Search TipsRenderTile Method
Renders and caches the specified tile at the specified level into an image.
| Visual Basic |
|---|
Public Function RenderTile( _
ByVal strFormat As String, _
ByVal level As Integer, _
ByVal x As Integer, _
ByVal y As Integer, _
ByVal mode As Integer _
) As Integer
|
| image/jpeg | JPEG is suitable for photographs, and is understood by almost all browsers. |
| image/gif | GIF is suitable for displaying linework and is preferable to JPEG. |
| image/png | PNG is the preferred format, suitable for displaying a mixture of vector and raster data, and understood by latest versions of most browsers. |
| image/x-MS-bmp | Windows BMP is an image file format understood by almost all browsers. |
| application/x-msmetafile | Windows Meta File is understood by Internet Explorer and other browsers. |
| application/pdf;PaperFormat=… | PDF will normally require a browser plugin. The PaperFormat parameter is mandatory; additional standard PDF formatting parameters can be supplied. |
The following list gives the parameter names and values for image formats:
PhotometricInterpretation: (for PNG only, GIF & JPEG are implicitly PaletteColor)
- PaletteColor
- RGB
- RGBA
DitherPalette: (for PaletteColor only)
- ColorCube125
- ColorCube216
- BlackWhite
- GrayScale/GreyScale
- Adaptive
- OctTree
- Custom
- a literal palette, in the form RRGGBBRRGGBBRRGGBBRRGGBB....
DitherAlgorithm: (for PaletteColor only)
- Default
- SystemSnap
- SystemDither
- PaletteSnap
- FloydSteinberg
Transparent: (for PaletteColor and RGB only)
- True
- False
BGColor: (for PaletteColor and RGB only)
- RGB color in format 0xRRGGBB
Quality: (for JPEG only)
- number from 1 to 10
level
level 0 corresponds to a scale of 1:1, Level 8
corresponds to a scale of 1:10, Level 16 corresponds to a scale of
1:100 and so on.
The intermediate levels (1 to 7, 9-15, and so on) have scale
multipliers 1.25, 2.5, 3.75, 5.0, 6.25, 7.5 and 8.75.
The size of a map extent which is covered by a tile depends not only on
the coordinate reference system, but also on the setting of the
_outputDpi& system variable. The maximum cache size is
configured with the registry value MaxMapCacheSize, specified in
Megabytes. The default value is 16MB.
These values define the tile location at the current level. The tile at x=0, y=0 has its lower-left corner at the origin of the coordinate system. Tiles always have a width and height of 256 pixels. To calculate the tile extent in coordinate system units at scale 1:1 (= level 0), use these expressions:
double pixmm = 25.4 / GetInt("_OutputDPI&");
double tileWH = 256 * pixmm / 1000.0 / toMetre;
At larger levels, multiply with the scale factor corresponding to the level.
The tile at (level, x, y) has its lower-left corner at:
- (x*tileWH*scale[level], y*tileWH*scale[level])
and its upper-right corner at:
- ((x+1)*tileWH*scale[level], (y+1)*tileWH*scale[level])
| SIS_RF_BACKGROUND | draws the background SWD |
| SIS_RF_FOREGROUND | draws the foreground SWD |
| SIS_RF_WATERMARK | draws the watermark as specified by the GeognoSIS manager |
This is a bitfield, so any of the constants can be combined by bit-wise OR.
Available: GEO
Groups:
sis.RenderTile ("image/png", level, posX + X, posY + Y, SIS_RF_BACKGROUND)
Some example format strings with parameters:
image/png;PhotometricInterpretation=RGB
image/png;PhotometricInterpretation=PaletteColor,DitherPalette=OctTree
image/png;PhotometricInterpretation=PaletteColor,DitherPalette=OctTree,DitherAlgorithm=SystemSnap
image/gif;DitherPalette=OctTree,DitherAlgorithm=SystemSnap
image/jpeg;Quality=95
application/pdf;paperformat=A4,... + the usual parameters