Skip to content
This repository was archived by the owner on Feb 25, 2025. It is now read-only.

[iOS] Skip unnecessary canvas operations #21863

Closed
wants to merge 3 commits into from
Closed

[iOS] Skip unnecessary canvas operations #21863

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
3c86861
Skip unnecessary canvas operations
zhongwuzw Oct 15, 2020
5ac5a63
clang-format
zhongwuzw Oct 15, 2020
f0f2f16
Empty line
zhongwuzw Oct 27, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
133 changes: 68 additions & 65 deletions shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -471,79 +471,82 @@

DisposeViews();

SkCanvas* background_canvas = frame->SkiaCanvas();
auto did_submit = true;
auto num_platform_views = composition_order_.size();

// Resolve all pending GPU operations before allocating a new surface.
background_canvas->flush();
// Clipping the background canvas before drawing the picture recorders requires to
// save and restore the clip context.
SkAutoCanvasRestore save(background_canvas, /*doSave=*/true);
// Maps a platform view id to a vector of `FlutterPlatformViewLayer`.
LayersMap platform_view_layers;

auto did_submit = true;
auto num_platform_views = composition_order_.size();

for (size_t i = 0; i < num_platform_views; i++) {
int64_t platform_view_id = composition_order_[i];
sk_sp<RTree> rtree = platform_view_rtrees_[platform_view_id];
sk_sp<SkPicture> picture = picture_recorders_[platform_view_id]->finishRecordingAsPicture();

// Check if the current picture contains overlays that intersect with the
// current platform view or any of the previous platform views.
for (size_t j = i + 1; j > 0; j--) {
int64_t current_platform_view_id = composition_order_[j - 1];
SkRect platform_view_rect = GetPlatformViewRect(current_platform_view_id);
std::list<SkRect> intersection_rects =
rtree->searchNonOverlappingDrawnRects(platform_view_rect);
auto allocation_size = intersection_rects.size();

// For testing purposes, the overlay id is used to find the overlay view.
// This is the index of the layer for the current platform view.
auto overlay_id = platform_view_layers[current_platform_view_id].size();

// If the max number of allocations per platform view is exceeded,
// then join all the rects into a single one.
//
// TODO(egarciad): Consider making this configurable.
// https://github.com/flutter/flutter/issues/52510
if (allocation_size > kMaxLayerAllocations) {
SkRect joined_rect;
for (const SkRect& rect : intersection_rects) {
joined_rect.join(rect);
if (num_platform_views > 0) {
Copy link

@blasten blasten Oct 26, 2020

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

cool. Android has this check too. Any chance we add a test for this?

Copy link
Member Author

@zhongwuzw zhongwuzw Oct 30, 2020

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

No idea about how to add a test. :)

Copy link
Member

@chinmaygarde chinmaygarde Nov 5, 2020

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@blasten Can you answer this query so progress is unblocked here?

SkCanvas* background_canvas = frame->SkiaCanvas();
// Resolve all pending GPU operations before allocating a new surface.
background_canvas->flush();
// Clipping the background canvas before drawing the picture recorders requires to
// save and restore the clip context.
SkAutoCanvasRestore save(background_canvas, /*doSave=*/true);

for (size_t i = 0; i < num_platform_views; i++) {
int64_t platform_view_id = composition_order_[i];
sk_sp<RTree> rtree = platform_view_rtrees_[platform_view_id];
sk_sp<SkPicture> picture = picture_recorders_[platform_view_id]->finishRecordingAsPicture();

// Check if the current picture contains overlays that intersect with the
// current platform view or any of the previous platform views.
for (size_t j = i + 1; j > 0; j--) {
int64_t current_platform_view_id = composition_order_[j - 1];
SkRect platform_view_rect = GetPlatformViewRect(current_platform_view_id);
std::list<SkRect> intersection_rects =
rtree->searchNonOverlappingDrawnRects(platform_view_rect);
auto allocation_size = intersection_rects.size();

// For testing purposes, the overlay id is used to find the overlay view.
// This is the index of the layer for the current platform view.
auto overlay_id = platform_view_layers[current_platform_view_id].size();

// If the max number of allocations per platform view is exceeded,
// then join all the rects into a single one.
//
// TODO(egarciad): Consider making this configurable.
// https://github.com/flutter/flutter/issues/52510
if (allocation_size > kMaxLayerAllocations) {
SkRect joined_rect;
for (const SkRect& rect : intersection_rects) {
joined_rect.join(rect);
}
// Replace the rects in the intersection rects list for a single rect that is
// the union of all the rects in the list.
intersection_rects.clear();
intersection_rects.push_back(joined_rect);
}
for (SkRect& joined_rect : intersection_rects) {
// Get the intersection rect between the current rect
// and the platform view rect.
joined_rect.intersect(platform_view_rect);
// Subpixels in the platform may not align with the canvas subpixels.
// To workaround it, round the floating point bounds and make the rect slighly larger.
// For example, {0.3, 0.5, 3.1, 4.7} becomes {0, 0, 4, 5}.
joined_rect.setLTRB(std::floor(joined_rect.left()), std::floor(joined_rect.top()),
std::ceil(joined_rect.right()), std::ceil(joined_rect.bottom()));
// Clip the background canvas, so it doesn't contain any of the pixels drawn
// on the overlay layer.
background_canvas->clipRect(joined_rect, SkClipOp::kDifference);
// Get a new host layer.
std::shared_ptr<FlutterPlatformViewLayer> layer = GetLayer(gr_context, //
ios_context, //
picture, //
joined_rect, //
current_platform_view_id, //
overlay_id //
);
did_submit &= layer->did_submit_last_frame;
platform_view_layers[current_platform_view_id].push_back(layer);
overlay_id++;
}
// Replace the rects in the intersection rects list for a single rect that is
// the union of all the rects in the list.
intersection_rects.clear();
intersection_rects.push_back(joined_rect);
}
for (SkRect& joined_rect : intersection_rects) {
// Get the intersection rect between the current rect
// and the platform view rect.
joined_rect.intersect(platform_view_rect);
// Subpixels in the platform may not align with the canvas subpixels.
// To workaround it, round the floating point bounds and make the rect slighly larger.
// For example, {0.3, 0.5, 3.1, 4.7} becomes {0, 0, 4, 5}.
joined_rect.setLTRB(std::floor(joined_rect.left()), std::floor(joined_rect.top()),
std::ceil(joined_rect.right()), std::ceil(joined_rect.bottom()));
// Clip the background canvas, so it doesn't contain any of the pixels drawn
// on the overlay layer.
background_canvas->clipRect(joined_rect, SkClipOp::kDifference);
// Get a new host layer.
std::shared_ptr<FlutterPlatformViewLayer> layer = GetLayer(gr_context, //
ios_context, //
picture, //
joined_rect, //
current_platform_view_id, //
overlay_id //
);
did_submit &= layer->did_submit_last_frame;
platform_view_layers[current_platform_view_id].push_back(layer);
overlay_id++;
}
background_canvas->drawPicture(picture);
}
background_canvas->drawPicture(picture);
}

// If a layer was allocated in the previous frame, but it's not used in the current frame,
// then it can be removed from the scene.
RemoveUnusedLayers();
Expand Down