feat(blur): add blur support (#9223)

docs/src/details/common-widget-features/styles/style-properties.rst

@@ -1408,6 +1408,48 @@ Sets the intensity of color mixing. Value 0, `LV_OPA_0` or `LV_OPA_TRANSP` means
   <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Ext. draw</strong> No</li>
   </ul>
 
+blur_radius
+~~~~~~~~~~~
+
+Sets the intensity of blurring. Applied on each lv_part separately before the children are rendered.
+
+.. raw:: html
+
+  <ul>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Default</strong> `0`</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Inherited</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Layout</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Ext. draw</strong> No</li>
+  </ul>
+
+blur_backdrop
+~~~~~~~~~~~~~
+
+If `true` the background of the widget will be blurred. The part should have < 100% opacity to make it visible. If `false` the given part will be blurred when it's rendered but before drawing the children.
+
+.. raw:: html
+
+  <ul>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Default</strong> `false`</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Inherited</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Layout</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Ext. draw</strong> No</li>
+  </ul>
+
+blur_quality
+~~~~~~~~~~~~
+
+Setting to `LV_BLUR_QUALITY_SPEED` the blurring algorithm will prefer speed over quality. `LV_BLUR_QUALITY_PRECISION` will force using higher quality but slower blur. With `LV_BLUR_QUALITY_AUTO` the quality will be selected automatically.
+
+.. raw:: html
+
+  <ul>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Default</strong> `LV_BLUR_QUALITY_AUTO`</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Inherited</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Layout</strong> No</li>
+  <li style='display:inline-block; margin-right: 20px; margin-left: 0px'><strong>Ext. draw</strong> No</li>
+  </ul>
+
 anim
 ~~~~
 

docs/src/details/main-modules/draw/draw_descriptors.rst

@@ -617,6 +617,25 @@ Functions for triangle drawing:
 
 
 
+Blur Draw Descriptor
+********************
+
+Blur is defined by :cpp:type:`lv_draw_blur_dsc_t`, which includes:
+
+:blur_radius:      The radius of the blur.
+:corner_radius:    The radius of the corners.
+:quality:          Tells whether to prefer speed or quality.
+
+Functions for blur drawing:
+
+- :cpp:expr:`lv_draw_blur_dsc_init(&dsc)` initializes a blur descriptor.
+- :cpp:expr:`lv_draw_blur(layer, &dsc, area)` creates a task to blur an area.
+- :cpp:expr:`lv_draw_task_get_blur_dsc(draw_task)` retrieves blur descriptor.
+
+.. lv_example:: widgets/canvas/lv_example_canvas_10
+  :language: c
+
+
 Vector Draw Descriptor
 **********************