// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gfx/skbitmap_operations.h"
#include <algorithm>
#include <string.h>
#include "base/logging.h"
#include "skia/ext/refptr.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkColorFilter.h"
#include "third_party/skia/include/core/SkColorPriv.h"
#include "third_party/skia/include/core/SkUnPreMultiply.h"
#include "third_party/skia/include/effects/SkBlurImageFilter.h"
#include "ui/gfx/insets.h"
#include "ui/gfx/point.h"
#include "ui/gfx/size.h"
// static
SkBitmap SkBitmapOperations::CreateInvertedBitmap(const SkBitmap& image) {
DCHECK(image.colorType() == kPMColor_SkColorType);
SkAutoLockPixels lock_image(image);
SkBitmap inverted;
inverted.allocN32Pixels(image.width(), image.height());
inverted.eraseARGB(0, 0, 0, 0);
for (int y = 0; y < image.height(); ++y) {
uint32* image_row = image.getAddr32(0, y);
uint32* dst_row = inverted.getAddr32(0, y);
for (int x = 0; x < image.width(); ++x) {
uint32 image_pixel = image_row[x];
dst_row[x] = (image_pixel & 0xFF000000) |
(0x00FFFFFF - (image_pixel & 0x00FFFFFF));
}
}
return inverted;
}
// static
SkBitmap SkBitmapOperations::CreateSuperimposedBitmap(const SkBitmap& first,
const SkBitmap& second) {
DCHECK(first.width() == second.width());
DCHECK(first.height() == second.height());
DCHECK(first.bytesPerPixel() == second.bytesPerPixel());
DCHECK(first.colorType() == kPMColor_SkColorType);
SkAutoLockPixels lock_first(first);
SkAutoLockPixels lock_second(second);
SkBitmap superimposed;
superimposed.allocN32Pixels(first.width(), first.height());
superimposed.eraseARGB(0, 0, 0, 0);
SkCanvas canvas(superimposed);
SkRect rect;
rect.fLeft = 0;
rect.fTop = 0;
rect.fRight = SkIntToScalar(first.width());
rect.fBottom = SkIntToScalar(first.height());
canvas.drawBitmapRect(first, NULL, rect);
canvas.drawBitmapRect(second, NULL, rect);
return superimposed;
}
// static
SkBitmap SkBitmapOperations::CreateBlendedBitmap(const SkBitmap& first,
const SkBitmap& second,
double alpha) {
DCHECK((alpha >= 0) && (alpha <= 1));
DCHECK(first.width() == second.width());
DCHECK(first.height() == second.height());
DCHECK(first.bytesPerPixel() == second.bytesPerPixel());
DCHECK(first.colorType() == kPMColor_SkColorType);
// Optimize for case where we won't need to blend anything.
static const double alpha_min = 1.0 / 255;
static const double alpha_max = 254.0 / 255;
if (alpha < alpha_min)
return first;
else if (alpha > alpha_max)
return second;
SkAutoLockPixels lock_first(first);
SkAutoLockPixels lock_second(second);
SkBitmap blended;
blended.allocN32Pixels(first.width(), first.height());
blended.eraseARGB(0, 0, 0, 0);
double first_alpha = 1 - alpha;
for (int y = 0; y < first.height(); ++y) {
uint32* first_row = first.getAddr32(0, y);
uint32* second_row = second.getAddr32(0, y);
uint32* dst_row = blended.getAddr32(0, y);
for (int x = 0; x < first.width(); ++x) {
uint32 first_pixel = first_row[x];
uint32 second_pixel = second_row[x];
int a = static_cast<int>((SkColorGetA(first_pixel) * first_alpha) +
(SkColorGetA(second_pixel) * alpha));
int r = static_cast<int>((SkColorGetR(first_pixel) * first_alpha) +
(SkColorGetR(second_pixel) * alpha));
int g = static_cast<int>((SkColorGetG(first_pixel) * first_alpha) +
(SkColorGetG(second_pixel) * alpha));
int b = static_cast<int>((SkColorGetB(first_pixel) * first_alpha) +
(SkColorGetB(second_pixel) * alpha));
dst_row[x] = SkColorSetARGB(a, r, g, b);
}
}
return blended;
}
// static
SkBitmap SkBitmapOperations::CreateMaskedBitmap(const SkBitmap& rgb,
const SkBitmap& alpha) {
DCHECK(rgb.width() == alpha.width());
DCHECK(rgb.height() == alpha.height());
DCHECK(rgb.bytesPerPixel() == alpha.bytesPerPixel());
DCHECK(rgb.colorType() == kPMColor_SkColorType);
DCHECK(alpha.colorType() == kPMColor_SkColorType);
SkBitmap masked;
masked.allocN32Pixels(rgb.width(), rgb.height());
masked.eraseARGB(0, 0, 0, 0);
SkAutoLockPixels lock_rgb(rgb);
SkAutoLockPixels lock_alpha(alpha);
SkAutoLockPixels lock_masked(masked);
for (int y = 0; y < masked.height(); ++y) {
uint32* rgb_row = rgb.getAddr32(0, y);
uint32* alpha_row = alpha.getAddr32(0, y);
uint32* dst_row = masked.getAddr32(0, y);
for (int x = 0; x < masked.width(); ++x) {
SkColor rgb_pixel = SkUnPreMultiply::PMColorToColor(rgb_row[x]);
SkColor alpha_pixel = SkUnPreMultiply::PMColorToColor(alpha_row[x]);
int alpha = SkAlphaMul(SkColorGetA(rgb_pixel),
SkAlpha255To256(SkColorGetA(alpha_pixel)));
int alpha_256 = SkAlpha255To256(alpha);
dst_row[x] = SkColorSetARGB(alpha,
SkAlphaMul(SkColorGetR(rgb_pixel), alpha_256),
SkAlphaMul(SkColorGetG(rgb_pixel), alpha_256),
SkAlphaMul(SkColorGetB(rgb_pixel),
alpha_256));
}
}
return masked;
}
// static
SkBitmap SkBitmapOperations::CreateButtonBackground(SkColor color,
const SkBitmap& image,
const SkBitmap& mask) {
DCHECK(image.colorType() == kPMColor_SkColorType);
DCHECK(mask.colorType() == kPMColor_SkColorType);
SkBitmap background;
background.allocN32Pixels(mask.width(), mask.height());
double bg_a = SkColorGetA(color);
double bg_r = SkColorGetR(color);
double bg_g = SkColorGetG(color);
double bg_b = SkColorGetB(color);
SkAutoLockPixels lock_mask(mask);
SkAutoLockPixels lock_image(image);
SkAutoLockPixels lock_background(background);
for (int y = 0; y < mask.height(); ++y) {
uint32* dst_row = background.getAddr32(0, y);
uint32* image_row = image.getAddr32(0, y % image.height());
uint32* mask_row = mask.getAddr32(0, y);
for (int x = 0; x < mask.width(); ++x) {
uint32 image_pixel = image_row[x % image.width()];
double img_a = SkColorGetA(image_pixel);
double img_r = SkColorGetR(image_pixel);
double img_g = SkColorGetG(image_pixel);
double img_b = SkColorGetB(image_pixel);
double img_alpha = static_cast<double>(img_a) / 255.0;
double img_inv = 1 - img_alpha;
double mask_a = static_cast<double>(SkColorGetA(mask_row[x])) / 255.0;
dst_row[x] = SkColorSetARGB(
static_cast<int>(std::min(255.0, bg_a + img_a) * mask_a),
static_cast<int>(((bg_r * img_inv) + (img_r * img_alpha)) * mask_a),
static_cast<int>(((bg_g * img_inv) + (img_g * img_alpha)) * mask_a),
static_cast<int>(((bg_b * img_inv) + (img_b * img_alpha)) * mask_a));
}
}
return background;
}
namespace {
namespace HSLShift {
// TODO(viettrungluu): Some things have yet to be optimized at all.
// Notes on and conventions used in the following code
//
// Conventions:
// - R, G, B, A = obvious; as variables: |r|, |g|, |b|, |a| (see also below)
// - H, S, L = obvious; as variables: |h|, |s|, |l| (see also below)
// - variables derived from S, L shift parameters: |sdec| and |sinc| for S
// increase and decrease factors, |ldec| and |linc| for L (see also below)
//
// To try to optimize HSL shifts, we do several things:
// - Avoid unpremultiplying (then processing) then premultiplying. This means
// that R, G, B values (and also L, but not H and S) should be treated as
// having a range of 0..A (where A is alpha).
// - Do things in integer/fixed-point. This avoids costly conversions between
// floating-point and integer, though I should study the tradeoff more
// carefully (presumably, at some point of processing complexity, converting
// and processing using simpler floating-point code will begin to win in
// performance). Also to be studied is the speed/type of floating point
// conversions; see, e.g., <http://www.stereopsis.com/sree/fpu2006.html>.
//
// Conventions for fixed-point arithmetic
// - Each function has a constant denominator (called |den|, which should be a
// power of 2), appropriate for the computations done in that function.
// - A value |x| is then typically represented by a numerator, named |x_num|,
// so that its actual value is |x_num / den| (casting to floating-point
// before division).
// - To obtain |x_num| from |x|, simply multiply by |den|, i.e., |x_num = x *
// den| (casting appropriately).
// - When necessary, a value |x| may also be represented as a numerator over
// the denominator squared (set |den2 = den * den|). In such a case, the
// corresponding variable is called |x_num2| (so that its actual value is
// |x_num^2 / den2|.
// - The representation of the product of |x| and |y| is be called |x_y_num| if
// |x * y == x_y_num / den|, and |xy_num2| if |x * y == x_y_num2 / den2|. In
// the latter case, notice that one can calculate |x_y_num2 = x_num * y_num|.
// Routine used to process a line; typically specialized for specific kinds of
// HSL shifts (to optimize).
typedef void (*LineProcessor)(const color_utils::HSL&,
const SkPMColor*,
SkPMColor*,
int width);
enum OperationOnH { kOpHNone = 0, kOpHShift, kNumHOps };
enum OperationOnS { kOpSNone = 0, kOpSDec, kOpSInc, kNumSOps };
enum OperationOnL { kOpLNone = 0, kOpLDec, kOpLInc, kNumLOps };
// Epsilon used to judge when shift values are close enough to various critical
// values (typically 0.5, which yields a no-op for S and L shifts. 1/256 should
// be small enough, but let's play it safe>
const double epsilon = 0.0005;
// Line processor: default/universal (i.e., old-school).
void LineProcDefault(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
for (int x = 0; x < width; x++) {
out[x] = SkPreMultiplyColor(color_utils::HSLShift(
SkUnPreMultiply::PMColorToColor(in[x]), hsl_shift));
}
}
// Line processor: no-op (i.e., copy).
void LineProcCopy(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
DCHECK(hsl_shift.l < 0 || fabs(hsl_shift.l - 0.5) < HSLShift::epsilon);
memcpy(out, in, static_cast<size_t>(width) * sizeof(out[0]));
}
// Line processor: H no-op, S no-op, L decrease.
void LineProcHnopSnopLdec(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
const uint32_t den = 65536;
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
DCHECK(hsl_shift.l <= 0.5 - HSLShift::epsilon && hsl_shift.l >= 0);
uint32_t ldec_num = static_cast<uint32_t>(hsl_shift.l * 2 * den);
for (int x = 0; x < width; x++) {
uint32_t a = SkGetPackedA32(in[x]);
uint32_t r = SkGetPackedR32(in[x]);
uint32_t g = SkGetPackedG32(in[x]);
uint32_t b = SkGetPackedB32(in[x]);
r = r * ldec_num / den;
g = g * ldec_num / den;
b = b * ldec_num / den;
out[x] = SkPackARGB32(a, r, g, b);
}
}
// Line processor: H no-op, S no-op, L increase.
void LineProcHnopSnopLinc(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
const uint32_t den = 65536;
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s < 0 || fabs(hsl_shift.s - 0.5) < HSLShift::epsilon);
DCHECK(hsl_shift.l >= 0.5 + HSLShift::epsilon && hsl_shift.l <= 1);
uint32_t linc_num = static_cast<uint32_t>((hsl_shift.l - 0.5) * 2 * den);
for (int x = 0; x < width; x++) {
uint32_t a = SkGetPackedA32(in[x]);
uint32_t r = SkGetPackedR32(in[x]);
uint32_t g = SkGetPackedG32(in[x]);
uint32_t b = SkGetPackedB32(in[x]);
r += (a - r) * linc_num / den;
g += (a - g) * linc_num / den;
b += (a - b) * linc_num / den;
out[x] = SkPackARGB32(a, r, g, b);
}
}
// Saturation changes modifications in RGB
//
// (Note that as a further complication, the values we deal in are
// premultiplied, so R/G/B values must be in the range 0..A. For mathematical
// purposes, one may as well use r=R/A, g=G/A, b=B/A. Without loss of
// generality, assume that R/G/B values are in the range 0..1.)
//
// Let Max = max(R,G,B), Min = min(R,G,B), and Med be the median value. Then L =
// (Max+Min)/2. If L is to remain constant, Max+Min must also remain constant.
//
// For H to remain constant, first, the (numerical) order of R/G/B (from
// smallest to largest) must remain the same. Second, all the ratios
// (R-G)/(Max-Min), (R-B)/(Max-Min), (G-B)/(Max-Min) must remain constant (of
// course, if Max = Min, then S = 0 and no saturation change is well-defined,
// since H is not well-defined).
//
// Let C_max be a colour with value Max, C_min be one with value Min, and C_med
// the remaining colour. Increasing saturation (to the maximum) is accomplished
// by increasing the value of C_max while simultaneously decreasing C_min and
// changing C_med so that the ratios are maintained; for the latter, it suffices
// to keep (C_med-C_min)/(C_max-C_min) constant (and equal to
// (Med-Min)/(Max-Min)).
// Line processor: H no-op, S decrease, L no-op.
void LineProcHnopSdecLnop(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
DCHECK(hsl_shift.l < 0 || fabs(hsl_shift.l - 0.5) < HSLShift::epsilon);
const int32_t denom = 65536;
int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
for (int x = 0; x < width; x++) {
int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
int32_t vmax, vmin;
if (r > g) { // This uses 3 compares rather than 4.
vmax = std::max(r, b);
vmin = std::min(g, b);
} else {
vmax = std::max(g, b);
vmin = std::min(r, b);
}
// Use denom * L to avoid rounding.
int32_t denom_l = (vmax + vmin) * (denom / 2);
int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
r = (denom_l + r * s_numer - s_numer_l) / denom;
g = (denom_l + g * s_numer - s_numer_l) / denom;
b = (denom_l + b * s_numer - s_numer_l) / denom;
out[x] = SkPackARGB32(a, r, g, b);
}
}
// Line processor: H no-op, S decrease, L decrease.
void LineProcHnopSdecLdec(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
DCHECK(hsl_shift.l >= 0 && hsl_shift.l <= 0.5 - HSLShift::epsilon);
// Can't be too big since we need room for denom*denom and a bit for sign.
const int32_t denom = 1024;
int32_t l_numer = static_cast<int32_t>(hsl_shift.l * 2 * denom);
int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
for (int x = 0; x < width; x++) {
int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
int32_t vmax, vmin;
if (r > g) { // This uses 3 compares rather than 4.
vmax = std::max(r, b);
vmin = std::min(g, b);
} else {
vmax = std::max(g, b);
vmin = std::min(r, b);
}
// Use denom * L to avoid rounding.
int32_t denom_l = (vmax + vmin) * (denom / 2);
int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
r = (denom_l + r * s_numer - s_numer_l) * l_numer / (denom * denom);
g = (denom_l + g * s_numer - s_numer_l) * l_numer / (denom * denom);
b = (denom_l + b * s_numer - s_numer_l) * l_numer / (denom * denom);
out[x] = SkPackARGB32(a, r, g, b);
}
}
// Line processor: H no-op, S decrease, L increase.
void LineProcHnopSdecLinc(const color_utils::HSL& hsl_shift,
const SkPMColor* in,
SkPMColor* out,
int width) {
DCHECK(hsl_shift.h < 0);
DCHECK(hsl_shift.s >= 0 && hsl_shift.s <= 0.5 - HSLShift::epsilon);
DCHECK(hsl_shift.l >= 0.5 + HSLShift::epsilon && hsl_shift.l <= 1);
// Can't be too big since we need room for denom*denom and a bit for sign.
const int32_t denom = 1024;
int32_t l_numer = static_cast<int32_t>((hsl_shift.l - 0.5) * 2 * denom);
int32_t s_numer = static_cast<int32_t>(hsl_shift.s * 2 * denom);
for (int x = 0; x < width; x++) {
int32_t a = static_cast<int32_t>(SkGetPackedA32(in[x]));
int32_t r = static_cast<int32_t>(SkGetPackedR32(in[x]));
int32_t g = static_cast<int32_t>(SkGetPackedG32(in[x]));
int32_t b = static_cast<int32_t>(SkGetPackedB32(in[x]));
int32_t vmax, vmin;
if (r > g) { // This uses 3 compares rather than 4.
vmax = std::max(r, b);
vmin = std::min(g, b);
} else {
vmax = std::max(g, b);
vmin = std::min(r, b);
}
// Use denom * L to avoid rounding.
int32_t denom_l = (vmax + vmin) * (denom / 2);
int32_t s_numer_l = (vmax + vmin) * s_numer / 2;
r = denom_l + r * s_numer - s_numer_l;
g = denom_l + g * s_numer - s_numer_l;
b = denom_l + b * s_numer - s_numer_l;
r = (r * denom + (a * denom - r) * l_numer) / (denom * denom);
g = (g * denom + (a * denom - g) * l_numer) / (denom * denom);
b = (b * denom + (a * denom - b) * l_numer) / (denom * denom);
out[x] = SkPackARGB32(a, r, g, b);
}
}
const LineProcessor kLineProcessors[kNumHOps][kNumSOps][kNumLOps] = {
{ // H: kOpHNone
{ // S: kOpSNone
LineProcCopy, // L: kOpLNone
LineProcHnopSnopLdec, // L: kOpLDec
LineProcHnopSnopLinc // L: kOpLInc
},
{ // S: kOpSDec
LineProcHnopSdecLnop, // L: kOpLNone
LineProcHnopSdecLdec, // L: kOpLDec
LineProcHnopSdecLinc // L: kOpLInc
},
{ // S: kOpSInc
LineProcDefault, // L: kOpLNone
LineProcDefault, // L: kOpLDec
LineProcDefault // L: kOpLInc
}
},
{ // H: kOpHShift
{ // S: kOpSNone
LineProcDefault, // L: kOpLNone
LineProcDefault, // L: kOpLDec
LineProcDefault // L: kOpLInc
},
{ // S: kOpSDec
LineProcDefault, // L: kOpLNone
LineProcDefault, // L: kOpLDec
LineProcDefault // L: kOpLInc
},
{ // S: kOpSInc
LineProcDefault, // L: kOpLNone
LineProcDefault, // L: kOpLDec
LineProcDefault // L: kOpLInc
}
}
};
} // namespace HSLShift
} // namespace
// static
SkBitmap SkBitmapOperations::CreateHSLShiftedBitmap(
const SkBitmap& bitmap,
const color_utils::HSL& hsl_shift) {
// Default to NOPs.
HSLShift::OperationOnH H_op = HSLShift::kOpHNone;
HSLShift::OperationOnS S_op = HSLShift::kOpSNone;
HSLShift::OperationOnL L_op = HSLShift::kOpLNone;
if (hsl_shift.h >= 0 && hsl_shift.h <= 1)
H_op = HSLShift::kOpHShift;
// Saturation shift: 0 -> fully desaturate, 0.5 -> NOP, 1 -> fully saturate.
if (hsl_shift.s >= 0 && hsl_shift.s <= (0.5 - HSLShift::epsilon))
S_op = HSLShift::kOpSDec;
else if (hsl_shift.s >= (0.5 + HSLShift::epsilon))
S_op = HSLShift::kOpSInc;
// Lightness shift: 0 -> black, 0.5 -> NOP, 1 -> white.
if (hsl_shift.l >= 0 && hsl_shift.l <= (0.5 - HSLShift::epsilon))
L_op = HSLShift::kOpLDec;
else if (hsl_shift.l >= (0.5 + HSLShift::epsilon))
L_op = HSLShift::kOpLInc;
HSLShift::LineProcessor line_proc =
HSLShift::kLineProcessors[H_op][S_op][L_op];
DCHECK(bitmap.empty() == false);
DCHECK(bitmap.colorType() == kPMColor_SkColorType);
SkBitmap shifted;
shifted.allocN32Pixels(bitmap.width(), bitmap.height());
shifted.eraseARGB(0, 0, 0, 0);
SkAutoLockPixels lock_bitmap(bitmap);
SkAutoLockPixels lock_shifted(shifted);
// Loop through the pixels of the original bitmap.
for (int y = 0; y < bitmap.height(); ++y) {
SkPMColor* pixels = bitmap.getAddr32(0, y);
SkPMColor* tinted_pixels = shifted.getAddr32(0, y);
(*line_proc)(hsl_shift, pixels, tinted_pixels, bitmap.width());
}
return shifted;
}
// static
SkBitmap SkBitmapOperations::CreateTiledBitmap(const SkBitmap& source,
int src_x, int src_y,
int dst_w, int dst_h) {
DCHECK(source.colorType() == kPMColor_SkColorType);
SkBitmap cropped;
cropped.allocN32Pixels(dst_w, dst_h);
cropped.eraseARGB(0, 0, 0, 0);
SkAutoLockPixels lock_source(source);
SkAutoLockPixels lock_cropped(cropped);
// Loop through the pixels of the original bitmap.
for (int y = 0; y < dst_h; ++y) {
int y_pix = (src_y + y) % source.height();
while (y_pix < 0)
y_pix += source.height();
uint32* source_row = source.getAddr32(0, y_pix);
uint32* dst_row = cropped.getAddr32(0, y);
for (int x = 0; x < dst_w; ++x) {
int x_pix = (src_x + x) % source.width();
while (x_pix < 0)
x_pix += source.width();
dst_row[x] = source_row[x_pix];
}
}
return cropped;
}
// static
SkBitmap SkBitmapOperations::DownsampleByTwoUntilSize(const SkBitmap& bitmap,
int min_w, int min_h) {
if ((bitmap.width() <= min_w) || (bitmap.height() <= min_h) ||
(min_w < 0) || (min_h < 0))
return bitmap;
// Since bitmaps are refcounted, this copy will be fast.
SkBitmap current = bitmap;
while ((current.width() >= min_w * 2) && (current.height() >= min_h * 2) &&
(current.width() > 1) && (current.height() > 1))
current = DownsampleByTwo(current);
return current;
}
// static
SkBitmap SkBitmapOperations::DownsampleByTwo(const SkBitmap& bitmap) {
// Handle the nop case.
if ((bitmap.width() <= 1) || (bitmap.height() <= 1))
return bitmap;
SkBitmap result;
result.allocN32Pixels((bitmap.width() + 1) / 2, (bitmap.height() + 1) / 2);
SkAutoLockPixels lock(bitmap);
const int resultLastX = result.width() - 1;
const int srcLastX = bitmap.width() - 1;
for (int dest_y = 0; dest_y < result.height(); ++dest_y) {
const int src_y = dest_y << 1;
const SkPMColor* SK_RESTRICT cur_src0 = bitmap.getAddr32(0, src_y);
const SkPMColor* SK_RESTRICT cur_src1 = cur_src0;
if (src_y + 1 < bitmap.height())
cur_src1 = bitmap.getAddr32(0, src_y + 1);
SkPMColor* SK_RESTRICT cur_dst = result.getAddr32(0, dest_y);
for (int dest_x = 0; dest_x <= resultLastX; ++dest_x) {
// This code is based on downsampleby2_proc32 in SkBitmap.cpp. It is very
// clever in that it does two channels at once: alpha and green ("ag")
// and red and blue ("rb"). Each channel gets averaged across 4 pixels
// to get the result.
int bump_x = (dest_x << 1) < srcLastX;
SkPMColor tmp, ag, rb;
// Top left pixel of the 2x2 block.
tmp = cur_src0[0];
ag = (tmp >> 8) & 0xFF00FF;
rb = tmp & 0xFF00FF;
// Top right pixel of the 2x2 block.
tmp = cur_src0[bump_x];
ag += (tmp >> 8) & 0xFF00FF;
rb += tmp & 0xFF00FF;
// Bottom left pixel of the 2x2 block.
tmp = cur_src1[0];
ag += (tmp >> 8) & 0xFF00FF;
rb += tmp & 0xFF00FF;
// Bottom right pixel of the 2x2 block.
tmp = cur_src1[bump_x];
ag += (tmp >> 8) & 0xFF00FF;
rb += tmp & 0xFF00FF;
// Put the channels back together, dividing each by 4 to get the average.
// |ag| has the alpha and green channels shifted right by 8 bits from
// there they should end up, so shifting left by 6 gives them in the
// correct position divided by 4.
*cur_dst++ = ((rb >> 2) & 0xFF00FF) | ((ag << 6) & 0xFF00FF00);
cur_src0 += 2;
cur_src1 += 2;
}
}
return result;
}
// static
SkBitmap SkBitmapOperations::UnPreMultiply(const SkBitmap& bitmap) {
if (bitmap.isNull())
return bitmap;
if (bitmap.isOpaque())
return bitmap;
SkImageInfo info = bitmap.info();
info.fAlphaType = kOpaque_SkAlphaType;
SkBitmap opaque_bitmap;
opaque_bitmap.allocPixels(info);
{
SkAutoLockPixels bitmap_lock(bitmap);
SkAutoLockPixels opaque_bitmap_lock(opaque_bitmap);
for (int y = 0; y < opaque_bitmap.height(); y++) {
for (int x = 0; x < opaque_bitmap.width(); x++) {
uint32 src_pixel = *bitmap.getAddr32(x, y);
uint32* dst_pixel = opaque_bitmap.getAddr32(x, y);
SkColor unmultiplied = SkUnPreMultiply::PMColorToColor(src_pixel);
*dst_pixel = unmultiplied;
}
}
}
return opaque_bitmap;
}
// static
SkBitmap SkBitmapOperations::CreateTransposedBitmap(const SkBitmap& image) {
DCHECK(image.colorType() == kPMColor_SkColorType);
SkBitmap transposed;
transposed.allocN32Pixels(image.height(), image.width());
SkAutoLockPixels lock_image(image);
SkAutoLockPixels lock_transposed(transposed);
for (int y = 0; y < image.height(); ++y) {
uint32* image_row = image.getAddr32(0, y);
for (int x = 0; x < image.width(); ++x) {
uint32* dst = transposed.getAddr32(y, x);
*dst = image_row[x];
}
}
return transposed;
}
// static
SkBitmap SkBitmapOperations::CreateColorMask(const SkBitmap& bitmap,
SkColor c) {
DCHECK(bitmap.colorType() == kPMColor_SkColorType);
SkBitmap color_mask;
color_mask.allocN32Pixels(bitmap.width(), bitmap.height());
color_mask.eraseARGB(0, 0, 0, 0);
SkCanvas canvas(color_mask);
skia::RefPtr<SkColorFilter> color_filter = skia::AdoptRef(
SkColorFilter::CreateModeFilter(c, SkXfermode::kSrcIn_Mode));
SkPaint paint;
paint.setColorFilter(color_filter.get());
canvas.drawBitmap(bitmap, SkIntToScalar(0), SkIntToScalar(0), &paint);
return color_mask;
}
// static
SkBitmap SkBitmapOperations::CreateDropShadow(
const SkBitmap& bitmap,
const gfx::ShadowValues& shadows) {
DCHECK(bitmap.colorType() == kPMColor_SkColorType);
// Shadow margin insets are negative values because they grow outside.
// Negate them here as grow direction is not important and only pixel value
// is of interest here.
gfx::Insets shadow_margin = -gfx::ShadowValue::GetMargin(shadows);
SkBitmap image_with_shadow;
image_with_shadow.allocN32Pixels(bitmap.width() + shadow_margin.width(),
bitmap.height() + shadow_margin.height());
image_with_shadow.eraseARGB(0, 0, 0, 0);
SkCanvas canvas(image_with_shadow);
canvas.translate(SkIntToScalar(shadow_margin.left()),
SkIntToScalar(shadow_margin.top()));
SkPaint paint;
for (size_t i = 0; i < shadows.size(); ++i) {
const gfx::ShadowValue& shadow = shadows[i];
SkBitmap shadow_image = SkBitmapOperations::CreateColorMask(bitmap,
shadow.color());
skia::RefPtr<SkBlurImageFilter> filter =
skia::AdoptRef(SkBlurImageFilter::Create(
SkDoubleToScalar(shadow.blur()), SkDoubleToScalar(shadow.blur())));
paint.setImageFilter(filter.get());
canvas.saveLayer(0, &paint);
canvas.drawBitmap(shadow_image,
SkIntToScalar(shadow.x()),
SkIntToScalar(shadow.y()));
canvas.restore();
}
canvas.drawBitmap(bitmap, SkIntToScalar(0), SkIntToScalar(0));
return image_with_shadow;
}
// static
SkBitmap SkBitmapOperations::Rotate(const SkBitmap& source,
RotationAmount rotation) {
SkBitmap result;
SkScalar angle = SkFloatToScalar(0.0f);
switch (rotation) {
case ROTATION_90_CW:
angle = SkFloatToScalar(90.0f);
result.setConfig(
SkBitmap::kARGB_8888_Config, source.height(), source.width());
break;
case ROTATION_180_CW:
angle = SkFloatToScalar(180.0f);
result.setConfig(
SkBitmap::kARGB_8888_Config, source.width(), source.height());
break;
case ROTATION_270_CW:
angle = SkFloatToScalar(270.0f);
result.setConfig(
SkBitmap::kARGB_8888_Config, source.height(), source.width());
break;
}
result.allocPixels();
SkCanvas canvas(result);
canvas.clear(SkColorSetARGB(0, 0, 0, 0));
canvas.translate(SkFloatToScalar(result.width() * 0.5f),
SkFloatToScalar(result.height() * 0.5f));
canvas.rotate(angle);
canvas.translate(-SkFloatToScalar(source.width() * 0.5f),
-SkFloatToScalar(source.height() * 0.5f));
canvas.drawBitmap(source, 0, 0);
canvas.flush();
return result;
}