Transparency patch for zathura

girara-alpha.patch

diff --git a/girara/session.c b/girara/session.c
index 927e9b5..040ac5c 100644
--- a/girara/session.c
+++ b/girara/session.c
@@ -378,6 +378,16 @@ girara_session_create(void)
   return session;
 }
 
+static void
+screen_changed(GtkWidget* widget, GdkScreen* GIRARA_UNUSED(old_screen), gpointer GIRARA_UNUSED(userdata)) {
+  GdkScreen *screen = gtk_widget_get_screen(widget);
+  GdkVisual *visual = gdk_screen_get_rgba_visual(screen);
+  if (!visual) {
+    visual = gdk_screen_get_system_visual(screen);
+  }
+  gtk_widget_set_visual(widget, visual);
+}
+
 bool
 girara_session_init(girara_session_t* session, const char* sessionname)
 {
@@ -410,6 +420,9 @@ girara_session_init(girara_session_t* session, const char* sessionname)
 
   gtk_widget_set_name(session->gtk.window, session->private_data->session_name);
 
+  g_signal_connect(G_OBJECT(session->gtk.window), "screen-changed", G_CALLBACK(screen_changed), NULL);
+  screen_changed(GTK_WIDGET(session->gtk.window), NULL, NULL);
+
   /* apply CSS style */
   css_template_changed(session->private_data->csstemplate, session);
 

PKGBUILD-girara

# Maintainer: none

_pkgname=girara

pkgname=girara-git-alpha
pkgver=0.3.4.r1.g051de04
pkgrel=1
pkgdesc="user interface library"
arch=('i686' 'x86_64')
url="http://pwmt.org/projects/girara"
license=('custom')
depends=('gtk3>=3.2' 'glib2>=2.28' 'intltool')
makedepends=('git' 'meson')
conflicts=('girara')
provides=('girara')
source=("${_pkgname}::git+https://git.pwmt.org/pwmt/girara.git#branch=develop" 'girara-alpha.patch')
md5sums=('SKIP' 'SKIP')

prepare() {
  mkdir -p build
  cd "$srcdir/girara"
  patch -Np1 -i "$srcdir/girara-alpha.patch"
}

build() {
  cd build
  meson --prefix=/usr --buildtype=release $srcdir/$_pkgname
  ninja
}

package() {
  cd build
  DESTDIR="$pkgdir/" ninja install
}

pkgver() {
  cd "$_pkgname"
  git describe --long | sed -r 's/([^-]*-g)/r\1/;s/-/./g'
}

# vim:set ts=2 sw=2 et:

PKGBUILD-zathura

# Maintainer: none

pkgname=zathura-git-alpha
pkgver=0.4.5.4.g99a4983
pkgrel=1
pkgdesc="a document viewer"
arch=('i686' 'x86_64')
url="http://pwmt.org/projects/zathura"
license=('custom')
depends=('girara-git-alpha' 'gtk3>=3.10' 'cairo>=1.8.8')
makedepends=('git' 'python-sphinx' 'intltool' 'meson')
conflicts=('zathura')
provides=('zathura')
source=('zathura::git+https://git.pwmt.org/pwmt/zathura.git#branch=develop' 'zathura-alpha.patch')
md5sums=('SKIP' 'SKIP')
_gitname=zathura

optdepends=(
  'zathura-pdf-poppler-git: PDF support by using poppler'
  'zathura-pdf-mupdf-git: PDF support by using mupdf'
  'zathura-djvu-git: djvu support by using djvulibre'
  'zathura-ps-git: PostSctipt support by using libspectre'
)

prepare() {
  mkdir -p build
  cd "$srcdir/zathura"
  patch -Np1 -i "$srcdir/zathura-alpha.patch"
}

build() {
  cd build
  meson --prefix=/usr --buildtype=release $srcdir/$_gitname
  ninja
}

package() {
  cd build
  DESTDIR="$pkgdir/" ninja install
}

pkgver() {
  cd "$_gitname"
  local ver="$(git describe --long)"
  printf "%s" "${ver//-/.}"
}

# vim:set ts=2 sw=2 et:

zathura-alpha.patch

diff --git a/zathura/page-widget.c b/zathura/page-widget.c
index 1132920..373afeb 100644
--- a/zathura/page-widget.c
+++ b/zathura/page-widget.c
@@ -629,7 +629,7 @@ zathura_page_widget_draw(GtkWidget* widget, cairo_t* cairo)
     if (zathura_renderer_recolor_enabled(priv->zathura->sync.render_thread) == true) {
       GdkRGBA color;
       zathura_renderer_get_recolor_colors(priv->zathura->sync.render_thread, &color, NULL);
-      cairo_set_source_rgb(cairo, color.red, color.green, color.blue);
+      cairo_set_source_rgba(cairo, color.red, color.green, color.blue, color.alpha);
     } else {
       const GdkRGBA color = priv->zathura->ui.colors.render_loading_bg;
       cairo_set_source_rgb(cairo, color.red, color.green, color.blue);
diff --git a/zathura/render.c b/zathura/render.c
index 9d67c63..b5a1041 100644
--- a/zathura/render.c
+++ b/zathura/render.c
@@ -594,6 +594,8 @@ recolor(ZathuraRendererPrivate* priv, zathura_page_t* page, unsigned int page_wi
 
   const double l1 = a[0]*rgb1.red + a[1]*rgb1.green + a[2]*rgb1.blue;
   const double l2 = a[0]*rgb2.red + a[1]*rgb2.green + a[2]*rgb2.blue;
+  const double negalph1 = 1. - rgb1.alpha;
+  const double negalph2 = 1. - rgb2.alpha;
 
   const double rgb_diff[] = {
     rgb2.red - rgb1.red,
@@ -601,6 +603,24 @@ recolor(ZathuraRendererPrivate* priv, zathura_page_t* page, unsigned int page_wi
     rgb2.blue - rgb1.blue
   };
 
+  const double h1[3] = {
+    rgb1.red*rgb1.alpha - l1,
+    rgb1.green*rgb1.alpha - l1,
+    rgb1.blue*rgb1.alpha - l1,
+  };
+
+  const double h2[3] = {
+    rgb2.red*rgb2.alpha - l2,
+    rgb2.green*rgb2.alpha - l2,
+    rgb2.blue*rgb2.alpha - l2,
+  };
+
+  /* Decide if we can use the older, faster formulas */
+  const bool fast_formula = (!priv->recolor.hue || (
+        fabs(rgb1.red - rgb1.blue) < DBL_EPSILON && fabs(rgb1.red - rgb1.green) < DBL_EPSILON &&
+        fabs(rgb2.red - rgb2.blue) < DBL_EPSILON && fabs(rgb2.red - rgb2.green) < DBL_EPSILON
+      )) && (rgb1.alpha >= 1. - DBL_EPSILON && rgb2.alpha >= 1. - DBL_EPSILON);
+
   girara_list_t* images     = NULL;
   girara_list_t* rectangles = NULL;
   bool found_images         = false;
@@ -645,6 +665,8 @@ recolor(ZathuraRendererPrivate* priv, zathura_page_t* page, unsigned int page_wi
         );
         /* If it's inside and image don't recolor */
         if (inside_image == true) {
+          /* It is not guaranteed that the pixel is already opaque. */
+          data[3] = 255;
           continue;
         }
       }
@@ -678,15 +700,38 @@ recolor(ZathuraRendererPrivate* priv, zathura_page_t* page, unsigned int page_wi
         l = l * (l2 - l1) + l1;
 
         const double su = s * colorumax(h, l, l1, l2);
-        data[2] = (unsigned char)round(255.*(l + su * h[0]));
-        data[1] = (unsigned char)round(255.*(l + su * h[1]));
-        data[0] = (unsigned char)round(255.*(l + su * h[2]));
+
+        if (fast_formula) {
+          data[3] = 255;
+          data[2] = (unsigned char)round(255.*(l + su * h[0]));
+          data[1] = (unsigned char)round(255.*(l + su * h[1]));
+          data[0] = (unsigned char)round(255.*(l + su * h[2]));
+        } else {
+          /* Mix lightcolor, darkcolor and the original color, according to the
+           * minimal and maximal channel of the original color */
+          const double tr1 = (1. - fmax(fmax(rgb[0], rgb[1]), rgb[2]));
+          const double tr2 = fmin(fmin(rgb[0], rgb[1]), rgb[2]);
+          data[3] = (unsigned char)round(255.*(1. - tr1*negalph1 - tr2*negalph2));
+          data[2] = (unsigned char)round(255.*fmin(1, fmax(0, tr1*h1[0] + tr2*h2[0] + (l + su * h[0]))));
+          data[1] = (unsigned char)round(255.*fmin(1, fmax(0, tr1*h1[1] + tr2*h2[1] + (l + su * h[1]))));
+          data[0] = (unsigned char)round(255.*fmin(1, fmax(0, tr1*h1[2] + tr2*h2[2] + (l + su * h[2]))));
+        }
       } else {
         /* linear interpolation between dark and light with color ligtness as
          * a parameter */
-        data[2] = (unsigned char)round(255.*(l * rgb_diff[0] + rgb1.red));
-        data[1] = (unsigned char)round(255.*(l * rgb_diff[1] + rgb1.green));
-        data[0] = (unsigned char)round(255.*(l * rgb_diff[2] + rgb1.blue));
+        if (fast_formula) {
+          data[3] = 255;
+          data[2] = (unsigned char)round(255.*(l * rgb_diff[0] + rgb1.red));
+          data[1] = (unsigned char)round(255.*(l * rgb_diff[1] + rgb1.green));
+          data[0] = (unsigned char)round(255.*(l * rgb_diff[2] + rgb1.blue));
+        } else {
+          const double f1 = 1. - (1. - fmax(fmax(rgb[0], rgb[1]), rgb[2]))*negalph1;
+          const double f2 = fmin(fmin(rgb[0], rgb[1]), rgb[2])*negalph2;
+          data[3] = (unsigned char)round(255.*(f1 - f2));
+          data[2] = (unsigned char)round(255.*(l * rgb_diff[0] - f2*rgb2.red + f1*rgb1.red));
+          data[1] = (unsigned char)round(255.*(l * rgb_diff[1] - f2*rgb2.green + f1*rgb1.green));
+          data[0] = (unsigned char)round(255.*(l * rgb_diff[2] - f2*rgb2.blue + f1*rgb1.blue));
+        }
       }
     }
   }
@@ -778,8 +823,16 @@ render(render_job_t* job, ZathuraRenderRequest* request, ZathuraRenderer* render
     page_height = height;
   }
 
-  cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24,
+  cairo_format_t format;
+  if (priv->recolor.enabled) {
+    format = CAIRO_FORMAT_ARGB32;
+  }
+  else {
+    format = CAIRO_FORMAT_RGB24;
+  }
+  cairo_surface_t* surface = cairo_image_surface_create(format,
       page_width, page_height);
+
   if (surface == NULL) {
     return false;
   }