skia2/include/effects/SkLayerDrawLooper.h
commit-bot@chromium.org 8f838259ab Add methods to SkLayerDrawLooper to allow adding layers on top
as well as on the bottom.

This is more convenient for some callers who generate layers
from a data structure in bottom-to-top, rather than top-to-bottom,
order.

BUG=242529
R=tomhudson@chromium.org

Author: jbroman@chromium.org

Review URL: https://chromiumcodereview.appspot.com/15314003

git-svn-id: http://skia.googlecode.com/svn/trunk@9233 2bbb7eff-a529-9590-31e7-b0007b416f81
2013-05-22 12:35:50 +00:00

140 lines
4.5 KiB
C++

/*
* 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 SkLayerDrawLooper_DEFINED
#define SkLayerDrawLooper_DEFINED
#include "SkDrawLooper.h"
#include "SkPaint.h"
#include "SkPoint.h"
#include "SkXfermode.h"
class SK_API SkLayerDrawLooper : public SkDrawLooper {
public:
SK_DECLARE_INST_COUNT(SkLayerDrawLooper)
SkLayerDrawLooper();
virtual ~SkLayerDrawLooper();
/**
* Bits specifies which aspects of the layer's paint should replace the
* corresponding aspects on the draw's paint.
* kEntirePaint_Bits means use the layer's paint completely.
* 0 means ignore the layer's paint... except that LayerInfo's fFlagsMask
* and fColorMode are always applied.
*/
enum Bits {
kStyle_Bit = 1 << 0, //!< use this layer's Style/stroke settings
kTextSkewX_Bit = 1 << 1, //!< use this layer's textskewx
kPathEffect_Bit = 1 << 2, //!< use this layer's patheffect
kMaskFilter_Bit = 1 << 3, //!< use this layer's maskfilter
kShader_Bit = 1 << 4, //!< use this layer's shader
kColorFilter_Bit = 1 << 5, //!< use this layer's colorfilter
kXfermode_Bit = 1 << 6, //!< use this layer's xfermode
/**
* Use the layer's paint entirely, with these exceptions:
* - We never override the draw's paint's text_encoding, since that is
* used to interpret the text/len parameters in draw[Pos]Text.
* - Flags and Color are always computed using the LayerInfo's
* fFlagsMask and fColorMode.
*/
kEntirePaint_Bits = -1
};
typedef int32_t BitFlags;
/**
* Info for how to apply the layer's paint and offset.
*
* fFlagsMask selects which flags in the layer's paint should be applied.
* result = (draw-flags & ~fFlagsMask) | (layer-flags & fFlagsMask)
* In the extreme:
* If fFlagsMask is 0, we ignore all of the layer's flags
* If fFlagsMask is -1, we use all of the layer's flags
*
* fColorMode controls how we compute the final color for the layer:
* The layer's paint's color is treated as the SRC
* The draw's paint's color is treated as the DST
* final-color = Mode(layers-color, draws-color);
* Any SkXfermode::Mode will work. Two common choices are:
* kSrc_Mode: to use the layer's color, ignoring the draw's
* kDst_Mode: to just keep the draw's color, ignoring the layer's
*/
struct SK_API LayerInfo {
uint32_t fFlagsMask; // SkPaint::Flags
BitFlags fPaintBits;
SkXfermode::Mode fColorMode;
SkVector fOffset;
bool fPostTranslate; //!< applies to fOffset
/**
* Initial the LayerInfo. Defaults to settings that will draw the
* layer with no changes: e.g.
* fPaintBits == 0
* fColorMode == kDst_Mode
* fOffset == (0, 0)
*/
LayerInfo();
};
/**
* Call for each layer you want to add (from top to bottom).
* This returns a paint you can modify, but that ptr is only valid until
* the next call made to addLayer().
*/
SkPaint* addLayer(const LayerInfo&);
/**
* This layer will draw with the original paint, at the specified offset
*/
void addLayer(SkScalar dx, SkScalar dy);
/**
* This layer will with the original paint and no offset.
*/
void addLayer() { this->addLayer(0, 0); }
/// Similar to addLayer, but adds a layer to the top.
SkPaint* addLayerOnTop(const LayerInfo&);
// overrides from SkDrawLooper
virtual void init(SkCanvas*);
virtual bool next(SkCanvas*, SkPaint* paint);
SK_DEVELOPER_TO_STRING()
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLayerDrawLooper)
protected:
SkLayerDrawLooper(SkFlattenableReadBuffer&);
virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
private:
struct Rec {
Rec* fNext;
SkPaint fPaint;
LayerInfo fInfo;
};
Rec* fRecs;
Rec* fTopRec;
int fCount;
// state-machine during the init/next cycle
Rec* fCurrRec;
static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&);
class MyRegistrar : public SkFlattenable::Registrar {
public:
MyRegistrar();
};
typedef SkDrawLooper INHERITED;
};
#endif