feat(obj): add transform matrix attribute (lvgl#7187)

examples/widgets/lv_example_widgets.h

@@ -111,6 +111,7 @@ void lv_example_msgbox_2(void);
 
 void lv_example_obj_1(void);
 void lv_example_obj_2(void);
+void lv_example_obj_3(void);
 
 void lv_example_roller_1(void);
 void lv_example_roller_2(void);

examples/widgets/obj/index.rst

@@ -11,3 +11,8 @@ Make an object draggable
 .. lv_example:: widgets/obj/lv_example_obj_2
   :language: c
 
+Transform object using a 3x3 matrix
+-----------------------------------
+
+.. lv_example:: widgets/obj/lv_example_obj_3
+  :language: c

examples/widgets/obj/lv_example_obj_3.c

@@ -0,0 +1,42 @@
+#include "../../lv_examples.h"
+#if LV_BUILD_EXAMPLES
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+
+static void timer_cb(lv_timer_t * timer)
+{
+    lv_obj_t * obj = lv_timer_get_user_data(timer);
+
+    static float value = 0.1f;
+    lv_matrix_t matrix;
+    lv_matrix_identity(&matrix);
+    lv_matrix_scale(&matrix, value, 1);
+    lv_matrix_rotate(&matrix, value * 360);
+    lv_obj_set_transform(obj, &matrix);
+
+    value += 0.01f;
+
+    if(value > 2.0f) {
+        lv_obj_reset_transform(obj);
+        value = 0.1f;
+    }
+}
+
+void lv_example_obj_3(void)
+{
+    lv_obj_t * obj = lv_obj_create(lv_screen_active());
+    lv_obj_center(obj);
+
+    lv_timer_create(timer_cb, 20, obj);
+}
+
+#else
+
+void lv_example_obj_3(void)
+{
+    lv_obj_t * label = lv_label_create(lv_screen_active());
+    lv_label_set_text_static(label, "LV_DRAW_TRANSFORM_USE_MATRIX is not enabled");
+    lv_obj_center(label);
+}
+
+#endif /*LV_DRAW_TRANSFORM_USE_MATRIX*/
+#endif /*LV_BUILD_EXAMPLES*/

src/core/lv_obj.c

@@ -541,6 +541,13 @@ static void lv_obj_destructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
 
         lv_event_remove_all(&obj->spec_attr->event_list);
 
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+        if(obj->spec_attr->matrix) {
+            lv_free(obj->spec_attr->matrix);
+            obj->spec_attr->matrix = NULL;
+        }
+#endif
+
         lv_free(obj->spec_attr);
         obj->spec_attr = NULL;
     }

src/core/lv_obj_pos.c

@@ -10,6 +10,7 @@
 #include "../layouts/lv_layout_private.h"
 #include "lv_obj_event_private.h"
 #include "lv_obj_draw_private.h"
+#include "lv_obj_style_private.h"
 #include "lv_obj_private.h"
 #include "../display/lv_display.h"
 #include "../display/lv_display_private.h"
@@ -983,6 +984,82 @@ void lv_obj_center(lv_obj_t * obj)
     lv_obj_align(obj, LV_ALIGN_CENTER, 0, 0);
 }
 
+void lv_obj_set_transform(lv_obj_t * obj, const lv_matrix_t * matrix)
+{
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+
+    if(!matrix) {
+        lv_obj_reset_transform(obj);
+        return;
+    }
+
+    lv_obj_allocate_spec_attr(obj);
+    if(!obj->spec_attr->matrix) {
+        obj->spec_attr->matrix = lv_malloc(sizeof(lv_matrix_t));;
+        LV_ASSERT_MALLOC(obj->spec_attr->matrix);
+    }
+
+    /* Invalidate the old area */
+    lv_obj_invalidate(obj);
+
+    /* Copy the matrix */
+    *obj->spec_attr->matrix = *matrix;
+
+    /* Matrix is set. Update the layer type */
+    lv_obj_update_layer_type(obj);
+
+    /* Invalidate the new area */
+    lv_obj_invalidate(obj);
+#else
+    LV_UNUSED(obj);
+    LV_UNUSED(matrix);
+    LV_LOG_WARN("Transform matrix is not used because LV_DRAW_TRANSFORM_USE_MATRIX is disabled");
+#endif
+}
+
+void lv_obj_reset_transform(lv_obj_t * obj)
+{
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+    if(!obj->spec_attr) {
+        return;
+    }
+
+    if(!obj->spec_attr->matrix) {
+        return;
+    }
+
+    /* Invalidate the old area */
+    lv_obj_invalidate(obj);
+
+    /* Free the matrix */
+    lv_free(obj->spec_attr->matrix);
+    obj->spec_attr->matrix = NULL;
+
+    /* Matrix is cleared. Update the layer type */
+    lv_obj_update_layer_type(obj);
+
+    /* Invalidate the new area */
+    lv_obj_invalidate(obj);
+#else
+    LV_UNUSED(obj);
+#endif
+}
+
+const lv_matrix_t * lv_obj_get_transform(const lv_obj_t * obj)
+{
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+    if(obj->spec_attr) {
+        return obj->spec_attr->matrix;
+    }
+#else
+    LV_UNUSED(obj);
+#endif
+    return NULL;
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/
@@ -1170,6 +1247,31 @@ static void layout_update_core(lv_obj_t * obj)
 
 static void transform_point_array(const lv_obj_t * obj, lv_point_t * p, size_t p_count, bool inv)
 {
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    const lv_matrix_t * obj_matrix = lv_obj_get_transform(obj);
+    if(obj_matrix) {
+        lv_matrix_t m;
+        lv_matrix_identity(&m);
+        lv_matrix_translate(&m, obj->coords.x1, obj->coords.y1);
+        lv_matrix_multiply(&m, obj_matrix);
+        lv_matrix_translate(&m, -obj->coords.x1, -obj->coords.y1);
+
+        if(inv) {
+            lv_matrix_t inv_m;
+            lv_matrix_inverse(&inv_m, &m);
+            m = inv_m;
+        }
+
+        for(size_t i = 0; i < p_count; i++) {
+            lv_point_precise_t p_precise = lv_point_to_precise(&p[i]);
+            lv_point_precise_t res = lv_matrix_transform_precise_point(&m, &p_precise);
+            p[i] = lv_point_from_precise(&res);
+        }
+
+        return;
+    }
+#endif /* LV_DRAW_TRANSFORM_USE_MATRIX */
+
     int32_t angle = lv_obj_get_style_transform_rotation(obj, 0);
     int32_t scale_x = lv_obj_get_style_transform_scale_x_safe(obj, 0);
     int32_t scale_y = lv_obj_get_style_transform_scale_y_safe(obj, 0);

src/core/lv_obj_pos.h

@@ -197,6 +197,21 @@ void lv_obj_align_to(lv_obj_t * obj, const lv_obj_t * base, lv_align_t align, in
  */
 void lv_obj_center(lv_obj_t * obj);
 
+/**
+ * Set the transfrom matrix of an object
+ * @param obj       pointer to an object
+ * @param matrix    pointer to a matrix to set
+ * @note `LV_DRAW_TRANSFORM_USE_MATRIX` needs to be enabled.
+ */
+void lv_obj_set_transform(lv_obj_t * obj, const lv_matrix_t * matrix);
+
+/**
+ * Reset the transfrom matrix of an object to identity matrix
+ * @param obj       pointer to an object
+ * @note `LV_DRAW_TRANSFORM_USE_MATRIX` needs to be enabled.
+ */
+void lv_obj_reset_transform(lv_obj_t * obj);
+
 /**
  * Copy the coordinates of an object to an area
  * @param obj       pointer to an object
@@ -342,6 +357,13 @@ void lv_obj_move_to(lv_obj_t * obj, int32_t x, int32_t y);
 
 void lv_obj_move_children_by(lv_obj_t * obj, int32_t x_diff, int32_t y_diff, bool ignore_floating);
 
+/**
+ * Get the transform matrix of an object
+ * @param obj       pointer to an object
+ * @return          pointer to the transform matrix or NULL if not set
+ */
+const lv_matrix_t * lv_obj_get_transform(const lv_obj_t * obj);
+
 /**
  * Transform a point using the angle and zoom style properties of an object
  * @param obj           pointer to an object whose style properties should be used

src/core/lv_obj_private.h

@@ -31,6 +31,9 @@ extern "C" {
 struct _lv_obj_spec_attr_t {
     lv_obj_t ** children;           /**< Store the pointer of the children in an array.*/
     lv_group_t * group_p;
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    lv_matrix_t * matrix;           /**< The transform matrix*/
+#endif
     lv_event_list_t event_list;
 
     lv_point_t scroll;              /**< The current X/Y scroll offset*/

src/core/lv_obj_style.c

@@ -966,6 +966,9 @@ static void trans_anim_completed_cb(lv_anim_t * a)
 
 static lv_layer_type_t calculate_layer_type(lv_obj_t * obj)
 {
+#if LV_DRAW_TRANSFORM_USE_MATRIX
+    if(lv_obj_get_transform(obj) != NULL) return LV_LAYER_TYPE_TRANSFORM;
+#endif
     if(lv_obj_get_style_transform_rotation(obj, 0) != 0) return LV_LAYER_TYPE_TRANSFORM;
     if(lv_obj_get_style_transform_scale_x(obj, 0) != 256) return LV_LAYER_TYPE_TRANSFORM;
     if(lv_obj_get_style_transform_scale_y(obj, 0) != 256) return LV_LAYER_TYPE_TRANSFORM;

src/core/lv_refr.c

@@ -969,11 +969,17 @@ static bool alpha_test_area_on_obj(lv_obj_t * obj, const lv_area_t * area)
 
 #if LV_DRAW_TRANSFORM_USE_MATRIX
 
-static void refr_obj_matrix(lv_layer_t * layer, lv_obj_t * obj)
+static bool obj_get_matrix(lv_obj_t * obj, lv_matrix_t * matrix)
 {
-    lv_matrix_t ori_matrix = layer->matrix;
-    lv_matrix_t obj_matrix;
-    lv_matrix_identity(&obj_matrix);
+    lv_matrix_identity(matrix);
+
+    const lv_matrix_t * obj_matrix = lv_obj_get_transform(obj);
+    if(obj_matrix) {
+        lv_matrix_translate(matrix, obj->coords.x1, obj->coords.y1);
+        lv_matrix_multiply(matrix, obj_matrix);
+        lv_matrix_translate(matrix, -obj->coords.x1, -obj->coords.y1);
+        return true;
+    }
 
     lv_point_t pivot = {
         .x = lv_obj_get_style_transform_pivot_x(obj, 0),
@@ -991,39 +997,55 @@ static void refr_obj_matrix(lv_layer_t * layer, lv_obj_t * obj)
 
     if(scale_x <= 0 || scale_y <= 0) {
         /* NOT draw if scale is negative or zero */
-        return;
+        return false;
     }
 
     /* generate the obj matrix */
-    lv_matrix_translate(&obj_matrix, pivot.x, pivot.y);
+    lv_matrix_translate(matrix, pivot.x, pivot.y);
     if(rotation != 0) {
-        lv_matrix_rotate(&obj_matrix, rotation * 0.1f);
+        lv_matrix_rotate(matrix, rotation * 0.1f);
     }
 
     if(scale_x != LV_SCALE_NONE || scale_y != LV_SCALE_NONE) {
         lv_matrix_scale(
-            &obj_matrix,
+            matrix,
             (float)scale_x / LV_SCALE_NONE,
             (float)scale_y / LV_SCALE_NONE
         );
     }
 
     if(skew_x != 0 || skew_y != 0) {
-        lv_matrix_skew(&obj_matrix, skew_x, skew_y);
+        lv_matrix_skew(matrix, skew_x, skew_y);
     }
 
-    lv_matrix_translate(&obj_matrix, -pivot.x, -pivot.y);
+    lv_matrix_translate(matrix, -pivot.x, -pivot.y);
+    return true;
+}
+
+static void refr_obj_matrix(lv_layer_t * layer, lv_obj_t * obj)
+{
+    lv_matrix_t obj_matrix;
+    if(!obj_get_matrix(obj, &obj_matrix)) {
+        /* NOT draw if obj matrix is not available */
+        return;
+    }
+
+    lv_matrix_t matrix_inv;
+    if(!lv_matrix_inverse(&matrix_inv, &obj_matrix)) {
+        /* NOT draw if matrix is not invertible */
+        return;
+    }
+
+    /* save original matrix */
+    lv_matrix_t ori_matrix = layer->matrix;
 
     /* apply the obj matrix */
     lv_matrix_multiply(&layer->matrix, &obj_matrix);
 
     /* calculate clip area without transform */
-    lv_matrix_t matrix_reverse;
-    lv_matrix_inverse(&matrix_reverse, &obj_matrix);
-
     lv_area_t clip_area = layer->_clip_area;
     lv_area_t clip_area_ori = layer->_clip_area;
-    clip_area = lv_matrix_transform_area(&matrix_reverse, &clip_area);
+    clip_area = lv_matrix_transform_area(&matrix_inv, &clip_area);
 
     /* increase the clip area by 1 pixel to avoid rounding errors */
     if(!lv_matrix_is_identity_or_translation(&obj_matrix)) {