            tileModes[1] == SkShader::kMirror_TileMode) {
+        SkMatrix mirror;
+        mirror.setScale(-1, -1);
+        mirror.postTranslate(2 * width, 2 * height);
+        canvas.drawBitmapMatrix(*image, mirror);
+    }
+
+    // Then handle Clamping, which requires expanding the pattern canvas to
+    // cover the entire surfaceBBox.
+
+    // If both x and y are in clamp mode, we start by filling in the corners.
+    // (Which are just a rectangles of the corner colors.)
+    if (tileModes[0] == SkShader::kClamp_TileMode &&
+            tileModes[1] == SkShader::kClamp_TileMode) {
+        SkPaint paint;
+        SkRect rect;
+        rect = SkRect::MakeLTRB(surfaceBBox.fLeft, surfaceBBox.fTop, 0, 0);
+        if (!rect.isEmpty()) {
+            paint.setColor(image->getColor(0, 0));
+            canvas.drawRect(rect, paint);
+        }
+
+        rect = SkRect::MakeLTRB(width, surfaceBBox.fTop, surfaceBBox.fRight, 0);
+        if (!rect.isEmpty()) {
+            paint.setColor(image->getColor(width - 1, 0));
+            canvas.drawRect(rect, paint);
+        }
+
+        rect = SkRect::MakeLTRB(width, height, surfaceBBox.fRight,
+                                surfaceBBox.fBottom);
+        if (!rect.isEmpty()) {
+            paint.setColor(image->getColor(width - 1, height - 1));
+            canvas.drawRect(rect, paint);
+        }
+
+        rect = SkRect::MakeLTRB(surfaceBBox.fLeft, height, 0,
+                                surfaceBBox.fBottom);
+        if (!rect.isEmpty()) {
+            paint.setColor(image->getColor(0, height - 1));
+            canvas.drawRect(rect, paint);
+        }
+    }
+
+    // Then expand the left, right, top, then bottom.
+    if (tileModes[0] == SkShader::kClamp_TileMode) {
+        SkIRect subset = SkIRect::MakeXYWH(0, 0, 1, height);
+        if (surfaceBBox.fLeft < 0) {
+            SkBitmap left;
+            SkAssertResult(image->extractSubset(&left, subset));
+
+            SkMatrix leftMatrix;
+            leftMatrix.setScale(-surfaceBBox.fLeft, 1);
+            leftMatrix.postTranslate(surfaceBBox.fLeft, 0);
+            canvas.drawBitmapMatrix(left, leftMatrix);
+
+            if (tileModes[1] == SkShader::kMirror_TileMode) {
+                leftMatrix.postScale(1, -1);
+                leftMatrix.postTranslate(0, 2 * height);
+                canvas.drawBitmapMatrix(left, leftMatrix);
+            }
+            patternBBox.fLeft = surfaceBBox.fLeft;
+        }
+
+        if (surfaceBBox.fRight > width) {
+            SkBitmap right;
+            subset.offset(width - 1, 0);
+            SkAssertResult(image->extractSubset(&right, subset));
+
+            SkMatrix rightMatrix;
+            rightMatrix.setScale(surfaceBBox.fRight - width, 1);
+            rightMatrix.postTranslate(width, 0);
+            canvas.drawBitmapMatrix(right, rightMatrix);
+
+            if (tileModes[1] == SkShader::kMirror_TileMode) {
+                rightMatrix.postScale(1, -1);
+                rightMatrix.postTranslate(0, 2 * height);
+                canvas.drawBitmapMatrix(right, rightMatrix);
+            }
+            patternBBox.fRight = surfaceBBox.fRight;
+        }
+    }
+
+    if (tileModes[1] == SkShader::kClamp_TileMode) {
+        SkIRect subset = SkIRect::MakeXYWH(0, 0, width, 1);
+        if (surfaceBBox.fTop < 0) {
+            SkBitmap top;
+            SkAssertResult(image->extractSubset(&top, subset));
+
+            SkMatrix topMatrix;
+            topMatrix.setScale(1, -surfaceBBox.fTop);
+            topMatrix.postTranslate(0, surfaceBBox.fTop);
+            canvas.drawBitmapMatrix(top, topMatrix);
+
+            if (tileModes[0] == SkShader::kMirror_TileMode) {
+                topMatrix.postScale(-1, 1);
+                topMatrix.postTranslate(2 * width, 0);
+                canvas.drawBitmapMatrix(top, topMatrix);
+            }
+            patternBBox.fTop = surfaceBBox.fTop;
+        }
+
+        if (surfaceBBox.fBottom > height) {
+            SkBitmap bottom;
+            subset.offset(0, height - 1);
+            SkAssertResult(image->extractSubset(&bottom, subset));
+
+            SkMatrix bottomMatrix;
+            bottomMatrix.setScale(1, surfaceBBox.fBottom - height);
+            bottomMatrix.postTranslate(0, height);
+            canvas.drawBitmapMatrix(bottom, bottomMatrix);
+
+            if (tileModes[0] == SkShader::kMirror_TileMode) {
+                bottomMatrix.postScale(-1, 1);
+                bottomMatrix.postTranslate(2 * width, 0);
+                canvas.drawBitmapMatrix(bottom, bottomMatrix);
+            }
+            patternBBox.fBottom = surfaceBBox.fBottom;
+        }
+    }
+
+    SkRefPtr<SkPDFArray> patternBBoxArray = new SkPDFArray;
+    patternBBoxArray->unref();  // SkRefPtr and new both took a reference.
+    patternBBoxArray->reserve(4);
+    patternBBoxArray->append(new SkPDFInt(patternBBox.fLeft))->unref();
+    patternBBoxArray->append(new SkPDFInt(patternBBox.fTop))->unref();
+    patternBBoxArray->append(new SkPDFInt(patternBBox.fRight))->unref();
+    patternBBoxArray->append(new SkPDFInt(patternBBox.fBottom))->unref();
+
+    // Put the canvas into the pattern stream (fContent).
+    SkRefPtr<SkStream> content = pattern.content();
+    content->unref();  // SkRefPtr and content() both took a reference.
+    pattern.getResources(&fResources);
+
+    fContent = new SkPDFStream(content.get());
+    fContent->unref();  // SkRefPtr and new both took a reference.
+    fContent->insert("Type", new SkPDFName("Pattern"))->unref();
+    fContent->insert("PatternType", new SkPDFInt(1))->unref();
+    fContent->insert("PaintType", new SkPDFInt(1))->unref();
+    fContent->insert("TilingType", new SkPDFInt(1))->unref();
+    fContent->insert("BBox", patternBBoxArray.get());
+    fContent->insert("XStep", new SkPDFInt(patternBBox.width()))->unref();
+    fContent->insert("YStep", new SkPDFInt(patternBBox.height()))->unref();
+    fContent->insert("Resources", pattern.getResourceDict().get());
+    fContent->insert("Matrix", SkPDFUtils::MatrixToArray(finalMatrix))->unref();
+
+    fState.get()->fImage.unlockPixels();
+}
+
+SkPDFStream* SkPDFShader::makePSFunction(const SkString& psCode,
+                                         SkPDFArray* domain) {
+    SkRefPtr<SkMemoryStream> funcStream =
+        new SkMemoryStream(psCode.c_str(), psCode.size(), true);
+    funcStream->unref();  // SkRefPtr and new both took a reference.
+
+    SkPDFStream* result = new SkPDFStream(funcStream.get());
+    result->insert("FunctionType", new SkPDFInt(4))->unref();
+    result->insert("Domain", domain);
+    result->insert("Range", rangeObject());
+    return result;
+}
+
+bool SkPDFShader::State::operator==(const SkPDFShader::State& b) const {
+    if (fType != b.fType ||
+            fCanvasTransform != b.fCanvasTransform ||
+            fShaderTransform != b.fShaderTransform ||
+            fBBox != b.fBBox) {
+        return false;
+    }
+
+    if (fType == SkShader::kNone_GradientType) {
+        if (fPixelGeneration != b.fPixelGeneration ||
+                fPixelGeneration == 0 ||
+                fImageTileModes[0] != b.fImageTileModes[0] ||
+                fImageTileModes[1] != b.fImageTileModes[1]) {
+            return false;
+        }
+    } else {
+        if (fInfo.fColorCount != b.fInfo.fColorCount ||
+                memcmp(fInfo.fColors, b.fInfo.fColors,
+                       sizeof(SkColor) * fInfo.fColorCount) != 0 ||
+                memcmp(fInfo.fColorOffsets, b.fInfo.fColorOffsets,
+                       sizeof(SkScalar) * fInfo.fColorCount) != 0 ||
+                fInfo.fPoint[0] != b.fInfo.fPoint[0] ||
+                fInfo.fTileMode != b.fInfo.fTileMode) {
+            return false;
+        }
+
+        switch (fType) {
+            case SkShader::kLinear_GradientType:
+                if (fInfo.fPoint[1] != b.fInfo.fPoint[1]) {
+                    return false;
+                }
+                break;
+            case SkShader::kRadial_GradientType:
+                if (fInfo.fRadius[0] != b.fInfo.fRadius[0]) {
+                    return false;
+                }
+                break;
+            case SkShader::kRadial2_GradientType:
+                if (fInfo.fPoint[1] != b.fInfo.fPoint[1] ||
+                        fInfo.fRadius[0] != b.fInfo.fRadius[0] ||
+                        fInfo.fRadius[1] != b.fInfo.fRadius[1]) {
+                    return false;
+                }
+                break;
+            case SkShader::kSweep_GradientType:
+            case SkShader::kNone_GradientType:
+            case SkShader::kColor_GradientType:
+                break;
+        }
+    }
+    return true;
+}
+
+SkPDFShader::State::State(const SkShader& shader,
+                          const SkMatrix& canvasTransform, const SkIRect& bbox)
+        : fCanvasTransform(canvasTransform),
+          fBBox(bbox) {
+
+    fInfo.fColorCount = 0;
+    fInfo.fColors = NULL;
+    fInfo.fColorOffsets = NULL;
+    shader.getLocalMatrix(&fShaderTransform);
+
+    fType = shader.asAGradient(&fInfo);
+
+    if (fType == SkShader::kNone_GradientType) {
+        SkShader::BitmapType bitmapType;
+        SkMatrix matrix;
+        bitmapType = shader.asABitmap(&fImage, &matrix, fImageTileModes, NULL);
+        if (bitmapType != SkShader::kDefault_BitmapType) {
+            fImage.reset();
+            return;
+        }
+        SkASSERT(matrix.isIdentity());
+        fPixelGeneration = fImage.getGenerationID();
+    } else {
+        fColorData.set(sk_malloc_throw(
+                    fInfo.fColorCount * (sizeof(SkColor) + sizeof(SkScalar))));
+        fInfo.fColors = (SkColor*)fColorData.get();
+        fInfo.fColorOffsets = (SkScalar*)(fInfo.fColors + fInfo.fColorCount);
+        shader.asAGradient(&fInfo);
+    }
+}
diff --git a/src/pdf/pdf_files.mk b/src/pdf/pdf_files.mk
index ededdd35cd..c9b4fb41d3 100644
--- a/src/pdf/pdf_files.mk
+++ b/src/pdf/pdf_files.mk
@@ -7,6 +7,7 @@ SOURCE := \
     SkPDFGraphicState.cpp \
     SkPDFImage.cpp \
     SkPDFPage.cpp \
+    SkPDFShader.cpp \
     SkPDFStream.cpp \
     SkPDFTypes.cpp \
     SkPDFUtils.cpp