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Download demo project - 176 Kb
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I wanted to have one of those fancy scrolling credits for an application I have been working on,
and I couldn't find anything suitable. So I did what most of us end up doing when we can't find
someone else's code to rip... I made my own. I wanted to be able to scroll text and bitmaps
transparently over a bitmapped background.
This code uses the CGDIThread class from the MTGDI MFC sample source code for the interface thread.
The transparent blitting is accomplished using the "True Mask Method" explained in the article
"Transparent Bitmap - True Mask Method" by Paul Reynolds.
The text and bitmaps of the credits are printed on a memory bitmapped during initialization. The
memory bitmap is then blitted to the screen repeatedly, each time starting at the next row, giving
the effect of scrolling.
The CCreditsThread class does all of the initialization and drawing of the credits. The fonts and
colors that will be used are initialized, followed by the actual contents of the credits.
The demo uses a dialog with an image covering it's entire surface. The credits can be displayed
anywhere on the dialog. Whatever is behind the area the credits are displayed in will be used for
the background of the scrolling.
The transparent color in the demo is white, but it can be changed
to whatever you like by changing the MASK_RGB #define in the CreditsThread.cpp file. Anything that
uses the transparent color will not show up. This includes text and areas on bitmaps. If you wanted
to use text that is the same color as the transparent color then use a color that is close
to the transparent color.
RGB(255, 255, 255);
RGB(250, 250, 250);
Any available font face can be used. The fonts are initialized in the InitFonts() function using
the LOGFONT structure and are added to an array of CFonts for quick retrieval. This also allows a
large number of different fonts to be used.
The font colors are initialized in the InitColors() function. Font color is independent of the
font face being used. Any color can be used with any face, without having to create a new font.
The font colors are also added to an array for quick retrieval.
The actual contents of the credits are initialized in the InitText() function. The credits are
stored as text strings describing the attributes and the content of each line.
If the line in the credits is a text string, it has the following format:
"02:04:Text to display"
The first 2 digits are in index into the array of fonts to describe the font face to use for that
line. Each line of text must specify the font to use. The font number must always be formatted as
a 2 digit number at the beginning of the string. Following the font number is a colon.
The next pair of digits are an index into the array of font colors, specifying the color to use for
that line of text. The color index must also be formatted as a 2 digit number. The color index is
followed by a colon.
The next part of the string is the actual text to display.
If the line in the credits is a bitmap, it will have the following format:
The bitmap resource must have a quoted name, like "BALL", instead of the customary style ID like IDB_BALL.
You can specify the amount of spacing between lines in the credits.
The number specifies the number of pixels to move down. Lines of text are automatically spaced one line.
You can also use spacing to cause the credits to start scrolling from the bottom of the screen initially,
or to simulate a pause before the next section of credits is displayed, or until the credits are repeated.
To use in your own projects