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Maps: Scale cached tiles from lower and higher zoom levels

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When zooming in or out, if a tile is not yet cached, Maps now also
checks the lower and higher zoom levels for cached tiles and composites
a preview tile that is shown until the actual tile is loaded in.
This commit is contained in:
Jelle Raaijmakers 2023-09-05 20:07:57 +02:00
parent cf898f08ab
commit 0f330a4dcf
Notes: sideshowbarker 2024-07-17 08:43:11 +09:00 
Author: https://github.com/gmta
Commit: https://github.com/SerenityOS/serenity/commit/0f330a4dcf
Pull-request: https://github.com/SerenityOS/serenity/pull/20963
2 changed files with 65 additions and 6 deletions
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64
Userland/Applications/Maps/MapWidget.cpp
View file

@ -151,15 +151,17 @@ void MapWidget::mousewheel_event(GUI::MouseEvent& event)
set_zoom(new_zoom);
}
Optional<RefPtr<Gfx::Bitmap>> MapWidget::get_tile_image(int x, int y)
Optional<RefPtr<Gfx::Bitmap>> MapWidget::get_tile_image(int x, int y, int zoom, TileDownloadBehavior download_behavior)
{
// Get the tile from tiles cache
TileKey const key = { x, y, m_zoom };
TileKey const key = { x, y, zoom };
if (auto it = m_tiles.find(key); it != m_tiles.end()) {
if (it->value)
return it->value;
return {};
}
if (download_behavior == TileDownloadBehavior::DoNotDownload)
return {};
// Register an empty tile so we don't send requests multiple times
if (m_tiles.size() >= TILES_CACHE_MAX)
@ -252,10 +254,62 @@ void MapWidget::paint_tiles(GUI::Painter& painter)
if (tile_x < 0 || tile_y < 0 || tile_x > pow(2, m_zoom) - 1 || tile_y > pow(2, m_zoom) - 1)
continue;
auto tile_rect = Gfx::IntRect {
static_cast<int>(width() / 2 + dx * TILE_SIZE - offset_x),
static_cast<int>(height() / 2 + dy * TILE_SIZE - offset_y),
TILE_SIZE,
TILE_SIZE,
};
if (!painter.clip_rect().intersects(tile_rect))
continue;
// Get tile, when it has a loaded image draw it at the right position
auto tile_image = get_tile_image(tile_x, tile_y);
if (tile_image.has_value())
painter.blit({ static_cast<int>(width() / 2 + dx * TILE_SIZE - offset_x), static_cast<int>(height() / 2 + dy * TILE_SIZE - offset_y) }, *tile_image.release_value(), { 0, 0, TILE_SIZE, TILE_SIZE }, 1);
auto tile_image = get_tile_image(tile_x, tile_y, m_zoom, TileDownloadBehavior::Download);
auto const tile_source = Gfx::IntRect { 0, 0, TILE_SIZE, TILE_SIZE };
if (tile_image.has_value()) {
painter.blit(tile_rect.location(), *tile_image.release_value(), tile_source, 1);
continue;
}
// Fallback: try to compose the tile from already cached tiles from a higher zoom level
auto cached_tiles_used = 0;
if (m_zoom < ZOOM_MAX) {
auto const child_top_left_tile_x = tile_x * 2;
auto const child_top_left_tile_y = tile_y * 2;
for (auto child_tile_x = child_top_left_tile_x; child_tile_x <= child_top_left_tile_x + 1; ++child_tile_x) {
for (auto child_tile_y = child_top_left_tile_y; child_tile_y <= child_top_left_tile_y + 1; ++child_tile_y) {
auto child_tile = get_tile_image(child_tile_x, child_tile_y, m_zoom + 1, TileDownloadBehavior::DoNotDownload);
if (!child_tile.has_value())
continue;
auto target_rect = tile_rect;
target_rect.set_size(TILE_SIZE / 2, TILE_SIZE / 2);
if ((child_tile_x & 1) > 0)
target_rect.translate_by(TILE_SIZE / 2, 0);
if ((child_tile_y & 1) > 0)
target_rect.translate_by(0, TILE_SIZE / 2);
painter.draw_scaled_bitmap(target_rect, *child_tile.release_value(), tile_source, 1.f, Gfx::Painter::ScalingMode::BoxSampling);
++cached_tiles_used;
}
}
}
// Fallback: try to use an already cached tile from a lower zoom level
// Note: we only want to try this if we did not find exactly 4 cached child tiles in the previous fallback (i.e. there are gaps)
if (m_zoom > ZOOM_MIN && cached_tiles_used < 4) {
auto const parent_tile_x = tile_x / 2;
auto const parent_tile_y = tile_y / 2;
auto larger_tile = get_tile_image(parent_tile_x, parent_tile_y, m_zoom - 1, TileDownloadBehavior::DoNotDownload);
if (larger_tile.has_value()) {
auto source_rect = Gfx::IntRect { 0, 0, TILE_SIZE / 2, TILE_SIZE / 2 };
if ((tile_x & 1) > 0)
source_rect.translate_by(TILE_SIZE / 2, 0);
if ((tile_y & 1) > 0)
source_rect.translate_by(0, TILE_SIZE / 2);
painter.draw_scaled_bitmap(tile_rect, *larger_tile.release_value(), source_rect, 1.f, Gfx::Painter::ScalingMode::BilinearBlend);
}
}
}
}
}

7
Userland/Applications/Maps/MapWidget.h
View file

@ -64,6 +64,11 @@ public:
}
};
enum class TileDownloadBehavior {
DoNotDownload,
Download,
};
private:
MapWidget(Options const&);
@ -77,7 +82,7 @@ private:
virtual void paint_event(GUI::PaintEvent&) override;
Optional<RefPtr<Gfx::Bitmap>> get_tile_image(int x, int y);
Optional<RefPtr<Gfx::Bitmap>> get_tile_image(int x, int y, int zoom, TileDownloadBehavior);
void process_tile_queue();
void clear_tile_queue();