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The information in this article applies to:
SUMMARY
One of the more interesting controls Windows 95 provides as part of its
new common controls is the image list. Image lists provide an easy way
to manage a group of bitmaps and draw them on the screen, without having
to worry about calling CreateCompatibleDC(), SelectObject(), BitBlt(),
StretchBlt(), and so on.
One interesting feature that image lists provide through the
ImageList_Draw() API is the ability to overlay images -- that is, to draw
an image transparently over another image. Calling ImageList_Draw() with
the last parameter set to an index to an overlay mask instructs the image
list to draw an image, and draw the overlay mask on top of it.
MORE INFORMATION
To overlay images correctly using image lists, follow these steps:
- Create a bitmap that will have the images you want to draw as well as
the overlay images you want drawn on top of these images.
For example, say you have a bitmap of four 16x16 images:
- a green circle.
- a red circle.
- a panda.
- a frog.
- Create an image list out of the bitmap you've created in step 1 by using
ImageList_LoadImage() as shown here:
hImageList = ImageList_LoadImage (hInst,
"MyBitmap",
16,
4,
RGB (255,0,0),
IMAGE_BITMAP,
0);
- Decide which images you want to specify as overlay masks, and tag them
as such by using the ImageList_SetOverlayImage() function. The following
code specifies the panda and the frog (with 0-based index, this comes
out to image 2 and 3) as overlay masks 1 and 2.
NOTE: You can only specify up to four overlay masks per image list.
ImageList_SetOverlayImage (hImageList,
2, // 0-based index to image list
1); // 1-based index to overlay mask.
ImageList_SetOverlayImage (hImageList,
3, // 0-based index to image list
2); // 1-based index to overlay mask.
- Draw the image. The following code draws the green circle (or image 0 in
the example image list). Then it draws the panda (overlay image 1 in the
example) on top of it.
ImageList_Draw (hImageList,
0, // 0-based index to imageList of image to draw
hDC, // handle to a DC
16, 16 // (x,y) location to draw
INDEXTOOVERLAYMASK (1)); // Overlay image #1
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