[gimp] plug-ins: dynamically lower width/height with impossible values.

[Jehan <jehanp src gnome org>]

commit a554349e5247d3158b67cda6f734219effc26612
Author: Jehan <jehan girinstud io>
Date:   Sun Jun 19 01:17:39 2022 +0200

    plug-ins: dynamically lower width/height with impossible values.
    
    Even though the scale entries have maximum values based on the file
    size, it's still too big for many formats (multi-byte ones) when
    thinking in terms of pixels.
    
    Moreover if growing the offset or any dimension, comes a point where the
    other dimension needs to shrink. So let's compute max pixels and update
    other values depending on this.
    
    Note that it's still quite easy to crash the dialog with big dimensions,
    triggering X Window System errors about unsufficient resources in
    GimpPreviewArea code. This will have to be handled accordingly.

 plug-ins/common/file-raw-data.c | 145 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
---
diff --git a/plug-ins/common/file-raw-data.c b/plug-ins/common/file-raw-data.c
index 6f374e06e5..046f11894a 100644
--- a/plug-ins/common/file-raw-data.c
+++ b/plug-ins/common/file-raw-data.c
@@ -210,6 +210,9 @@ static gboolean         save_image           (GFile                *file,
                                               GimpProcedureConfig  *config,
                                               GError              **error);
 
+static void            get_bpp               (GimpProcedureConfig     *config,
+                                              gint                    *bpp,
+                                              gint                    *bitspp);
 static gboolean        detect_sample_spacing (GimpProcedureConfig     *config,
                                               GFile                   *file,
                                               GError                 **error);
@@ -1193,6 +1196,79 @@ save_image (GFile                *file,
   return ret;
 }
 
+static void
+get_bpp (GimpProcedureConfig *config,
+         gint                *bpp,
+         gint                *bitspp)
+{
+  GimpProcedure *procedure;
+
+  procedure = gimp_procedure_config_get_procedure (config);
+
+  *bitspp = 8;
+  if (g_strcmp0 (gimp_procedure_get_name (procedure), LOAD_HGT_PROC) == 0)
+    {
+      *bpp = 2;
+    }
+  else
+    {
+      RawType image_type;
+
+      g_object_get (config,
+                    "color-representation", &image_type,
+                    NULL);
+      switch (image_type)
+        {
+        case RAW_RGB:
+        case RAW_PLANAR:
+          *bpp = 3;
+          break;
+
+        case RAW_RGB565_BE:
+        case RAW_RGB565_LE:
+        case RAW_BGR565_BE:
+        case RAW_BGR565_LE:
+          *bpp = 2;
+          break;
+
+        case RAW_RGBA:
+          *bpp = 4;
+          break;
+
+        case RAW_GRAY_1BPP:
+          *bpp    = 1;
+          *bitspp = 1;
+          break;
+        case RAW_GRAY_2BPP:
+          *bpp    = 1;
+          *bitspp = 2;
+          break;
+        case RAW_GRAY_4BPP:
+          *bpp    = 1;
+          *bitspp = 4;
+          break;
+        case RAW_GRAY_8BPP:
+          *bpp   = 1;
+          break;
+
+        case RAW_INDEXED:
+          *bpp   = 1;
+          break;
+
+        case RAW_INDEXEDA:
+          *bpp   = 2;
+          break;
+
+        case RAW_GRAY_16BPP_BE:
+        case RAW_GRAY_16BPP_LE:
+        case RAW_GRAY_16BPP_SBE:
+        case RAW_GRAY_16BPP_SLE:
+          *bpp   = 2;
+          break;
+        }
+    }
+}
+
 static gboolean
 detect_sample_spacing (GimpProcedureConfig  *config,
                        GFile                *file,
@@ -1854,10 +1930,77 @@ load_config_notify (GimpProcedureConfig  *config,
                     GimpPreviewArea      *preview)
 {
   gboolean preview_cmap_update = FALSE;
+  gboolean width_update        = FALSE;
+  gboolean height_update       = FALSE;
+  gboolean offset_update       = FALSE;
 
   if (g_str_has_prefix (pspec->name, "palette-"))
     preview_cmap_update = TRUE;
 
+  if ((width_update  = (g_strcmp0 (pspec->name, "width") == 0))  ||
+      (height_update = (g_strcmp0 (pspec->name, "height") == 0)) ||
+      (offset_update = (g_strcmp0 (pspec->name, "offset") == 0)))
+    {
+      GimpProcedure *procedure;
+      GFile         *file;
+      goffset        file_size;
+      gint           width;
+      gint           height;
+      gint           offset;
+      gint           bpp;
+      gint           bitspp;
+      goffset        max_pixels;
+
+      get_bpp (config, &bpp, &bitspp);
+      g_object_get (config,
+                    "width",  &width,
+                    "height", &height,
+                    "offset", &offset,
+                    NULL);
+
+      procedure = gimp_procedure_config_get_procedure (config);
+      file = g_object_get_data (G_OBJECT (preview), "procedure-file");
+      file_size = get_file_info (file);
+
+      max_pixels = (file_size - offset) / (bpp * bitspp / 8);
+      if ((goffset) width * height > max_pixels)
+        {
+          g_signal_handlers_block_by_func (config,
+                                           G_CALLBACK (load_config_notify),
+                                           preview);
+          if (width_update && width >= max_pixels)
+            {
+              g_object_set (config,
+                            "width",  (gint) max_pixels,
+                            "height", 1,
+                            NULL);
+            }
+          else if (height_update && height >= max_pixels)
+            {
+              g_object_set (config,
+                            "width",  1,
+                            "height", (gint) max_pixels,
+                            NULL);
+            }
+          else if (width_update || offset_update)
+            {
+              height = MAX (max_pixels / width, 1);
+              g_object_set (config,
+                            "height", height,
+                            NULL);
+            }
+          else /* height_update */
+            {
+              width = MAX (max_pixels / height, 1);
+              g_object_set (config,
+                            "width", width,
+                            NULL);
+            }
+          g_signal_handlers_unblock_by_func (config,
+                                             G_CALLBACK (load_config_notify),
+                                             preview);
+        }
+    }
   preview_update (preview, preview_cmap_update);
 }
 
@@ -1929,6 +2072,8 @@ load_dialog (GFile         *file,
 
   g_object_set_data (G_OBJECT (preview), "procedure-config",
                      config);
+  g_object_set_data (G_OBJECT (preview), "procedure-file",
+                     file);
 
   g_signal_connect_after (preview, "size-allocate",
                           G_CALLBACK (preview_allocate),