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Vertical scrolling in text viewer

This commit is contained in:
Saumya Bhatnagar 2018-05-29 00:03:14 +05:30
parent ef04c3795c
commit 848c16e8df
2 changed files with 27 additions and 12 deletions
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BIN
editor
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39
editor.c
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@ -40,12 +40,13 @@ typedef struct editorrow {
struct editorConfig {
struct termios originalTermi;
int screenrows;
int screencols;
int cursorX;
int cursorY;
int screenrows; // 1 indexed
int screencols; // 1 indexed
int cursorX; // 0 indexed
int cursorY; // 0 indexed
editorrow* erow;
int numrows;
int numrows; // 1 indexed
int rowOff; // 0 indexed
} E;
/*** struct append buffer ***/
@ -228,7 +229,8 @@ void editorOpen(char * file) {
void editorDrawRows(struct AppendBuffer* ab) {
for (int i = 0 ; i < E.screenrows ; i++) {
if (i >= E.numrows) {
int fileRow = i + E.rowOff;
if (fileRow >= E.numrows) {
if (E.numrows == 0 && i == E.screenrows / 2) {
char welcome[80];
@ -249,11 +251,11 @@ void editorDrawRows(struct AppendBuffer* ab) {
abAppend(ab, "~", 1);
}
} else {
int len = E.erow[i].length;
int len = E.erow[fileRow].length;
if (len > E.screencols) {
len = E.screencols;
}
abAppend(ab, E.erow[i].text, len);
abAppend(ab, E.erow[fileRow].text, len);
}
abAppend(ab, "\x1b[K", 3); // clear rest of current line
@ -263,7 +265,19 @@ void editorDrawRows(struct AppendBuffer* ab) {
}
}
void editorScroll() {
if (E.cursorY < E.rowOff) {
E.rowOff = E.cursorY;
}
if (E.cursorY >= E.rowOff + E.screenrows) {
E.rowOff = E.cursorY - E.screenrows + 1;
}
}
void editorRefreshTerminal() {
editorScroll();
struct AppendBuffer ab = APPEND_BUFFER_INIT;
abAppend(&ab, "\x1b[?25l", 6); // hide cursor
@ -272,7 +286,7 @@ void editorRefreshTerminal() {
editorDrawRows(&ab);
char buf[32];
snprintf(buf, sizeof(buf), "\x1b[%d;%dH", E.cursorY + 1, E.cursorX + 1); // cursorX and cursorY are 0 indexed
snprintf(buf, sizeof(buf), "\x1b[%d;%dH", E.cursorY - E.rowOff + 1, E.cursorX + 1); // cursorX and cursorY are 0 indexed
abAppend(&ab, buf, strlen(buf));
abAppend(&ab, "\x1b[?25h", 6); // show cursor
@ -291,9 +305,9 @@ void editorMoveCursor(int c) {
}
break;
case ARROW_DOWN:
if (E.cursorY != E.screenrows - 1) {
E.cursorY++;
}
if (E.cursorY < E.numrows) { // allow scroll till end of file
E.cursorY++;
}
break;
case ARROW_RIGHT:
if (E.cursorX != E.screencols - 1) {
@ -347,6 +361,7 @@ void initEditor() {
E.cursorY = 0;
E.numrows = 0;
E.erow = NULL;
E.rowOff = 0;
if (getWindowSize(&E.screenrows, &E.screencols) == -1) {
die("getWindowSize");