Skip clip masks with tiled blobs, instead of crashing.

We don't currently support tiled blobs for clip masks (see
issue #2852). This patch detects that case, and skips applying
a clip mask in that case. It's not ideal, but it's better
than crashing inside the resource cache, which is the current
behavior.

webrender/src/batch.rs

@@ -2018,25 +2018,30 @@ impl ClipBatcher {
             let gpu_address = gpu_cache.get_address(&clip_node.gpu_cache_handle);
 
             match clip_node.item {
-                ClipItem::Image(ref mask) => {
-                    if let Ok(cache_item) = resource_cache.get_cached_image(
-                        ImageRequest {
-                            key: mask.image,
-                            rendering: ImageRendering::Auto,
-                            tile: None,
+                ClipItem::Image(ref mask, is_valid) => {
+                    if is_valid {
+                        if let Ok(cache_item) = resource_cache.get_cached_image(
+                            ImageRequest {
+                                key: mask.image,
+                                rendering: ImageRendering::Auto,
+                                tile: None,
+                            }
+                        ) {
+                            self.images
+                                .entry(cache_item.texture_id)
+                                .or_insert(Vec::new())
+                                .push(ClipMaskInstance {
+                                    clip_data_address: gpu_address,
+                                    resource_address: gpu_cache.get_address(&cache_item.uv_rect_handle),
+                                    ..instance
+                                });
+                        } else {
+                            warn!("Warnings: skip a image mask");
+                            debug!("Key:{:?} Rect::{:?}", mask.image, mask.rect);
+                            continue;
                         }
-                    ) {
-                        self.images
-                            .entry(cache_item.texture_id)
-                            .or_insert(Vec::new())
-                            .push(ClipMaskInstance {
-                                clip_data_address: gpu_address,
-                                resource_address: gpu_cache.get_address(&cache_item.uv_rect_handle),
-                                ..instance
-                            });
                     } else {
-                        warn!("Warnings: skip a image mask");
-                        debug!("Key:{:?} Rect::{:?}", mask.image, mask.rect);
+                        warn!("Warnings: clip masks that are tiled blobs are not yet supported (#2852)");
                         continue;
                     }
                 }

webrender/src/clip.rs

@@ -145,11 +145,14 @@ impl From<ClipItemKey> for ClipNode {
                 )
             }
             ClipItemKey::ImageMask(rect, image, repeat) => {
-                ClipItem::Image(ImageMask {
-                    image,
-                    rect: LayoutRect::from_au(rect),
-                    repeat,
-                })
+                ClipItem::Image(
+                    ImageMask {
+                        image,
+                        rect: LayoutRect::from_au(rect),
+                        repeat,
+                    },
+                    true,
+                )
             }
             ClipItemKey::BoxShadow(shadow_rect, shadow_radius, prim_shadow_rect, blur_radius, clip_mode) => {
                 ClipItem::new_box_shadow(
@@ -263,7 +266,7 @@ impl ClipNode {
     ) {
         if let Some(mut request) = gpu_cache.request(&mut self.gpu_cache_handle) {
             match self.item {
-                ClipItem::Image(ref mask) => {
+                ClipItem::Image(ref mask, ..) => {
                     let data = ImageMaskData { local_rect: mask.rect };
                     data.write_gpu_blocks(request);
                 }
@@ -294,15 +297,25 @@ impl ClipNode {
         }
 
         match self.item {
-            ClipItem::Image(ref mask) => {
-                resource_cache.request_image(
-                    ImageRequest {
-                        key: mask.image,
-                        rendering: ImageRendering::Auto,
-                        tile: None,
-                    },
-                    gpu_cache,
-                );
+            ClipItem::Image(ref mask, ref mut is_valid) => {
+                if let Some(properties) = resource_cache.get_image_properties(mask.image) {
+                    // Clip masks with tiled blob images are not currently supported.
+                    // This results in them being ignored, which is not ideal, but
+                    // is better than crashing in resource cache!
+                    // See https://github.com/servo/webrender/issues/2852.
+                    *is_valid = properties.tiling.is_none();
+                }
+
+                if *is_valid {
+                    resource_cache.request_image(
+                        ImageRequest {
+                            key: mask.image,
+                            rendering: ImageRendering::Auto,
+                            tile: None,
+                        },
+                        gpu_cache,
+                    );
+                }
             }
             ClipItem::BoxShadow(ref mut info) => {
                 // Quote from https://drafts.csswg.org/css-backgrounds-3/#shadow-blur
@@ -760,7 +773,7 @@ impl ClipItemKey {
 pub enum ClipItem {
     Rectangle(LayoutRect, ClipMode),
     RoundedRectangle(LayoutRect, BorderRadius, ClipMode),
-    Image(ImageMask),
+    Image(ImageMask, bool),
     BoxShadow(BoxShadowClipSource),
 }
 
@@ -873,8 +886,8 @@ impl ClipItem {
             ClipItem::Rectangle(_, ClipMode::ClipOut) => None,
             ClipItem::RoundedRectangle(clip_rect, _, ClipMode::Clip) => Some(clip_rect),
             ClipItem::RoundedRectangle(_, _, ClipMode::ClipOut) => None,
-            ClipItem::Image(ref mask) if mask.repeat => None,
-            ClipItem::Image(ref mask) => Some(mask.rect),
+            ClipItem::Image(ref mask, ..) if mask.repeat => None,
+            ClipItem::Image(ref mask, ..) => Some(mask.rect),
             ClipItem::BoxShadow(..) => None,
         }
     }
@@ -1006,7 +1019,7 @@ impl ClipItem {
                     }
                 }
             }
-            ClipItem::Image(ref mask) => {
+            ClipItem::Image(ref mask, ..) => {
                 if mask.repeat {
                     ClipResult::Partial
                 } else {

webrender/src/hit_test.rs

@@ -39,7 +39,7 @@ impl HitTestClipNode {
             ClipItem::Rectangle(ref rect, mode) => HitTestRegion::Rectangle(*rect, mode),
             ClipItem::RoundedRectangle(ref rect, ref radii, ref mode) =>
                 HitTestRegion::RoundedRectangle(*rect, *radii, *mode),
-            ClipItem::Image(ref mask) => HitTestRegion::Rectangle(mask.rect, ClipMode::Clip),
+            ClipItem::Image(ref mask, ..) => HitTestRegion::Rectangle(mask.rect, ClipMode::Clip),
             ClipItem::BoxShadow(_) => HitTestRegion::Invalid,
         };