Rendering a text image following a line

• US 8,416,244 B2
• Filed: 09/26/2011
• Issued: 04/09/2013
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Cornell, Brian
• Primary Examiner(s): Wu, Xiao M.
• Assistant Examiner(s): BUTTRAM, ALAN T
• Application Number:
  US13/244,771
• Publication Number:
  US 20130002705A1
• Time in Patent Office: 561 Days
• Field of Search: 345467-4691, 345471-472, 382177-178
• US Class Current: 345/467
• CPC Class Codes: G06T 11/20 Drawing from basic elements, e.g. lines or circles
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves

Abstract

A graphics or image rendering system, such as a map image rendering system, receives image data from an image database in the form of vector data that defines various image objects, such as roads, geographical boundaries, etc., and textures defining text strings to be displayed on the image to provide, for example, labels for the image objects. The imaging rendering system renders the images such that the individual characters of the text strings are placed on the image following a multi-segmented or curved line.

Claims

1. A computer-implemented method for rendering an image on a display device, comprising:

determining, using a computer device, a line within the image along which to render a text string that is stored as a set of pixelated text characters within an image lookup table;

determining, using the computer device, a plurality of line segments associated with the line and a range associated with each line segment wherein the different ranges for each of the line segments relate to different portions of the line;

forming, using the computer device, a text box for each of the plurality of line segments, each of the text boxes being oriented to draw text in an upright position along an associated line segment;

selecting, using the computer device, one of the text boxes in which to render a text character of the text string;

selecting, using the computer device, one of the text characters from the text string stored as a set of pixelated text characters within the image lookup table;

determining, using the computer device, if a center of the one of the text characters, when rendered in the one of the text boxes on the image, will be within the range of the line segment associated with the one of the text boxes including reading a set of encoding data for the one of the text characters, the encoding data specifying the center of the one of the text characters in at least one direction; and

rendering, using the computer device, the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes; and

not rendering the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the one of the text boxes will not be within the range of the line segment associated with the one of the text boxes.

2. The computer implemented method of claim 1, further including selecting a different one of the plurality of text boxes as the one of the text boxes for use in rendering the one of the text characters on the display device if the center of the one of the text characters, when rendered in the one of the text boxes, will not be within the range of the line segment associated with the one of the text boxes.

3. The computer-implemented method of claim 1, further including selecting each one of the text characters from the text string stored within the image lookup table in turn and, for each selected one of the text characters, performing the steps of;

determining, using the computer device, if the center of the selected one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes,

rendering, using the computer device, the selected one of the text characters on the display device using the one of the text boxes if the center of the selected one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes, and

selecting a different one of the plurality of text boxes as the one of the text boxes for use in rendering the selected one of the text characters on the display device if the center of the selected one of the text characters, when rendered in the one of the text boxes, will not be within the range of the line segment associated with the one of the text boxes.

4. The computer-implemented method of claim 1, wherein reading a set of encoding data for the one of the text characters includes reading encoding data specifying the width of the one of the text characters.

5. The computer-implemented method of claim 1, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes oriented along a length of an associated one of the line segments and having a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment.

6. The computer-implemented method of claim 5, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes so that the start of each text box extends a predetermined distance, in the direction of the length of the associated line segment, before the start of the line segment and so that the end of the text box extends the predetermined distance, in the direction of the line segment, past the end of the line segment.

7. The computer-implemented method of claim 6, wherein the predetermined distance is half the width of one of the text characters of the text string stored in the image lookup table when formed in the text box.

8. The computer-implemented method of claim 5, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes so that the height of the text box extends a predetermined distance orthogonally to the direction of an associated line segment.

9. The computer-implemented method of claim 1, further including using a fragment shader within the computer device to determine if the center of the one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes and to render the one of the text characters on the display device using the one of the text boxes if the one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes.

10. A method of rendering text along a line within an image being rendered on a display device, comprising:

storing a text string lookup table in a computer memory, the text string lookup table including a multiplicity of text characters associated with a text string and encoding data defining a center position of each of the multiplicity of text characters associated with the text string;

determining using a computer device a plurality of line segments associated with a line in the image along which the text string is to be rendered and a range associated with each line segment wherein the different ranges for each of the line segments relate to different portions of the line;

forming a text box for each of the plurality of line segments using the computer device, each of the text boxes being oriented to draw text in an upright position along an associated line segment in the image; and

for each text character in the text string;

selecting using the computer device one of the text boxes in which to render the text character of the text string;

reading the encoding data from the text string lookup table using the computer device and determining if the center position of the text character, when rendered in the selected one of the text boxes, will be within the range of the line segment associated with the selected one of the text boxes; and

rendering the text character in the image on the display device using the selected one of the text boxes if the center position of the text character when rendered in the selected one of the text boxes will be within the range of the line segment associated with the selected one of the text boxes or otherwise selecting a different one of the plurality of text boxes as the selected one of the text boxes if the center position of the text character, when rendered in the selected one of the text boxes, will not be within the range of the line segment associated with the selected one of the text boxes.

11. A method of rendering text along a line of claim 10, wherein reading the encoding data from the text string lookup table for one of the text characters includes reading encoding data specifying the center position of the one of the text characters in a direction along the length of the text string.

12. A method of rendering text along a line of claim 11, wherein reading the encoding data from the text string lookup table for the one of the text characters includes reading encoding data specifying the width of the one of the text characters along the length of the text string.

13. A method of rendering text along a line of claim 10, wherein forming a text box for each of the plurality of line segments includes forming each text box oriented along a length of an associated one of the line segments and having a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment, wherein forming a text box for each of the plurality of line segments includes forming each text box so that the start of each text box extends a predetermined distance, in the direction of the length of the associated line segment, before the start of the line segment and so that the end of each text box extends the predetermined distance, in the direction of the line segment, past the end of the associated line segment.

14. A method of rendering text along a line of claim 13, wherein the predetermined distance is half the width of one of the multiplicity of text characters associated with the text string when formed in the text box.

15. A method of rendering text along a line of claim 10, wherein storing the text string lookup table in a computer memory includes storing encoding data defining a center position of each of the multiplicity of text characters associated with the text string as a pixel value for each column of pixels of the text string.

16. A method of rendering text along a line of claim 10, wherein storing the text string lookup table in a computer memory includes storing encoding data defining a center position of each of the multiplicity of text characters associated with the text string as a pixel value for each column of pixels of the text string, wherein a particular pixel value is used to define a center position of a text character and pixel values that are incremented or decremented from the particular pixel value are used to indicate at each pixel column of a text character, a distance to the center position of the text character.

17. A method of rendering text along a line of claim 10, wherein storing the text string lookup table in a computer memory includes storing a set of glyphs within a field of glyphs in the text string lookup table, and storing further encoding data for each text character within the text string, the further encoding data referencing one of the glyphs to use as the text character at a position within the text string.

18. A method of rendering text along a line of claim 17, including storing the encoding data and the further encoding data as being correlated to one another by location in the text string lookup table.