Google user map text labeling method based on SVG

Abstract

The invention discloses a Google user map text labeling method based on an SVG. The method includes the steps that an SVG object with a path text is added to a self-defining overlaying layer of a Google map, and when the overlaying layer is drawn, a current map projection is acquired through a getProjection method; a labeled path represented by longitudes and latitudes is converted into a pixel path under the current projection; the length of the pixel path is calculated and compared with the length of a labeled text, if the pixel path is too short, the SVG object is not displayed; the starting point position of the labeled text on the pixel path is determined so that it can be guaranteed that the text is located in the middle of the path; the space, actually occupied by the labeled text, of the pixel path is determined according to the length of the text; the minimum coordinate value of the labeled text on the pixel path is determined through comparison and serves as a top left corner coordinate of the SVG object; the pixel path of the labeled text relative to the SVG top left corner is calculated; the text pixel path expressed by coordinate strings is converted into a path of path elements in the SVG, and d attributes of the path are replaced. The text labeling problem is solved, and a new way is found for Google user map text labeling.

Description

technical field [0001] The invention belongs to the technical field of computers, and relates to an SVG-based Google user map text labeling method. Background technique [0002] Maps are difficult to understand without text, and each map element requires a text annotation. Traditional GIS (Geographic Information System, Geographic Information System) software, such as ArcGIS, Maplnfo, etc., has rich automatic text labeling functions, and there is no need to consider labeling issues when establishing application systems for secondary development. However, with the widespread use of Google Maps in recent years, more and more users hope to build applications on Google Maps. Google Maps API V3 is a basic tool for building Google Maps application system, which provides many map drawing functions, but lacks corresponding text labeling functions. [0003] For labeling problems, Google provides several solutions, that is, using Marker symbols (default or custom symbols), pop-up In...

AI Technical Summary

Problems solved by technology

[0005] However, the HTML5Canvas element has great limitations in text drawing, and can only be drawn from left to right in the horizontal direction

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