Add --y[r]range command line arguments.

They have the format [min]:[max] where either min or max can be left
out, if you like.

src/main.c

@@ -69,6 +69,14 @@ struct context {
 	char* yrlab;
 	PangoLayout* yrlab_layout;
 
+	struct {
+		char* arg;
+		struct {
+			bool set;
+			double value;
+		} max, min;
+	} yrange, yrrange;
+
 	PangoFontDescription* tick_font_description;
 
 	double margins[4];
@@ -183,6 +191,22 @@ int main( int argc, char** argv ) {
 			.description = "Ignore columns matching regex "
 				"(can be given multiple times)",
 			.arg_description = "regex"
+		}, {
+			.long_name = "yrange",
+			.short_name = '\0',
+			.flags = G_OPTION_FLAG_IN_MAIN,
+			.arg = G_OPTION_ARG_STRING,
+			.arg_data = &( context->yrange.arg ),
+			.description = "Y-axis range [min]:[max]",
+			.arg_description = "range",
+		}, {
+			.long_name = "yrrange",
+			.short_name = '\0',
+			.flags = G_OPTION_FLAG_IN_MAIN,
+			.arg = G_OPTION_ARG_STRING,
+			.arg_data = &( context->yrrange.arg ),
+			.description = "Right y-axis range [min]:[max]",
+			.arg_description = "range",
 		}, {
 			.long_name = "font",
 			.short_name = 'f',
@@ -357,6 +381,92 @@ static void app_activate( GtkApplication* app, void* data ) {
 	g_source_set_callback(
 		(GSource*) source, &data_callback, context, NULL );
 
+	char* yrange = context->yrange.arg;
+
+	if ( NULL != yrange ) {
+		while ( '\0' != *yrange && isspace( *yrange ) ) {
+			yrange++;
+		}
+		if ( ':' == *yrange ) {
+			context->yrange.min.set = false;
+		} else {
+			context->yrange.min.set = true;
+			char* end;
+			context->yrange.min.value = strtod( yrange, &end );
+			if ( end == yrange ) {
+				fprintf( stderr, "Invalid yrange format\n" );
+				exit( 1 );
+			} else {
+				while ( '\0' != *end && isspace( *end ) ) {
+					end++;
+				}
+				if ( ':' != *end ) {
+					fprintf( stderr, "Invalid yrange format\n" );
+					exit( 1 );
+				}
+				yrange = end;
+			}
+		}
+		yrange++;
+		while ( '\0' != *yrange && isspace( *yrange ) ) {
+			yrange++;
+		}
+		if ( '\0' == *yrange ) {
+			context->yrange.max.set = false;
+		} else  {
+			char* end;
+			context->yrange.max.value = strtod( yrange, &end );
+			if ( end == yrange ) {
+				fprintf( stderr, "Invalid yrange format\n" );
+				exit( 1 );
+			}
+			context->yrange.max.set = true;
+		}
+	}
+
+	char* yrrange = context->yrrange.arg;
+
+	if ( NULL != yrrange ) {
+		while ( '\0' != *yrrange && isspace( *yrrange ) ) {
+			yrrange++;
+		}
+		if ( ':' == *yrrange ) {
+			context->yrrange.min.set = false;
+		} else {
+			context->yrrange.min.set = true;
+			char* end;
+			context->yrrange.min.value = strtod( yrrange, &end );
+			if ( end == yrrange ) {
+				fprintf( stderr, "Invalid yrrange format\n" );
+				exit( 1 );
+			} else {
+				while ( '\0' != *end && isspace( *end ) ) {
+					end++;
+				}
+				if ( ':' != *end ) {
+					fprintf( stderr, "Invalid yrrange format\n" );
+					exit( 1 );
+				}
+				yrrange = end;
+			}
+		}
+		yrrange++;
+		while ( '\0' != *yrrange && isspace( *yrrange ) ) {
+			yrrange++;
+		}
+		if ( '\0' == *yrrange ) {
+			context->yrrange.max.set = false;
+		} else  {
+			char* end;
+			context->yrrange.max.value = strtod( yrrange, &end );
+			if ( end == yrrange ) {
+				fprintf( stderr, "Invalid yrrange format\n" );
+				exit( 1 );
+			}
+			context->yrrange.max.set = true;
+		}
+	}
+
 	gtk_window_present( GTK_WINDOW( window ) );
 
 }
@@ -1092,6 +1202,22 @@ static void plot_draw( GtkDrawingArea* plot,
 		context->xdist = xrange[1] - xrange[0];
 	}
 
+	if ( context->yrange.min.set ) {
+		ylrange[0] = context->yrange.min.value;
+	}
+
+	if ( context->yrange.max.set ) {
+		ylrange[1] = context->yrange.max.value;
+	}
+
+	if ( context->yrrange.min.set ) {
+		yrrange[0] = context->yrrange.min.value;
+	}
+
+	if ( context->yrrange.max.set ) {
+		yrrange[1] = context->yrrange.max.value;
+	}
+
 	int xdivs = pretty( &( xrange[0] ), &( xrange[1] ), 10 );
 	int yldivs = lset ?
 		pretty( &( ylrange[0] ), &( ylrange[1] ), 10 ) : 0;