[gthumb] cairo metadata: use a flag to check whether a value is valid

[Paolo Bacchilega <paobac src gnome org>]

commit 3a8d835bb74c5c24a26e5f3601a3e164d17010ac
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Thu Feb 5 19:24:53 2015 +0100

    cairo metadata: use a flag to check whether a value is valid

 extensions/cairo_io/cairo-image-surface-jpeg.c |    5 +-
 extensions/cairo_io/cairo-image-surface-png.c  |    5 +-
 extensions/cairo_io/cairo-image-surface-tiff.c |    5 +-
 extensions/cairo_io/cairo-image-surface-webp.c |    2 +-
 gthumb/cairo-scale.c                           |    6 +--
 gthumb/cairo-utils.c                           |   66 ++++++++++++++++++++++--
 gthumb/cairo-utils.h                           |   19 +++++++
 gthumb/pixbuf-io.c                             |    5 +-
 8 files changed, 92 insertions(+), 21 deletions(-)
---
diff --git a/extensions/cairo_io/cairo-image-surface-jpeg.c b/extensions/cairo_io/cairo-image-surface-jpeg.c
index a6d6630..6ea9ef8 100644
--- a/extensions/cairo_io/cairo-image-surface-jpeg.c
+++ b/extensions/cairo_io/cairo-image-surface-jpeg.c
@@ -283,7 +283,7 @@ _cairo_image_surface_create_from_jpeg (GInputStream  *istream,
        }
 
        metadata = _cairo_image_surface_get_metadata (surface);
-       metadata->has_alpha = FALSE;
+       _cairo_metadata_set_has_alpha (metadata, FALSE);
        surface_data = _cairo_image_surface_flush_and_get_data (surface);
        surface_row = surface_data + line_start;
 
@@ -554,8 +554,7 @@ _cairo_image_surface_create_from_jpeg (GInputStream  *istream,
                        original_height = srcinfo.image_height;
                }
 
-               metadata->original_width = original_width;
-               metadata->original_height = original_height;
+               _cairo_metadata_set_original_size (metadata, original_width, original_height);
 
                if (original_width_p != NULL)
                        *original_width_p = original_width;
diff --git a/extensions/cairo_io/cairo-image-surface-png.c b/extensions/cairo_io/cairo-image-surface-png.c
index 2df3efd..038e092 100644
--- a/extensions/cairo_io/cairo-image-surface-png.c
+++ b/extensions/cairo_io/cairo-image-surface-png.c
@@ -204,9 +204,8 @@ _cairo_image_surface_create_from_png (GInputStream  *istream,
        }
 
        metadata = _cairo_image_surface_get_metadata (cairo_png_data->surface);
-       metadata->has_alpha = (color_type & PNG_COLOR_MASK_ALPHA);
-       metadata->original_width = width;
-       metadata->original_height = height;
+       _cairo_metadata_set_has_alpha (metadata, (color_type & PNG_COLOR_MASK_ALPHA));
+       _cairo_metadata_set_original_size (metadata, width, height);
 
        /* Set the data transformations */
 
diff --git a/extensions/cairo_io/cairo-image-surface-tiff.c b/extensions/cairo_io/cairo-image-surface-tiff.c
index d61f6b9..2ffbfef 100644
--- a/extensions/cairo_io/cairo-image-surface-tiff.c
+++ b/extensions/cairo_io/cairo-image-surface-tiff.c
@@ -250,9 +250,8 @@ _cairo_image_surface_create_from_tiff (GInputStream  *istream,
        }
 
        metadata = _cairo_image_surface_get_metadata (surface);
-       metadata->has_alpha = (extrasamples == 1) || (spp == 4);
-       metadata->original_width = max_width;
-       metadata->original_width = max_height;
+       _cairo_metadata_set_has_alpha (metadata, (extrasamples == 1) || (spp == 4));
+       _cairo_metadata_set_original_size (metadata, max_width, max_height);
 
        raster = (uint32*) _TIFFmalloc (image_width * image_height * sizeof (uint32));
        if (raster == NULL) {
diff --git a/extensions/cairo_io/cairo-image-surface-webp.c b/extensions/cairo_io/cairo-image-surface-webp.c
index cfa6e80..b4a4d93 100644
--- a/extensions/cairo_io/cairo-image-surface-webp.c
+++ b/extensions/cairo_io/cairo-image-surface-webp.c
@@ -81,7 +81,7 @@ _cairo_image_surface_create_from_webp (GInputStream  *istream,
 
        surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
        metadata = _cairo_image_surface_get_metadata (surface);
-       metadata->has_alpha = (config.input.has_alpha);
+       _cairo_metadata_set_has_alpha (metadata, config.input.has_alpha);
 
        config.options.no_fancy_upsampling = 1;
 
diff --git a/gthumb/cairo-scale.c b/gthumb/cairo-scale.c
index e663864..5b5015e 100644
--- a/gthumb/cairo-scale.c
+++ b/gthumb/cairo-scale.c
@@ -533,10 +533,8 @@ _cairo_image_surface_scale (cairo_surface_t  *image,
                                              scaled_height);
        _cairo_image_surface_copy_metadata (image, scaled);
        metadata = _cairo_image_surface_get_metadata (scaled);
-       if (metadata->original_width <= 0) {
-               metadata->original_width = src_width;
-               metadata->original_height = src_height;
-       }
+       if (metadata->original_width <= 0)
+               _cairo_metadata_set_original_size (metadata, src_width, src_height);
 
        if (scaled == NULL)
                return NULL;
diff --git a/gthumb/cairo-utils.c b/gthumb/cairo-utils.c
index 304b336..2393264 100644
--- a/gthumb/cairo-utils.c
+++ b/gthumb/cairo-utils.c
@@ -100,6 +100,37 @@ _gdk_rgba_to_cairo_color_255 (GdkRGBA           *g_color,
 
 
 void
+_cairo_metadata_set_has_alpha (cairo_surface_metadata_t        *metadata,
+                              gboolean                  has_alpha)
+{
+       metadata->valid_data |= _CAIRO_METADATA_FLAG_HAS_ALPHA;
+       metadata->has_alpha = has_alpha;
+}
+
+
+void
+_cairo_metadata_set_original_size (cairo_surface_metadata_t *metadata,
+                                  int                       width,
+                                  int                       height)
+{
+       metadata->valid_data |= _CAIRO_METADATA_FLAG_ORIGINAL_SIZE;
+       metadata->original_width = width;
+       metadata->original_height = height;
+}
+
+
+void
+_cairo_metadata_set_thumbnail_size (cairo_surface_metadata_t *metadata,
+                                   int                       width,
+                                   int                       height)
+{
+       metadata->valid_data |= _CAIRO_METADATA_FLAG_THUMBNAIL_SIZE;
+       metadata->thumbnail.image_width = width;
+       metadata->thumbnail.image_height = height;
+}
+
+
+void
 _cairo_clear_surface (cairo_surface_t  **surface)
 {
        if (surface == NULL)
@@ -123,6 +154,7 @@ _cairo_image_surface_flush_and_get_data (cairo_surface_t *surface)
 static void
 _cairo_surface_metadata_init (cairo_surface_metadata_t *metadata)
 {
+       metadata->valid_data = _CAIRO_METADATA_FLAG_NONE;
        metadata->has_alpha = FALSE;
        metadata->original_width = 0;
        metadata->original_height = 0;
@@ -157,6 +189,7 @@ _cairo_image_surface_copy_metadata (cairo_surface_t *src,
        src_metadata = _cairo_image_surface_get_metadata (src);
        dest_metadata = _cairo_image_surface_get_metadata (dest);
 
+       dest_metadata->valid_data = src_metadata->valid_data;
        dest_metadata->has_alpha = src_metadata->has_alpha;
        dest_metadata->original_width = src_metadata->original_width;
        dest_metadata->original_height = src_metadata->original_height;
@@ -180,15 +213,40 @@ gboolean
 _cairo_image_surface_get_has_alpha (cairo_surface_t *surface)
 {
        cairo_surface_metadata_t *metadata;
+       int                       width;
+       int                       height;
+       int                       row_stride;
+       guchar                   *row;
+       int                       h, w;
 
        if (surface == NULL)
                return FALSE;
 
        metadata = cairo_surface_get_user_data (surface, &surface_metadata_key);
-       if (metadata != NULL)
+       if ((metadata != NULL) && (metadata->valid_data & _CAIRO_METADATA_FLAG_HAS_ALPHA))
                return metadata->has_alpha;
 
-       return cairo_image_surface_get_format (surface) == CAIRO_FORMAT_ARGB32;
+       if (cairo_image_surface_get_format (surface) != CAIRO_FORMAT_ARGB32)
+               return FALSE;
+
+       /* search an alpha value lower than 255 */
+
+       width = cairo_image_surface_get_width (surface);
+       height = cairo_image_surface_get_height (surface);
+       row_stride = cairo_image_surface_get_stride (surface);
+       row = _cairo_image_surface_flush_and_get_data (surface);
+
+       for (h = 0; h < height; h++) {
+               guchar *pixel = row;
+               for (w = 0; w < width; w++) {
+                       if (pixel[CAIRO_ALPHA] < 255)
+                               return TRUE;
+                       pixel += 4;
+               }
+               row += row_stride;
+       }
+
+       return FALSE;
 }
 
 
@@ -206,7 +264,7 @@ _cairo_image_surface_get_original_size (cairo_surface_t *surface,
        if (metadata == NULL)
                return FALSE;
 
-       if ((metadata->original_width <= 0) || (metadata->original_height <= 0))
+       if ((metadata->valid_data & _CAIRO_METADATA_FLAG_ORIGINAL_SIZE) == 0)
                return FALSE;
 
        if (original_width)
@@ -339,7 +397,7 @@ _cairo_image_surface_create_from_pixbuf (GdkPixbuf *pixbuf)
        s_pixels = _cairo_image_surface_flush_and_get_data (surface);
 
        metadata = _cairo_image_surface_get_metadata (surface);
-       metadata->has_alpha = (p_n_channels == 4);
+       _cairo_metadata_set_has_alpha (metadata, (p_n_channels == 4));
 
        if (p_n_channels == 4) {
                guchar *s_iter;
diff --git a/gthumb/cairo-utils.h b/gthumb/cairo-utils.h
index 84ca643..85efc31 100644
--- a/gthumb/cairo-utils.h
+++ b/gthumb/cairo-utils.h
@@ -135,7 +135,15 @@ typedef struct {
        int image_height;
 } thumbnail_metadata_t;
 
+typedef enum {
+       _CAIRO_METADATA_FLAG_NONE = 0,
+       _CAIRO_METADATA_FLAG_HAS_ALPHA = 1 << 0,
+       _CAIRO_METADATA_FLAG_ORIGINAL_SIZE = 1 << 1,
+       _CAIRO_METADATA_FLAG_THUMBNAIL_SIZE = 1 << 2
+} cairo_metadata_flags_t;
+
 typedef struct {
+       cairo_metadata_flags_t  valid_data;
        gboolean                has_alpha;
        int                     original_width;
        int                     original_height;
@@ -161,6 +169,17 @@ void               _gdk_color_to_cairo_color_255            (GdkColor
 void               _gdk_rgba_to_cairo_color_255             (GdkRGBA               *g_color,
                                                             cairo_color_255_t     *c_color);
 
+/* metadata */
+
+void               _cairo_metadata_set_has_alpha            (cairo_surface_metadata_t  *metadata,
+                                                            gboolean                    has_alpha);
+void               _cairo_metadata_set_original_size        (cairo_surface_metadata_t  *metadata,
+                                                            int                         width,
+                                                            int                         height);
+void               _cairo_metadata_set_thumbnail_size       (cairo_surface_metadata_t  *metadata,
+                                                            int                         width,
+                                                            int                         height);
+
 /* surface */
 
 void               _cairo_clear_surface                     (cairo_surface_t      **surface);
diff --git a/gthumb/pixbuf-io.c b/gthumb/pixbuf-io.c
index d028700..5573461 100644
--- a/gthumb/pixbuf-io.c
+++ b/gthumb/pixbuf-io.c
@@ -214,9 +214,8 @@ gth_pixbuf_new_from_file (GInputStream  *istream,
 
                surface = _cairo_image_surface_create_from_pixbuf (pixbuf);
                metadata = _cairo_image_surface_get_metadata (surface);
-               metadata->original_width = scale_data.original_width;
-               metadata->original_height = scale_data.original_height;
-               metadata->has_alpha = gdk_pixbuf_get_has_alpha (pixbuf);
+               _cairo_metadata_set_has_alpha (metadata, gdk_pixbuf_get_has_alpha (pixbuf));
+               _cairo_metadata_set_original_size (metadata, scale_data.original_width, 
scale_data.original_height);
                gth_image_set_cairo_surface (image, surface);
        }