src/pdf/SkPDFDevice.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkPDFDevice_DEFINED
#define SkPDFDevice_DEFINED

#include "SkBitmap.h"
#include "SkCanvas.h"
#include "SkClipStack.h"
#include "SkClipStackDevice.h"
#include "SkData.h"
#include "SkPaint.h"
#include "SkRect.h"
#include "SkRefCnt.h"
#include "SkSinglyLinkedList.h"
#include "SkStream.h"
#include "SkTDArray.h"
#include "SkTextBlobPriv.h"
#include "SkKeyedImage.h"

class SkGlyphRunList;
class SkKeyedImage;
class SkPath;
class SkPDFArray;
class SkPDFCanon;
class SkPDFDevice;
class SkPDFDocument;
class SkPDFDict;
class SkPDFFont;
class SkPDFObject;
class SkPDFStream;
class SkRRect;

/**
 *  \class SkPDFDevice
 *
 *  An SkPDFDevice is the drawing context for a page or layer of PDF
 *  content.
 */
class SkPDFDevice final : public SkClipStackDevice {
public:
    /**
     *  @param pageSize Page size in point units.
     *         1 point == 127/360 mm == 1/72 inch
     *  @param document  A non-null pointer back to the
     *         PDFDocument object.  The document is repsonsible for
     *         de-duplicating across pages (via the SkPDFCanon) and
     *         for early serializing of large immutable objects, such
     *         as images (via SkPDFDocument::serialize()).
     */
    SkPDFDevice(SkISize pageSize, SkPDFDocument* document);

    /**
     *  Apply a scale-and-translate transform to move the origin from the
     *  bottom left (PDF default) to the top left (Skia default).
     */
    void setFlip();

    sk_sp<SkPDFDevice> makeCongruentDevice() {
        return sk_make_sp<SkPDFDevice>(fPageSize, fDocument);
    }

    ~SkPDFDevice() override;

    /**
     *  These are called inside the per-device-layer loop for each draw call.
     *  When these are called, we have already applied any saveLayer
     *  operations, and are handling any looping from the paint.
     */
    void drawPaint(const SkPaint& paint) override;
    void drawPoints(SkCanvas::PointMode mode,
                    size_t count, const SkPoint[],
                    const SkPaint& paint) override;
    void drawRect(const SkRect& r, const SkPaint& paint) override;
    void drawOval(const SkRect& oval, const SkPaint& paint) override;
    void drawRRect(const SkRRect& rr, const SkPaint& paint) override;
    void drawPath(const SkPath& origpath, const SkPaint& paint, bool pathIsMutable) override;
    void drawBitmapRect(const SkBitmap& bitmap, const SkRect* src,
                        const SkRect& dst, const SkPaint&, SkCanvas::SrcRectConstraint) override;
    void drawBitmap(const SkBitmap& bitmap, SkScalar x, SkScalar y, const SkPaint&) override;
    void drawSprite(const SkBitmap& bitmap, int x, int y,
                    const SkPaint& paint) override;
    void drawImage(const SkImage*,
                   SkScalar x,
                   SkScalar y,
                   const SkPaint&) override;
    void drawImageRect(const SkImage*,
                       const SkRect* src,
                       const SkRect& dst,
                       const SkPaint&,
                       SkCanvas::SrcRectConstraint) override;
    void drawPosText(const void* text, size_t len,
                     const SkScalar pos[], int scalarsPerPos,
                     const SkPoint& offset, const SkPaint&) override { SkASSERT(false); }
    void drawGlyphRunList(const SkGlyphRunList& glyphRunList) override;
    void drawVertices(const SkVertices*, const SkVertices::Bone bones[], int boneCount, SkBlendMode,
                      const SkPaint&) override;
    void drawDevice(SkBaseDevice*, int x, int y,
                    const SkPaint&) override;

    // PDF specific methods.

    /** Create the resource dictionary for this device. */
    sk_sp<SkPDFDict> makeResourceDict() const;

    /** Add our annotations (link to urls and destinations) to the supplied
     *  array.
     *  @param array Array to add annotations to.
     */
    void appendAnnotations(SkPDFArray* array) const;

    /** Add our named destinations to the supplied dictionary.
     *  @param dict  Dictionary to add destinations to.
     *  @param page  The PDF object representing the page for this device.
     */
    void appendDestinations(SkPDFDict* dict, SkPDFObject* page) const;

    /** Returns a copy of the media box for this device. */
    sk_sp<SkPDFArray> copyMediaBox() const;

    /** Returns a SkStream with the page contents.
     */
    std::unique_ptr<SkStreamAsset> content() const;

    SkPDFCanon* getCanon() const;

    SkIRect bounds() const { return this->imageInfo().bounds(); }

    // It is important to not confuse GraphicStateEntry with SkPDFGraphicState, the
    // later being our representation of an object in the PDF file.
    struct GraphicStateEntry {
        GraphicStateEntry();

        // Compare the fields we care about when setting up a new content entry.
        bool compareInitialState(const GraphicStateEntry& b);

        SkMatrix fMatrix;
        // We can't do set operations on Paths, though PDF natively supports
        // intersect.  If the clip stack does anything other than intersect,
        // we have to fall back to the region.  Treat fClipStack as authoritative.
        // See https://bugs.skia.org/221
        SkClipStack fClipStack;

        // When emitting the content entry, we will ensure the graphic state
        // is set to these values first.
        SkColor fColor;
        SkScalar fTextScaleX;  // Zero means we don't care what the value is.
        SkPaint::Style fTextFill;  // Only if TextScaleX is non-zero.
        int fShaderIndex;
        int fGraphicStateIndex;
    };

protected:
    sk_sp<SkSurface> makeSurface(const SkImageInfo&, const SkSurfaceProps&) override;

    void drawAnnotation(const SkRect&, const char key[], SkData* value) override;

    void drawSpecial(SkSpecialImage*, int x, int y, const SkPaint&,
                     SkImage*, const SkMatrix&) override;
    sk_sp<SkSpecialImage> makeSpecial(const SkBitmap&) override;
    sk_sp<SkSpecialImage> makeSpecial(const SkImage*) override;
    sk_sp<SkSpecialImage> snapSpecial() override;
    SkImageFilterCache* getImageFilterCache() override;

private:
    struct RectWithData {
        SkRect rect;
        sk_sp<SkData> data;
    };

    struct NamedDestination {
        sk_sp<SkData> nameData;
        SkPoint point;
    };

    // TODO(vandebo): push most of SkPDFDevice's state into a core object in
    // order to get the right access levels without using friend.
    friend class ScopedContentEntry;

    SkISize fPageSize;
    SkMatrix fInitialTransform;
    SkClipStack fExistingClipStack;

    SkTArray<RectWithData> fLinkToURLs;
    SkTArray<RectWithData> fLinkToDestinations;
    SkTArray<NamedDestination> fNamedDestinations;

    SkTDArray<SkPDFObject*> fGraphicStateResources;
    SkTDArray<SkPDFObject*> fXObjectResources;
    SkTDArray<SkPDFFont*> fFontResources;
    SkTDArray<SkPDFObject*> fShaderResources;

    struct ContentEntry {
        GraphicStateEntry fState;
        SkDynamicMemoryWStream fContent;
    };
    SkSinglyLinkedList<ContentEntry> fContentEntries;

    SkPDFDocument* fDocument;

    ////////////////////////////////////////////////////////////////////////////

    SkBaseDevice* onCreateDevice(const CreateInfo&, const SkPaint*) override;

    void init();
    void cleanUp();
    // Set alpha to true if making a transparency group form x-objects.
    sk_sp<SkPDFObject> makeFormXObjectFromDevice(bool alpha = false);

    void drawFormXObjectWithMask(int xObjectIndex,
                                 sk_sp<SkPDFObject> mask,
                                 const SkClipStack& clipStack,
                                 SkBlendMode,
                                 bool invertClip);

    // If the paint or clip is such that we shouldn't draw anything, this
    // returns nullptr and does not create a content entry.
    // setUpContentEntry and finishContentEntry can be used directly, but
    // the preferred method is to use the ScopedContentEntry helper class.
    ContentEntry* setUpContentEntry(const SkClipStack& clipStack,
                                    const SkMatrix& matrix,
                                    const SkPaint& paint,
                                    bool hasText,
                                    sk_sp<SkPDFObject>* dst);
    void finishContentEntry(SkBlendMode, sk_sp<SkPDFObject> dst, SkPath* shape);
    bool isContentEmpty();

    void populateGraphicStateEntryFromPaint(const SkMatrix& matrix,
                                            const SkClipStack& clipStack,
                                            const SkPaint& paint,
                                            bool hasText,
                                            GraphicStateEntry* entry);
    int addGraphicStateResource(SkPDFObject* gs);
    int addXObjectResource(SkPDFObject* xObject);

    int getFontResourceIndex(SkTypeface* typeface, uint16_t glyphID);

    void internalDrawGlyphRun(const SkGlyphRun& glyphRun, SkPoint offset);

    void internalDrawPaint(const SkPaint& paint, ContentEntry* contentEntry);

    void internalDrawImageRect(SkKeyedImage,
                               const SkRect* src,
                               const SkRect& dst,
                               const SkPaint&,
                               const SkMatrix& canvasTransformationMatrix);

    void internalDrawPath(const SkClipStack&,
                          const SkMatrix&,
                          const SkPath&,
                          const SkPaint&,
                          bool pathIsMutable);

    void internalDrawPathWithFilter(const SkClipStack& clipStack,
                                    const SkMatrix& ctm,
                                    const SkPath& origPath,
                                    const SkPaint& paint);

    bool handleInversePath(const SkPath& origPath, const SkPaint& paint, bool pathIsMutable);

    void addSMaskGraphicState(sk_sp<SkPDFDevice> maskDevice, SkDynamicMemoryWStream*);
    void clearMaskOnGraphicState(SkDynamicMemoryWStream*);

    bool hasEmptyClip() const { return this->cs().isEmpty(this->bounds()); }

    typedef SkClipStackDevice INHERITED;
};

#endif