add rectf_intersect

docs/changes.md

@@ -1,5 +1,8 @@
 # 最新动态
 
+2025/04/08
+  * 增加 rectf_intersect (感谢智明提供补丁)
+
 2025/04/07
   * 给window增加accept_button和cancel_button的属性(感谢智明提供补丁)
   * 增加文档 how_to_set_form_enter_and_esc.md(感谢智明提供补丁)

src/base/vgcanvas.h

@@ -791,7 +791,19 @@ ret_t vgcanvas_clip_path(vgcanvas_t* vg);
 /**
  * @method vgcanvas_clip_rect
  * 矩形裁剪。
- *
+ * 备注：
+ * 1. 在绘图的时候脏矩形和裁剪区是一样的。
+ * 2. 该函数是不合并裁剪区的，所有可能出现裁剪区被扩大导致绘图在脏矩形以外的情况，导致残影的情况。
+ * 3. 如果旋转或者缩放了，请使用 vgcanvas_intersect_clip_rect 函数，不要使用该函数。
+ * ........
+ *   rect_t r;
+ *   rect_t r_save;
+ *   r = rectf_init(c->ox, c->oy, widget->w, widget->h); 
+ *   r_save = *vgcanvas_get_clip_rect(vg);
+ *   r = rectf_intersect(&r, &r_save);
+ *   vgcanvas_clip_rect(vg, (float_t)r.x, (float_t)r.y, (float_t)r.w, (float_t)r.h);
+ * ........
+ * 
  * @annotation ["scriptable"]
  * @param {vgcanvas_t*} vg vgcanvas对象。
  * @param {float_t} x x坐标。

src/tkc/rect.c

@@ -194,6 +194,37 @@ rect_t rect_intersect(const rect_t* r1, const rect_t* r2) {
   return r;
 }
 
+rectf_t rectf_intersect(const rectf_t* r1, const rectf_t* r2) {
+  float_t top = 0;
+  float_t left = 0;
+  float_t bottom = 0;
+  float_t right = 0;
+  float_t bottom1 = 0;
+  float_t right1 = 0;
+  float_t bottom2 = 0;
+  float_t right2 = 0;
+  rectf_t r = rectf_init(0.0f, 0.0f, 0.0f, 0.0f);
+
+  return_value_if_fail(r1 != NULL && r2 != NULL, r);
+
+  bottom1 = r1->y + r1->h - 1.0f;
+  bottom2 = r2->y + r2->h - 1.0f;
+  right1 = r1->x + r1->w - 1.0f;
+  right2 = r2->x + r2->w - 1.0f;
+
+  top = tk_max(r1->y, r2->y);
+  left = tk_max(r1->x, r2->x);
+  right = tk_min(right1, right2);
+  bottom = tk_min(bottom1, bottom2);
+
+  r.x = left;
+  r.y = top;
+  r.w = right >= left ? (right - left + 1) : 0.0f;
+  r.h = bottom >= top ? (bottom - top + 1) : 0.0f;
+
+  return r;
+}
+
 rect_t rect_fix(rect_t* r, wh_t max_w, wh_t max_h) {
   rectX_fix;
   return *r;

src/tkc/rect.h

@@ -297,6 +297,17 @@ rect_t rect_fix(rect_t* r, wh_t max_w, wh_t max_h);
  */
 rect_t rect_intersect(const rect_t* r1, const rect_t* r2);
 
+/**
+ * @method rectf_intersect
+ * 求两个rectf的交集。
+ *
+ * @param {const rectf_t*} r1 rect对象。
+ * @param {const rectf_t*} r2 rect对象。
+ *
+ * @return {rectf_t} 返回交集。
+ */
+rectf_t rectf_intersect(const rectf_t* r1, const rectf_t* r2);
+
 /**
  * @method rect_has_intersect
  * 判断两个rect的是否存在交集。

tests/rect_test.cc

@@ -450,6 +450,36 @@ TEST(Rect, intersect) {
   ASSERT_EQ(r.h, 4);
 }
 
+TEST(Rect, float_intersect) {
+  rectf_t r;
+  rectf_t r1;
+  rectf_t r2;
+
+  r1 = rectf_init(0.5f, 0.5f, 10.5f, 10.5f);
+  r2 = rectf_init(10.5f, 10.5f, 10.5f, 10.5f);
+  r = rectf_intersect(&r1, &r2);
+  ASSERT_EQ(r.x, 10.5f);
+  ASSERT_EQ(r.y, 10.5f);
+  ASSERT_EQ(r.w, 0.0f);
+  ASSERT_EQ(r.h, 0.0f);
+
+  r1 = rectf_init(0.5f, 0.5f, 11.5f, 11.5f);
+  r2 = rectf_init(10.5f, 10.5f, 10.5f, 10.5f);
+  r = rectf_intersect(&r1, &r2);
+  ASSERT_EQ(r.x, 10.5f);
+  ASSERT_EQ(r.y, 10.5f);
+  ASSERT_EQ(r.w, 1.5f);
+  ASSERT_EQ(r.h, 1.5f);
+
+  r1 = rectf_init(0.5f, 0.5f, 14.5f, 14.5f);
+  r2 = rectf_init(10.5f, 10.5f, 10.5f, 10.5f);
+  r = rectf_intersect(&r1, &r2);
+  ASSERT_EQ(r.x, 10.5f);
+  ASSERT_EQ(r.y, 10.5f);
+  ASSERT_EQ(r.w, 4.5f);
+  ASSERT_EQ(r.h, 4.5f);
+}
+
 TEST(Point, init) {
   point_t p = point_init(10, 20);
   ASSERT_EQ(p.x, 10);