finish revising draw_line

TODO

@@ -1,21 +1,9 @@
-- redo draw_line following the draw_circle model: have a simple
-  "iterator"-style line draw which calls a function per pixel
-
-  include a _direct version
-
-  get rid of draw_line_user and draw_line_mask
+- hough_circle can use circle thing to incremet in circles
 
 - test draw_mask on labq images
 
   we probably need to unpack the ink back to double before blending
 
-- vips_draw_image() might need a direct mode? see vips_flood_direct()
-
-- need call operation along a circle, see line draw
-
-- use with vips_draw_add() to make a mask image for each radius for
-  vips_hough_circle()
-
 
 
 - think of a better way to support skipahead

libvips/deprecated/vips7compat.c

@@ -4566,13 +4566,37 @@ im_draw_line( VipsImage *image, int x1, int y1, int x2, int y2, VipsPel *ink )
 	return( vips_draw_line( image, vec, n, x1, y1, x2, y2, NULL ) ); 
 }
 
+typedef struct _Line {
+	VipsPlotFn plot;
+	void *a;
+	void *b;
+	void *c;
+} Line;
+
+static void
+draw_line_wrapper( VipsImage *image, int x, int y, void *client )
+{
+	Line *line = (Line *) client;
+
+	line->plot( image, x, y, line->a, line->b, line->c ); 
+}
+
 int 
 im_draw_line_user( VipsImage *image, 
 	int x1, int y1, int x2, int y2, 
 	VipsPlotFn plot, void *a, void *b, void *c )
 {
-	return( vips_draw_line_user( image, x1, y1, x2, y2, 
-		plot, a, b, c, NULL ) ); 
+	Line line;
+
+	line.plot = plot;
+	line.a = a;
+	line.b = b;
+	line.c = c;
+
+	vips__draw_line_direct( image, x1, y1, x2, y2, 
+		draw_line_wrapper, &line ); 
+	
+	return( 0 );
 }
 
 int

libvips/draw/draw_circle.c

@@ -56,6 +56,7 @@
 #include <string.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
 
 #include "drawink.h"
 
@@ -67,8 +68,6 @@ typedef struct _VipsDrawCircle {
 	int radius;
 	gboolean fill;
 
-	VipsDrawPoint draw_point;
-	VipsDrawScanline draw_scanline;
 } VipsDrawCircle;
 
 typedef struct _VipsDrawCircleClass {

libvips/draw/draw_line.c

@@ -60,6 +60,9 @@
 #include <stdlib.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
+
+#include "drawink.h"
 
 typedef struct _VipsDrawLine {
 	VipsDrawink parent_object;
@@ -237,6 +240,7 @@ static int
 vips_draw_line_build( VipsObject *object )
 {
 	VipsDraw *draw = VIPS_DRAW( object );
+	VipsDrawink *drawink = VIPS_DRAWINK( object );
 	VipsDrawLine *line = (VipsDrawLine *) object;
 
 	VipsDrawPoint draw_point;