fuchsia: Fix first_layer handling (#26085)
diff --git a/shell/platform/fuchsia/flutter/fuchsia_external_view_embedder.cc b/shell/platform/fuchsia/flutter/fuchsia_external_view_embedder.cc
index f14d5e8..313146b 100644
--- a/shell/platform/fuchsia/flutter/fuchsia_external_view_embedder.cc
+++ b/shell/platform/fuchsia/flutter/fuchsia_external_view_embedder.cc
@@ -388,41 +388,44 @@
// Scenic currently lacks an API to enable rendering of alpha channel;
// Flutter Embedder also lacks an API to detect if a layer has alpha or
// not. Alpha channels are only rendered if there is a OpacityNode
- // higher in the tree with opacity != 1. For now, always assume t he
- // layer has alpha and clamp to a infinitesimally smaller value than 1.
+ // higher in the tree with opacity != 1. For now, assume any layer
+ // beyond the first has alpha and clamp to a infinitesimally smaller
+ // value than 1. The first layer retains an opacity of 1 to avoid
+ // blending with anything underneath.
//
// This does not cause visual problems in practice, but probably has
// performance implications.
- auto& scenic_layer = scenic_layers_[scenic_layer_index];
- auto& scenic_rect = found_rects->second[rect_index];
+ const SkAlpha layer_opacity =
+ first_layer ? SK_AlphaOPAQUE : SK_AlphaOPAQUE - 1;
const float layer_elevation =
kScenicZElevationBetweenLayers * scenic_layer_index +
embedded_views_height;
+ auto& scenic_layer = scenic_layers_[scenic_layer_index];
+ auto& scenic_rect = found_rects->second[rect_index];
scenic_layer.shape_node.SetLabel("Flutter::Layer");
scenic_layer.shape_node.SetShape(scenic_rect);
scenic_layer.shape_node.SetTranslation(
layer->second.surface_size.width() * 0.5f,
layer->second.surface_size.height() * 0.5f, -layer_elevation);
scenic_layer.material.SetColor(SK_AlphaOPAQUE, SK_AlphaOPAQUE,
- SK_AlphaOPAQUE, SK_AlphaOPAQUE - 1);
+ SK_AlphaOPAQUE, layer_opacity);
scenic_layer.material.SetTexture(surface_image_id);
// Only the first (i.e. the bottom-most) layer should receive input.
// TODO: Workaround for invisible overlays stealing input. Remove when
// the underlying bug is fixed.
- if (first_layer) {
- scenic_layer.shape_node.SetHitTestBehavior(
- fuchsia::ui::gfx::HitTestBehavior::kDefault);
- } else {
- scenic_layer.shape_node.SetHitTestBehavior(
- fuchsia::ui::gfx::HitTestBehavior::kSuppress);
- }
- first_layer = false;
+ const fuchsia::ui::gfx::HitTestBehavior layer_hit_test_behavior =
+ first_layer ? fuchsia::ui::gfx::HitTestBehavior::kDefault
+ : fuchsia::ui::gfx::HitTestBehavior::kSuppress;
+ scenic_layer.shape_node.SetHitTestBehavior(layer_hit_test_behavior);
// Attach the ScenicLayer to the main scene graph.
layer_tree_node_.AddChild(scenic_layer.shape_node);
- // Account for the ScenicLayer's height when positioning the next layer.
+ // Reset for the next pass:
+ // +The next layer will not be the first layer.
+ // +Account for the current layer's height when positioning the next.
+ first_layer = false;
scenic_layer_index++;
}
}
