[gimp] app: add utility function gimp_transform_polygon_is_convex()
- From: Michael Natterer <mitch src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gimp] app: add utility function gimp_transform_polygon_is_convex()
- Date: Sun, 27 Mar 2011 20:05:15 +0000 (UTC)
commit eb4f01039a4a9a746ccc39ca599418c90ff2a497
Author: Michael Natterer <mitch gimp org>
Date: Sun Mar 27 22:04:33 2011 +0200
app: add utility function gimp_transform_polygon_is_convex()
and use it in GimpTransformTool and GimpCanvasTransformPreview.
app/core/gimp-transform-utils.c | 27 ++++++
app/core/gimp-transform-utils.h | 139 ++++++++++++++++--------------
app/display/gimpcanvastransformpreview.c | 16 +---
app/tools/gimptransformtool.c | 21 +----
4 files changed, 111 insertions(+), 92 deletions(-)
---
diff --git a/app/core/gimp-transform-utils.c b/app/core/gimp-transform-utils.c
index 89896f1..482cb6b 100644
--- a/app/core/gimp-transform-utils.c
+++ b/app/core/gimp-transform-utils.c
@@ -327,3 +327,30 @@ gimp_transform_matrix_perspective (GimpMatrix3 *matrix,
gimp_matrix3_mult (&trafo, matrix);
}
+
+gboolean
+gimp_transform_polygon_is_convex (gdouble x1,
+ gdouble y1,
+ gdouble x2,
+ gdouble y2,
+ gdouble x3,
+ gdouble y3,
+ gdouble x4,
+ gdouble y4)
+{
+ gdouble z1, z2, z3, z4;
+
+ /* We test if the transformed polygon is convex. if z1 and z2 have
+ * the same sign as well as z3 and z4 the polygon is convex.
+ */
+ z1 = ((x2 - x1) * (y4 - y1) -
+ (x4 - x1) * (y2 - y1));
+ z2 = ((x4 - x1) * (y3 - y1) -
+ (x3 - x1) * (y4 - y1));
+ z3 = ((x4 - x2) * (y3 - y2) -
+ (x3 - x2) * (y4 - y2));
+ z4 = ((x3 - x2) * (y1 - y2) -
+ (x1 - x2) * (y3 - y2));
+
+ return (z1 * z2 > 0) && (z3 * z4 > 0);
+}
diff --git a/app/core/gimp-transform-utils.h b/app/core/gimp-transform-utils.h
index 532c525..098a490 100644
--- a/app/core/gimp-transform-utils.h
+++ b/app/core/gimp-transform-utils.h
@@ -19,72 +19,81 @@
#define __GIMP_TRANSFORM_UTILS_H__
-void gimp_transform_get_rotate_center (gint x,
- gint y,
- gint width,
- gint height,
- gboolean auto_center,
- gdouble *center_x,
- gdouble *center_y);
-void gimp_transform_get_flip_axis (gint x,
- gint y,
- gint width,
- gint height,
- GimpOrientationType flip_type,
- gboolean auto_center,
- gdouble *axis);
+void gimp_transform_get_rotate_center (gint x,
+ gint y,
+ gint width,
+ gint height,
+ gboolean auto_center,
+ gdouble *center_x,
+ gdouble *center_y);
+void gimp_transform_get_flip_axis (gint x,
+ gint y,
+ gint width,
+ gint height,
+ GimpOrientationType flip_type,
+ gboolean auto_center,
+ gdouble *axis);
-void gimp_transform_matrix_flip (GimpMatrix3 *matrix,
- GimpOrientationType flip_type,
- gdouble axis);
-void gimp_transform_matrix_flip_free (GimpMatrix3 *matrix,
- gdouble x1,
- gdouble y1,
- gdouble x2,
- gdouble y2);
-void gimp_transform_matrix_rotate (GimpMatrix3 *matrix,
- GimpRotationType rotate_type,
- gdouble center_x,
- gdouble center_y);
-void gimp_transform_matrix_rotate_rect (GimpMatrix3 *matrix,
- gint x,
- gint y,
- gint width,
- gint height,
- gdouble angle);
-void gimp_transform_matrix_rotate_center (GimpMatrix3 *matrix,
- gdouble center_x,
- gdouble center_y,
- gdouble angle);
-void gimp_transform_matrix_scale (GimpMatrix3 *matrix,
- gint x,
- gint y,
- gint width,
- gint height,
- gdouble t_x,
- gdouble t_y,
- gdouble t_width,
- gdouble t_height);
-void gimp_transform_matrix_shear (GimpMatrix3 *matrix,
- gint x,
- gint y,
- gint width,
- gint height,
- GimpOrientationType orientation,
- gdouble amount);
-void gimp_transform_matrix_perspective (GimpMatrix3 *matrix,
- gint x,
- gint y,
- gint width,
- gint height,
- gdouble t_x1,
- gdouble t_y1,
- gdouble t_x2,
- gdouble t_y2,
- gdouble t_x3,
- gdouble t_y3,
- gdouble t_x4,
- gdouble t_y4);
+void gimp_transform_matrix_flip (GimpMatrix3 *matrix,
+ GimpOrientationType flip_type,
+ gdouble axis);
+void gimp_transform_matrix_flip_free (GimpMatrix3 *matrix,
+ gdouble x1,
+ gdouble y1,
+ gdouble x2,
+ gdouble y2);
+void gimp_transform_matrix_rotate (GimpMatrix3 *matrix,
+ GimpRotationType rotate_type,
+ gdouble center_x,
+ gdouble center_y);
+void gimp_transform_matrix_rotate_rect (GimpMatrix3 *matrix,
+ gint x,
+ gint y,
+ gint width,
+ gint height,
+ gdouble angle);
+void gimp_transform_matrix_rotate_center (GimpMatrix3 *matrix,
+ gdouble center_x,
+ gdouble center_y,
+ gdouble angle);
+void gimp_transform_matrix_scale (GimpMatrix3 *matrix,
+ gint x,
+ gint y,
+ gint width,
+ gint height,
+ gdouble t_x,
+ gdouble t_y,
+ gdouble t_width,
+ gdouble t_height);
+void gimp_transform_matrix_shear (GimpMatrix3 *matrix,
+ gint x,
+ gint y,
+ gint width,
+ gint height,
+ GimpOrientationType orientation,
+ gdouble amount);
+void gimp_transform_matrix_perspective (GimpMatrix3 *matrix,
+ gint x,
+ gint y,
+ gint width,
+ gint height,
+ gdouble t_x1,
+ gdouble t_y1,
+ gdouble t_x2,
+ gdouble t_y2,
+ gdouble t_x3,
+ gdouble t_y3,
+ gdouble t_x4,
+ gdouble t_y4);
+
+gboolean gimp_transform_polygon_is_convex (gdouble x1,
+ gdouble y1,
+ gdouble x2,
+ gdouble y2,
+ gdouble x3,
+ gdouble y3,
+ gdouble x4,
+ gdouble y4);
#endif /* __GIMP_TRANSFORM_UTILS_H__ */
diff --git a/app/display/gimpcanvastransformpreview.c b/app/display/gimpcanvastransformpreview.c
index 2a9d9d5..e5e9428 100644
--- a/app/display/gimpcanvastransformpreview.c
+++ b/app/display/gimpcanvastransformpreview.c
@@ -33,6 +33,7 @@
#include "core/gimpchannel.h"
#include "core/gimpimage.h"
+#include "core/gimp-transform-utils.h"
#include "gimpcanvas.h"
#include "gimpcanvastransformpreview.h"
@@ -354,7 +355,6 @@ gimp_canvas_transform_preview_transform (GimpCanvasItem *item,
gdouble tx2, ty2;
gdouble tx3, ty3;
gdouble tx4, ty4;
- gdouble z1, z2, z3, z4;
gimp_matrix3_transform_point (&private->transform,
private->x1, private->y1,
@@ -369,16 +369,10 @@ gimp_canvas_transform_preview_transform (GimpCanvasItem *item,
private->x2, private->y2,
&tx4, &ty4);
- z1 = ((tx2 - tx1) * (ty4 - ty1) -
- (tx4 - tx1) * (ty2 - ty1));
- z2 = ((tx4 - tx1) * (ty3 - ty1) -
- (tx3 - tx1) * (ty4 - ty1));
- z3 = ((tx4 - tx2) * (ty3 - ty2) -
- (tx3 - tx2) * (ty4 - ty2));
- z4 = ((tx3 - tx2) * (ty1 - ty2) -
- (tx1 - tx2) * (ty3 - ty2));
-
- if (! ((z1 * z2 > 0) && (z3 * z4 > 0)))
+ if (! gimp_transform_polygon_is_convex (tx1, ty1,
+ tx2, ty2,
+ tx3, ty3,
+ tx4, ty4))
return FALSE;
if (extents)
diff --git a/app/tools/gimptransformtool.c b/app/tools/gimptransformtool.c
index ee7c393..a64202c 100644
--- a/app/tools/gimptransformtool.c
+++ b/app/tools/gimptransformtool.c
@@ -44,6 +44,7 @@
#include "core/gimplayer.h"
#include "core/gimpprogress.h"
#include "core/gimptoolinfo.h"
+#include "core/gimp-transform-utils.h"
#include "vectors/gimpvectors.h"
#include "vectors/gimpstroke.h"
@@ -754,7 +755,6 @@ gimp_transform_tool_draw (GimpDrawTool *draw_tool)
if (tr_tool->use_grid)
{
GimpCanvasGroup *stroke_group;
- gdouble z1, z2, z3, z4;
if (gimp_transform_options_show_preview (options))
{
@@ -777,23 +777,12 @@ gimp_transform_tool_draw (GimpDrawTool *draw_tool)
gimp_draw_tool_push_group (draw_tool, stroke_group);
- /* We test if the transformed polygon is convex.
- * if z1 and z2 have the same sign as well as z3 and z4
- * the polygon is convex.
- */
- z1 = ((tr_tool->tx2 - tr_tool->tx1) * (tr_tool->ty4 - tr_tool->ty1) -
- (tr_tool->tx4 - tr_tool->tx1) * (tr_tool->ty2 - tr_tool->ty1));
- z2 = ((tr_tool->tx4 - tr_tool->tx1) * (tr_tool->ty3 - tr_tool->ty1) -
- (tr_tool->tx3 - tr_tool->tx1) * (tr_tool->ty4 - tr_tool->ty1));
- z3 = ((tr_tool->tx4 - tr_tool->tx2) * (tr_tool->ty3 - tr_tool->ty2) -
- (tr_tool->tx3 - tr_tool->tx2) * (tr_tool->ty4 - tr_tool->ty2));
- z4 = ((tr_tool->tx3 - tr_tool->tx2) * (tr_tool->ty1 - tr_tool->ty2) -
- (tr_tool->tx1 - tr_tool->tx2) * (tr_tool->ty3 - tr_tool->ty2));
-
/* draw the grid */
if (tr_tool->grid_coords &&
- z1 * z2 > 0 &&
- z3 * z4 > 0)
+ gimp_transform_polygon_is_convex (tr_tool->tx1, tr_tool->ty1,
+ tr_tool->tx2, tr_tool->ty2,
+ tr_tool->tx3, tr_tool->ty3,
+ tr_tool->tx4, tr_tool->ty4))
{
gint k = tr_tool->ngx + tr_tool->ngy;
gint i, gci;
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