2fbf1bc8c9
This CL enables us to set the default visibility of the symbols on Android to hidden. It is the intent that all of he SK_APIs that have been added to /src directies should be removed as soon as we can remove their callers within Android. Bug: b/31971097 Change-Id: Ic787f94df0fb0c2b8d941aa7095a12b317c4b5de Reviewed-on: https://skia-review.googlesource.com/49501 Reviewed-by: Mike Reed <reed@google.com> Commit-Queue: Derek Sollenberger <djsollen@google.com>
112 lines
4.9 KiB
C++
112 lines
4.9 KiB
C++
|
|
/*
|
|
* Copyright 2017 Google Inc.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license that can be
|
|
* found in the LICENSE file.
|
|
*/
|
|
#ifndef SkShadowUtils_DEFINED
|
|
#define SkShadowUtils_DEFINED
|
|
|
|
#include "SkColor.h"
|
|
#include "SkPoint3.h"
|
|
#include "SkScalar.h"
|
|
#include "../private/SkShadowFlags.h"
|
|
|
|
class SkCanvas;
|
|
class SkPath;
|
|
class SkResourceCache;
|
|
|
|
class SK_API SkShadowUtils {
|
|
public:
|
|
/**
|
|
* Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
|
|
* light. The shadow may be cached, depending on the path type and canvas matrix. If the
|
|
* matrix is perspective or the path is volatile, it will not be cached.
|
|
*
|
|
* @param canvas The canvas on which to draw the shadows.
|
|
* @param path The occluder used to generate the shadows.
|
|
* @param zPlaneParams Values for the plane function which returns the Z offset of the
|
|
* occluder from the canvas based on local x and y values (the current matrix is not applied).
|
|
* @param lightPos The 3D position of the light relative to the canvas plane. This is
|
|
* independent of the canvas's current matrix.
|
|
* @param lightRadius The radius of the disc light.
|
|
* @param ambientAlpha The maximum alpha of the ambient shadow.
|
|
* @param spotAlpha The maxium alpha of the spot shadow.
|
|
* @param color The shadow color.
|
|
* @param flags Options controlling opaque occluder optimizations and shadow appearance. See
|
|
* SkShadowFlags.
|
|
*/
|
|
static void DrawShadow(SkCanvas* canvas, const SkPath& path, const SkPoint3& zPlaneParams,
|
|
const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha,
|
|
SkScalar spotAlpha, SkColor color,
|
|
uint32_t flags = SkShadowFlags::kNone_ShadowFlag);
|
|
|
|
/**
|
|
* Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
|
|
* light.
|
|
*
|
|
* Deprecated version with height value (to be removed when Flutter is updated).
|
|
*
|
|
* @param canvas The canvas on which to draw the shadows.
|
|
* @param path The occluder used to generate the shadows.
|
|
* @param occluderHeight The vertical offset of the occluder from the canvas. This is
|
|
* independent of the canvas's current matrix.
|
|
* @param lightPos The 3D position of the light relative to the canvas plane. This is
|
|
* independent of the canvas's current matrix.
|
|
* @param lightRadius The radius of the disc light.
|
|
* @param ambientAlpha The maximum alpha of the ambient shadow.
|
|
* @param spotAlpha The maxium alpha of the spot shadow.
|
|
* @param color The shadow color.
|
|
* @param flags Options controlling opaque occluder optimizations and shadow appearance. See
|
|
* SkShadowFlags.
|
|
*/
|
|
static void DrawShadow(SkCanvas* canvas, const SkPath& path, SkScalar occluderHeight,
|
|
const SkPoint3& lightPos, SkScalar lightRadius, SkScalar ambientAlpha,
|
|
SkScalar spotAlpha, SkColor color,
|
|
uint32_t flags = SkShadowFlags::kNone_ShadowFlag) {
|
|
SkPoint3 zPlane = SkPoint3::Make(0, 0, occluderHeight);
|
|
DrawShadow(canvas, path, zPlane, lightPos, lightRadius, ambientAlpha, spotAlpha,
|
|
color, flags);
|
|
}
|
|
|
|
/**
|
|
* Helper routine to compute scale alpha values for one-pass tonal alpha.
|
|
*
|
|
* The final color we want to emulate is generated by rendering a color shadow (C_rgb) using an
|
|
* alpha computed from the color's luminance (C_a), and then a black shadow with alpha (S_a)
|
|
* which is an adjusted value of 'a'. Assuming SrcOver, a background color of B_rgb, and
|
|
* ignoring edge falloff, this becomes
|
|
*
|
|
* (C_a - S_a*C_a)*C_rgb + (1 - (S_a + C_a - S_a*C_a))*B_rgb
|
|
*
|
|
* Since we use premultiplied alpha, this means we can scale the color by (C_a - S_a*C_a) and
|
|
* set the alpha to (S_a + C_a - S_a*C_a).
|
|
*
|
|
* @param r Red value of color
|
|
* @param g Red value of color
|
|
* @param b Red value of color
|
|
* @param a Red value of color
|
|
* @param colorScale Factor to scale color values by
|
|
* @param tonalAlpha Value to set alpha to
|
|
*/
|
|
static inline void ComputeTonalColorParams(SkScalar r, SkScalar g, SkScalar b, SkScalar a,
|
|
SkScalar* colorScale, SkScalar* tonalAlpha) {
|
|
SkScalar max = SkTMax(SkTMax(r, g), b);
|
|
SkScalar min = SkTMin(SkTMin(r, g), b);
|
|
SkScalar luminance = 0.5f*(max + min);
|
|
|
|
// We get best results with a luminance between 0.3 and 0.5, with smoothstep applied
|
|
SkScalar adjustedLuminance = (0.6f - 0.4f*luminance)*luminance*luminance + 0.3f;
|
|
// Similarly, we need to tone down the given greyscale alpha depending on how
|
|
// much color we're applying.
|
|
a -= (0.5f*adjustedLuminance - 0.15f);
|
|
|
|
*colorScale = adjustedLuminance*(SK_Scalar1 - a);
|
|
*tonalAlpha = *colorScale + a;
|
|
}
|
|
|
|
};
|
|
|
|
#endif
|