feat(vector): add API to append arc (#5510)

Signed-off-by: Xu Xingliang <xuxingliang@xiaomi.com>

demos/vector_graphic/lv_demo_vector_graphic.c

@@ -189,6 +189,37 @@ static void draw_blend(lv_vector_dsc_t * ctx, lv_vector_path_t * path)
     lv_vector_dsc_add_path(ctx, path); // draw a path
 }
 
+static void draw_arc(lv_vector_dsc_t * ctx, lv_vector_path_t * path)
+{
+    lv_vector_path_clear(path);
+    lv_vector_dsc_identity(ctx);
+
+    lv_area_t rect = {100, 0, 150, 50};
+    lv_vector_dsc_set_fill_color(ctx, lv_color_lighten(lv_color_black(), 50));
+    lv_vector_clear_area(ctx, &rect); // clear screen
+
+    lv_fpoint_t p = {100, 50}; /* Center */
+    lv_vector_dsc_set_stroke_color(ctx, lv_color_make(0x00, 0xff, 0xff));
+    lv_vector_dsc_set_stroke_opa(ctx, LV_OPA_COVER);
+    lv_vector_dsc_set_stroke_width(ctx, 2.0f);
+    lv_vector_dsc_set_stroke_dash(ctx, NULL, 0);
+    lv_vector_dsc_set_fill_color32(ctx, lv_color32_make(0xFF, 0x00, 0x00, 0x80));
+
+    lv_vector_path_move_to(path, &p);
+    lv_fpoint_t temp = {p.x + 50, p.y};
+    lv_vector_path_line_to(path, &temp);
+    lv_vector_path_append_arc(path, &p, 50, 0, -90, false);
+    lv_vector_path_line_to(path, &p);
+    lv_vector_path_close(path);
+
+    lv_vector_dsc_add_path(ctx, path);
+
+    /* Below code has same effect as above one. */
+    lv_vector_path_clear(path);
+    lv_vector_path_append_arc(path, &p, 50, 45, 45, true);
+    lv_vector_dsc_add_path(ctx, path); // draw a path
+}
+
 static void draw_vector(lv_layer_t * layer)
 {
     lv_vector_dsc_t * ctx = lv_vector_dsc_create(layer);
@@ -205,7 +236,7 @@ static void draw_vector(lv_layer_t * layer)
     draw_radial_gradient(ctx, path);
     draw_gradient(ctx, path);
     draw_blend(ctx, path);
-
+    draw_arc(ctx, path);
     lv_draw_vector(ctx); // submit draw
     lv_vector_path_delete(path);
     lv_vector_dsc_delete(ctx);

scripts/code-format.cfg

@@ -47,3 +47,5 @@
 --exclude=../tests/unity/unity_support.c
 --exclude=../tests/unity/unity_support.h
 --exclude=../tests/test_images
+--exclude=../tests/build_test_defheap
+--exclude=../tests/build_test_sysheap

src/draw/lv_draw_vector.c

@@ -14,6 +14,16 @@
 #include "../stdlib/lv_string.h"
 #include <stdbool.h>
 #include <math.h>
+#include <float.h>
+
+#define MATH_PI  3.14159265358979323846f
+#define MATH_HALF_PI 1.57079632679489661923f
+
+#define DEG_TO_RAD 0.017453292519943295769236907684886f
+#define RAD_TO_DEG 57.295779513082320876798154814105f
+
+#define MATH_RADIANS(deg) ((deg) * DEG_TO_RAD)
+#define MATH_DEGRESS(rad) ((rad) * RAD_TO_DEG)
 
 /*********************
 *      DEFINES
@@ -470,6 +480,92 @@ void lv_vector_path_append_circle(lv_vector_path_t * path, const lv_fpoint_t * c
     lv_vector_path_close(path);
 }
 
+/**
+ * Add a arc to the path
+ * @param path              pointer to a path
+ * @param c                 pointer to a `lv_fpoint_t` variable for center of the circle
+ * @param radius            the radius for arc
+ * @param start_angle       the start angle for arc
+ * @param sweep             the sweep angle for arc, could be negative
+ * @param pie               true: draw a pie, false: draw a arc
+ */
+void lv_vector_path_append_arc(lv_vector_path_t * path, const lv_fpoint_t * c, float radius, float start_angle,
+                               float sweep, bool pie)
+{
+    float cx = c->x;
+    float cy = c->y;
+
+    /* just circle */
+    if(sweep >= 360.0f || sweep <= -360.0f) {
+        lv_vector_path_append_circle(path, c, radius, radius);
+        return;
+    }
+
+    start_angle = MATH_RADIANS(start_angle);
+    sweep = MATH_RADIANS(sweep);
+
+    int n_curves = (int)ceil(fabsf(sweep / MATH_HALF_PI));
+    float sweep_sign = sweep < 0 ? -1.f : 1.f;
+    float fract = fmodf(sweep, MATH_HALF_PI);
+    fract = (fabsf(fract) < FLT_EPSILON) ? MATH_HALF_PI * sweep_sign : fract;
+
+    /* Start from here */
+    lv_fpoint_t start = {
+        .x = radius * cosf(start_angle),
+        .y = radius * sinf(start_angle),
+    };
+
+    if(pie) {
+        lv_vector_path_move_to(path, &(lv_fpoint_t) {
+            cx, cy
+        });
+        lv_vector_path_line_to(path, &(lv_fpoint_t) {
+            start.x + cx, start.y + cy
+        });
+    }
+    else {
+        lv_vector_path_move_to(path, &(lv_fpoint_t) {
+            start.x + cx, start.y + cy
+        });
+    }
+
+    for(int i = 0; i < n_curves; ++i) {
+        float end_angle = start_angle + ((i != n_curves - 1) ? MATH_HALF_PI * sweep_sign : fract);
+        float end_x = radius * cosf(end_angle);
+        float end_y = radius * sinf(end_angle);
+
+        /* variables needed to calculate bezier control points */
+
+        /** get bezier control points using article:
+         * (http://itc.ktu.lt/index.php/ITC/article/view/11812/6479)
+         */
+        float ax = start.x;
+        float ay = start.y;
+        float bx = end_x;
+        float by = end_y;
+        float q1 = ax * ax + ay * ay;
+        float q2 = ax * bx + ay * by + q1;
+        float k2 = (4.0f / 3.0f) * ((sqrtf(2 * q1 * q2) - q2) / (ax * by - ay * bx));
+
+        /* Next start point is the current end point */
+        start.x = end_x;
+        start.y = end_y;
+
+        end_x += cx;
+        end_y += cy;
+
+        lv_fpoint_t ctrl1 = {ax - k2 * ay + cx, ay + k2 * ax + cy};
+        lv_fpoint_t ctrl2 = {bx + k2 * by + cx, by - k2 * bx + cy};
+        lv_fpoint_t end = {end_x, end_y};
+        lv_vector_path_cubic_to(path, &ctrl1, &ctrl2, &end);
+        start_angle = end_angle;
+    }
+
+    if(pie) {
+        lv_vector_path_close(path);
+    }
+}
+
 void lv_vector_path_append_path(lv_vector_path_t * path, const lv_vector_path_t * subpath)
 {
     uint32_t ops_size = lv_array_size(&path->ops);

src/draw/lv_draw_vector.h

@@ -308,6 +308,18 @@ void lv_vector_path_append_rect(lv_vector_path_t * path, const lv_area_t * rect,
  */
 void lv_vector_path_append_circle(lv_vector_path_t * path, const lv_fpoint_t * c, float rx, float ry);
 
+/**
+ * Add a arc to the path
+ * @param path              pointer to a path
+ * @param c                 pointer to a `lv_fpoint_t` variable for center of the circle
+ * @param radius            the radius for arc
+ * @param start_angle       the start angle for arc
+ * @param sweep             the sweep angle for arc, could be negative
+ * @param pie               true: draw a pie, false: draw a arc
+ */
+void lv_vector_path_append_arc(lv_vector_path_t * path, const lv_fpoint_t * c, float radius, float start_angle,
+                               float sweep, bool pie);
+
 /**
  * Add an sub path to the path
  * @param path              pointer to a path

tests/src/test_cases/draw/test_draw_vector.c

@@ -94,6 +94,38 @@ static void draw_shapes(lv_layer_t * layer)
     lv_vector_dsc_set_fill_rule(ctx, LV_VECTOR_FILL_EVENODD);
     lv_vector_dsc_add_path(ctx, path);
 
+    lv_vector_path_clear(path);
+    lv_vector_dsc_identity(ctx);
+    lv_vector_dsc_set_blend_mode(ctx, LV_VECTOR_BLEND_SRC_OVER);
+
+    rect = (lv_area_t) {
+        500, 50, 550, 100
+    };
+    lv_vector_dsc_set_fill_color(ctx, lv_color_lighten(lv_color_black(), 50));
+    lv_vector_clear_area(ctx, &rect); // clear screen
+
+    lv_fpoint_t p = {500, 100}; /* Center */
+    lv_vector_dsc_set_stroke_color(ctx, lv_color_make(0x00, 0xff, 0xff));
+    lv_vector_dsc_set_stroke_opa(ctx, LV_OPA_COVER);
+    lv_vector_dsc_set_stroke_width(ctx, 2.0f);
+    lv_vector_dsc_set_stroke_dash(ctx, NULL, 0);
+    lv_vector_dsc_set_fill_opa(ctx, LV_OPA_TRANSP);
+    lv_vector_path_move_to(path, &p);
+    lv_fpoint_t temp = {p.x + 50, p.y};
+    lv_vector_path_line_to(path, &temp);
+    lv_vector_path_append_arc(path, &p, 50, 0, -90, false);
+    lv_vector_path_line_to(path, &p);
+    lv_vector_path_close(path);
+
+    lv_vector_dsc_add_path(ctx, path);
+
+    /* Below code has same effect as above one but with solid fill */
+    lv_vector_dsc_set_fill_color(ctx, lv_color_make(0xFF, 0x00, 0x00));
+    lv_vector_dsc_set_fill_opa(ctx, LV_OPA_COVER);
+    lv_vector_path_clear(path);
+    lv_vector_path_append_arc(path, &p, 50, 45, 45, true);
+    lv_vector_dsc_add_path(ctx, path); // draw a path
+
     lv_draw_vector(ctx);
     lv_vector_path_delete(path);
     lv_vector_dsc_delete(ctx);