Implemented transparent gradients

src/pdf/SkPDFFormXObject.cpp

 
 /*
  * Copyright 2010 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 "SkPDFFormXObject.h"
 
 #include "SkMatrix.h"
 #include "SkPDFCatalog.h"
 #include "SkPDFDevice.h"
 #include "SkPDFUtils.h"
 #include "SkStream.h"
 #include "SkTypes.h"
 
+static SkPDFArray* rectToArray(SkRect rect) {

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

Put this in SkPDFUtil and use it in SkPDFDevice::copyMediaBox().

[ducky, 2013/07/03 23:32:09]

Done.

+    SkPDFArray* mediaBox = SkNEW(SkPDFArray);
+    mediaBox->reserve(4);
+    mediaBox->appendScalar(rect.left());
+    mediaBox->appendScalar(rect.top());
+    mediaBox->appendScalar(rect.right());
+    mediaBox->appendScalar(rect.bottom());
+    return mediaBox;
+}
+
 SkPDFFormXObject::SkPDFFormXObject(SkPDFDevice* device) {
     // We don't want to keep around device because we'd have two copies
     // of content, so reference or copy everything we need (content and
     // resources).
     SkTSet<SkPDFObject*> emptySet;
     device->getResources(emptySet, &fResources, false);
 
     SkAutoTUnref<SkStream> content(device->content());
     setData(content.get());
 
     insertName("Type", "XObject");
     insertName("Subtype", "Form");
     SkSafeUnref(this->insert("BBox", device->copyMediaBox()));
     insert("Resources", device->getResourceDict());
 
     // We invert the initial transform and apply that to the xobject so that
     // it doesn't get applied twice. We can't just undo it because it's
     // embedded in things like shaders and images.
     if (!device->initialTransform().isIdentity()) {

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

In your uses of the new constructor, do you take into consideration  the
initialtransform?

[ducky, 2013/07/03 23:32:09]

I don't think there's a way to specify the initial transform from just a content
stream. It just defaults to identity, right?
Unless you think it would be a good idea to include an initial transform matrix
in the constructor?

[vandebo (ex-Chrome), 2013/07/08 19:02:25]

Since SkGradientShader is implemented in terms of two SkFunctionShaders, which
both take into account the initial transform, I think it works out ok.  You
probably should test with an initial transform though.

It might be a bit cleaner/smaller to deal with the initial transform in the top
level object and have the dependent objects not have to worry about it, but I
suspect the code to make that happen would be more complicated.

         SkMatrix inverse;
         if (!device->initialTransform().invert(&inverse)) {
             // The initial transform should be invertible.
             SkASSERT(false);
             inverse.reset();
         }
         insert("Matrix", SkPDFUtils::MatrixToArray(inverse))->unref();
     }
 
     // Right now SkPDFFormXObject is only used for saveLayer, which implies
     // isolated blending.  Do this conditionally if that changes.
     SkAutoTUnref<SkPDFDict> group(new SkPDFDict("Group"));
     group->insertName("S", "Transparency");
     group->insert("I", new SkPDFBool(true))->unref();  // Isolated.
     insert("Group", group.get());
 }
 
+/**
+ * Creates a FormXObject from a content stream and associated resources.
+ */
+SkPDFFormXObject::SkPDFFormXObject(SkStream* content,
+                                   SkPDFDict* resourceDict,
+                                   SkTSet<SkPDFObject*>& resources,
+                                   SkRect bbox) {
+    setData(content);

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

This whole body can be shared with the other constructor.  Pull it out into a
private init method (since you can't call one constructor from another). 

[ducky, 2013/07/03 23:32:09]

Done.

+    resourceDict->ref();

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

This should be next to where the reference is used.

[ducky, 2013/07/03 23:32:09]

Done.

+
+    insertName("Type", "XObject");
+    insertName("Subtype", "Form");
+    SkSafeUnref(this->insert("BBox", rectToArray(bbox)));
+    insert("Resources", resourceDict);
+    fResources = resources;
+
+    // Right now SkPDFFormXObject is only used for saveLayer, which implies
+    // isolated blending.  Do this conditionally if that changes.
+    SkAutoTUnref<SkPDFDict> group(new SkPDFDict("Group"));
+    group->insertName("S", "Transparency");
+    group->insertName("CS", "DeviceRGB");
+    group->insert("I", new SkPDFBool(true))->unref();  // Isolated.
+    insert("Group", group.get());
+}
+
 SkPDFFormXObject::~SkPDFFormXObject() {
     fResources.unrefAll();
 }
 
 void SkPDFFormXObject::getResources(
         const SkTSet<SkPDFObject*>& knownResourceObjects,
         SkTSet<SkPDFObject*>* newResourceObjects) {
     GetResourcesHelper(&fResources.toArray(),
                        knownResourceObjects,
                        newResourceObjects);
 }