[gtk+] css: An opaque background does not allow omitting push_group

[Benjamin Otte <otte src gnome org>]

commit dd1cf1ac0f1f35f1d5810cbfbd445d8241f76414
Author: Benjamin Otte <otte redhat com>
Date:   Tue Dec 13 23:00:26 2016 +0100

    css: An opaque background does not allow omitting push_group
    
    When the background-clip of the background is smaller than the
    background-clip of blended images, not pushing a group is wrong.
    
    Test testing exactly that included.

 gtk/gtkrenderbackground.c                          |    9 -------
 testsuite/reftests/Makefile.am                     |    3 ++
 .../background-blend-mode-clip-interaction.css     |   24 ++++++++++++++++++++
 .../background-blend-mode-clip-interaction.ref.ui  |   17 ++++++++++++++
 .../background-blend-mode-clip-interaction.ui      |   16 +++++++++++++
 5 files changed, 60 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtkrenderbackground.c b/gtk/gtkrenderbackground.c
index 658bfd1..5450460 100644
--- a/gtk/gtkrenderbackground.c
+++ b/gtk/gtkrenderbackground.c
@@ -77,18 +77,9 @@ _gtk_theming_background_paint_color (GtkThemingBackground *bg,
 static gboolean
 _gtk_theming_background_needs_push_group (GtkCssStyle *style)
 {
-  const GdkRGBA *bg_color;
-  GtkCssValue *background_color;
   GtkCssValue *blend_modes;
   gint i;
 
-  background_color = gtk_css_style_get_value (style, GTK_CSS_PROPERTY_BACKGROUND_COLOR);
-  bg_color = _gtk_css_rgba_value_get_rgba (background_color);
-
-  /* An opaque background-color means we don't need to push the group */
-  if (bg_color->alpha == 1)
-    return FALSE;
-
   blend_modes = gtk_css_style_get_value (style, GTK_CSS_PROPERTY_BACKGROUND_BLEND_MODE);
 
   /*
diff --git a/testsuite/reftests/Makefile.am b/testsuite/reftests/Makefile.am
index f5d0a5b..c0c1bea 100644
--- a/testsuite/reftests/Makefile.am
+++ b/testsuite/reftests/Makefile.am
@@ -84,6 +84,9 @@ testdata = \
        background-area.css \
        background-area.ref.ui \
        background-area.ui \
+       background-blend-mode-clip-interaction.css \
+       background-blend-mode-clip-interaction.ref.ui \
+       background-blend-mode-clip-interaction.ui \
        background-color-transparent.css \
        background-color-transparent.ref.ui \
        background-color-transparent.ui \
diff --git a/testsuite/reftests/background-blend-mode-clip-interaction.css 
b/testsuite/reftests/background-blend-mode-clip-interaction.css
new file mode 100644
index 0000000..227f14e
--- /dev/null
+++ b/testsuite/reftests/background-blend-mode-clip-interaction.css
@@ -0,0 +1,24 @@
+* {all: unset; }
+
+window {
+  background: lime;
+}
+
+box {
+  background-color: red;
+  background-image: linear-gradient(yellow, yellow), linear-gradient(white, white);
+  background-clip: border-box, content-box;
+  background-size: 50% 100%, 100% 50%;
+  background-repeat: no-repeat;
+  background-blend-mode: multiply;
+  padding: 10px;
+  border: 1px solid blue;
+}
+
+window#reference box {
+  background-image: linear-gradient(red,red), linear-gradient(yellow, yellow);
+  background-clip: content-box, border-box;
+  background-size: 100% 100%, 50% 100%;
+  background-color: transparent;
+  background-blend-mode: normal;
+}
diff --git a/testsuite/reftests/background-blend-mode-clip-interaction.ref.ui 
b/testsuite/reftests/background-blend-mode-clip-interaction.ref.ui
new file mode 100644
index 0000000..fdedb42
--- /dev/null
+++ b/testsuite/reftests/background-blend-mode-clip-interaction.ref.ui
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.0 -->
+  <object class="GtkWindow" id="window1">
+    <property name="width_request">50</property>
+    <property name="height_request">50</property>
+    <property name="can_focus">False</property>
+    <property name="type">popup</property>
+    <property name="name">reference</property>
+    <child>
+      <object class="GtkBox">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+      </object>
+    </child>
+  </object>
+</interface>
diff --git a/testsuite/reftests/background-blend-mode-clip-interaction.ui 
b/testsuite/reftests/background-blend-mode-clip-interaction.ui
new file mode 100644
index 0000000..82d787a
--- /dev/null
+++ b/testsuite/reftests/background-blend-mode-clip-interaction.ui
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.0 -->
+  <object class="GtkWindow" id="window1">
+    <property name="width_request">50</property>
+    <property name="height_request">50</property>
+    <property name="can_focus">False</property>
+    <property name="type">popup</property>
+    <child>
+      <object class="GtkBox">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+      </object>
+    </child>
+  </object>
+</interface>