Merge pull request #34 from olin/adam/fix_canvasbounds

fix writing canvas past bounds

src/canvas.c

@@ -4,6 +4,7 @@
  * TODO: assert get/set positions are within canvas sizes?
  */
 #include "canvas.h"
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -81,7 +82,11 @@ void canvas_schari(Canvas *canvas, int i, char c) {
 /* Get the character at position (x, y)
  *
  */
-char canvas_gcharyx(Canvas *canvas, int y, int x) { return canvas->rows[y][x]; }
+char canvas_gcharyx(Canvas *canvas, int y, int x) {
+  assert(x <= canvas->num_cols);
+  assert(y <= canvas->num_rows);
+  return canvas->rows[y][x];
+}
 
 /* Get the character at index i
  *

src/cursor.c

@@ -23,7 +23,11 @@ void cursor_move_up(Cursor *cursor, View *view) {
 }
 
 void cursor_move_down(Cursor *cursor, View *view) {
-  if (cursor->y == view_max_y) {
+  if (cursor->y + 1 >= view->canvas->num_rows - view->y) {
+    cursor->y = view->canvas->num_rows - view->y - 1;
+    return;
+  }
+  if (cursor->y + 1 >= view_max_y) {
     view_move_down(view);
     return;
   }
@@ -39,7 +43,11 @@ void cursor_move_left(Cursor *cursor, View *view) {
 }
 
 void cursor_move_right(Cursor *cursor, View *view) {
-  if (cursor->x == view_max_x) {
+  if (cursor->x >= view->canvas->num_cols - view->x - 1) {
+    cursor->x = view->canvas->num_cols - view->x - 1;
+    return;
+  }
+  if (cursor->x + 1 >= view_max_x) {
     view_move_right(view);
     return;
   }

src/frontend.c

@@ -146,12 +146,34 @@ void front_setcharcursor(char ch) {
 }
 
 void redraw_canvas_win() {
-  for (int x = 0; x < view_max_x; x++) {
-    for (int y = 0; y < view_max_y; y++) {
+  // find max ranges to draw canvas
+  int max_x = view_max_x;
+  int max_y = view_max_y;
+
+  if (max_x >= view->canvas->num_cols - view->x)
+    (max_x = view->canvas->num_cols - view->x);
+  if (max_y >= view->canvas->num_rows - view->y)
+    (max_y = view->canvas->num_rows - view->y);
+
+  // draw canvas onto window
+  for (int x = 0; x < max_x; x++) {
+    for (int y = 0; y < max_y; y++) {
       mvwaddch(canvas_win, y + 1, x + 1,
                canvas_gcharyx(view->canvas, y + view->y, x + view->x));
     }
   }
+
+  // draw fill in rest of window
+  for (int x = max_x; x < view_max_x; x++) {
+    for (int y = 0; y < view_max_y; y++) {
+      mvwaddch(canvas_win, y + 1, x + 1, 'X');
+    }
+  }
+  for (int y = max_y; y < view_max_y; y++) {
+    for (int x = 0; x < view_max_x; x++) {
+      mvwaddch(canvas_win, y + 1, x + 1, 'X');
+    }
+  }
 }
 
 void refresh_screen() {

src/view.c

@@ -23,7 +23,7 @@ void view_move_up(View *view) {
 }
 
 void view_move_down(View *view) {
-  if (view->y - view_max_y == view->canvas->num_rows) {
+  if (view->y + view_max_y > view->canvas->num_rows) {
     return;
   }
   view->y++;
@@ -37,7 +37,7 @@ void view_move_left(View *view) {
 }
 
 void view_move_right(View *view) {
-  if (view->x + view_max_x == view->canvas->num_cols) {
+  if (view->x + view_max_x > view->canvas->num_cols) {
     return;
   }
   view->x++;

src/view.h

@@ -6,8 +6,8 @@
 #include "canvas.h"
 
 #define STATUS_HEIGHT 2  // not including borders
-#define view_max_x (COLS - 3)
-#define view_max_y (LINES - 4 - STATUS_HEIGHT)
+#define view_max_x (COLS - 2)
+#define view_max_y (LINES - 3 - STATUS_HEIGHT)
 
 typedef struct {
   int x, y;