Sparklight
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scrolling an offscreen bitmap
I am implementing a strip chart, a display that gradually scrolls itself horizontally.I find that I must use an offscreen bitmap, or else the display will scroll fragments of any window that overlies it. Now I'm looking for an operation to scroll an offscreen I am implementing a strip chart, a display that gradually scrolls itself horizontally.I find that I must use an offscreen bitmap, or else the display will scroll fragments of any window that overlies it. Now I'm looking for an operation to scroll an offscreen bitmap.
To scroll a window one uses CopyFromScreen. But this has the problem that it will copy material from an overlying window. So I try to scroll and bitmap using DrawImage to draw a part of my offscreen bitmap into a graphics context that refers to that bitmap itself. Nothing happens.
So what I want to know is, is there an operation that will allow me to, for example, copy the left half of a bitmap onto the right half?
Ken
To scroll a window one uses CopyFromScreen. But this has the problem that it will copy material from an overlying window. So I try to scroll and bitmap using DrawImage to draw a part of my offscreen bitmap into a graphics context that refers to that bitmap itself. Nothing happens.
So what I want to know is, is there an operation that will allow me to, for example, copy the left half of a bitmap onto the right half?
Ken
Bob Learned
It would be nice to have a little more detail, so that I can understand what you are really looking for.
ASKER
I am looking for an operation that will allow me to copy (or better yet, full BitBlt) one portion of an offscreen bitmap into another portion of the same bitmap. The reason I need this is that doing it on screen is unreliable, because CopyFromScreen will copy bits from an overlying window, if my window is obscured.
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