Медленный код захвата экрана на OSX. Зачем?

Я выполнил некоторые экрана код захвата, который может быть viewed here Медленный код захвата экрана на OSX. Зачем?

Я использую GetTimeInNanoseconds из this article

функция вызывается каждые 100 мс. Я приуроченный сколько миллисекунд требуется, чтобы выполнить часть функции, а именно:

screenShotStart = GetTimeInNanoseconds(); 
CGImageRef image = CGWindowListCreateImage(rect, kCGWindowListOptionIncludingWindow|kCGWindowListOptionOnScreenBelowWindow, 0, kCGWindowImageDefault); 
CGImageRelease(image); 

screenShotStop = GetTimeInNanoseconds(); 
screenShotElapsed = screenShotStop - screenShotStart; 
/* Current Delta Time */ 
screenShotElapsedF = ((float) screenShotElapsed)/1000000.0f; 
/* Smooth Delta Time */ 
screenShotTime = 0.9f*screenShotTime + 0.1f*screenShotElapsedF;

измерение времени ниже показаны результаты. Я поражен тем, насколько медленно это происходит, и мне интересно, почему. Есть ли опытный разработчик Cocoa/Core Graphics OSX, который может объяснить это мне? И, возможно, скажите мне, как это должно быть исправлено?

Гладкое: усредненное время дельта в миллисекундах. Текущее: последнее, самое последнее дельта-время в миллисекундах.

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источник

2013-10-10 user1884325

ли вы по этой ссылке https://developer.apple.com/library/mac/samplecode/ScreenSnapshot/Listings/ScreenSnapshot_ScreenSnapshotAppDelegate_h.html#//apple_ref/doc/uid/DTS40011158-ScreenSnapshot_ScreenSnapshotAppDelegate_h-DontLinkElementID_8? ? –

Да. но это действительно не отвечает на мой вопрос. – user1884325

Вы профилировали свое приложение в Инструментах? –

CGWindow API не предназначен для захвата высокой частоты кадров. Во-первых, он не захватывает отображаемое в данный момент изображение на экране. Он обобщается для потенциального захвата различных частей содержимого. Он может включать или исключать окна, элементы рабочего стола, тени и т. Д. Это означает, что он создает новое изображение для каждого вызова. И, да, это означает, что он должен заблокировать буфер поддержки всех окон.

Apple предоставляет пару технических вопросов & Статьи о захвате содержимого экрана. Один из них предназначен для захвата отдельных изображений, где они рекомендуют использовать CGDisplayCreateImage(). Другой - для захвата фильма активности экрана с течением времени, где они рекомендуют использовать AV Foundation. Technical Q&A QA1741: How to take an image snapshot of the screen on Mac OS X Lion Technical Q&A QA1740: How to capture screen activity to a movie file using AV Foundation on Mac OS X Lion

источник

2013-10-13 04:18:58

Угадайте, какой API, который TeamViewer использует сегодня? Это верно! CGWindow API! Это объясняет, почему вся машина читает всякий раз, когда она захватывает изображения на рабочем столе! Возможно, я смогу убедить их обновить ситуацию сейчас, когда 10.7 уже несколько лет. – kode54

Медленный код захвата экрана на OSX. Зачем?

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