GUI: rename widget to ViewPort. Update GUI API usage. (#317)

applications/gui/view_port.h

@@ -0,0 +1,78 @@
+#pragma once
+
+#include <input/input.h>
+#include "canvas.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct ViewPort ViewPort;
+
+/*
+ * ViewPort Draw callback
+ * @warning called from GUI thread
+ */
+typedef void (*ViewPortDrawCallback)(Canvas* canvas, void* context);
+
+/*
+ * ViewPort Input callback
+ * @warning called from GUI thread
+ */
+typedef void (*ViewPortInputCallback)(InputEvent* event, void* context);
+
+/*
+ * ViewPort allocator
+ * always returns view_port or stops system if not enough memory.
+ */
+ViewPort* view_port_alloc();
+
+/*
+ * ViewPort deallocator
+ * Ensure that view_port was unregistered in GUI system before use.
+ */
+void view_port_free(ViewPort* view_port);
+
+/*
+ * Set view_port width.
+ * Will be used to limit canvas drawing area and autolayout feature.
+ * @param width - wanted width, 0 - auto.
+ */
+void view_port_set_width(ViewPort* view_port, uint8_t width);
+uint8_t view_port_get_width(ViewPort* view_port);
+
+/*
+ * Set view_port height.
+ * Will be used to limit canvas drawing area and autolayout feature.
+ * @param height - wanted height, 0 - auto.
+ */
+void view_port_set_height(ViewPort* view_port, uint8_t height);
+uint8_t view_port_get_height(ViewPort* view_port);
+
+/*
+ * Enable or disable view_port rendering.
+ * @param enabled.
+ */
+void view_port_enabled_set(ViewPort* view_port, bool enabled);
+bool view_port_is_enabled(ViewPort* view_port);
+
+/*
+ * ViewPort event callbacks
+ * @param callback - appropriate callback function
+ * @param context - context to pass to callback
+ */
+void view_port_draw_callback_set(ViewPort* view_port, ViewPortDrawCallback callback, void* context);
+void view_port_input_callback_set(
+    ViewPort* view_port,
+    ViewPortInputCallback callback,
+    void* context);
+
+/*
+ * Emit update signal to GUI system.
+ * Rendering will happen later after GUI system process signal.
+ */
+void view_port_update(ViewPort* view_port);
+
+#ifdef __cplusplus
+}
+#endif