| // Copyright 2013 The Flutter 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 "flutter/flow/layers/physical_shape_layer.h" |
| |
| #include "flutter/flow/paint_utils.h" |
| #include "third_party/skia/include/utils/SkShadowUtils.h" |
| |
| namespace flutter { |
| |
| const SkScalar kLightHeight = 600; |
| const SkScalar kLightRadius = 800; |
| |
| PhysicalShapeLayer::PhysicalShapeLayer(SkColor color, |
| SkColor shadow_color, |
| float elevation, |
| const SkPath& path, |
| Clip clip_behavior) |
| : color_(color), |
| shadow_color_(shadow_color), |
| elevation_(elevation), |
| path_(path), |
| clip_behavior_(clip_behavior) {} |
| |
| void PhysicalShapeLayer::Preroll(PrerollContext* context, |
| const SkMatrix& matrix) { |
| TRACE_EVENT0("flutter", "PhysicalShapeLayer::Preroll"); |
| Layer::AutoPrerollSaveLayerState save = |
| Layer::AutoPrerollSaveLayerState::Create(context, UsesSaveLayer()); |
| |
| SkRect child_paint_bounds; |
| PrerollChildren(context, matrix, &child_paint_bounds); |
| |
| if (elevation_ == 0) { |
| set_paint_bounds(path_.getBounds()); |
| } else { |
| // We will draw the shadow in Paint(), so add some margin to the paint |
| // bounds to leave space for the shadow. We fill this whole region and clip |
| // children to it so we don't need to join the child paint bounds. |
| set_paint_bounds(ComputeShadowBounds(path_.getBounds(), elevation_, |
| context->frame_device_pixel_ratio)); |
| } |
| } |
| |
| void PhysicalShapeLayer::Paint(PaintContext& context) const { |
| TRACE_EVENT0("flutter", "PhysicalShapeLayer::Paint"); |
| FML_DCHECK(needs_painting(context)); |
| |
| if (elevation_ != 0) { |
| DrawShadow(context.leaf_nodes_canvas, path_, shadow_color_, elevation_, |
| SkColorGetA(color_) != 0xff, context.frame_device_pixel_ratio); |
| } |
| |
| // Call drawPath without clip if possible for better performance. |
| SkPaint paint; |
| paint.setColor(color_); |
| paint.setAntiAlias(true); |
| if (clip_behavior_ != Clip::antiAliasWithSaveLayer) { |
| context.leaf_nodes_canvas->drawPath(path_, paint); |
| } |
| |
| int saveCount = context.internal_nodes_canvas->save(); |
| switch (clip_behavior_) { |
| case Clip::hardEdge: |
| context.internal_nodes_canvas->clipPath(path_, false); |
| break; |
| case Clip::antiAlias: |
| context.internal_nodes_canvas->clipPath(path_, true); |
| break; |
| case Clip::antiAliasWithSaveLayer: |
| context.internal_nodes_canvas->clipPath(path_, true); |
| context.internal_nodes_canvas->saveLayer(paint_bounds(), nullptr); |
| break; |
| case Clip::none: |
| break; |
| } |
| |
| if (UsesSaveLayer()) { |
| // If we want to avoid the bleeding edge artifact |
| // (https://github.com/flutter/flutter/issues/18057#issue-328003931) |
| // using saveLayer, we have to call drawPaint instead of drawPath as |
| // anti-aliased drawPath will always have such artifacts. |
| context.leaf_nodes_canvas->drawPaint(paint); |
| } |
| |
| PaintChildren(context); |
| |
| context.internal_nodes_canvas->restoreToCount(saveCount); |
| |
| if (UsesSaveLayer()) { |
| if (context.checkerboard_offscreen_layers) { |
| DrawCheckerboard(context.internal_nodes_canvas, paint_bounds()); |
| } |
| } |
| } |
| |
| SkRect PhysicalShapeLayer::ComputeShadowBounds(const SkRect& bounds, |
| float elevation, |
| float pixel_ratio) { |
| // The shadow offset is calculated as follows: |
| // .--- (kLightRadius) |
| // -------/ (light) |
| // | / |
| // | / |
| // |/ |
| // |O |
| // /| (kLightHeight) |
| // / | |
| // / | |
| // / | |
| // / | |
| // ------------- (layer) |
| // /| | |
| // / | | (elevation) |
| // A / | |B |
| // ------------------------------------------------ (canvas) |
| // --- (extent of shadow) |
| // |
| // E = lt } t = (r + w/2)/h |
| // } => |
| // r + w/2 = ht } E = (l/h)(r + w/2) |
| // |
| // Where: E = extent of shadow |
| // l = elevation of layer |
| // r = radius of the light source |
| // w = width of the layer |
| // h = light height |
| // t = tangent of AOB, i.e., multiplier for elevation to extent |
| // tangent for x |
| double tx = |
| (kLightRadius * pixel_ratio + bounds.width() * 0.5) / kLightHeight; |
| // tangent for y |
| double ty = |
| (kLightRadius * pixel_ratio + bounds.height() * 0.5) / kLightHeight; |
| SkRect shadow_bounds(bounds); |
| shadow_bounds.outset(elevation * tx, elevation * ty); |
| |
| return shadow_bounds; |
| } |
| |
| void PhysicalShapeLayer::DrawShadow(SkCanvas* canvas, |
| const SkPath& path, |
| SkColor color, |
| float elevation, |
| bool transparentOccluder, |
| SkScalar dpr) { |
| const SkScalar kAmbientAlpha = 0.039f; |
| const SkScalar kSpotAlpha = 0.25f; |
| |
| SkShadowFlags flags = transparentOccluder |
| ? SkShadowFlags::kTransparentOccluder_ShadowFlag |
| : SkShadowFlags::kNone_ShadowFlag; |
| const SkRect& bounds = path.getBounds(); |
| SkScalar shadow_x = (bounds.left() + bounds.right()) / 2; |
| SkScalar shadow_y = bounds.top() - 600.0f; |
| SkColor inAmbient = SkColorSetA(color, kAmbientAlpha * SkColorGetA(color)); |
| SkColor inSpot = SkColorSetA(color, kSpotAlpha * SkColorGetA(color)); |
| SkColor ambientColor, spotColor; |
| SkShadowUtils::ComputeTonalColors(inAmbient, inSpot, &ambientColor, |
| &spotColor); |
| SkShadowUtils::DrawShadow( |
| canvas, path, SkPoint3::Make(0, 0, dpr * elevation), |
| SkPoint3::Make(shadow_x, shadow_y, dpr * kLightHeight), |
| dpr * kLightRadius, ambientColor, spotColor, flags); |
| } |
| |
| } // namespace flutter |