Commit 14236761 authored by Committed by Jehan
Bug 793722 - Capture screenshot of single window fails if...
... thewindow is IE 11. The screenshot plugin for windows had a problem when capturing applications that use hardware rendering acceleration (e.g. Chromium-based Apps, IE11). Those applications seem to render their content to a device context (DC) that is different from the one that can be retrieved via GetDCEx(hWnd). So a screenshot that simply copies the main window DC will be incomplete (see bug attachment) or just plain black. This patch removes the code that uses GetDCEx for single window screenshots and always uses the display device context instead. This makes sure that all window contents are actually visible in the screenshot. With this change, we now have to set the source coordinates in the call to BitBlt() to the window's coordinates to exclude everything that isn't the window from the screenshot when doing a single window screenshot. Review comment by Jehan: as Simon notes in bug 793722, there is a regression though, which is that this new code cannot capture any part of a window which is not in any screen. This is still an improvement because at least for what is on screen, we always get exactly the same as what is displayed. This is especially true since hardware-accelerated applications are more and more common. So let's push this first commit and hope for further improvements.
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