set_content_update_callbackT_set_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback (算子)

名称

set_content_update_callbackT_set_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback — 设置缓冲窗口中内容更新的回调。

签名

描述

set_content_update_callbackset_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback sets a callback CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function, which is called whenever the contents of the buffer window WindowHandleWindowHandleWindowHandleWindowHandlewindowHandlewindow_handle change. The parameter CallbackContextCallbackContextCallbackContextCallbackContextcallbackContextcallback_context is always passed to the callback.

The type of CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function is: Herror callback(void *context)

On Windows systems, the __stdcall calling convention is used: Herror __stdcall callback(void *context)

The callback function must not call a HALCON operator. Doing so is undefined behavior. It is advised to perform only computationally inexpensive tasks in the callback, e.g., setting a flag or triggering an asynchronous operation.

In combination with the operators send_mouse_down_eventsend_mouse_down_eventSendMouseDownEventSendMouseDownEventSendMouseDownEventsend_mouse_down_event, send_mouse_up_eventsend_mouse_up_eventSendMouseUpEventSendMouseUpEventSendMouseUpEventsend_mouse_up_event, and send_mouse_double_click_eventsend_mouse_double_click_eventSendMouseDoubleClickEventSendMouseDoubleClickEventSendMouseDoubleClickEventsend_mouse_double_click_event, set_content_update_callbackset_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback can be used to create a buffer based control for a GUI Toolkit (such as Qt), where the control passes mouse events to the buffer, while the buffer notifies the control on changes by calling the function CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function. The control then can obtain the contents of the buffer with dump_window_imagedump_window_imageDumpWindowImageDumpWindowImageDumpWindowImagedump_window_image and display them.

注意

set_content_update_callbackset_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback 依赖于 libcanvas 库，该库在嵌入式系统上可能不可用。

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 未采用并行化处理。

参数

结果

If the window exists and is a buffer window, set_content_update_callbackset_content_update_callbackSetContentUpdateCallbackSetContentUpdateCallbackSetContentUpdateCallbackset_content_update_callback 返回 2 ( H_MSG_TRUE )。

另见

flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer

模块

基础