Support left handed option

README.md

@@ -2,20 +2,42 @@
 
 <img src="./resources/minor_chord_example.svg">
 
-## Building
+## Building the program
 
-```
-$ go build -o bin/ cmd/main.go
-```
+1. Install git on your system. See https://git-scm.com/book/en/v2/Getting-Started-Installing-Git.
+
+2. Install the Go programming language on your system. See https://golang.org/doc/install.
+
+3. Clone this repository. See https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/cloning-a-repository-from-github/cloning-a-repository.
+
+4. Go into the cloned directory, for example in Unix / Linux systems by running `cd guitar-chord-shapes`.
+
+5. Build the program by running `go build -o bin/ cmd/main.go`.
+
+## Running the program
+
+### Basics
+
+To run the program, just type `./bin/main` with the appropriate command line arguments as will be shown below. This needs to be done from the command line terminal. If you have only used graphical interfaces in the past, this might sound daunting, but it is easy. There are several resources online.
+
+### Available printers
+
+The program will print output to STDOUT. In simple words, this means that the output will print to the screen.
+
+There are two output options available.
+
+ * ASCII (default) - lightweight for those who prefer to stay on the terminal.
+ * SVG (when run with `-svg`) - convenient because the SVG output can be converted to JPG or PNG using free converter tools available online.
+
+If you want the output to go to a file (which you will likely need when using the SVG option), you will need to redirect the output to the file such as `./bin/main -svg {some args} > somefileonthecomputer.svg`.
 
-## Available printers
+### Accessibility options
 
-All printers write to STDOUT.
+Run with the `-left` argument if you are left handed.
 
- * ASCII (default)
- * SVG (when run with `-svg`)
+### Use cases
 
-## Use cases
+*All examples shown here print in ASCII and use right-handedness.*
 
 **Simple chord - e.g. minor chord**
 

cmd/main.go

@@ -67,6 +67,15 @@ func (gsp *gStringPattern) add(n *note) {
     gsp.notes = append(gsp.notes, n)
 }
 
+func (gsp *gStringPattern) mirrored() *gStringPattern {
+
+    out := newGStringPattern()
+    for i := len(gsp.notes) - 1; i >= 0; i -- {
+        out.add(gsp.notes[i])
+    }
+    return out
+}
+
 func (gsp *gStringPattern) leftAligned() bool {
     return len(gsp.notes) > 0 && gsp.notes[0] != nil
 }
@@ -98,6 +107,14 @@ func (p *pattern) add(gsp *gStringPattern) {
     p.gStringPatterns = append(p.gStringPatterns, gsp)
 }
 
+func (p *pattern) mirrored() *pattern {
+    out := newPattern()
+    for _, gsp := range p.gStringPatterns {
+        out.add(gsp.mirrored()) 
+    }
+    return out
+}
+
 func (p *pattern) leftAligned() bool {
     for _, gsp := range p.gStringPatterns {
         if gsp.leftAligned() {
@@ -409,6 +426,8 @@ var aliasedRoot uint
 
 var numFretsPerPattern uint
 
+var leftHanded bool
+
 var printSvg bool
 
 func main() {
@@ -423,6 +442,8 @@ func main() {
 
     flag.UintVar(&numFretsPerPattern, "frets", uint(4), "the number of frets per pattern")
 
+    flag.BoolVar(&leftHanded, "left", false, "format for lefties")
+
     flag.BoolVar(&printSvg, "svg", false, "whether to print in SVG format")
 
     flag.Parse()
@@ -484,7 +505,11 @@ func main() {
         acceptPattern := pattern.leftAligned() && (pattern.rightAligned() || lastAcceptedPattern == nil || !pattern.rtrim().subPatternOf(lastAcceptedPattern))
         if acceptPattern {
             lastAcceptedPattern = pattern
-            pp.accept(pattern)
+            if leftHanded {
+                pp.accept(pattern.mirrored())
+            } else {
+                pp.accept(pattern)
+            }
         }
     }
     pp.pprint()