skia2/include/core/SkBitmapDevice.h

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkBitmapDevice_DEFINED
#define SkBitmapDevice_DEFINED

#include "SkDevice.h"

///////////////////////////////////////////////////////////////////////////////
class SK_API SkBitmapDevice : public SkBaseDevice {
public:
    /**
     *  Construct a new device with the specified bitmap as its backend. It is
     *  valid for the bitmap to have no pixels associated with it. In that case,
     *  any drawing to this device will have no effect.
     */
    SkBitmapDevice(const SkBitmap& bitmap);

    /**
     * Create a new device along with its requisite pixel memory using
     * default SkSurfaceProps (i.e., kLegacyFontHost_InitType-style).
     * Note: this entry point is slated for removal - no one should call it.
     */
    static SkBitmapDevice* Create(const SkImageInfo& info);

    /**
     *  Construct a new device with the specified bitmap as its backend. It is
     *  valid for the bitmap to have no pixels associated with it. In that case,
     *  any drawing to this device will have no effect.
     */
    SkBitmapDevice(const SkBitmap& bitmap, const SkSurfaceProps& surfaceProps);

    static SkBitmapDevice* Create(const SkImageInfo&, const SkSurfaceProps&);

    SkImageInfo imageInfo() const override;

protected:
    bool onShouldDisableLCD(const SkPaint&) const 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, and any effects from the
     DrawFilter.
     */
    void drawPaint(const SkDraw&, const SkPaint& paint) override;
    virtual void drawPoints(const SkDraw&, SkCanvas::PointMode mode, size_t count,
                            const SkPoint[], const SkPaint& paint) override;
    virtual void drawRect(const SkDraw&, const SkRect& r,
                          const SkPaint& paint) override;
    virtual void drawOval(const SkDraw&, const SkRect& oval,
                          const SkPaint& paint) override;
    virtual void drawRRect(const SkDraw&, const SkRRect& rr,
                           const SkPaint& paint) override;

    /**
     *  If pathIsMutable, then the implementation is allowed to cast path to a
     *  non-const pointer and modify it in place (as an optimization). Canvas
     *  may do this to implement helpers such as drawOval, by placing a temp
     *  path on the stack to hold the representation of the oval.
     *
     *  If prePathMatrix is not null, it should logically be applied before any
     *  stroking or other effects. If there are no effects on the paint that
     *  affect the geometry/rasterization, then the pre matrix can just be
     *  pre-concated with the current matrix.
     */
    virtual void drawPath(const SkDraw&, const SkPath& path,
                          const SkPaint& paint,
                          const SkMatrix* prePathMatrix = NULL,
                          bool pathIsMutable = false) override;
    virtual void drawBitmap(const SkDraw&, const SkBitmap& bitmap,
                            const SkMatrix& matrix, const SkPaint& paint) override;
    virtual void drawSprite(const SkDraw&, const SkBitmap& bitmap,
                            int x, int y, const SkPaint& paint) override;

    /**
     *  The default impl. will create a bitmap-shader from the bitmap,
     *  and call drawRect with it.
     */
    void drawBitmapRect(const SkDraw&, const SkBitmap&, const SkRect*, const SkRect&,
                        const SkPaint&, SK_VIRTUAL_CONSTRAINT_TYPE) override;

    /**
     *  Does not handle text decoration.
     *  Decorations (underline and stike-thru) will be handled by SkCanvas.
     */
    virtual void drawText(const SkDraw&, const void* text, size_t len,
                          SkScalar x, SkScalar y, const SkPaint& paint) override;
    virtual void drawPosText(const SkDraw&, const void* text, size_t len,
                             const SkScalar pos[], int scalarsPerPos,
                             const SkPoint& offset, const SkPaint& paint) override;
    virtual void drawVertices(const SkDraw&, SkCanvas::VertexMode, int vertexCount,
                              const SkPoint verts[], const SkPoint texs[],
                              const SkColor colors[], SkXfermode* xmode,
                              const uint16_t indices[], int indexCount,
                              const SkPaint& paint) override;
    virtual void drawDevice(const SkDraw&, SkBaseDevice*, int x, int y, const SkPaint&) override;

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

    /** Update as needed the pixel value in the bitmap, so that the caller can
        access the pixels directly. Note: only the pixels field should be
        altered. The config/width/height/rowbytes must remain unchanged.
        @return the device contents as a bitmap
    */
    const SkBitmap& onAccessBitmap() override;

    SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
    // just for subclasses, to assign a custom pixelref
    SkPixelRef* setPixelRef(SkPixelRef* pr) {
        fBitmap.setPixelRef(pr);
        return pr;
    }

    bool onReadPixels(const SkImageInfo&, void*, size_t, int x, int y) override;
    bool onWritePixels(const SkImageInfo&, const void*, size_t, int, int) override;
    bool onPeekPixels(SkPixmap*) override;
    bool onAccessPixels(SkPixmap*) override;
    void onAttachToCanvas(SkCanvas*) override;
    void onDetachFromCanvas() override;

private:
    friend class SkCanvas;
    friend struct DeviceCM; //for setMatrixClip
    friend class SkDraw;
    friend class SkDrawIter;
    friend class SkDeviceFilteredPaint;

    friend class SkSurface_Raster;

    // used to change the backend's pixels (and possibly config/rowbytes)
    // but cannot change the width/height, so there should be no change to
    // any clip information.
    void replaceBitmapBackendForRasterSurface(const SkBitmap&) override;

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

    SkSurface* newSurface(const SkImageInfo&, const SkSurfaceProps&) override;

    SkImageFilter::Cache* getImageFilterCache() override;

    SkBitmap    fBitmap;

    void setNewSize(const SkISize&);  // Used by SkCanvas for resetForNextPicture().

    typedef SkBaseDevice INHERITED;
};

#endif // SkBitmapDevice_DEFINED