Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 823 insertions, 0 deletions

diff --git a/gfx/wr/webrender/src/image_tiling.rs b/gfx/wr/webrender/src/image_tiling.rs
new file mode 100644
index 0000000000..e2fb3b05b9
--- /dev/null
+++ b/gfx/wr/webrender/src/image_tiling.rs
@@ -0,0 +1,823 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use crate::api::TileSize;
+use crate::api::units::*;
+use crate::segment::EdgeAaSegmentMask;
+use euclid::{point2, size2};
+use std::i32;
+use std::ops::Range;
+
+/// If repetitions are far enough apart that only one is within
+/// the primitive rect, then we can simplify the parameters and
+/// treat the primitive as not repeated.
+/// This can let us avoid unnecessary work later to handle some
+/// of the parameters.
+pub fn simplify_repeated_primitive(
+    stretch_size: &LayoutSize,
+    tile_spacing: &mut LayoutSize,
+    prim_rect: &mut LayoutRect,
+) {
+    let stride = *stretch_size + *tile_spacing;
+
+    if stride.width >= prim_rect.width() {
+        tile_spacing.width = 0.0;
+        prim_rect.max.x = f32::min(prim_rect.min.x + stretch_size.width, prim_rect.max.x);
+    }
+    if stride.height >= prim_rect.height() {
+        tile_spacing.height = 0.0;
+        prim_rect.max.y = f32::min(prim_rect.min.y + stretch_size.height, prim_rect.max.y);
+    }
+}
+
+pub struct Repetition {
+    pub origin: LayoutPoint,
+    pub edge_flags: EdgeAaSegmentMask,
+}
+
+pub struct RepetitionIterator {
+    current_x: i32,
+    x_count: i32,
+    current_y: i32,
+    y_count: i32,
+    row_flags: EdgeAaSegmentMask,
+    current_origin: LayoutPoint,
+    initial_origin: LayoutPoint,
+    stride: LayoutSize,
+}
+
+impl RepetitionIterator {
+    pub fn num_repetitions(&self) -> usize {
+        (self.y_count * self.x_count) as usize
+    }
+}
+
+impl Iterator for RepetitionIterator {
+    type Item = Repetition;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_x == self.x_count {
+            self.current_y += 1;
+            if self.current_y >= self.y_count {
+                return None;
+            }
+            self.current_x = 0;
+
+            self.row_flags = EdgeAaSegmentMask::empty();
+            if self.current_y == self.y_count - 1 {
+                self.row_flags |= EdgeAaSegmentMask::BOTTOM;
+            }
+
+            self.current_origin.x = self.initial_origin.x;
+            self.current_origin.y += self.stride.height;
+        }
+
+        let mut edge_flags = self.row_flags;
+        if self.current_x == 0 {
+            edge_flags |= EdgeAaSegmentMask::LEFT;
+        }
+
+        if self.current_x == self.x_count - 1 {
+            edge_flags |= EdgeAaSegmentMask::RIGHT;
+        }
+
+        let repetition = Repetition {
+            origin: self.current_origin,
+            edge_flags,
+        };
+
+        self.current_origin.x += self.stride.width;
+        self.current_x += 1;
+
+        Some(repetition)
+    }
+}
+
+pub fn repetitions(
+    prim_rect: &LayoutRect,
+    visible_rect: &LayoutRect,
+    stride: LayoutSize,
+) -> RepetitionIterator {
+    let visible_rect = match prim_rect.intersection(&visible_rect) {
+        Some(rect) => rect,
+        None => {
+            return RepetitionIterator {
+                current_origin: LayoutPoint::zero(),
+                initial_origin: LayoutPoint::zero(),
+                current_x: 0,
+                current_y: 0,
+                x_count: 0,
+                y_count: 0,
+                stride,
+                row_flags: EdgeAaSegmentMask::empty(),
+            }
+        }
+    };
+
+    assert!(stride.width > 0.0);
+    assert!(stride.height > 0.0);
+
+    let nx = if visible_rect.min.x > prim_rect.min.x {
+        f32::floor((visible_rect.min.x - prim_rect.min.x) / stride.width)
+    } else {
+        0.0
+    };
+
+    let ny = if visible_rect.min.y > prim_rect.min.y {
+        f32::floor((visible_rect.min.y - prim_rect.min.y) / stride.height)
+    } else {
+        0.0
+    };
+
+    let x0 = prim_rect.min.x + nx * stride.width;
+    let y0 = prim_rect.min.y + ny * stride.height;
+
+    let x_most = visible_rect.max.x;
+    let y_most = visible_rect.max.y;
+
+    let x_count = f32::ceil((x_most - x0) / stride.width) as i32;
+    let y_count = f32::ceil((y_most - y0) / stride.height) as i32;
+
+    let mut row_flags = EdgeAaSegmentMask::TOP;
+    if y_count == 1 {
+        row_flags |= EdgeAaSegmentMask::BOTTOM;
+    }
+
+    RepetitionIterator {
+        current_origin: LayoutPoint::new(x0, y0),
+        initial_origin: LayoutPoint::new(x0, y0),
+        current_x: 0,
+        current_y: 0,
+        x_count,
+        y_count,
+        row_flags,
+        stride,
+    }
+}
+
+#[derive(Debug)]
+pub struct Tile {
+    pub rect: LayoutRect,
+    pub offset: TileOffset,
+    pub edge_flags: EdgeAaSegmentMask,
+}
+
+#[derive(Debug)]
+pub struct TileIteratorExtent {
+    /// Range of visible tiles to iterate over in number of tiles.
+    tile_range: Range<i32>,
+    /// Range of tiles of the full image including tiles that are culled out.
+    image_tiles: Range<i32>,
+    /// Size of the first tile in layout space.
+    first_tile_layout_size: f32,
+    /// Size of the last tile in layout space.
+    last_tile_layout_size: f32,
+    /// Position of blob point (0, 0) in layout space.
+    layout_tiling_origin: f32,
+    /// Position of the top-left corner of the primitive rect in layout space.
+    layout_prim_start: f32,
+}
+
+#[derive(Debug)]
+pub struct TileIterator {
+    current_tile: TileOffset,
+    x: TileIteratorExtent,
+    y: TileIteratorExtent,
+    regular_tile_size: LayoutSize,
+}
+
+impl Iterator for TileIterator {
+    type Item = Tile;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // If we reach the end of a row, reset to the beginning of the next row.
+        if self.current_tile.x >= self.x.tile_range.end {
+            self.current_tile.y += 1;
+            self.current_tile.x = self.x.tile_range.start;
+        }
+
+        // Stop iterating if we reach the last tile. We may start here if there
+        // were no tiles to iterate over.
+        if self.current_tile.x >= self.x.tile_range.end || self.current_tile.y >= self.y.tile_range.end {
+            return None;
+        }
+
+        let tile_offset = self.current_tile;
+
+        let mut segment_rect = LayoutRect::from_origin_and_size(
+            LayoutPoint::new(
+                self.x.layout_tiling_origin + tile_offset.x as f32 * self.regular_tile_size.width,
+                self.y.layout_tiling_origin + tile_offset.y as f32 * self.regular_tile_size.height,
+            ),
+            self.regular_tile_size,
+        );
+
+        let mut edge_flags = EdgeAaSegmentMask::empty();
+
+        if tile_offset.x == self.x.image_tiles.start {
+            edge_flags |= EdgeAaSegmentMask::LEFT;
+            segment_rect.min.x = self.x.layout_prim_start;
+            // TODO(nical) we may not need to do this.
+            segment_rect.max.x = segment_rect.min.x + self.x.first_tile_layout_size;
+        }
+        if tile_offset.x == self.x.image_tiles.end - 1 {
+            edge_flags |= EdgeAaSegmentMask::RIGHT;
+            segment_rect.max.x = segment_rect.min.x + self.x.last_tile_layout_size;
+        }
+
+        if tile_offset.y == self.y.image_tiles.start {
+            segment_rect.min.y = self.y.layout_prim_start;
+            segment_rect.max.y = segment_rect.min.y + self.y.first_tile_layout_size;
+            edge_flags |= EdgeAaSegmentMask::TOP;
+        }
+        if tile_offset.y == self.y.image_tiles.end - 1 {
+            segment_rect.max.y = segment_rect.min.y + self.y.last_tile_layout_size;
+            edge_flags |= EdgeAaSegmentMask::BOTTOM;
+        }
+
+        assert!(tile_offset.y < self.y.tile_range.end);
+        let tile = Tile {
+            rect: segment_rect,
+            offset: tile_offset,
+            edge_flags,
+        };
+
+        self.current_tile.x += 1;
+
+        Some(tile)
+    }
+}
+
+pub fn tiles(
+    prim_rect: &LayoutRect,
+    visible_rect: &LayoutRect,
+    image_rect: &DeviceIntRect,
+    device_tile_size: i32,
+) -> TileIterator {
+    // The image resource is tiled. We have to generate an image primitive
+    // for each tile.
+    // We need to do this because the image is broken up into smaller tiles in the texture
+    // cache and the image shader is not able to work with this type of sparse representation.
+
+    // The tiling logic works as follows:
+    //
+    //  +-#################-+  -+
+    //  | #//|    |    |//# |   | image size
+    //  | #//|    |    |//# |   |
+    //  +-#--+----+----+--#-+   |  -+
+    //  | #//|    |    |//# |   |   | regular tile size
+    //  | #//|    |    |//# |   |   |
+    //  +-#--+----+----+--#-+   |  -+-+
+    //  | #//|////|////|//# |   |     | "leftover" height
+    //  | ################# |  -+  ---+
+    //  +----+----+----+----+
+    //
+    // In the ascii diagram above, a large image is split into tiles of almost regular size.
+    // The tiles on the edges (hatched in the diagram) can be smaller than the regular tiles
+    // and are handled separately in the code (we'll call them boundary tiles).
+    //
+    // Each generated segment corresponds to a tile in the texture cache, with the
+    // assumption that the boundary tiles are sized to fit their own irregular size in the
+    // texture cache.
+    //
+    // Because we can have very large virtual images we iterate over the visible portion of
+    // the image in layer space instead of iterating over all device tiles.
+
+    let visible_rect = match prim_rect.intersection(&visible_rect) {
+        Some(rect) => rect,
+        None => {
+            return TileIterator {
+                current_tile: TileOffset::zero(),
+                x: TileIteratorExtent {
+                    tile_range: 0..0,
+                    image_tiles: 0..0,
+                    first_tile_layout_size: 0.0,
+                    last_tile_layout_size: 0.0,
+                    layout_tiling_origin: 0.0,
+                    layout_prim_start: prim_rect.min.x,
+                },
+                y: TileIteratorExtent {
+                    tile_range: 0..0,
+                    image_tiles: 0..0,
+                    first_tile_layout_size: 0.0,
+                    last_tile_layout_size: 0.0,
+                    layout_tiling_origin: 0.0,
+                    layout_prim_start: prim_rect.min.y,
+                },
+                regular_tile_size: LayoutSize::zero(),
+            }
+        }
+    };
+
+    // Size of regular tiles in layout space.
+    let layout_tile_size = LayoutSize::new(
+        device_tile_size as f32 / image_rect.width() as f32 * prim_rect.width(),
+        device_tile_size as f32 / image_rect.height() as f32 * prim_rect.height(),
+    );
+
+    // The decomposition logic is exactly the same on each axis so we reduce
+    // this to a 1-dimensional problem in an attempt to make the code simpler.
+
+    let x_extent = tiles_1d(
+        layout_tile_size.width,
+        visible_rect.x_range(),
+        prim_rect.min.x,
+        image_rect.x_range(),
+        device_tile_size,
+    );
+
+    let y_extent = tiles_1d(
+        layout_tile_size.height,
+        visible_rect.y_range(),
+        prim_rect.min.y,
+        image_rect.y_range(),
+        device_tile_size,
+    );
+
+    TileIterator {
+        current_tile: point2(
+            x_extent.tile_range.start,
+            y_extent.tile_range.start,
+        ),
+        x: x_extent,
+        y: y_extent,
+        regular_tile_size: layout_tile_size,
+    }
+}
+
+/// Decompose tiles along an arbitrary axis.
+///
+/// This does most of the heavy lifting needed for `tiles` but in a single dimension for
+/// the sake of simplicity since the problem is independent on the x and y axes.
+fn tiles_1d(
+    layout_tile_size: f32,
+    layout_visible_range: Range<f32>,
+    layout_prim_start: f32,
+    device_image_range: Range<i32>,
+    device_tile_size: i32,
+) -> TileIteratorExtent {
+    // A few sanity checks.
+    debug_assert!(layout_tile_size > 0.0);
+    debug_assert!(layout_visible_range.end >= layout_visible_range.start);
+    debug_assert!(device_image_range.end > device_image_range.start);
+    debug_assert!(device_tile_size > 0);
+
+    // Sizes of the boundary tiles in pixels.
+    let first_tile_device_size = first_tile_size_1d(&device_image_range, device_tile_size);
+    let last_tile_device_size = last_tile_size_1d(&device_image_range, device_tile_size);
+
+    // [start..end[ Range of tiles of this row/column (in number of tiles) without
+    // taking culling into account.
+    let image_tiles = tile_range_1d(&device_image_range, device_tile_size);
+
+    // Layout offset of tile (0, 0) with respect to the top-left corner of the display item.
+    let layout_offset = device_image_range.start as f32 * layout_tile_size / device_tile_size as f32;
+    // Position in layout space of tile (0, 0).
+    let layout_tiling_origin = layout_prim_start - layout_offset;
+
+    // [start..end[ Range of the visible tiles (because of culling).
+    let visible_tiles_start = f32::floor((layout_visible_range.start - layout_tiling_origin) / layout_tile_size) as i32;
+    let visible_tiles_end = f32::ceil((layout_visible_range.end - layout_tiling_origin) / layout_tile_size) as i32;
+
+    // Combine the above two to get the tiles in the image that are visible this frame.
+    let mut tiles_start = i32::max(image_tiles.start, visible_tiles_start);
+    let tiles_end = i32::min(image_tiles.end, visible_tiles_end);
+    if tiles_start > tiles_end {
+        tiles_start = tiles_end;
+    }
+
+    // The size in layout space of the boundary tiles.
+    let first_tile_layout_size = if tiles_start == image_tiles.start {
+        first_tile_device_size as f32 * layout_tile_size / device_tile_size as f32
+    } else {
+        // boundary tile was culled out, so the new first tile is a regularly sized tile.
+        layout_tile_size
+    };
+
+    // Same here.
+    let last_tile_layout_size = if tiles_end == image_tiles.end {
+        last_tile_device_size as f32 * layout_tile_size / device_tile_size as f32
+    } else {
+        layout_tile_size
+    };
+
+    TileIteratorExtent {
+        tile_range: tiles_start..tiles_end,
+        image_tiles,
+        first_tile_layout_size,
+        last_tile_layout_size,
+        layout_tiling_origin,
+        layout_prim_start,
+    }
+}
+
+/// Compute the range of tiles (in number of tiles) that intersect the provided
+/// image range (in pixels) in an arbitrary dimension.
+///
+/// ```ignore
+///
+///         0
+///         :
+///   #-+---+---+---+---+---+--#
+///   # |   |   |   |   |   |  #
+///   #-+---+---+---+---+---+--#
+/// ^       :                   ^
+///
+///  +------------------------+  image_range
+///        +---+  regular_tile_size
+///
+/// ```
+fn tile_range_1d(
+    image_range: &Range<i32>,
+    regular_tile_size: i32,
+) -> Range<i32> {
+    // Integer division truncates towards zero so with negative values if the first/last
+    // tile isn't a full tile we can get offset by one which we account for here.
+
+    let mut start = image_range.start / regular_tile_size;
+    if image_range.start % regular_tile_size < 0 {
+        start -= 1;
+    }
+
+    let mut end = image_range.end / regular_tile_size;
+    if image_range.end % regular_tile_size > 0 {
+        end += 1;
+    }
+
+    start..end
+}
+
+// Sizes of the first boundary tile in pixels.
+//
+// It can be smaller than the regular tile size if the image is not a multiple
+// of the regular tile size.
+fn first_tile_size_1d(
+    image_range: &Range<i32>,
+    regular_tile_size: i32,
+) -> i32 {
+    // We have to account for how the % operation behaves for negative values.
+    let image_size = image_range.end - image_range.start;
+    i32::min(
+        match image_range.start % regular_tile_size {
+            //             .      #------+------+      .
+            //             .      #//////|      |      .
+            0 => regular_tile_size,
+            //   (zero) -> 0      .   #--+------+      .
+            //             .      .   #//|      |      .
+            // %(m):                  ~~>
+            m if m > 0 => regular_tile_size - m,
+            //             .      .   #--+------+      0 <- (zero)
+            //             .      .   #//|      |      .
+            // %(m):                  <~~
+            m => -m,
+        },
+        image_size
+    )
+}
+
+// Sizes of the last boundary tile in pixels.
+//
+// It can be smaller than the regular tile size if the image is not a multiple
+// of the regular tile size.
+fn last_tile_size_1d(
+    image_range: &Range<i32>,
+    regular_tile_size: i32,
+) -> i32 {
+    // We have to account for how the modulo operation behaves for negative values.
+    let image_size = image_range.end - image_range.start;
+    i32::min(
+        match image_range.end % regular_tile_size {
+            //                    +------+------#      .
+            // tiles:      .      |      |//////#      .
+            0 => regular_tile_size,
+            //             .      +------+--#   .      0 <- (zero)
+            //             .      |      |//#   .      .
+            // modulo (m):                   <~~
+            m if m < 0 => regular_tile_size + m,
+            //   (zero) -> 0      +------+--#   .      .
+            //             .      |      |//#   .      .
+            // modulo (m):                ~~>
+            m => m,
+        },
+        image_size,
+    )
+}
+
+pub fn compute_tile_rect(
+    image_rect: &DeviceIntRect,
+    regular_tile_size: TileSize,
+    tile: TileOffset,
+) -> DeviceIntRect {
+    let regular_tile_size = regular_tile_size as i32;
+    DeviceIntRect::from_origin_and_size(
+        point2(
+            compute_tile_origin_1d(image_rect.x_range(), regular_tile_size, tile.x as i32),
+            compute_tile_origin_1d(image_rect.y_range(), regular_tile_size, tile.y as i32),
+        ),
+        size2(
+            compute_tile_size_1d(image_rect.x_range(), regular_tile_size, tile.x as i32),
+            compute_tile_size_1d(image_rect.y_range(), regular_tile_size, tile.y as i32),
+        ),
+    )
+}
+
+fn compute_tile_origin_1d(
+    img_range: Range<i32>,
+    regular_tile_size: i32,
+    tile_offset: i32,
+) -> i32 {
+    let tile_range = tile_range_1d(&img_range, regular_tile_size);
+    if tile_offset == tile_range.start {
+        img_range.start
+    } else {
+        tile_offset * regular_tile_size
+    }
+}
+
+// Compute the width and height in pixels of a tile depending on its position in the image.
+pub fn compute_tile_size(
+    image_rect: &DeviceIntRect,
+    regular_tile_size: TileSize,
+    tile: TileOffset,
+) -> DeviceIntSize {
+    let regular_tile_size = regular_tile_size as i32;
+    size2(
+        compute_tile_size_1d(image_rect.x_range(), regular_tile_size, tile.x as i32),
+        compute_tile_size_1d(image_rect.y_range(), regular_tile_size, tile.y as i32),
+    )
+}
+
+fn compute_tile_size_1d(
+    img_range: Range<i32>,
+    regular_tile_size: i32,
+    tile_offset: i32,
+) -> i32 {
+    let tile_range = tile_range_1d(&img_range, regular_tile_size);
+
+    // Most tiles are going to have base_size as width and height,
+    // except for tiles around the edges that are shrunk to fit the image data.
+    let actual_size = if tile_offset == tile_range.start {
+        first_tile_size_1d(&img_range, regular_tile_size)
+    } else if tile_offset == tile_range.end - 1 {
+        last_tile_size_1d(&img_range, regular_tile_size)
+    } else {
+        regular_tile_size
+    };
+
+    assert!(actual_size > 0);
+
+    actual_size
+}
+
+pub fn compute_tile_range(
+    visible_area: &DeviceIntRect,
+    tile_size: u16,
+) -> TileRange {
+    let tile_size = tile_size as i32;
+    let x_range = tile_range_1d(&visible_area.x_range(), tile_size);
+    let y_range = tile_range_1d(&visible_area.y_range(), tile_size);
+
+    TileRange {
+        min: point2(x_range.start, y_range.start),
+        max: point2(x_range.end, y_range.end),
+    }
+}
+
+pub fn for_each_tile_in_range(
+    range: &TileRange,
+    mut callback: impl FnMut(TileOffset),
+) {
+    for y in range.y_range() {
+        for x in range.x_range() {
+            callback(point2(x, y));
+        }
+    }
+}
+
+pub fn compute_valid_tiles_if_bounds_change(
+    prev_rect: &DeviceIntRect,
+    new_rect: &DeviceIntRect,
+    tile_size: u16,
+) -> Option<TileRange> {
+    let intersection = match prev_rect.intersection(new_rect) {
+        Some(rect) => rect,
+        None => {
+            return Some(TileRange::zero());
+        }
+    };
+
+    let left = prev_rect.min.x != new_rect.min.x;
+    let right = prev_rect.max.x != new_rect.max.x;
+    let top = prev_rect.min.y != new_rect.min.y;
+    let bottom = prev_rect.max.y != new_rect.max.y;
+
+    if !left && !right && !top && !bottom {
+        // Bounds have not changed.
+        return None;
+    }
+
+    let tw = 1.0 / (tile_size as f32);
+    let th = 1.0 / (tile_size as f32);
+
+    let tiles = intersection
+        .cast::<f32>()
+        .scale(tw, th);
+
+    let min_x = if left { f32::ceil(tiles.min.x) } else { f32::floor(tiles.min.x) };
+    let min_y = if top { f32::ceil(tiles.min.y) } else { f32::floor(tiles.min.y) };
+    let max_x = if right { f32::floor(tiles.max.x) } else { f32::ceil(tiles.max.x) };
+    let max_y = if bottom { f32::floor(tiles.max.y) } else { f32::ceil(tiles.max.y) };
+
+    Some(TileRange {
+        min: point2(min_x as i32, min_y as i32),
+        max: point2(max_x as i32, max_y as i32),
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::collections::HashSet;
+    use euclid::rect;
+
+    // this checks some additional invariants
+    fn checked_for_each_tile(
+        prim_rect: &LayoutRect,
+        visible_rect: &LayoutRect,
+        device_image_rect: &DeviceIntRect,
+        device_tile_size: i32,
+        callback: &mut dyn FnMut(&LayoutRect, TileOffset, EdgeAaSegmentMask),
+    ) {
+        let mut coverage = LayoutRect::zero();
+        let mut seen_tiles = HashSet::new();
+        for tile in tiles(
+            prim_rect,
+            visible_rect,
+            device_image_rect,
+            device_tile_size,
+        ) {
+            // make sure we don't get sent duplicate tiles
+            assert!(!seen_tiles.contains(&tile.offset));
+            seen_tiles.insert(tile.offset);
+            coverage = coverage.union(&tile.rect);
+            assert!(prim_rect.contains_box(&tile.rect));
+            callback(&tile.rect, tile.offset, tile.edge_flags);
+        }
+        assert!(prim_rect.contains_box(&coverage));
+        assert!(coverage.contains_box(&visible_rect.intersection(&prim_rect).unwrap_or(LayoutRect::zero())));
+    }
+
+    #[test]
+    fn basic() {
+        let mut count = 0;
+        checked_for_each_tile(&rect(0., 0., 1000., 1000.).to_box2d(),
+            &rect(75., 75., 400., 400.).to_box2d(),
+            &rect(0, 0, 400, 400).to_box2d(),
+            36,
+            &mut |_tile_rect, _tile_offset, _tile_flags| {
+                count += 1;
+            },
+        );
+        assert_eq!(count, 36);
+    }
+
+    #[test]
+    fn empty() {
+        let mut count = 0;
+        checked_for_each_tile(&rect(0., 0., 74., 74.).to_box2d(),
+            &rect(75., 75., 400., 400.).to_box2d(),
+            &rect(0, 0, 400, 400).to_box2d(),
+            36,
+            &mut |_tile_rect, _tile_offset, _tile_flags| {
+              count += 1;
+            },
+        );
+        assert_eq!(count, 0);
+    }
+
+    #[test]
+    fn test_tiles_1d() {
+        // Exactly one full tile at positive offset.
+        let result = tiles_1d(64.0, -10000.0..10000.0, 0.0, 0..64, 64);
+        assert_eq!(result.tile_range.start, 0);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 64.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+
+        // Exactly one full tile at negative offset.
+        let result = tiles_1d(64.0, -10000.0..10000.0, -64.0, -64..0, 64);
+        assert_eq!(result.tile_range.start, -1);
+        assert_eq!(result.tile_range.end, 0);
+        assert_eq!(result.first_tile_layout_size, 64.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+
+        // Two full tiles at negative and positive offsets.
+        let result = tiles_1d(64.0, -10000.0..10000.0, -64.0, -64..64, 64);
+        assert_eq!(result.tile_range.start, -1);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 64.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+
+        // One partial tile at positive offset, non-zero origin, culled out.
+        let result = tiles_1d(64.0, -100.0..10.0, 64.0, 64..310, 64);
+        assert_eq!(result.tile_range.start, result.tile_range.end);
+
+        // Two tiles at negative and positive offsets, one of which is culled out.
+        // The remaining tile is partially culled but it should still generate a full tile.
+        let result = tiles_1d(64.0, 10.0..10000.0, -64.0, -64..64, 64);
+        assert_eq!(result.tile_range.start, 0);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 64.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+        let result = tiles_1d(64.0, -10000.0..-10.0, -64.0, -64..64, 64);
+        assert_eq!(result.tile_range.start, -1);
+        assert_eq!(result.tile_range.end, 0);
+        assert_eq!(result.first_tile_layout_size, 64.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+
+        // Stretched tile in layout space device tile size is 64 and layout tile size is 128.
+        // So the resulting tile sizes in layout space should be multiplied by two.
+        let result = tiles_1d(128.0, -10000.0..10000.0, -64.0, -64..32, 64);
+        assert_eq!(result.tile_range.start, -1);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 128.0);
+        assert_eq!(result.last_tile_layout_size, 64.0);
+
+        // Two visible tiles (the rest is culled out).
+        let result = tiles_1d(10.0, 0.0..20.0, 0.0, 0..64, 64);
+        assert_eq!(result.tile_range.start, 0);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 10.0);
+        assert_eq!(result.last_tile_layout_size, 10.0);
+
+        // Two visible tiles at negative layout offsets (the rest is culled out).
+        let result = tiles_1d(10.0, -20.0..0.0, -20.0, 0..64, 64);
+        assert_eq!(result.tile_range.start, 0);
+        assert_eq!(result.tile_range.end, 1);
+        assert_eq!(result.first_tile_layout_size, 10.0);
+        assert_eq!(result.last_tile_layout_size, 10.0);
+    }
+
+    #[test]
+    fn test_tile_range_1d() {
+        assert_eq!(tile_range_1d(&(0..256), 256), 0..1);
+        assert_eq!(tile_range_1d(&(0..257), 256), 0..2);
+        assert_eq!(tile_range_1d(&(-1..257), 256), -1..2);
+        assert_eq!(tile_range_1d(&(-256..256), 256), -1..1);
+        assert_eq!(tile_range_1d(&(-20..-10), 6), -4..-1);
+        assert_eq!(tile_range_1d(&(20..100), 256), 0..1);
+    }
+
+    #[test]
+    fn test_first_last_tile_size_1d() {
+        assert_eq!(first_tile_size_1d(&(0..10), 64), 10);
+        assert_eq!(first_tile_size_1d(&(-20..0), 64), 20);
+
+        assert_eq!(last_tile_size_1d(&(0..10), 64), 10);
+        assert_eq!(last_tile_size_1d(&(-20..0), 64), 20);
+    }
+
+    #[test]
+    fn doubly_partial_tiles() {
+        // In the following tests the image is a single tile and none of the sides of the tile
+        // align with the tile grid.
+        // This can only happen when we have a single non-aligned partial tile and no regular
+        // tiles.
+        assert_eq!(first_tile_size_1d(&(300..310), 64), 10);
+        assert_eq!(first_tile_size_1d(&(-20..-10), 64), 10);
+
+        assert_eq!(last_tile_size_1d(&(300..310), 64), 10);
+        assert_eq!(last_tile_size_1d(&(-20..-10), 64), 10);
+
+
+        // One partial tile at positve offset, non-zero origin.
+        let result = tiles_1d(64.0, -10000.0..10000.0, 0.0, 300..310, 64);
+        assert_eq!(result.tile_range.start, 4);
+        assert_eq!(result.tile_range.end, 5);
+        assert_eq!(result.first_tile_layout_size, 10.0);
+        assert_eq!(result.last_tile_layout_size, 10.0);
+    }
+
+    #[test]
+    fn smaller_than_tile_size_at_origin() {
+        let r = compute_tile_rect(
+            &rect(0, 0, 80, 80).to_box2d(),
+            256,
+            point2(0, 0),
+        );
+
+        assert_eq!(r, rect(0, 0, 80, 80).to_box2d());
+    }
+
+    #[test]
+    fn smaller_than_tile_size_with_offset() {
+        let r = compute_tile_rect(
+            &rect(20, 20, 80, 80).to_box2d(),
+            256,
+            point2(0, 0),
+        );
+
+        assert_eq!(r, rect(20, 20, 80, 80).to_box2d());
+    }
+}