# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1542128061 -3600
# Node ID ddb4b7db1d9bb48f32927007d836b30343647b7d
# Parent  ea0474d3418207040aebf08f5ccea9310ac140d9
Separated sprite position and key details from the plotting operation.

diff -r ea0474d34182 -r ddb4b7db1d9b examples/vga/main.c
--- a/examples/vga/main.c	Tue Nov 13 15:17:37 2018 +0100
+++ b/examples/vga/main.c	Tue Nov 13 17:54:21 2018 +0100
@@ -94,7 +94,7 @@
 extern image_t screendata;
 extern image_t sprite;
 
-static SpriteOverwriting(scr, &screendata, &display_config, FRAME_COUNT, SOURCE_YSTEP);
+static SpriteOverwriting(scr, &screendata, &display_config, FRAME_COUNT, -1, SOURCE_YSTEP);
 
 extern uint8_t fontchars[];
 extern font_range_t fontbase;
@@ -118,7 +118,7 @@
 {
     /* Stores of background details, replotted when moving the sprite. */
 
-    Sprite(s, &sprite, &display_config, FRAME_COUNT, SOURCE_YSTEP);
+    Sprite(s, &sprite, &display_config, FRAME_COUNT, 0x0c, SOURCE_YSTEP);
 
     /* Sprite position. */
 
@@ -149,7 +149,8 @@
         {
             for (x = 0; x < display_config.line_length - s.image->width; x++)
             {
-                image_plot_sprite(&s, x, y, 0x0c);
+                image_set_sprite_position(&s, x, y);
+                image_plot_sprite(&s);
 
                 /* Update the display with the frame details. */
 
diff -r ea0474d34182 -r ddb4b7db1d9b include/image.h
--- a/include/image.h	Tue Nov 13 15:17:37 2018 +0100
+++ b/include/image.h	Tue Nov 13 17:54:21 2018 +0100
@@ -81,6 +81,10 @@
 
     position_t *pos;
 
+    /* Colour key for transparency. */
+
+    int key;
+
     /* The vertical scaling factor translating display rows to image
        coordinates. */
 
@@ -102,9 +106,9 @@
 #define Stored_Regions(NAME, FRAMES, SIZE)          \
     uint8_t __##NAME##_image[(FRAMES) * (SIZE)];    \
     stored_regions_t NAME = {                       \
-        .image=__##NAME##_image,                    \
-        .size=SIZE,                                 \
-        .stored=0};
+        .image = __##NAME##_image,                  \
+        .size = SIZE,                               \
+        .stored = 0};
 
 /* Access functions. */
 
@@ -117,44 +121,56 @@
 /* Initialise a sprite object using an existing image without the capability of
    storing regions of the screen.
 
-   SpriteOverwriting(<name>, image_t *image, display_config_t *cfg, int frames, int yscale)
+   SpriteOverwriting(<name>, image_t *image, display_config_t *cfg, int frames,
+                     int key, int yscale)
 */
 
-#define SpriteOverwriting(NAME, IMAGE, CFG, FRAMES, YSCALE)         \
+#define SpriteOverwriting(NAME, IMAGE, CFG, FRAMES, KEY, YSCALE)    \
     position_t __##NAME##_pos[FRAMES];                              \
+                                                                    \
     sprite_t NAME = {                                               \
-        .image=IMAGE,                                               \
-        .regions=0,                                                 \
-        .yscale=YSCALE,                                             \
-        .cfg=CFG,                                                   \
-        .pos=__##NAME##_pos};
+        .image = IMAGE,                                             \
+        .regions = 0,                                               \
+        .key = KEY,                                                 \
+        .yscale = YSCALE,                                           \
+        .cfg = CFG,                                                 \
+        .pos = __##NAME##_pos};
 
 /* Initialise a sprite object using an existing image, creating stored regions
    for the animation of the sprite.
 
-   Sprite(<name>, image_t *image, display_config_t *cfg, int frames, int yscale)
+   Sprite(<name>, image_t *image, display_config_t *cfg, int frames, int key,
+          int yscale)
 */
 
-#define Sprite(NAME, IMAGE, CFG, FRAMES, YSCALE)                    \
+#define Sprite(NAME, IMAGE, CFG, FRAMES, KEY, YSCALE)               \
     Stored_Regions(__##NAME##_regions, FRAMES,                      \
                    (IMAGE)->width * (IMAGE)->height * (YSCALE));    \
     position_t __##NAME##_pos[FRAMES];                              \
+                                                                    \
     sprite_t NAME = {                                               \
-        .image=IMAGE,                                               \
-        .regions=&(__##NAME##_regions),                             \
-        .yscale=YSCALE,                                             \
-        .cfg=CFG,                                                   \
-        .pos=__##NAME##_pos};
+        .image = IMAGE,                                             \
+        .regions = &(__##NAME##_regions),                           \
+        .key = KEY,                                                 \
+        .yscale = YSCALE,                                           \
+        .cfg = CFG,                                                 \
+        .pos = __##NAME##_pos};
 
 /* Sprite plotting operations. */
 
-void image_plot_sprite(sprite_t *s, int x, int y, int key);
+void image_plot_sprite(sprite_t *s);
 
 void image_unplot_sprite(sprite_t *s);
 
 void image_unplot_sprite_from_image(sprite_t *s, sprite_t *bg,
                                     int xorigin, int yorigin);
 
+/* Update operations. */
+
+position_t *image_get_sprite_position(sprite_t *s);
+
+void image_set_sprite_position(sprite_t *s, int x, int y);
+
 /* Convenience operations. */
 
 void image_plot_sprite_section(sprite_t *s,
diff -r ea0474d34182 -r ddb4b7db1d9b lib/image.c
--- a/lib/image.c	Tue Nov 13 15:17:37 2018 +0100
+++ b/lib/image.c	Tue Nov 13 17:54:21 2018 +0100
@@ -39,9 +39,28 @@
 
 
 
+/* Get a sprite's position. */
+
+position_t *image_get_sprite_position(sprite_t *s)
+{
+    return image_get_stored_position(s, s->cfg->frame);
+}
+
+/* Set a sprite's position. */
+
+void image_set_sprite_position(sprite_t *s, int x, int y)
+{
+    position_t *p = image_get_sprite_position(s);
+
+    p->x = x;
+    p->y = y;
+}
+
+
+
 /* Copy a region from the screen to the store, then blit the image. */
 
-void image_plot_sprite(sprite_t *s, int x, int y, int key)
+void image_plot_sprite(sprite_t *s)
 {
     int frame = 0;
     position_t *p = 0;
@@ -55,22 +74,19 @@
 
         display_copy(s->cfg, image_get_stored_region(s->regions, frame),
                      s->image->width, s->image->height / s->yscale, 1,
-                     x, y, -1, 0);
+                     p->x, p->y, -1, 0);
     }
 
     /* Plot to the screen. */
 
     display_copy(s->cfg, s->image->image,
                  s->image->width, s->image->height, s->yscale,
-                 x, y, key, 1);
+                 p->x, p->y, s->key, 1);
 
     if (s->regions)
     {
         /* Record the stored background details. */
 
-        p->x = x;
-        p->y = y;
-
         if (frame >= s->regions->stored)
             s->regions->stored = frame + 1;
     }