need help converting an txt file to a jpg to display as a thumbnail

[jklosak]

I have been writing a program for about 10 years and I display image files as thumbnails much as picassa does. I would like an image of a txt file to be displayed also.
GdipLoadImageFromFile fails with non image file.
any suggestions how to write code to display an image of a .txt file ?
many thanks
I know it is possible as one can purchase software that converts rtf to jpg but I need it in my program.
john

[dedndave]

unless it is a large thumbnail, there won't be much detail - not enough to make the text legible
if you want the thumbnail to be representative of the appearance of the text file, you can make a small BMP image with a simple reduction
you may want to line wrap at 80 characters and just make a little black and white bitmap
i think windows has the code to generate JPG's from bitmaps - i haven't as yet played with enough of it to know for sure

[jklosak]

It is a large thumbnail andit has to be high resolution and readable.
thanks for your thoughts
John

[dedndave]

ok - reducing text to readable small text is not a graphics issue
if you do it that way, it will not be legible
what you want to do is create a custom font of your own
using about 5 x 6 pixels, you can make a very legible font
smaller fonts may be made, but are a little more difficult to read - i have used 4 x 5 for some uses
you are going to read the text file in and convert it to the graphics font, creating a bitmap

[jj2007]

It is a large thumbnail andit has to be high resolution and readable.
thanks for your thoughts
John

Technically it might be possible to grab the DC of a richedit window, and save the bitmap to a file. Png would probably yield much smaller thumbnails than jpg, but that is a matter of taste. In any case, it would be great if you could take an existing text, make a screenshot and produce the thumbnail "by hand" with paintshop etc, in order to get an idea of the desired output. As Dave pointed out, fonts may be stumbling block.

[Ficko]

I would use GDI+

The steps:

1.) Define a BITMAPINFO
2.) Fill it like this

Code Select Expand


BMI.bmiHeader.biSize = SIZEOF(BITMAPINFOHEADER)
BMI.bmiHeader.biWidth = 1728
BMI.bmiHeader.biHeight = -2290
BMI.bmiHeader.biPlanes = 1
BMI.bmiHeader.biBitCount = 1
BMI.bmiColors[1].rgbBlue = 0xFF
BMI.bmiColors[1].rgbGreen = 0xFF
BMI.bmiColors[1].rgbRed = 0xFF

3.) Hdc = CreateCompatibleDC(NULL)
4.) hBitmap = CreateDIBSection(Hdc,BMI,DIB_RGB_COLORS,pvBits,0,0)

So you have a B/W DIB section.

5.) hOldBMP = SelectObject(Hdc,hBitmap)
     PatBlt(Hdc,0,0,1728,2290,WHITENESS)
6.) You can set fonts and linestyles
7.) SetTextAlign, DCh,TA_UPDATECP to move the cursor.
8.) Use TextOutA, DCh......  to write on the bitmap
9.) Convert the GDI bitmap to GDI+ and clone it
pImage1 = GDIP_BITMAPFROMHBITMAP(hBitmap)
pImage2 = GDIP_CLONE(pImage1)

use resize or what else you want.

EDIT :
Actually you can also leave out GDI+ and just use
CopyImage, hdc,IMAGE_BITMAP,pWidth,pHeight,LR_COPYDELETEORG OR LR_COPYRETURNORG OR LR_MONOCHROME
to resize.

GDI+ may does a better job by converting it to true color and you can set the "GdipSetSmoothingMode" to "SmoothingModeHighQuality" before resize.

[MichaelW]

At least for CRTs, very small fonts tend to be unreadable on the screen because the effective dot density is too low. I suspect that converting text to an image and then scaling the image would make this problem much worse. I think simply drawing the text in a smaller font would produce better results. The attachment is a crude test app that allows you to view text in an edit control, in a specified font over a range of point sizes. Note that not all fonts are available in the full range of sizes.

[raymond]

converting an txt file to a jpg to display as a thumbnail

Just like everything must be converted to binary to run on your computer, ALL images must be converted to a bitmap before being displayed by Windows. Producing an image in any other format would simply require it to be converted back to a bitmap. Ficko's solution to produce a bitmap immediately is definitely the best (and simplest) approach.

[jklosak]

Thanks a lot.
I think the use GDI+ sound great else I will try to work with the DC of a richedit window.

thanks very much for all your help

John Klosak