I've recently started learning how to use MFC in Visual Studio. My program uses many small 32x32 pixel images that for convenience are put together in one large .png. I've figured out how to load the big image into a CImage and display it on a CClientDC, but I can't find anything that helps me split the image into those smaller 32x32 images.
Alternatively, I can get the pixel data for the big image using DevIL, but I can't find anything that constructs a CImage from pixel data.
As I've only started learning MFC a few days ago, I don't know the API too well and I'm probably missing something obvious. Can anyone point me in the right direction?
You'll need to use the CImage::Draw() overload that lets you specify the source rectangle. So that you can clip the image that you want to paint from the original. There are two candidates, the Draw(HDC hDestDC, const RECT& rectDest, const RECT& rectSrc) for example. The other one is the first one listed on this doc page.
Usually you don't want to create a small image if you're just using the multi-icon image in a GUI.
When you come to draw the icon, pass its offset and size to the bitblt function rather than the dimensions of the whole image.
If you do want to store the sub-image in a bitmap, create a memory DC for the target bitmap and draw into that.
Related
i have a little problem .. i am developing an SkinEngine that allow Delphi Vcl Application to be Skined . for this goal, i had developed a new file format (mSkin) in order to host my skin data .so my skin file contains 2 header , the first contains some information about the colors used by the skin , the second contains the bitmap used by skin (the bitmap type is Alpha channel bitmap in order to support transparency ).in my control i use a function to extract object bitmap from the bitmap(mSkin.Bitmap) and draw this bitmap onto my control . the problem is that when the bitmap is not shaped i got a bad quality when scaling the source bitmap .the size of the object bitmap is proportional to the control size (when the contol size changed ==> the bitmap siwe change too .)
i had try to read the vcl style to solve the problem .. but it seems to be very difficult to read .
is there a way to copy bitmap and Maintaining the quality ?
If you use bitmaps you simple can't do scaling without the problems you have. If you want scaling where e.g. a one-pixel border stays a one-pixel border, then you have to use a vector-based format for your images.
You need to divide that into 9 different bitmaps, like a 3x3 grid. then you only scale the middle on, the rest stay the same size but move. This link is for android but the same principles apply.
Here is another link. This is for flash, but it also explains the principle.
Try to use a resampling algorithm.
For upscaling, I like very much the B-Spline.
For simple content like yours, the hqnx family sometimes gives good results, and is very fast to render (even in real-time). For some pascal source code, you may take a look at this forum thread.
See also this more general question.
So I have made this program for a game and need help with making it a bit more automatic.
The program takes in an image and then displays it. I'm doing this over textures in OpenGL. When I take the screenshot of the game it is usually something about 700x400. I input the height and width into my program, resize the image to 1024x1024 (making it a POT texture for better compatibility) by adding blank space (the original image stays at the top left corner and goes all the way to (700,400) and the rest is just blank; does anyone know the term for this?) and then load it into my program and adjust the corners so only the part from (0,0) to (700,400) is shown.
That's how I handle the display of the image. Now, I would like to make this automatic. So I'd take a 700x400 picture, pass it to the program which would get the image's width and height (700x400), resize it to 1024x1024 by adding blank space and then load it.
So does anyone know a C++ library capable of doing this? I would still be taking the screenshot manually though.
I am using the Simple OpenGL Image Library (SOIL) for loading the picture (.bmp) and converting it into a texture.
Thanks!
You don't really have to resize by adding blank space to display image properly. In fact, it's really unefficient way to do it, especially because you store images in .bmp format.
SOIL is able to automatically add the blank space when loading textures - maybe just try to load the file as-is, without doing any operations.
From SOIL Documentation:
Can automatically rescale the image to the next largest power-of-two
size
Can load rectangluar textures for GUI elements or splash screens
(requires GL_ARB/EXT/NV_texture_rectangle)
Anyway, you don't have to use texture to display pixels on the screen. I presume you aren't using shaders for rendering - if it all goes through fixed pipeline, there's glDrawPixels function, which will be much simpler. Just remember to change your SOIL call to SOIL_load_image.
I'm building a program to convert an image file (whatever file type would be easiest) to G-Code for use on a rep-rap with a pen plotter attachment.
I'm wondering if i wanted to process the image pixel by pixel and check things like pixel color, how could I do this with C++?
I would really like to know how I can process a bitmap image, pixel by pixel, to check the color of the pixel.
The best way is to use a library, like for example Magick++.
When you load an image, you can access it's pixels data with Blob
You will probably want to use an existing library that has been tested.
But for fun/practice/etc, this would be a good exercise and wouldn't be impossible to do. The Bitmap Format is (relatively) simple compared with other image formats. The Wikipedia page has some tons of info, including some C++ code. It looks like once you've gotten past the header information, you get to a pixel array that shouldn't be difficult to parse.
Good luck.
Most image formats consist of a header and the actual raw image data. A bimpap image is no different. If you don't want to use one of the existing libraries, or if you are not allowed to, you should read about bitmap format :
http://en.wikipedia.org/wiki/BMP_file_format
Once you understand this you could create appropriate structs/classes to store the information you want from the header such as x,y size, bpp etc. And also have a pointer to the raw image data. You could then simpy iterate through every pixel and do whatever you want with it :)
Once you decipher the image file, I suggest you place the pixels into a matrix, for the first pass. (Future revisions can use other methods to access the pixels).
You can apply transformations to the pixels by using matrix multiplication. You can also access the pixels individually by using array indexing.
Search the web and SO for "introduction to graphics c++".
I'll first tell you the problem and then I'll tell you my solution.
Problem: I have a blank white PNG image approximately 900x900 pixels. I want to copy circles 30x30 pixels in size, which are essentially circles with a different colour. There are 8 different circles, and placed on the image depending on data values which I've created elsewhere.
Solution: I've used ImageMagicK, it's suppose to be good for general purpose image editing etc. I created a blank image
Image.outimage("900x900","white");
I upload all other small 30x30 pixel images with 'read' function.
I upload the data and extract vales.
I place the small 'circle' images on the blank one using the composite command.
outimage.composite("some file.png",pixelx,pixely,InCompositeOp);
This all works fine and the images come up the way I want them too.
However its painfully SLOW. It takes 20 seconds to do one image, and I have 1000 of them. Surely there must be a better way to do this. I've seen other researchers simulate images way more complex and way faster. It's quite possible I took the wrong approach. Maybe I sould be 'drawing' circles instead of 'pasting' them or something. I'm quite baffled. Any input is appreciated.
I suspect that you just need some library that is capable of drawing circles on bitmap and saving that bitmap as png.
For example my Graphin library: http://code.google.com/p/graphin/
Or some such. With Graphin you can also draw one PNG on surface of another as in your case.
You did not give any information about the platform you are using (only "C++"), so if you are looking for a platform independent solution, the CImg library might be worth a try.
http://cimg.sourceforge.net/
By the way, did you try drawing the circles using the ImageMagick C++ API Magick++ instead of "composing" them? I cannot believe that it is that slow.
I am trying to create a piece of software that can be used to create VERY large (10000x10000) sized bitmaps. All I need is something that can work in monochrome, since the required output is a matrix containing details of black and white pixels in the bitmap. The closest thing I can think of is a font editor, but the size is a problem.
Is there any library out there that I can use to create the software, or will I have to write the whole thing from the start?
Edited on May 25: OK, so I've been searching around and I have found that using the GtkTree Widget is a good way to create grids. Has anybody tried that with the large sizes that I require? And if so, can it be made to look like a drawing surface rather than a Spreadsheet like view?
Why don't you use bitmap objects, like gdk pixmaps if you use GTK?
10,000 x 10,000 pixels with a depth of 1 (monochrome) is 100,000,000 bits, which is 12,500,000 bytes, around 12 megabytes.
Not that large.