feat(style): add lv_style_merge and appropriate tests (#8680)

src/misc/lv_style.c

@@ -210,10 +210,27 @@ void lv_style_copy(lv_style_t * dst, const lv_style_t * src)
 
     lv_style_reset(dst);
 
-    /*Source is empty*/
-    if(src->values_and_props == NULL) return;
-    if(src->prop_cnt == 0) return;
+    lv_style_merge(dst, src);
+}
 
+void lv_style_merge(lv_style_t * dst, const lv_style_t * src)
+{
+    if(lv_style_is_const(dst)) {
+        LV_LOG_WARN("The destination can not be a constant style");
+        return;
+    }
+
+    /*Source is empty*/
+    if(src->values_and_props == NULL) {
+        LV_LOG_TRACE("Source style is empty");
+        return;
+    }
+    if(src->prop_cnt == 0) {
+        LV_LOG_TRACE("Source style has no properties");
+        return;
+    }
+
+    /* Merge the styles */
     int32_t i;
     if(lv_style_is_const(src)) {
         lv_style_const_prop_t * props_and_values = (lv_style_const_prop_t *)src->values_and_props;

src/misc/lv_style.h

@@ -363,6 +363,19 @@ void lv_style_reset(lv_style_t * style);
  */
 void lv_style_copy(lv_style_t * dst, const lv_style_t * src);
 
+/**
+ * Copy all properties of a style to an other without resetting the dst style.
+ * It has the same effect as calling the same `lv_set_style_...`
+ * functions on both styles.
+ * It means new memory will be allocated to store the properties in
+ * the destination style.
+ * After the copy the destination style is fully independent of the source
+ * and source can removed without affecting the destination style.
+ * @param dst   the destination to copy into (cannot be a constant style)
+ * @param src   the source style to copy from.
+ */
+void lv_style_merge(lv_style_t * dst, const lv_style_t * src);
+
 
 /**
  * Check if a style is constant

tests/src/test_cases/test_style.c

@@ -118,6 +118,87 @@ void test_style_replacement(void)
     lv_style_reset(&style_blue);
 }
 
+void test_style_copy(void)
+{
+    lv_style_t style1;
+    lv_style_t style2;
+    lv_style_t copied_style;
+
+    const lv_color_t copied_bg_color = lv_color_hex(0x0000ff);
+    const lv_color_t copied_border_color = lv_color_hex(0x00ff00);
+    const lv_color_t copied_outline_color = lv_color_hex(0xffff00);
+
+    lv_style_init(&style1);
+    lv_style_set_bg_color(&style1, lv_color_hex(0xff0000)); // this should get overwritten
+    lv_style_set_outline_color(&style1, copied_outline_color);
+
+    lv_style_init(&style2);
+    lv_style_set_bg_color(&style2, copied_bg_color);
+    lv_style_set_border_color(&style2, copied_border_color);
+
+    lv_style_init(&copied_style);
+    lv_style_copy(&copied_style, &style1);
+    lv_style_copy(&copied_style, &style2); // This should reset `copied_style` then duplicate the properties of `style2`
+
+    lv_style_value_t value;
+
+    TEST_ASSERT_TRUE(lv_style_get_prop(&copied_style, LV_STYLE_BG_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(copied_bg_color, value.color);
+    TEST_ASSERT_TRUE(lv_style_get_prop(&copied_style, LV_STYLE_BORDER_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(copied_border_color, value.color);
+    TEST_ASSERT_TRUE(lv_style_get_prop(&copied_style, LV_STYLE_OUTLINE_COLOR, &value) == LV_STYLE_RES_NOT_FOUND);
+
+    /* Changing the original style should not impact the style that copied it */
+    lv_style_set_bg_color(&style2, lv_color_hex(0x00ff00));
+    TEST_ASSERT_TRUE(lv_style_get_prop(&copied_style, LV_STYLE_BG_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(copied_bg_color, value.color);
+
+    lv_style_reset(&style1);
+    lv_style_reset(&style2);
+    lv_style_reset(&copied_style);
+}
+
+void test_style_merge(void)
+{
+    lv_style_t style1;
+    lv_style_t style2;
+    lv_style_t merged_style;
+
+    const lv_color_t merged_bg_color = lv_color_hex(0x0000ff);
+    const lv_color_t merged_border_color = lv_color_hex(0x00ff00);
+    const lv_color_t merged_outline_color = lv_color_hex(0xffff00);
+
+    lv_style_init(&style1);
+    lv_style_set_bg_color(&style1, lv_color_hex(0xff0000)); // this should get overwritten
+    lv_style_set_outline_color(&style1, merged_outline_color);
+
+    lv_style_init(&style2);
+    lv_style_set_bg_color(&style2, merged_bg_color);
+    lv_style_set_border_color(&style2, merged_border_color);
+
+    lv_style_init(&merged_style);
+    lv_style_merge(&merged_style, &style1);
+    lv_style_merge(&merged_style, &style2);
+
+    lv_style_value_t value;
+
+    TEST_ASSERT_TRUE(lv_style_get_prop(&merged_style, LV_STYLE_BG_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(merged_bg_color, value.color);
+    TEST_ASSERT_TRUE(lv_style_get_prop(&merged_style, LV_STYLE_BORDER_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(merged_border_color, value.color);
+    TEST_ASSERT_TRUE(lv_style_get_prop(&merged_style, LV_STYLE_OUTLINE_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(merged_outline_color, value.color);
+
+    /* Changing the original style should not impact the style that copied it */
+    lv_style_set_bg_color(&style2, lv_color_hex(0x00ff00));
+    TEST_ASSERT_TRUE(lv_style_get_prop(&merged_style, LV_STYLE_BG_COLOR, &value) == LV_STYLE_RES_FOUND);
+    TEST_ASSERT_EQUAL_COLOR(merged_bg_color, value.color);
+
+    lv_style_reset(&style1);
+    lv_style_reset(&style2);
+    lv_style_reset(&merged_style);
+}
+
 void test_style_has_prop(void)
 {
     lv_style_t style;