Colour variations on the Print1456 1456 applet landscape.

William Overington

Here are six variations on the Print1456 1456 applet landscape. The original version of the Print1456 1456 applet landscape is also updated. The only difference of the six new variations from the new version of the Print1456 1456 applet landscape is that instead of a white background, these six versions each have a coloured background. Each of the new versions has the same update as the Print1456 1456 applet landscape itself. Each version is supplied here as a Java class file together with an HTML file. A link to the Print1456 1456 applet landscape is also here. The original link in the document where the Print1456 1456 applet landscape was introduced will now also supply this updated version. A link to the 1456 engine is also supplied, for convenience. The Print1456.htm file has not been altered and programs produced that use the Print1456 1456 applet landscape are not affected as the update is concerned with the redrawing of the display produced if the applet display is scrolled off the screen and then scrolled back onto the screen. This updating made on 17 October 2000.

Print1456.htm	Print1456.class
Print1456blue.htm	Print1456blue.class
Print1456darkGray.htm	Print1456darkGray.class
Print1456gray.htm	Print1456gray.class
Print1456magenta.htm	Print1456magenta.class
Print1456red.htm	Print1456red.class
Print1456yellow.htm	Print1456yellow.class
	Engine1456.class

The nature of the update and the background to it being made are now described, in the hope that readers will regard the background as to why the update was made as being interesting. The Print1456 1456 applet landscape is useful for making line drawings and drawing graphs, for example in the illustrating of free to the end user distance education material. The section from the <applet all the way through to </applet> may be copied from one of the HTML files above and pasted into the HTML file of a document that it is desired to illustrate. The values of width and height being used may be reduced from those used in the original file. In this document, for example, a value of 200 is used for both width and height. The 200 means 200 pixels. Where the background of a page of text is white, a diagram drawn on a blue background with white lines can be stylishly effective. Here is an example of a diagram produced at a size of 200 pixels by 200 pixels and placed within the main body of some text. The size of 200 pixels by 200 pixels was selected in the call of the applet from within this HTML file. The triangle is drawn using 1456 object code in the HTML file of this document. The 24 point sans serif italic lettering is produced using a 1242? command within the 1456 software. Although this is a static diagram, the facility of using the mouse button press is available if a diagram that changes when the user clicks upon it is desired. This feature, until the update that is being described in this document, had an unfortunate effect in a diagram that is intended to be a static diagram if the user happens to press the mouse button upon it and then scroll the page so that the diagram goes off the visible page and then the user scrolls the page so that the diagram reappears. The applet remembered that it has an obeycode of 41 active and tried to obey 1456 object code at label 41. This, by default, is just a Halt command. So, a blank display of just the background colour was produced. One option, I thought, would be to supply a 1456 applet landscape called Static1456 or some similar name where the mouse is not active. However, this has not been done as the effect could easily be switched off by placing the code 41:1JH as the entry point 41 code. This simply caused the applet to produce a display exactly the same as if it had had an obeycode of 1 remembered. In view of the fact that this adding of 1J is so easily done and that it would have presented no great inconvenience to a 1456 programmer to do it, I did not provide a 1456 applet landscape called Static1456 as a variant of the Print1456 1456 applet landscape. In order to demonstrate the effect I have prepared a version of the Print1456 1456 applet landscape specifically for the purpose. It is called Print1456blueold and is simply a blue background version of Print1456 as it was before the update. Here I have included two separate usages of the Print1456blueold 1456 applet landscape identical except that the one on the left of the page has the 1J added and the one on the right does not have the 1J added. The purpose of the picture on the right is solely to demonstrate the effect. In normal usage the 1J would have been added. In order to view the demonstration, please click on the two diagrams of triangles that are shown on a blue field. Next scroll the document so that both pictures go off the screen. Next scroll the document so that both pictures are back on the screen.

However, a better method of resolving the problem occured to me. The problem is resolved by making the obeycode value that is held within the applet while it is idling be set to 1 rather than left at the value just used. Those readers who have been looking at the underlying Java implementation of the Print1456 1456 applet landscape might like to know that this change is implemented by adding one line of code at the end of the paint function of the Java software. Thus that part of the software that was programmed as follows has one line added.

                resultchar =
                firefly.obeySoftwareAfterSoftwareInterrupt(screen);
              } while (resultchar == '?');
          }

      }

                resultchar =
                firefly.obeySoftwareAfterSoftwareInterrupt(screen);
              } while (resultchar == '?');
          }
        obeycode = 1;
      }