This is a screen capturing that features multiple monitor support, including methods for capturing windows and window icons. Includes Spy++ style window finder!
First up, the desktop. Obviously it can be captured, but how'd they do that? Easy, using just a few API calls and some GDI+, we can recreate the functionality that the print screen command offers, with one advantage.
We're not going to touch the Window's Clipboard. Too many times, I have seen improper usage of the clipboard, and in my opinion, slapping a big fat image onto it, erasing whatever you had there before with no warning, is just a bad idea.
The command is 'print screen', not 'erase my clipboard data'. So, why do it? Would you really want to write code that has to use the user's workspace to accomplish it's task? I don't think so. We can capture the image, without storing it on the clipboard and making you paste it into your favorite image editor.
So a little background. Let's start with device contexts. If you are familiar, skip ahead. If not, read on. Device contexts are just generic ways to represent devices, or things you can draw on or interact with graphically. This is hugely over simplified, and I'm going to get flamed, but for the sake of brevity, let's just go with that for now. You can get device context's, or dc's as they are commonly referred to, from images, windows, monitors, and even printers.
Every window has them, and you can use them to draw with. Everything you see on your screen is being drawn upon a device context. The desktop, every window, your taskbar, and anything you see. You can draw upon them, or copy what they have drawn upon them. If you can get a hold of them, you can pretty much draw or steal whatever you want graphically speaking. Working with device contexts is fast, and both GDI and GDI+ are based on them.
What's all that mean? Well, in the case of capturing the screen, we know that somewhere Windows is drawing upon a device context, so that we can see it. In fact, there's one for each monitor you have attached to your system, and that desktop that you are seeing on it, is being drawn on that monitor's device context. All we have to do is grab a hold of that device context, create another one of our own, and copy the screen's device context image data to our own, and we've got a screen capture.
Using our knowledge of the .NET framework, and some additional knowledge of the Windows APIs, we can pretty effectively duplicate how the print screen command works. Let's take a look at some code. Here's a method that is used in the example, that will enumerate all of the monitors attached to the system, figure out just how big the combined desktop is, and then copy what each monitor has displayed on it, into a final bitmap image. Instant screen capture. Here's the code.
First up, the desktop. Obviously it can be captured, but how'd they do that? Easy, using just a few API calls and some GDI+, we can recreate the functionality that the print screen command offers, with one advantage.
We're not going to touch the Window's Clipboard. Too many times, I have seen improper usage of the clipboard, and in my opinion, slapping a big fat image onto it, erasing whatever you had there before with no warning, is just a bad idea.
The command is 'print screen', not 'erase my clipboard data'. So, why do it? Would you really want to write code that has to use the user's workspace to accomplish it's task? I don't think so. We can capture the image, without storing it on the clipboard and making you paste it into your favorite image editor.
So a little background. Let's start with device contexts. If you are familiar, skip ahead. If not, read on. Device contexts are just generic ways to represent devices, or things you can draw on or interact with graphically. This is hugely over simplified, and I'm going to get flamed, but for the sake of brevity, let's just go with that for now. You can get device context's, or dc's as they are commonly referred to, from images, windows, monitors, and even printers.
Every window has them, and you can use them to draw with. Everything you see on your screen is being drawn upon a device context. The desktop, every window, your taskbar, and anything you see. You can draw upon them, or copy what they have drawn upon them. If you can get a hold of them, you can pretty much draw or steal whatever you want graphically speaking. Working with device contexts is fast, and both GDI and GDI+ are based on them.
What's all that mean? Well, in the case of capturing the screen, we know that somewhere Windows is drawing upon a device context, so that we can see it. In fact, there's one for each monitor you have attached to your system, and that desktop that you are seeing on it, is being drawn on that monitor's device context. All we have to do is grab a hold of that device context, create another one of our own, and copy the screen's device context image data to our own, and we've got a screen capture.
Using our knowledge of the .NET framework, and some additional knowledge of the Windows APIs, we can pretty effectively duplicate how the print screen command works. Let's take a look at some code. Here's a method that is used in the example, that will enumerate all of the monitors attached to the system, figure out just how big the combined desktop is, and then copy what each monitor has displayed on it, into a final bitmap image. Instant screen capture. Here's the code.
Developer: License / Price: Size / OS: | Mark Belles Freeware / FREE 20 KB / Windows All |
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Screen Capturing