Récapitulatif
Exports the page layout or data frame of a map document (.mxd) to the Portable Network Graphics (PNG) format.
Discussion
PNG is a raster format designed for use on the Web as an alternative to GIF. It supports 24-bit color and is compressed using a lossless compression. PNG files also have the ability to define a transparent color; part of the image can display as transparent in a Web browser, allowing backgrounds, images, or colors to show through. On most images, PNG can achieve greater compression (and thus smaller file sizes) than GIF. PNGs exported from the data view in ArcMap can be generated with an accompanying world file for use as georeferenced raster data. This format is gaining popularity in the Web design community.
To export a single data frame instead of the entire page layout, pass a DataFrame object to the function's data_frame parameter. Because data frame exports do not have an associated page to provide height and width information, you must provide this via the df_export_width and df_export_height parameters.
Controlling graphic quality of the generated image differs for page layout exports versus data frame exports. When exporting a page layout, control image detail by changing the resolution parameter. When exporting a data frame, keep the resolution parameter at its default value, and change the df_export_width and df_export_height parameters to alter image detail. The height and width parameters directly control the number of pixels generated in the export file and are only used when exporting a data frame. Images with larger numbers of pixels will have higher image detail. For most page layout exports, the default parameter values should generate good results and nice looking export images on the first try. For data frame exports, you may need to experiment with the df_export_width and df_export_height values a few times before getting the result you want.
World files are not generated for page layouts; a referenced data frame must be provided or the export will fail.
Refer to the Exporting your map topic in ArcGIS Help for more detailed discussions on exporting maps.
Syntaxe
ExportToPNG (map_document, out_png, {data_frame}, {df_export_width}, {df_export_height}, {resolution}, {world_file}, {color_mode}, {background_color}, {transparent_color}, {interlaced})| Paramètre | Explication | Type de données |
map_document | A variable that references a MapDocument object. | MapDocument |
out_png | A string that represents the path and file name for the output export file. | String |
data_frame | A variable that references a DataFrame object. Use the string/constant "PAGE_LAYOUT" to export the map document's page layout instead of an individual data frame. (La valeur par défaut est PAGE_LAYOUT) | Object |
df_export_width | A number that defines the width of the export image in pixels for a data frame export. df_export_width is only used when exporting a data frame. Exporting a page layout uses the map document page width instead of df_export_width. (La valeur par défaut est 640) | Integer |
df_export_height | A number that defines the height of the export image in pixels for a data frame export. df_export_height is only used when exporting a data frame. Exporting a page layout uses the map document page height instead of df_export_height. (La valeur par défaut est 480) | Integer |
resolution | A number that defines the resolution of the export file in dots per inch (DPI). (La valeur par défaut est 96) | Integer |
world_file | If set to True, a georeferenced world file is created. The file contains pixel scale information and real-world coordinate information. (La valeur par défaut est False) | Boolean |
color_mode | This value specifies the number of bits used to describe color.
(La valeur par défaut est 24-BIT_TRUE_COLOR) | String |
background_color | A defined color is used as a background to the image, or as a mask in the case of monochrome masked exports. (La valeur par défaut est 255, 255, 255) | String |
transparent_color | A defined color to be displayed as transparent in the image. | String |
interlaced | If set to True, an interlaced image will be created. An interlaced image displays as a series of scan lines rather than as a whole image at one time. (La valeur par défaut est False) | Boolean |
Exemple de code
ExportToPNG example 1
This script opens a map document and exports the page layout to a PNG file using default values for all options.
import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
arcpy.mapping.ExportToPNG(mxd, r"C:\Project\Output\Project.png")
del mxd
ExportToPNG example 2
This script will export a single data frame instead of the entire page layout, similar to exporting from data view in the ArcMap application. The default values for df_export_width and df_export_height are 640 and 480. By passing larger values for these parameters, we are able to produce an output image with higher detail. Setting world_file = True generates a georeferenced world file in the same directory as the output file.
import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Transportation")[0]
arcpy.mapping.ExportToPNG(mxd, r"C:\Project\Output\ProjectDataFrame.png", df,
df_export_width=1600,
df_export_height=1200,
world_file=True)
del mxd