1 files changed, 152 insertions, 0 deletions
diff --git a/screenbuffer.cpp b/screenbuffer.cpp
new file mode 100644
index 0000000..a382e82
--- /dev/null
+++ b/screenbuffer.cpp
@@ -0,0 +1,152 @@
+#define _GNU_SOURCE
+#include <iostream>
+#include <cstdarg>
+#include <cstdlib>
+#include <cstring>
+#include <cassert>
+#include <unistd.h>
+#include "screenbuffer.h"
+
+using namespace std;
+
+
+static void initTerminal(){
+	cout<<"\x1B[?1049h"  // start alternate screen
+	      "\x1B[2J"  // clear screen
+	      "\x1B[H"  // move to top left
+	    <<flush;
+}
+
+static void deinitTerminal(){
+	cout<<"\x1B[?1049l"  // end alternate screen
+	    <<flush;
+}
+
+
+ScreenBuffer::ScreenBuffer(int W,int H)
+		:W(W),H(H){
+	screen=new char[W*H];
+	prevscreen=new char[W*H];
+	memset(screen,' ',W*H);
+	memset(prevscreen,' ',W*H);
+	initTerminal();
+}
+
+ScreenBuffer::~ScreenBuffer(){
+	delete[] screen;
+	delete[] prevscreen;
+	deinitTerminal();
+}
+
+void ScreenBuffer::moveto(int x,int y){
+	assert(x>=0&&x<W&&y>=0&&y<H);
+	curx=x;
+	cury=y;
+}
+
+void ScreenBuffer::printstr(const char *buf){
+	int basex=curx;
+	for(int i=0;buf[i];i++){
+		if(buf[i]!='\n'){
+			if(curx==W){
+				if(cury==H-1){
+					curx--;
+					break;
+				}
+				curx=basex;
+				cury++;
+			}
+			screen[W*cury+curx]=buf[i];
+			curx++;
+		} else {
+			if(cury==H-1)break;
+			curx=basex;
+		}
+	}
+
+	if(curx==W){
+		if(cury==H-1){
+			curx--;
+		} else {
+			curx=basex;
+			cury++;
+		}
+	}
+}
+
+__attribute__((format (printf, 2, 3)))
+int ScreenBuffer::printf(const char *format,...){
+	va_list ap;
+	va_start(ap,format);
+	char *buf;
+	int ret=vasprintf(&buf,format,ap);
+	va_end(ap);
+	assert(buf);
+
+	printstr(buf);
+
+	free(buf);
+	return ret;
+}
+
+__attribute__((format (printf, 4, 5)))
+int ScreenBuffer::mvprintf(int x,int y,const char *format,...){
+	moveto(x,y);
+
+	va_list ap;
+	va_start(ap,format);
+	char *buf;
+	int ret=vasprintf(&buf,format,ap);
+	va_end(ap);
+	assert(buf);
+
+	printstr(buf);
+
+	free(buf);
+	return ret;
+}
+
+void ScreenBuffer::draw(){
+	bool changed[W*H];
+	for(int i=0;i<W*H;i++){
+		changed[i]=screen[i]!=prevscreen[i];
+	}
+	for(int y=0;y<H;y++){
+		for(int x=1;x<W-1;x++){
+			changed[W*y+x]|=changed[W*y+x-1]&changed[W*y+x+1];
+		}
+	}
+
+	bool prepped=false;
+
+	for(int y=0;y<H;y++){
+		bool needtomove=true;
+		for(int x=0;x<W;x++){
+			if(!changed[W*y+x]){
+				needtomove=true;
+				continue;
+			}
+			if(!prepped){
+				cout<<"\x1B[?25l";  // invisible cursor
+				prepped=true;
+			}
+			if(needtomove){
+				cout<<"\x1B["<<y+1<<';'<<x+1<<'H';
+				needtomove=false;
+			}
+			cout.put(screen[W*y+x]);
+		}
+	}
+	if(prepped){
+		cout<<"\x1B[?12;25h"  // visible cursor
+		    <<"\x1B["<<H<<';'<<W<<'H'  // move past screen
+		    <<flush;
+	}
+
+	memcpy(prevscreen,screen,W*H);
+}
+
+void ScreenBuffer::emergencyDeinit(){
+	static const char *str="\n\x1B[?1049l\x1B[12;25h^C\n";
+	write(1,str,strlen(str));
+}