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- // Copyright (c) 2011 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 "pdf/draw_utils/shadow.h"
- #include <math.h>
- #include <stddef.h>
- #include <algorithm>
- #include "base/check_op.h"
- #include "third_party/skia/include/core/SkBitmap.h"
- #include "ui/gfx/geometry/rect.h"
- #include "ui/gfx/geometry/size.h"
- namespace chrome_pdf {
- namespace draw_utils {
- constexpr uint8_t kOpaqueAlpha = 0xFF;
- constexpr uint8_t kTransparentAlpha = 0x00;
- inline uint8_t GetBlue(const uint32_t& pixel) {
- return static_cast<uint8_t>(pixel & 0xFF);
- }
- inline uint8_t GetGreen(const uint32_t& pixel) {
- return static_cast<uint8_t>((pixel >> 8) & 0xFF);
- }
- inline uint8_t GetRed(const uint32_t& pixel) {
- return static_cast<uint8_t>((pixel >> 16) & 0xFF);
- }
- inline uint8_t GetAlpha(const uint32_t& pixel) {
- return static_cast<uint8_t>((pixel >> 24) & 0xFF);
- }
- inline uint32_t MakePixel(uint8_t red,
- uint8_t green,
- uint8_t blue,
- uint8_t alpha) {
- return (static_cast<uint32_t>(alpha) << 24) |
- (static_cast<uint32_t>(red) << 16) |
- (static_cast<uint32_t>(green) << 8) | static_cast<uint32_t>(blue);
- }
- inline uint8_t ProcessColor(uint8_t src_color,
- uint8_t dest_color,
- uint8_t alpha) {
- uint32_t processed = static_cast<uint32_t>(src_color) * alpha +
- static_cast<uint32_t>(dest_color) * (0xFF - alpha);
- return static_cast<uint8_t>((processed / 0xFF) & 0xFF);
- }
- ShadowMatrix::ShadowMatrix(uint32_t depth, double factor, uint32_t background)
- : depth_(depth) {
- DCHECK_GT(depth_, 0U);
- matrix_.resize(depth_ * depth_);
- // pv - is a rounding power factor for smoothing corners.
- // pv = 2.0 will make corners completely round.
- constexpr double pv = 4.0;
- // pow_pv - cache to avoid recalculating pow(x, pv) every time.
- std::vector<double> pow_pv(depth_, 0.0);
- double r = static_cast<double>(depth_);
- double coef = 256.0 / pow(r, factor);
- for (uint32_t y = 0; y < depth_; y++) {
- // Since matrix is symmetrical, we can reduce the number of calculations
- // by mirroring results.
- for (uint32_t x = 0; x <= y; x++) {
- // Fill cache if needed.
- if (pow_pv[x] == 0.0)
- pow_pv[x] = pow(x, pv);
- if (pow_pv[y] == 0.0)
- pow_pv[y] = pow(y, pv);
- // v - is a value for the smoothing function.
- // If x == 0 simplify calculations.
- double v = (x == 0) ? y : pow(pow_pv[x] + pow_pv[y], 1 / pv);
- // Smoothing function.
- // If factor == 1, smoothing will be linear from 0 to the end,
- // if 0 < factor < 1, smoothing will drop faster near 0.
- // if factor > 1, smoothing will drop faster near the end (depth).
- double f = 256.0 - coef * pow(v, factor);
- uint8_t alpha = 0;
- if (f > kOpaqueAlpha)
- alpha = kOpaqueAlpha;
- else if (f < kTransparentAlpha)
- alpha = kTransparentAlpha;
- else
- alpha = static_cast<uint8_t>(f);
- uint8_t red = ProcessColor(0, GetRed(background), alpha);
- uint8_t green = ProcessColor(0, GetGreen(background), alpha);
- uint8_t blue = ProcessColor(0, GetBlue(background), alpha);
- uint32_t pixel = MakePixel(red, green, blue, GetAlpha(background));
- // Mirror matrix.
- matrix_[y * depth_ + x] = pixel;
- matrix_[x * depth_ + y] = pixel;
- }
- }
- }
- ShadowMatrix::~ShadowMatrix() = default;
- namespace {
- void PaintShadow(SkBitmap& image,
- const gfx::Rect& clip_rc,
- const gfx::Rect& shadow_rc,
- const ShadowMatrix& matrix) {
- gfx::Rect draw_rc = gfx::IntersectRects(shadow_rc, clip_rc);
- if (draw_rc.IsEmpty())
- return;
- int32_t depth = static_cast<int32_t>(matrix.depth());
- for (int32_t y = draw_rc.y(); y < draw_rc.bottom(); y++) {
- for (int32_t x = draw_rc.x(); x < draw_rc.right(); x++) {
- int32_t matrix_x = std::max(depth + shadow_rc.x() - x - 1,
- depth - shadow_rc.right() + x);
- int32_t matrix_y = std::max(depth + shadow_rc.y() - y - 1,
- depth - shadow_rc.bottom() + y);
- uint32_t* pixel = image.getAddr32(x, y);
- if (matrix_x < 0)
- matrix_x = 0;
- else if (matrix_x >= static_cast<int32_t>(depth))
- matrix_x = depth - 1;
- if (matrix_y < 0)
- matrix_y = 0;
- else if (matrix_y >= static_cast<int32_t>(depth))
- matrix_y = depth - 1;
- *pixel = matrix.GetValue(matrix_x, matrix_y);
- }
- }
- }
- } // namespace
- void DrawShadow(SkBitmap& image,
- const gfx::Rect& shadow_rc,
- const gfx::Rect& object_rc,
- const gfx::Rect& clip_rc,
- const ShadowMatrix& matrix) {
- if (shadow_rc == object_rc)
- return; // Nothing to paint.
- // Fill top part.
- gfx::Rect rc(shadow_rc.origin(),
- gfx::Size(shadow_rc.width(), object_rc.y() - shadow_rc.y()));
- PaintShadow(image, gfx::IntersectRects(rc, clip_rc), shadow_rc, matrix);
- // Fill bottom part.
- rc = gfx::Rect(shadow_rc.x(), object_rc.bottom(), shadow_rc.width(),
- shadow_rc.bottom() - object_rc.bottom());
- PaintShadow(image, gfx::IntersectRects(rc, clip_rc), shadow_rc, matrix);
- // Fill left part.
- rc = gfx::Rect(shadow_rc.x(), object_rc.y(), object_rc.x() - shadow_rc.x(),
- object_rc.height());
- PaintShadow(image, gfx::IntersectRects(rc, clip_rc), shadow_rc, matrix);
- // Fill right part.
- rc = gfx::Rect(object_rc.right(), object_rc.y(),
- shadow_rc.right() - object_rc.right(), object_rc.height());
- PaintShadow(image, gfx::IntersectRects(rc, clip_rc), shadow_rc, matrix);
- }
- } // namespace draw_utils
- } // namespace chrome_pdf
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