flush_bufferT_flush_bufferFlushBufferFlushBufferflush_buffer (算子)

名称

flush_bufferT_flush_bufferFlushBufferFlushBufferflush_buffer — 清空窗口内容。

签名

flush_buffer( : : WindowHandle : )

描述

flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer flushes the contents of the window WindowHandleWindowHandleWindowHandleWindowHandlewindowHandlewindow_handle。

flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer is only necessary if the window parameter 'flush'"flush""flush""flush""flush""flush" has been set to 'false'"false""false""false""false""false" with set_window_paramset_window_paramSetWindowParamSetWindowParamSetWindowParamset_window_param。If 'flush'"flush""flush""flush""flush""flush" is 'false'"false""false""false""false""false" all display operations (such as disp_objdisp_objDispObjDispObjDispObjdisp_obj or disp_textdisp_textDispTextDispTextDispTextdisp_text) are redirected to a buffer and have no effect on WindowHandleWindowHandleWindowHandleWindowHandlewindowHandlewindow_handle (this applies for all window modes). flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer copies the contents of this buffer to the window WindowHandleWindowHandleWindowHandleWindowHandlewindowHandlewindow_handle。

This is very useful to avoid flickering by batching several display operations (e.g., a clear_windowclear_windowClearWindowClearWindowClearWindowclear_window followed by a disp_objdisp_objDispObjDispObjDispObjdisp_obj) and displaying the final result with flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer.

This does not apply to drawing objects, which are always updated.

注意

flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer 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

WindowHandleWindowHandleWindowHandleWindowHandlewindowHandlewindow_handle (输入控制) window → (handle)

窗口句柄。

示例（HDevelop）

read_image (Image, 'printer_chip/printer_chip_01')
threshold (Image, Region, 128, 255)
dev_open_window (0, 0, 512, 512, 'black', WindowHandle)
set_window_param (WindowHandle, 'flush', 'false')
dev_display (Image)
dev_display (Region)
disp_text (WindowHandle, 'Result of threshold', 'window', \
           12, 12, 'black', [], [])
* nothing is displayed until flush_buffer is called
flush_buffer (WindowHandle)

结果

If the window exists flush_bufferflush_bufferFlushBufferFlushBufferFlushBufferflush_buffer 返回 2 ( H_MSG_TRUE )。

可能的前趋

disp_objdisp_objDispObjDispObjDispObjdisp_obj

可能的后继

dump_window_imagedump_window_imageDumpWindowImageDumpWindowImageDumpWindowImagedump_window_image

另见

set_window_paramset_window_paramSetWindowParamSetWindowParamSetWindowParamset_window_param

模块

基础

算子