support tiles extending outside of the canvas (crop to intersection), only update...

diff --git a/io-xcf.c b/io-xcf.c
index b4cebb0..c8b3fa8 100644 (file)
--- a/io-xcf.c
+++ b/io-xcf.c
@@ -202,6 +202,33 @@ apply_opacity (guchar* ptr, int size, guint32 opacity)
                ptr[4*i + 3] = (guchar)((ptr[4*i+3] * opacity) / 0xff);
 }
 
+void
+intersect_tile (guchar* ptr, int im_width, int im_height, int *ox, int *oy, int *tw, int *th)
+{
+       int i;
+       if (*ox < 0) {
+               for (i=0; i<*th; i++) {
+                       memmove (ptr + 4 * i * (*tw + *ox), ptr + 4 * i * (*tw), 4 * (*tw + *ox));
+               }
+               *tw = *tw + *ox;
+               *ox = 0;
+       }
+       if (*oy < 0) {
+               memmove (ptr, ptr + 4 * *tw * -*oy, 4 * *tw * (*th + *oy));
+               *th = *th + *oy;
+               *oy = 0;
+       }
+       if (*ox + *tw > im_width) {
+               for (i=0; i<*th; i++) {
+                       memmove (ptr + 4 * i * (im_width - *ox), ptr + 4 * i * (*tw), 4 * (im_width - *ox));
+               }
+               *tw = im_width - *ox;
+       }
+       if (*oy + *th > im_height) {
+               *th = im_height - *oy;
+       }
+}
+
 static GdkPixbuf*
 xcf_image_load_real (FILE *f, XcfContext *context, GError **error)
 {
@@ -493,10 +520,12 @@ xcf_image_load_real (FILE *f, XcfContext *context, GError **error)
                        int oy = 64 * (tile_id / line_width);
                        int tw = MIN (64, layer->width - ox);
                        int th = MIN (64, layer->height - oy);
+                       ox += layer->dx;
+                       oy += layer->dy;
                        LOG("\tTile %d %d (%d %d) (%d %d)\n", tile_id, tptr, ox, oy, tw, th);
 
                        //if the tile doesn't intersect with the canvas, ignore
-                       if (ox + layer->dx + tw < 0 || oy + layer->dy + th < 0 || ox + layer->dx > (int)width || oy + layer->dy > (int)height ) {
+                       if (ox + tw < 0 || oy + th < 0 || ox > (int)width || oy > (int)height ) {
                                fseek (f, lpos, SEEK_SET);
                                tile_id++;
                                continue;
@@ -505,6 +534,7 @@ xcf_image_load_real (FILE *f, XcfContext *context, GError **error)
                        rle_decode (f, pixels, tw*th, layer->type);
 
                        //reduce the tile to its intersection with the canvas
+                       intersect_tile (pixels, width, height, &ox, &oy, &tw, &th);
                        
                        //apply layer opacity
                        apply_opacity (pixels, tw*th, layer->opacity);
@@ -514,16 +544,15 @@ xcf_image_load_real (FILE *f, XcfContext *context, GError **error)
 
                        //composite
 
-                       int origin = 4 * (ox + layer->dx) + rowstride * (oy + layer->dy) ;
+                       int origin = 4 * ox + rowstride * oy ;
 
                        int j;
                        for (j=0; j<th;j++) {
                                memcpy (pixs + origin + j * rowstride, pixels + j*tw*4 , tw*4);
                        }
                        
-                       //FIXME: only update the tile region
                        if (context && context->update_func)
-                               (* context->update_func) (pixbuf, 0, 0, width, height, context->user_data);
+                               (* context->update_func) (pixbuf, ox, oy, tw, th, context->user_data);
 
 
                        fseek (f, lpos, SEEK_SET);