Graphics scaled by variable

[Anon]

I am trying to build a snow themomerter for a web site. What this would be is a graphic that looks like a themometer. Inside this graphic i would need a black bar to grow upwards according to a numerical value. The bottom of the graphic should be a numberical value of 0 and the very top is 355. Is this possible and if so what do i need to read up on to implement this. I guess the approach i would need would be something similar to a poll.

Thanks for any help you could give me.

Ira

[[deleted]]

You could chop the thermometer into pieces and fit them into a table so that you have one TD for the middle bar (the bit that moves up and down)
Then you make two images, one white and one blue, of one pixel high, and the width of the bar itself.

Then you print the bar, and in the center cell you print the two images. For thw white image you force the height to the "empty" height of the bar, and for the blue you enter the height that the thermometer should indicate.

This is just a fast hack, it would be nicer (but slower)
to make an image of the thermometer, load that into a GD image, draw the center bar over the image, and print the GD image back to the browser.
but like I said, this is probably not something you want to do for every pageview, but you could use it to create a new image every time the values change.

[Anon]

I like the idea of the second version using an image of the themometer. But the questions I have is how do i make the bar grow up and down. And make it grow up and down via the numerical value of the variable. And have bounds of 0 and 355.

Thanks.

Ira

[[deleted]]

Check the manual about the "image" functions using the GD library, there is a function that can draw filled-rectangles (bars).
This simply takes coordinates of on corner and coordinates of the opposite corner, so you can use the Y-axis (plus an offset to get to where the bar should be) to determine how long the bar should be.

If you don't have enough Y-axis space you can devide or multiply the value to make it fit inside the thermometer.