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How to FAQ
Date: Jul-26-2002 04:14
1. How can I make the yellow acknowledgement message at the bottom of my charts disappear?

The acknowledgement message only appears in the free public version of ChartDirector. The licensed version will not have such a message. Please refer to our purchase page for details of available type of licenses.

2. How can I made a chart with a transparent background?

You can use the setTransparentColor method of the BaseChart object to set the transparent color. For example, if you want to set the white color as the transparent color, the ASP/VBScript code to do that is "c.setTransparentColor(&Hffffff)". Note that only PNG and GIF image formats support transparent background.

3. How can I display multiple charts on the same web page?

Simply put multiple <IMG> tags in your web page, and use them to reference the scripts that generate the charts.

4. How can I make one image containing two (or more) charts?

If you are displaying the charts in a web page, you may consider to simply leave the charts as two separate images. By putting them together in a web page, they will look like one image. You web site may load faster with two small chart images instead of one big chart image.

If you really want to have one image containing two charts, you can use the "merge" method of the DrawArea object. The "merge" method allows you to merge two arbitrary images together. You can use it to merge two charts together.

5. How can I make my chart small in file size?

The followings are some tips if you are concerned your image is getting too large in file size.

  • Use fewer colors. Image compression works much better if you have fewer colors. Also, ChartDirector uses 4 bits per pixel if you have 16 colors or less, 8 bits per pixel for 256 colors or less. For more than 256 colors, it will use true color mode (24 bits per pixel) for image formats that support true color mode.

  • Use PNG image format for images with less than 256 colors. It offers the best compression. See the Image Formats FAQ for the properties for various image formats.

  • Try not to use complex background image or wallpaper. This may increase color count significantly. If you have to use a background image, third party graphics program (e.g. Paint Shop Pro or PhotoShop) to to reduce its number of colors and save it in GIF or PNG format.

  • Using semi-transparent colors carefully. The semi-transparent color will mix in with the original background color to produce new colors. If you are using complex background images as well, this may multiply the number of colors very quickly.

  • Do not use interlace mode. By default, ChartDirector does not use interlacing, but you can enable it by using ChartDirector API. Note that interlacing will typically increase image size by 20% - 30%, because interlacing makes image compression less efficient.

  • Use force palette mode. If you cannot think of a way to ensure your chart is less than 256 colors, you may ask ChartDirector to force the image to 256 colors by using the setPaletteMode method. The ASP/VBScript code to do this is "c.getDrawArea().setPaletteMode(cd.ForcePalette)". In force palette mode, ChartDirector will use dithering if necessary to reduce the number of colors to 256 or less.

  • Disable anti-alias text. ChartDirector by default uses anti-alias text if for large fonts or bold fonts. (Small fonts may look worst if using anti-alias.) Anti-alias increases grey levels and hence number of colors. The ASP code to disable anti-alias is "c.getDrawArea().setAntiAliasText(cd.NoAntiAlias)".

? 2002 Advanced Software Engineering Limited