Fix some problems with 3-way buffer blitting

Author: GrieferAtWork

kos/include/libvideo/gfx/blend.h

@@ -141,15 +141,19 @@ __DECL_END
 
 /* Same as `GFX_BLENDMODE_ALPHA', but with an additional constant factor "ca"
  * that gets multiplied in in every calculation (useful for defining "global"
- * alpha values) */
+ * alpha values)
+ *
+ * NOTE: "ca" is the SOURCE-alpha factor (iow: 0xff means "GFX_BLENDMODE_ALPHA") */
 #define GFX_BLENDMODE_ALPHA_FACTOR(ca)                                                                  \
 	GFX_BLENDMODE_EX(/*RGB=*/SRC_ALPHA_MUL_CONSTANT_ALPHA, ADD, ONE_MINUS_SRC_ALPHA_MUL_CONSTANT_ALPHA, \
 	                 /*A  =*/ONE, ADD, ONE_MINUS_SRC_ALPHA_MUL_CONSTANT_ALPHA,                          \
 	                 0, 0, 0, ca)
 
 /* Same as `GFX_BLENDMODE_ALPHA', but use "ca" instead of source alpha values
  * In  this sense, this is the same as "GFX_BLENDMODE_ALPHA_FACTOR()", but is
- * faster when the source colors always use `VIDEO_CHANNEL_MAX' for alpha. */
+ * faster when the source colors always use `VIDEO_CHANNEL_MAX' for alpha.
+ *
+ * NOTE: "ca" is the SOURCE-alpha factor (iow: 0xff means "GFX_BLENDMODE_OVERRIDE") */
 #define GFX_BLENDMODE_ALPHA_OVERRIDE(ca)                                    \
 	GFX_BLENDMODE_EX(/*RGB=*/CONSTANT_ALPHA, ADD, ONE_MINUS_CONSTANT_ALPHA, \
 	                 /*A  =*/ONE, ADD, ONE_MINUS_CONSTANT_ALPHA,            \

kos/src/apps/showpic/main.c

@@ -345,8 +345,8 @@ do_showpic(struct screen_buffer *screen,
 #elif 1
 	{
 		struct video_gfx flipgfx = image_gfx;
-		video_gfx_hmirror(&flipgfx);
-		video_gfx_setblend(&flipgfx, GFX_BLENDMODE_ALPHA_OVERRIDE(240));
+		video_gfx_lrot90(&flipgfx);
+		video_gfx_setblend(&flipgfx, GFX_BLENDMODE_ALPHA_OVERRIDE(200));
 		video_gfx_stretch3(&screen_gfx, blit_x, blit_y,
 		                   &flipgfx, 0, 0,
 		                   blit_w, blit_h,

kos/src/libvideo/gfx/gfx-debug.h

@@ -33,6 +33,11 @@
 
 DECL_BEGIN
 
+#undef GFX_DEBUG
+#if !defined(NDEBUG) && 0
+#define GFX_DEBUG
+#endif
+
 #ifndef PRIdOFF
 #include <inttypes.h>
 #define PRIdOFF __PRIN_PREFIX(__SIZEOF_VIDEO_OFFSET_T__) "d"
@@ -44,11 +49,6 @@ DECL_BEGIN
 #define PRIxCOL __PRIN_PREFIX(__SIZEOF_VIDEO_COLOR_T__) "x"
 #endif /* !PRIdOFF */
 
-#undef GFX_DEBUG
-#if !defined(NDEBUG) && 0
-#define GFX_DEBUG
-#endif
-
 #ifdef GFX_DEBUG
 #include <sys/syslog.h>
 #define TRACE_START(...) syslog(LOG_DEBUG, "[gfx] start: " __VA_ARGS__)

kos/src/libvideo/gfx/swgfx/hl_blit-nowrap.c.inl

@@ -532,7 +532,7 @@ LOCAL_libvideo_swblitter_blit(LOCAL_struct_video_blitter const *__restrict self
 	}
 #undef LOCAL_dst_vx_flags
 
-	/* Calculate rddst->wrdst transformation matrix */
+	/* Calculate dst->out transformation matrix */
 #ifdef LOCAL_USE_SWBLITTER3
 	dst_matrix = VIDEO_IMATRIX2D_INIT(1, 0, 0, 1);
 	if ((dst->vx_flags ^ out->vx_flags) & VIDEO_GFX_F_XMIRROR) {
@@ -543,7 +543,14 @@ LOCAL_libvideo_swblitter_blit(LOCAL_struct_video_blitter const *__restrict self
 		video_imatrix2d_set(&dst_matrix, 1, 1, -1);
 		dst_y += LOCAL_dst_size_y - 1;
 	}
-	if ((dst->vx_flags ^ out->vx_flags) & VIDEO_GFX_F_XYSWAP) {
+
+	/* Apply X/Y-swap rules and finalize dst_x/dst_y coords */
+	if (dst->vx_flags & VIDEO_GFX_F_XYSWAP) {
+		video_imatrix2d_swap(&dst_matrix, 0, 0, /**/ 1, 0);
+		video_imatrix2d_swap(&dst_matrix, 1, 1, /**/ 0, 1);
+		Tswap(video_offset_t, dst_x, dst_y);
+	}
+	if (out->vx_flags & VIDEO_GFX_F_XYSWAP) {
 		video_imatrix2d_swap(&dst_matrix, 0, 0, /**/ 0, 1);
 		video_imatrix2d_swap(&dst_matrix, 1, 1, /**/ 1, 0);
 		Tswap(video_offset_t, dst_x, dst_y);