Bug 1618939 - Hit MOZ_CRASH(explicit panic) at gfx/wr/webrender/src/render_task.rs:37 r=gw

Adding a repro-case reftest that asks for a 19996x5000 RenderTask (at
-p1), then fix it in analogy with the clamping to reasonable values that
happens for `NormalBorder`.

Differential Revision: https://phabricator.services.mozilla.com/D65660

--HG--
extra : moz-landing-system : lando

gfx/wr/webrender/src/prim_store/line_dec.rs

@@ -18,6 +18,8 @@ use crate::prim_store::{
 };
 use crate::prim_store::PrimitiveInstanceKind;
 
+/// Maximum resolution in device pixels at which line decorations are rasterized.
+pub const MAX_LINE_DECORATION_RESOLUTION: u32 = 4096;
 
 #[derive(Clone, Debug, Hash, MallocSizeOf, PartialEq, Eq)]
 #[cfg_attr(feature = "capture", derive(Serialize))]

gfx/wr/webrender/src/prim_store/mod.rs

@@ -34,7 +34,7 @@ use crate::prim_store::borders::{ImageBorderDataHandle, NormalBorderDataHandle};
 use crate::prim_store::gradient::{GRADIENT_FP_STOPS, GradientCacheKey, GradientStopKey};
 use crate::prim_store::gradient::{LinearGradientPrimitive, LinearGradientDataHandle, RadialGradientDataHandle, ConicGradientDataHandle};
 use crate::prim_store::image::{ImageDataHandle, ImageInstance, VisibleImageTile, YuvImageDataHandle};
-use crate::prim_store::line_dec::LineDecorationDataHandle;
+use crate::prim_store::line_dec::{LineDecorationDataHandle,MAX_LINE_DECORATION_RESOLUTION};
 use crate::prim_store::picture::PictureDataHandle;
 use crate::prim_store::text_run::{TextRunDataHandle, TextRunPrimitive};
 #[cfg(debug_assertions)]
@@ -2920,7 +2920,14 @@ impl PrimitiveStore {
                     // TODO(gw): Do we ever need / want to support scales for text decorations
                     //           based on the current transform?
                     let scale_factor = Scale::new(1.0) * device_pixel_scale;
-                    let task_size = (LayoutSize::from_au(cache_key.size) * scale_factor).ceil().to_i32();
+                    let mut task_size = (LayoutSize::from_au(cache_key.size) * scale_factor).ceil().to_i32();
+                    if task_size.width > MAX_LINE_DECORATION_RESOLUTION as i32 ||
+                       task_size.height > MAX_LINE_DECORATION_RESOLUTION as i32 {
+                         let max_extent = cmp::max(task_size.width, task_size.height);
+                         let task_scale_factor = Scale::new(MAX_LINE_DECORATION_RESOLUTION as f32 / max_extent as f32);
+                         task_size = (LayoutSize::from_au(cache_key.size) * scale_factor * task_scale_factor)
+                                        .ceil().to_i32();
+                    }
 
                     // Request a pre-rendered image task.
                     // TODO(gw): This match is a bit untidy, but it should disappear completely

gfx/wr/wrench/reftests/text/large-line-decoration.yaml

@@ -0,0 +1,43 @@
+---
+root:
+  items:
+    - type: line
+      baseline: 0
+      start: 0
+      end: 50
+      width: 5000
+      thickness: 5000
+      orientation: horizontal
+      color: red
+      style: solid
+
+    - type: line
+      baseline: 0
+      start: 100
+      end: 150
+      width: 5000
+      thickness: 5000
+      orientation: horizontal
+      color: green
+      style: dashed
+
+    - type: line
+      baseline: 0
+      start: 200
+      end: 250
+      width: 5000
+      thickness: 5000
+      orientation: horizontal
+      color: blue
+      style: dotted
+
+    - type: line
+      baseline: 0
+      start: 300
+      end: 350
+      width: 5000
+      thickness: 5000
+      orientation: horizontal
+      color: yellow
+      style: wavy
+

gfx/wr/wrench/reftests/text/reftest.list

@@ -66,6 +66,7 @@ fuzzy(1,113) platform(linux) == raster-space.yaml raster-space.png
 skip_on(android) skip_on(mac,>=10.14) != allow-subpixel.yaml allow-subpixel-ref.yaml  # Android: we don't enable sub-px aa on this platform.
 skip_on(android,device) == bg-color.yaml bg-color-ref.yaml  # Fails on Pixel2
 != large-glyphs.yaml blank.yaml
+!= large-line-decoration.yaml blank.yaml
 skip_on(android,device) == snap-text-offset.yaml snap-text-offset-ref.yaml
 fuzzy(5,4435) == shadow-border.yaml shadow-solid-ref.yaml
 fuzzy(5,4435) == shadow-image.yaml shadow-solid-ref.yaml