Question

我在更新MATLAB GUI中的等待栏时遇到问题。

我创建了一个按预期工作的简单示例。

steps = 5;
hWaitBar = waitbar(0, 'Testing...');
for i = 1:steps
   waitbar(i/steps, hWaitBar);
   pause(1);
end
close(hWaitBar);

然而，当我在GUI中使用这种结构时......

numSteps = %calculated
hWaitBar = waitbar(0, 'Processing...');

if %conditional
    for i = 1:numSteps
        waitbar(i/numSteps, hWaitBar)
        % additional processing
    end
else %conditional
    % additional processing
end

close(hWaitBar);

...等待条只能正确显示第一个for循环迭代。

第二次交互因执行失败而失败：

Error using waitbar(109)
Improper arguments for waitbar.

我已验证等待栏进度值不超过1.
我已经确认等待栏在if / else循环之外没有被关闭。

Answer 1

我找到了解决方案 - 我错过了处理图形。

在原始代码中：

numSteps = %calculated 
hWaitBar = waitbar(0, 'Processing...'); 

if %conditional 
    for i = 1:numSteps 
        waitbar(i/numSteps, hWaitBar) 
        % additional processing
        % *** call to imagesc caused the error
    end 
else %conditional 
    % additional processing 
end 

close(hWaitBar);

使用调试器，我看到等待栏成为当前图形，imagesc尝试绘制到它而不是主窗体上的轴。在引用调用之前立即将适当的数字设置为当前行为产生了正确的行为。

更正后的代码：

numSteps = %calculated 
hForm = gcf; % save the handle of the main form
hWaitBar = waitbar(0, 'Processing...'); 

if %conditional 
    for i = 1:numSteps 
        % set the waitbar to be the current figure before it is updated
        % note: this syntax will ensure window order will be preserved
        %       with waitbar on top
        set(0, 'CurrentFigure', hWaitBar); 
        waitbar(i/numSteps, hWaitBar); 

        % additional processing
        set(0, 'CurrentFigure', hForm);
        imagesc(...);
        % more processing
    end 
else %conditional 
    % additional processing 
end 

close(hWaitBar);

首次更新后，更新MATLAB等待栏失败

1 个答案: