Matlab Timer回調函數的執行中rawnow函數的用途是什么

本篇文章為大家展示了Matlab Timer回調函數的執行中rawnow函數的用途是什么 ，內容簡明扼要并且容易理解，絕對能使你眼前一亮，通過這篇文章的詳細介紹希望你能有所收獲。

    由前一篇文章可以看出，按照所設定的時間間隔調用Timer的回調函數時，并不是真的即刻執行該回調函數，而是先將該回調函數放入事件隊列中，待前面的事件都執行完時才執行該事件。但有時我們需要當所設定的時間到達時立刻執行我們的回調函數，此時我們就可以用功能強大的drawnow函數了。在回調函數中加入drawnow就可以在時間到達時強制執行該回調函數。

下面給出的是matlab幫助里關于drawnow的用法：

drawnow

Flush event queue and update figure window
Syntax

drawnow
drawnow expose
drawnow update
Description

drawnow causes figure windows and their children to update and flushes the system event queue. Any callbacks generated by incoming events (e.g. mouse or key events) are dispatched before drawnow returns.

drawnow expose causes only graphics objects to refresh, if needed. It does not allow callbacks to execute and does not process other events in the queue.

drawnow update causes only non-graphics objects to refresh, if needed. It does not allow callbacks to execute and does not process other events in the queue.

You can combine the expose and update options to obtain both effects.

drawnow expose update

Other Events That Cause Event Queue Processing

Other events that cause MATLAB to flush the event queue and draw the figure includes:

    *

      Returning to the MATLAB prompt
    *

      Executing the following functions
          o

            figure
          o

            getframe
          o

            input
          o

            keyboard
          o

            pause
    *

      Functions that wait for user input (i.e., waitforbuttonpress, waitfor, ginput)
    *

      Any code that causes one of the above functions to be executed. For example, suppose h is the handle of an axes. Calling axes(h) causes its parent figure to be made the current figure and brought to the front of all displayed figures, which results in the event queue being flushed.

Examples

Using drawnow in a loop causes the display to update while the loop executes:

t = 0:pi/20:2*pi;
y = exp(sin(t));
h = plot(t,y,'YDataSource','y');
for k = 1:.1:10
 y = exp(sin(t.*k));
 refreshdata(h,'caller') % Evaluate y in the function workspace
 drawnow; pause(.1)
end

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