Fix T42008: Dragging and packing issue about new blank image

The issue was caused by the fact that we never used to store the
generated image color in DNA, so image reload will loose this
information.

Now we store the color in DNA, making ti so re-loading the image
will preserve it's generated color.

It is now also possible to change generated image color using the
color swatch in image properties after the image was created.

source/blender/blenkernel/intern/image.c

@@ -62,6 +62,7 @@
 #include "DNA_meshdata_types.h"
 
 #include "BLI_blenlib.h"
+#include "BLI_math_vector.h"
 #include "BLI_threads.h"
 #include "BLI_timecode.h"  /* for stamp timecode format */
 #include "BLI_utildefines.h"
@@ -365,6 +366,7 @@ Image *BKE_image_copy(Main *bmain, Image *ima)
 	nima->gen_x = ima->gen_x;
 	nima->gen_y = ima->gen_y;
 	nima->gen_type = ima->gen_type;
+	copy_v4_v4(nima->gen_color, ima->gen_color);
 
 	nima->animspeed = ima->animspeed;
 
@@ -769,6 +771,7 @@ Image *BKE_image_add_generated(Main *bmain, unsigned int width, unsigned int hei
 		ima->gen_type = gen_type;
 		ima->gen_flag |= (floatbuf ? IMA_GEN_FLOAT : 0);
 		ima->gen_depth = depth;
+		copy_v4_v4(ima->gen_color, color);
 
 		ibuf = add_ibuf_size(width, height, ima->name, depth, floatbuf, gen_type, color, &ima->colorspace_settings);
 		image_assign_ibuf(ima, ibuf, IMA_NO_INDEX, 0);
@@ -2996,7 +2999,6 @@ BLI_INLINE bool image_quick_test(Image *ima, ImageUser *iuser)
 static ImBuf *image_acquire_ibuf(Image *ima, ImageUser *iuser, void **lock_r)
 {
 	ImBuf *ibuf = NULL;
-	float color[] = {0, 0, 0, 1};
 	int frame = 0, index = 0;
 
 	if (lock_r)
@@ -3041,7 +3043,7 @@ static ImBuf *image_acquire_ibuf(Image *ima, ImageUser *iuser, void **lock_r)
 			if (ima->gen_y == 0) ima->gen_y = 1024;
 			if (ima->gen_depth == 0) ima->gen_depth = 24;
 			ibuf = add_ibuf_size(ima->gen_x, ima->gen_y, ima->name, ima->gen_depth, (ima->gen_flag & IMA_GEN_FLOAT) != 0, ima->gen_type,
-			                     color, &ima->colorspace_settings);
+			                     ima->gen_color, &ima->colorspace_settings);
 			image_assign_ibuf(ima, ibuf, IMA_NO_INDEX, 0);
 			ima->ok = IMA_OK_LOADED;
 		}

source/blender/blenloader/intern/versioning_270.c

@@ -390,4 +390,11 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *main)
 			}
 		}
 	}
+
+	if (!DNA_struct_elem_find(fd->filesdna, "Image", "float", "gen_color")) {
+		Image *image;
+		for (image = main->image.first; image != NULL; image = image->id.next) {
+			image->gen_color[3] - 1.0f;
+		}
+	}
 }

source/blender/editors/space_image/image_buttons.c

@@ -809,6 +809,10 @@ void uiTemplateImage(uiLayout *layout, bContext *C, PointerRNA *ptr, const char
 				uiItemR(col, &imaptr, "use_generated_float", 0, NULL, ICON_NONE);
 
 				uiItemR(split, &imaptr, "generated_type", UI_ITEM_R_EXPAND, NULL, ICON_NONE);
+
+				if (ima->gen_type == IMA_GENTYPE_BLANK) {
+					uiItemR(layout, &imaptr, "generated_color", 0, NULL, ICON_NONE);
+				}
 			}
 
 		}

source/blender/makesdna/DNA_image_types.h

@@ -109,6 +109,7 @@ typedef struct Image {
 	int gen_x, gen_y;
 	char gen_type, gen_flag;
 	short gen_depth;
+	float gen_color[4];
 	
 	/* display aspect - for UV editing images resized for faster openGL display */
 	float aspx, aspy;

source/blender/makesrna/intern/rna_image.c

@@ -589,6 +589,13 @@ static void rna_def_image(BlenderRNA *brna)
 	RNA_def_property_update(prop, NC_IMAGE | ND_DISPLAY, "rna_Image_generated_update");
 	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
 
+	prop = RNA_def_property(srna, "generated_color", PROP_FLOAT, PROP_COLOR);
+	RNA_def_property_float_sdna(prop, NULL, "gen_color");
+	RNA_def_property_array(prop, 4);
+	RNA_def_property_ui_text(prop, "Color", "Fill color for the generated image");
+	RNA_def_property_update(prop, NC_IMAGE | ND_DISPLAY, "rna_Image_generated_update");
+	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+
 	/* realtime properties */
 	prop = RNA_def_property(srna, "mapping", PROP_ENUM, PROP_NONE);
 	RNA_def_property_enum_bitflag_sdna(prop, NULL, "flag");