Merge branch 'fix-negative-scales' into 'master'

ngl: Handle negative scales

Closes #4096

See merge request GNOME/gtk!3755

4 files changed, 55 insertions, 2 deletions

diff --git a/gsk/ngl/gsknglrenderjob.c b/gsk/ngl/gsknglrenderjob.c
index 3f36d506ab..72efcae92a 100644
--- a/gsk/ngl/gsknglrenderjob.c
+++ b/gsk/ngl/gsknglrenderjob.c
@@ -3725,19 +3725,23 @@ gsk_ngl_render_job_visit_node_with_offscreen (GskNglRenderJob       *job,
   {
     int max_texture_size = job->command_queue->max_texture_size;
 
-    scaled_width = ceilf (offscreen->bounds->size.width * job->scale_x);
+    scaled_width = ceilf (offscreen->bounds->size.width * fabs (job->scale_x));
     if (scaled_width > max_texture_size)
       {
         downscale_x = (float)max_texture_size / scaled_width;
         scaled_width = max_texture_size;
       }
+    if (job->scale_x < 0)
+      downscale_x = -downscale_x;
 
-    scaled_height = ceilf (offscreen->bounds->size.height * job->scale_y);
+    scaled_height = ceilf (offscreen->bounds->size.height * fabs (job->scale_y));
     if (scaled_height > max_texture_size)
       {
         downscale_y = (float)max_texture_size / scaled_height;
         scaled_height = max_texture_size;
       }
+    if (job->scale_y < 0)
+      downscale_y = -downscale_y;
   }
 
   GskNglRenderTarget *render_target;
diff --git a/testsuite/gsk/compare/scale-textures-negative-ngl.node b/testsuite/gsk/compare/scale-textures-negative-ngl.node
new file mode 100644
index 0000000000..fbf1d8205e
--- /dev/null
+++ b/testsuite/gsk/compare/scale-textures-negative-ngl.node
@@ -0,0 +1,48 @@
+transform {
+  transform: scale(1, 1);
+  child: opacity {
+    opacity: 0.6;
+    child: container {
+      texture {
+        bounds: 0 0 50 50;
+        texture: url("data:,<svg width='50' height='50'><rect x='25' y='25' width='25' height='25' fill='red'/></svg>");
+      }
+    }
+  }
+}
+transform {
+  transform: scale(1, -1);
+  child: opacity {
+    opacity: 0.6;
+    child: container {
+      texture {
+        bounds: 0 0 50 50;
+        texture: url("data:,<svg width='50' height='50'><rect x='25' y='25' width='25' height='25' fill='lime'/></svg>");
+      }
+    }
+  }
+}
+transform {
+  transform: scale(-1, -1);
+  child: opacity {
+    opacity: 0.6;
+    child: container {
+      texture {
+        bounds: 0 0 50 50;
+        texture: url("data:,<svg width='50' height='50'><rect x='25' y='25' width='25' height='25' fill='blue'/></svg>");
+      }
+    }
+  }
+}
+transform {
+  transform: scale(-1, 1);
+  child: opacity {
+    opacity: 0.6;
+    child: container {
+      texture {
+        bounds: 0 0 50 50;
+        texture: url("data:,<svg width='50' height='50'><rect x='25' y='25' width='25' height='25' fill='yellow'/></svg>");
+      }
+    }
+  }
+}
diff --git a/testsuite/gsk/compare/scale-textures-negative-ngl.png b/testsuite/gsk/compare/scale-textures-negative-ngl.png
new file mode 100644
index 0000000000..8624e6c403
--- /dev/null
+++ b/testsuite/gsk/compare/scale-textures-negative-ngl.png
diff --git a/testsuite/gsk/meson.build b/testsuite/gsk/meson.build
index 4bdfc8ceaf..e6901e5ef9 100644
--- a/testsuite/gsk/meson.build
+++ b/testsuite/gsk/meson.build
@@ -69,6 +69,7 @@ compare_render_tests = [
   'outset_shadow_rounded_top',
   'outset_shadow_simple',
   'scaled-cairo',
+  'scale-textures-negative-ngl',
   'scale-up-down',
   'shadow-in-opacity',
   'texture-url',