| /* |
| * Copyright 2006 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. |
| */ |
| |
| #ifndef SkColorFilter_DEFINED |
| #define SkColorFilter_DEFINED |
| |
| #include "SkColor.h" |
| #include "SkFlattenable.h" |
| #include "SkTDArray.h" |
| #include "SkXfermode.h" |
| |
| class GrContext; |
| class GrFragmentProcessor; |
| class GrProcessorDataManager; |
| class SkBitmap; |
| |
| /** |
| * ColorFilters are optional objects in the drawing pipeline. When present in |
| * a paint, they are called with the "src" colors, and return new colors, which |
| * are then passed onto the next stage (either ImageFilter or Xfermode). |
| * |
| * All subclasses are required to be reentrant-safe : it must be legal to share |
| * the same instance between several threads. |
| */ |
| class SK_API SkColorFilter : public SkFlattenable { |
| public: |
| /** |
| * If the filter can be represented by a source color plus Mode, this |
| * returns true, and sets (if not NULL) the color and mode appropriately. |
| * If not, this returns false and ignores the parameters. |
| */ |
| virtual bool asColorMode(SkColor* color, SkXfermode::Mode* mode) const; |
| |
| /** |
| * If the filter can be represented by a 5x4 matrix, this |
| * returns true, and sets the matrix appropriately. |
| * If not, this returns false and ignores the parameter. |
| */ |
| virtual bool asColorMatrix(SkScalar matrix[20]) const; |
| |
| /** |
| * If the filter can be represented by per-component table, return true, |
| * and if table is not null, copy the bitmap containing the table into it. |
| * |
| * The table bitmap will be in SkBitmap::kA8_Config. Each row corresponding |
| * to each component in ARGB order. e.g. row[0] == alpha, row[1] == red, |
| * etc. To transform a color, you (logically) perform the following: |
| * |
| * a' = *table.getAddr8(a, 0); |
| * r' = *table.getAddr8(r, 1); |
| * g' = *table.getAddr8(g, 2); |
| * b' = *table.getAddr8(b, 3); |
| * |
| * The original component value is the horizontal index for a given row, |
| * and the stored value at that index is the new value for that component. |
| */ |
| virtual bool asComponentTable(SkBitmap* table) const; |
| |
| /** Called with a scanline of colors, as if there was a shader installed. |
| The implementation writes out its filtered version into result[]. |
| Note: shader and result may be the same buffer. |
| @param src array of colors, possibly generated by a shader |
| @param count the number of entries in the src[] and result[] arrays |
| @param result written by the filter |
| */ |
| virtual void filterSpan(const SkPMColor src[], int count, SkPMColor result[]) const = 0; |
| |
| enum Flags { |
| /** If set the filter methods will not change the alpha channel of the colors. |
| */ |
| kAlphaUnchanged_Flag = 0x01, |
| }; |
| |
| /** Returns the flags for this filter. Override in subclasses to return custom flags. |
| */ |
| virtual uint32_t getFlags() const { return 0; } |
| |
| /** |
| * If this subclass can optimally createa composition with the inner filter, return it as |
| * a new filter (which the caller must unref() when it is done). If no such optimization |
| * is known, return NULL. |
| * |
| * e.g. result(color) == this_filter(inner(color)) |
| */ |
| virtual SkColorFilter* newComposed(const SkColorFilter* /*inner*/) const { return NULL; } |
| |
| /** |
| * Apply this colorfilter to the specified SkColor. This routine handles |
| * converting to SkPMColor, calling the filter, and then converting back |
| * to SkColor. This method is not virtual, but will call filterSpan() |
| * which is virtual. |
| */ |
| SkColor filterColor(SkColor) const; |
| |
| /** Create a colorfilter that uses the specified color and mode. |
| If the Mode is DST, this function will return NULL (since that |
| mode will have no effect on the result). |
| @param c The source color used with the specified mode |
| @param mode The xfermode mode that is applied to each color in |
| the colorfilter's filterSpan[16,32] methods |
| @return colorfilter object that applies the src color and mode, |
| or NULL if the mode will have no effect. |
| */ |
| static SkColorFilter* CreateModeFilter(SkColor c, SkXfermode::Mode mode); |
| |
| /** Create a colorfilter that multiplies the RGB channels by one color, and |
| then adds a second color, pinning the result for each component to |
| [0..255]. The alpha components of the mul and add arguments |
| are ignored. |
| */ |
| static SkColorFilter* CreateLightingFilter(SkColor mul, SkColor add); |
| |
| /** Construct a colorfilter whose effect is to first apply the inner filter and then apply |
| * the outer filter to the result of the inner's. |
| * The reference counts for outer and inner are incremented. |
| * |
| * Due to internal limits, it is possible that this will return NULL, so the caller must |
| * always check. |
| */ |
| static SkColorFilter* CreateComposeFilter(SkColorFilter* outer, SkColorFilter* inner); |
| |
| /** |
| * A subclass may implement this factory function to work with the GPU backend. It returns |
| * a GrFragmentProcessor that implemets the color filter in GPU shader code. |
| * |
| * The fragment processor receives a premultiplied input color and produces a premultiplied |
| * output color. |
| * |
| * A null return indicates that the color filter isn't implemented for the GPU backend. |
| */ |
| virtual const GrFragmentProcessor* asFragmentProcessor(GrContext*, |
| GrProcessorDataManager*) const { |
| return nullptr; |
| } |
| |
| bool affectsTransparentBlack() const { |
| return this->filterColor(0) != 0; |
| } |
| |
| SK_TO_STRING_PUREVIRT() |
| |
| SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() |
| SK_DEFINE_FLATTENABLE_TYPE(SkColorFilter) |
| |
| protected: |
| SkColorFilter() {} |
| |
| private: |
| /* |
| * Returns 1 if this is a single filter (not a composition of other filters), otherwise it |
| * reutrns the number of leaf-node filters in a composition. This should be the same value |
| * as the number of GrFragmentProcessors returned by asFragmentProcessors's array parameter. |
| * |
| * e.g. compose(filter, compose(compose(filter, filter), filter)) --> 4 |
| */ |
| virtual int privateComposedFilterCount() const { return 1; } |
| friend class SkComposeColorFilter; |
| |
| typedef SkFlattenable INHERITED; |
| }; |
| |
| #endif |